Professor Alex MacGregor Mr Peter Howard (Chairman) Mr ......Professor Paul Dieppe Dr Linda Hunt Dr...

201310th Annual Report

ISSN 2054-183X (Online)

HIPS

KNEES

ANKLES

ELBOWS

SHOULDERS

PROMs

National Joint Registry for England, Wales and Northern IrelandSurgical data to 31 December 2012

Prepared by

The NJR Editorial Board

NJRSC MembersMr Martyn Porter (Chairman)Mick BorroffProfessor Paul GreggProfessor Alex MacGregorMr Keith Tucker

NJR RCC Network RepresentativesMr Peter Howard (Chairman)Mr Colin EslerMr Alun JohnMr Matthew Porteous

Orthopaedic SpecialistsProfessor Andy CarrMr Andy Goldberg

NJR Research FellowsMr Jeya Palan

Healthcare Quality Improvement PartnershipNJR Management Team and NJR CommunicationsRebecca BeaumontJames ThorntonMelissa WrightElaine Young

Northgate Information Solutions (UK) LtdNJR Centre, IT and data managementOlivia ForsythAnita MistryDr Claire NewellDr Martin PickfordMartin RoyallMike Swanson

University of BristolNJR Statistical support, analysis and research teamProfessor Yoav Ben ShlomoProfessor Ashley BlomDr Emma ClarkProfessor Paul DieppeDr Linda HuntDr Michèle SmithProfessor Jonathan TobiasKelly Vernon

Pad Creative Ltd (design and production)

This document is available in PDF format for download from the NJR website at www.njrcentre.org.uk

This document is available in PDF format for download from the NJR website at www.njrcentre.org.uk

National Joint Registry for England, Wales and Northern Ireland | 10th Annual Report

3www.njrcentre.org.uk

Contents

Chairman’s introduction 10

Foreword from the Chairman of the Editorial Board 12

Executive summary 13

Part 1: Annual progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Part 2: Clinical activity 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Part 3: Outcomes after joint replacement 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Part 1 Annual progress 23

1.1 Introduction 23

1.1.1 The National Joint Registry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241.1.2 Management and funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241.1.3 Content of the 10th Annual Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

1.2 Data completeness and quality 26

1.2.1 Key indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .271.2.2 Operation totals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

1.3 Work of the NJR Steering Committee and its Sub-committees 33

1.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341.3.2 NJR Steering Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 1.3.3 NJR Editorial Board - Mr Martyn Porter, Chairman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .351.3.4 Implant Performance Sub-committee - Mr Keith Tucker, Chairman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361.3.5 Surgeon Outliers Sub-committee - Professor Paul Gregg, Chairman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361.3.6 NJR Research Sub-committee - Professor Alex MacGregor, Chairman . . . . . . . . . . . . . . . . . . . . . . . . . . . . .381.3.7 NJR Data Quality Group - Professor Paul Gregg, Chairman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .391.3.8 NJR Regional Clinical Coordinators’ (RCC) Network - Mr Peter Howard, Chairman . . . . . . . . . . . . . . . . . . . .40

1.4 Highlights 41

1.4.1 Geographic extension of the NJR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421.4.2 Extension of the NJR: Elbows and shoulders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421.4.3 Beyond Compliance: ‘Protecting Patients, Supporting Innovation’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421.4.4 Publication of consultant-level data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441.4.5 Patient-focused initiatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441.4.6 NJR Feedback Services: Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441.4.7 Proposed changes to the Minimum Dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451.4.8 Price Benchmarking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451.4.9 International developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .461.4.10 Patient Reported Outcomes Measures (PROMs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .461.4.11 NJR Fellowships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47 1.4.12 Orthopaedic Data Evaluation Panel (ODEP) overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

1.5 Finance 48

1.5.1 Income and expenditure 2012/13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Appendix 1 NJR Steering Committee 2012/13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

4 www.njrcentre.org.uk

Appendix 2 List of papers, publications and research requests using NJR data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52Appendix 3 Additional information on the NJR website . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Part 2 Clinical activity 2012 56

2.1 Introduction 56

2.1.1 Hospitals and treatment centres participating in the NJR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

2.2 Hip replacement procedures 2012 60

2.2.1 Primary total hip replacement procedures (THR) 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .622.2.2 Hip revision procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

2.3 Knee replacement procedures 2012 84

2.3.1 Primary knee replacement procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .862.3.2 Knee revision procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

2.4 Ankle replacement procedures 2012 103

2.4.1 Primary ankle replacement procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1042.4.2 Ankle revision procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

2.5 Elbow replacement procedures 2012 111

2.5.1 Primary elbow replacement procedures 2012 (nine months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1122.5.2 Elbow revision procedures 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1152.5.3 Elbow components used in primary and revision procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

2.6 Shoulder replacement procedures 2012 117

2.6.1 Primary shoulder replacement procedures 2012 (nine months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1182.6.2 Shoulder components used in primary procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1212.6.3 Shoulder revision procedures 2012 (nine months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Part 3 Outcomes after joint replacement 2003 to 2012 123

3.1 Summary of data sources and linkage 123

3.2 Outcomes after primary hip replacement 126

3.2.1 Overview of primary hip surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1283.2.2 Revisions after primary hip surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1313.2.3 Revisions for different causes after primary hip surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1363.2.4 Revisions after primary hip surgery for the main stem-cup brand combinations . . . . . . . . . . . . . . . . . . . . . .1403.2.5 Revisions after primary hip surgery: Effect of head sizes for polyethylene liners . . . . . . . . . . . . . . . . . . . . . .1443.2.6 Mortality after primary hip surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1483.2.7 In-depth study: Metal-on-metal hip resurfacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1503.2.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158

3.3 Outcomes after primary knee replacement 159

3.3.1 Overview of primary knee surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1603.3.2 Revisions after primary knee surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1653.3.3 Revisions for different causes after primary knee surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169



3.3.4 Revisions after primary knee surgery by main brands for TKR and UKR . . . . . . . . . . . . . . . . . . . . . . . . . . . .1733.3.5 Mortality after primary knee surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1793.3.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181

3.4 Outcomes after primary ankle replacement 182

3.4.1 Overview of primary ankle surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1833.4.2 Revisions after primary ankle surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1843.4.3 Mortality after primary ankle surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184

3.5 PROMs outcomes 186

3.5.1 Background to Patient Reported Outcome Measures (PROMs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1873.5.2 Data linkage from PROMs to HES to NJR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1873.5.3 PROMs outcomes for primary hip replacements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1883.5.4 PROMs outcomes for primary knee replacements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1963.5.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201

Part 4 Trust-, Local Health Board- and unit-level activity and outcomes 2012 202

4.1 Introduction 202

4.2 Unit outlier analysis methodology 204

Trust-, Local Health Board- and unit-level data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206

Part 1 tablesTable 1.1 Total joint replacement procedures entered into the NJR, 2008/09 to 2012/13, recorded by country in which the procedure took place. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Table 1.2 Total joint replacement procedures entered into the NJR, 2008/09 to 2012/13, recorded by procedure type 30Table 1.3 Proportion of reported procedures by type of provider, 2008/09 to 2012/13. . . . . . . . . . . . . . . . . . . . . . . . .31

Part 1 figuresFigure 1.1 Compliance, Consent, and Linkability Rates from 2003 to 2013. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Figure 1.2 Beyond Compliance data flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Part 2 tablesTable 2.1 Total number of hospitals and treatment centres in England and Wales able to participate in the NJR and the proportion actually participating in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58Table 2.2 Number of participating hospitals, according to number of procedures performed during 2012 . . . . . . . . . . .58Table 2.3 Procedure details, according to type of provider for hip procedures in 2012. . . . . . . . . . . . . . . . . . . . . . . . . .61Table 2.4 Patient characteristics for primary hip replacement procedures in 2012, according to

procedure type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64Table 2.5 Age and gender for primary hip replacement patients in 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Table 2.6 Indications for hip primary procedure based on age groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Table 2.7 Surgical technique for primary hip replacement patients in 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71


Table 2.8 Thromboprophylaxis regime for primary hip replacement patients, prescribed at time of operation . . . . . . . . . .73Table 2.9 Reported untoward intra-operative events for primary hip replacement patients in 2012,

according to procedure type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73Table 2.10 Patient characteristics for hip revision procedures in 2012, according to procedure type . . . . . . . . . . . . . . . .81Table 2.11 Indication for surgery for hip revision procedures 2008 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82Table 2.12 Components removed during hip revision procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82Table 2.13 Components used during single-stage hip revision procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83Table 2.14 Procedure details, according to type of provider for knee procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . .85Table 2.15 Patient characteristics for primary knee replacement procedures in 2012, according to procedure type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87Table 2.16 Age and gender for primary knee replacement patients in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91Table 2.17 Characteristics of surgical practice for primary knee replacement procedures in 2012, according to procedure type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95Table 2.18 Thromboprophylaxis regime for primary knee replacement patients, prescribed at time of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97Table 2.19 Reported untoward intra-operative events for primary knee replacement patients in 2012, according to procedure type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98Table 2.20 Patient characteristics for knee revision procedures in 2012, according to procedure type . . . . . . . . . . . . .102Table 2.21 Patient characteristics for primary ankle replacement procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . .105Table 2.22 Age and gender for primary ankle replacement patients in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106Table 2.23 Characteristics of surgical practice for primary ankle replacement procedures in 2012. . . . . . . . . . . . . . . . .107 Table 2.24 Thromboprophylaxis regime for primary ankle replacement patients, prescribed at time of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108Table 2.25 Reported untoward intra-operative events for primary ankle replacement patients in 2012 . . . . . . . . . . . . . .108Table 2.26 Details for ankle revision procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109 Table 2.27 Patient characteristics for ankle revision procedures in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110Table 2.28 Details for replacement primary elbow procedures in 2012 (nine months) . . . . . . . . . . . . . . . . . . . . . . . . . .112Table 2.29 Patient characteristics of primary elbow replacement procedures in 2012 (nine months) . . . . . . . . . . . . . . .113Table 2.30 Characteristics of surgical practice for primary elbow replacement procedures in 2012 (nine months). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114Table 2.31 Thromboprophylaxis regime for primary elbow replacement patients, prescribed at time of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 Table 2.32 Details for elbow revision procedures in 2012 (nine months). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116Table 2.33 Details for primary shoulder procedures in 2012 (nine months).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118Table 2.34 Patient characteristics for primary shoulder procedures in 2012 (nine months). . . . . . . . . . . . . . . . . . . . . . .119 Table 2.35 Characteristics of surgical practice for primary shoulder replacement procedures in 2012 (nine months) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 Table 2.36 Thromboprophylaxis regime for primary shoulder replacement patients, prescribed at time of operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 Table 2.37 Details for shoulder revision procedures in 2012 (nine months). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Part 2 figuresFigure 2.1 Percentage of participating hospitals by number of procedures per annum, 2004 to 2012 . . . . . . . . . . . . .59Figure 2.2 Primary hip procedures by type of provider 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62Figure 2.3 Type of primary hip replacement procedures undertaken between 2005 and 2012. . . . . . . . . . . . . . . . . . . . .63Figure 2.4 Age and gender for primary hip replacement patients in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Figure 2.5 Age for primary hip replacement patients between 2003 and 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68Figure 2.6 ASA grades for primary hip replacement patients between 2003 and 2012 . . . . . . . . . . . . . . . . . . . . . . . . . .69Figure 2.7 BMI for primary hip replacement patients between 2004 and 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70Figure 2.8 Bone cement types for primary hip replacement procedures undertaken between 2004 and 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72



Figure 2.9 Top five cemented hip stem brands, trends 2003 to 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75Figure 2.10 Top five cemented hip cup brands, trends 2003 to 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75Figure 2.11 Top five cementless hip stem brands, trends 2003 to 2012.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76Figure 2.12 Top five cementless hip cup brands, trends 2003 to 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77Figure 2.13 Top five resurfacing head brands, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78Figure 2.14 Femoral head size, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79Figure 2.15 Hip articulation, trends 2003 to 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79Figure 2.16 Primary knee procedures by type of provider 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86Figure 2.17 Type of primary knee replacement procedures undertaken between 2006 and 2012. . . . . . . . . . . . . . . . . . .88Figure 2.18 Implant constraint for bicondylar primary knee replacement procedures between 2006 and 2012 . . . . . . . . . 89Figure 2.19 Bearing type for unicondylar implant used in primary knee replacement procedures undertaken between 2006 and 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90Figure 2.20 Age and gender for primary knee replacement patients in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92Figure 2.21 ASA grades for primary knee replacement patients between 2003 and 2012 . . . . . . . . . . . . . . . . . . . . . . . . .93Figure 2.22 BMI for primary knee replacement patients between 2004 and 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94Figure 2.23 Bone cement types for primary knee replacement procedures undertaken between 2003 and 2012 . . . . .96Figure 2.24 Top five total condylar knee brands, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98Figure 2.25 Top five unicondylar knee brands, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99Figure 2.26 Top five patello-femoral knee brands, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100Figure 2.27 Top five fixed hinged knee brands, trends 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Part 3 tablesTable 3.1 Summary description of datasets used for survivorship analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124Table 3.2 Composition of person-level datasets for survivorship analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125Table 3.3 Numbers (%) of primary hip replacements by fixation and, within each fixation sub-group, by bearing surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128Table 3.4 Percentage of primary hip replacements performed each year by type of hip fixation and constraint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129Table 3.5 Distribution of consultant surgeon and unit caseload for each fixation type . . . . . . . . . . . . . . . . . . . . . . . . .130Table 3.6 Age (in years) at primary hip replacement, by fixation and main bearing surface . . . . . . . . . . . . . . . . . . . . . .131Table 3.7 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI), at different times after the primary operation, for each fixation/bearing surface sub-group . . . . . . . . . . . . . .132Table 3.8 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded reason for first hip revision. Rates shown are for all revised cases and by fixation and bearing surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137Table 3.9 Revision rates, expressed as numbers per 1,000 patient-years, for any reason, according to time interval from primary operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139Table 3.10 Revision rates (95% CI), expressed as numbers per 1,000 patient-years, for each reason, by time interval from primary operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139Table 3.11 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) at different times after the primary operation, for cup-stem brand combinations with large group sizes (>2,500 or >1,000 in the case of resurfacings) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141Table 3.12 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) at different times after the primary operation for cup-stem brand combinations with large group sizes (>10,000) with further subdivision by main bearing surface (provided the sub-group size >1,000). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143Table 3.13 Kaplan-Meier estimates of the cumulative percentage mortality (95% CI), at different times after primary hip operation, for all cases and by age/gender. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149Table L1 Description of comparison groups: number of cases (percentage of total).. . . . . . . . . . . . . . . . . . . . . . . . . .154Table L2 Predicted revision rates for 55-year-old males by prosthesis and head size (95% CI) . . . . . . . . . . . . . . . . . .155


Table L3 Predicted revision rates for 55-year-old females by prosthesis and head size (95% CI). . . . . . . . . . . . . . . . .155Table L4 Comparison of most commonly used brands; predicted revision rates for 55-year-old patients (95% CI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156Table L5 Reasons for revision (95% CI), expressed as incidence per 1,000 patient-years, by articulation and fixation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157Table 3.14 Numbers and percentages of primary knee replacements by fixation method and bearing type . . . . . . . . . .161 Table 3.15 Percentage of primary knee replacements performed each year by method of fixation and, within each fixation group, by bearing type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162Table 3.16 Distribution of consultant surgeon and unit caseload for each fixation type . . . . . . . . . . . . . . . . . . . . . . . . .163Table 3.17 Age (in years) at primary operation for different types of knee replacement; by fixation and bearing type . . .164Table 3.18 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) at specified

times after primary knee replacement, by fixation and bearing type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .166Table 3.19 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded

reason for first knee revision. Rates shown are for all revised cases and by fixation type . . . . . . . . . . . . . . .170Table 3.20 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded

reason for first knee revision. Rates shown are for each fixation/bearing surface sub-group . . . . . . . . . . . . .171Table 3.21 Kaplan-Meier estimated cumulative percentage probability of first revision (95% CI) of a primary total knee

replacement by main type of implant brand at the indicated number of years after primary operation) . . . . .174Table 3.22 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) of a

primary unicompartmental knee replacement by main type of implant brand at the indicated number of years after primary operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175

Table 3.23 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) of a total knee replacement at the indicated number of years after primary operation, by main implant brands and type of fixation and constraint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176

Table 3.24 Age and gender distribution of patients undergoing all types of primary knee replacement operations for the period 2003 to 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

Table 3.25 Kaplan-Meier estimated cumulative percentage probability (95% CI) of a patient dying at the indicated number of years after a primary knee joint replacement operation (i) by age group and gender and (ii) for all patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Table 3.26 Number of primary ankle operations by year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183Table 3.27 Number of primary ankles by ankle brand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183Table 3.28 Reasons for ankle revision (not mutually exclusive) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184Table 3.29 Overall outcomes after primary hip surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .189Table 3.30 Bias in Q2 completion of EQ-5D Index, EQ-5D Health Scale (VAS), Oxford Hip Score . . . . . . . . . . . . . . . . .190Table 3.31 Changes in EQ-5D Index for hip primaries with index scores at both time points . . . . . . . . . . . . . . . . . . . . .190Table 3.32 Changes in EQ-5D Health Scale Score (VAS) for hip primaries with scores at both time points . . . . . . . . . .192Table 3.33 Changes in Oxford Hip Score for hip primaries with scores at both time points . . . . . . . . . . . . . . . . . . . . . .193Table 3.34 Overall outcomes after primary knee surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .196Table 3.35 Bias in Q2 completion of EQ-5D Index, EQ-5D Health Scale (VAS), Oxford Knee Score . . . . . . . . . . . . . . . .197Table 3.36 Changes in EQ-5D Index for knee primaries with index scores at both time points . . . . . . . . . . . . . . . . . . . .198Table 3.37 Changes in EQ-5D Health Scale score (VAS) for knee primaries with scores at both time points . . . . . . . . .198Table 3.38 Changes in Oxford Knee Score for knee primaries with scores at both time points . . . . . . . . . . . . . . . . . . .198

Part 3 figuresFigure 3.1 Patients with hip, knee and ankle primary operations within the survivorship data sets . . . . . . . . . . . . . . . . .125Figure 3.2 Comparison of cumulative hazard of first revision for cemented hips with different bearing

surfaces (with 95% CI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133Figure 3.3 Comparison of cumulative hazard of first hip revision for uncemented hips with different

bearing surfaces (with 95% CI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134



Figure 3.4 Comparison of cumulative hazard of a first hip revision for hybrid (not including reverse hybrid) hips with different bearing surfaces (with 95% CI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

Figure 3.5 (i) Comparison of the cumulative hazard for revision for different head sizes for metal-on-polyethylene monobloc cup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145

Figure 3.5 (ii) Comparison of the cumulative hazard for revision for different head sizes for metal-on-polyethylene with metal shell/polyethylene liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146

Figure 3.5 (iii) Comparison of the cumulative hazard for revision for different head sizes for ceramic-on-polyethylene with polyethylene monobloc cup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147

Figure 3.5 (iv) Comparison of the cumulative hazard for revision for different head sizes for ceramic-on-polyethylene with metal shell/polyethylene liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148

Figure L1 Cumulative hazard of revision after resurfacing by gender (with 95% CI). . . . . . . . . . . . . . . . . . . . . . . . . . . .152Figure L2 Estimated cumulative incidence of revision for 55-year-old male by prosthesis type . . . . . . . . . . . . . . . . . . .153Figure L3 Estimated cumulative incidence of revision for 55-year-old female by prosthesis type . . . . . . . . . . . . . . . . . .153Figure 3.6 Cumulative hazard (x100) of a first revision for different types of primary knee replacement at

increasing years after the primary surgery (with 95% CI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168Figure 3.7 Comparison of the cumulative hazard (x100) of a knee prosthesis first revision for different

bearing types at increasing years after the primary surgery when the primary arthroplasty method of fixation was cemented only (with 95% CI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

Figure 3.8 (i) Histogram to compare the distributions of the EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=80,394). At Q1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194

Figure 3.8 (ii) Histogram to compare the distributions of the EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=80,394). At Q2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194

Figure 3.9 (i) Histogram to compare the distributions of the Oxford Hip Score between Q1 and Q2 in cases with scores at both time points (n=92,133). At Q1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195

Figure 3.9 (ii) Histogram to compare the distributions of the Oxford Hip Score between Q1 and Q2 in cases with scores at both time points (n=92,133). At Q2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195

Figure 3.10 (i) Histogram to compare the distributions of EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=84,031). At Q1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199

Figure 3.10 (ii) Histogram to compare the distributions of EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=84,031). At Q2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199

Figure 3.11 (i) Histogram to compare the distributions of the Oxford Knee Score between Q1 and Q2 in cases with scores at both time points (n=93,353). At Q1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

Figure 3.11 (ii) Histogram to compare the distributions of the Oxford Knee Score between Q1 and Q2 in cases with scores at both time points (n=93,353). At Q2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

GlossaryGlossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232


It has been another busy year for the National Joint Registry (NJR), which continues to develop and mature as the world’s largest orthopaedic registry and show leadership in analysis and communication of insights we glean from our rich pool of data. Normally my ‘thanks to colleagues’ goes at the end of the Chairman’s Introduction, but given the extraordinary efforts and change we have seen this year, I want to acknowledge up-front my gratitude to the NJR Steering Committee, and in particular to note the outstanding contributions made by our Vice Chairman, Professor Paul Gregg, Mr Martyn Porter, Mr Keith Tucker, Professor Alex MacGregor and Mr Peter Howard. Without their commitment and generosity of time and spirit, much of the work of the NJR would not have been possible. I would also like to thank our partners: University of Bristol, led by Professor Ashley Blom; Northgate Information Solutions; as well as the NJR management team at the Healthcare Quality Improvement Partnership, led by Elaine Young, who receives our special thanks for her dedication and hard work.

Historically, the data collection and analysis done by the NJR has focused on hip and knee replacement, and from April 2010 ankle replacement, and has done so only for procedures done in England and Wales. In April 2012, however, we extended our data collection to include elbow and shoulder joint replacements, as well as implementing a two-year pilot study of Patient Reported Outcomes Measures for shoulders, with data collected from patients at six months post-surgery. As well as new joint types, we have also extended the NJR geographically with the inclusion of data from Northern Ireland, and are currently in discussions to incorporate data from the Isle of Man.

Given the growth and development of the NJR, we took the opportunity in this, our tenth year of operation, to step back and review our purpose and strategic aims, as well as considering how our

structure, funding model and major activities support our aims. Key developments from this review include the establishment of a new Executive Committee to handle the rapidly expanding day-to-day management of the NJR; establishment of a new Medical Advisory Committee intended to provide a forum to gather views from our medical stakeholders, in particular the medical societies; the creation of a new NJR Medical Director executive post to partially relieve the burden carried by volunteers on the Steering Committee; and, we have established a formal Patient Network to ensure that the voice of the patient is heard in all the work we do. In addition, we plan to broaden the membership of the NJR Sub-committees to include a wider representation of stakeholders than those exclusively on the NJR Steering Committee. Work is ongoing to finalise these arrangements.

In September 2012, we launched our new Annual Clinical Reports, which were circulated to Trust, Local Health Board and independent provider Chief Executives detailing a range of performance information for their hospitals. This was a major step forward in providing units with feedback on the data held for them by the NJR.

Another important initiative in which the NJR has been an integral member is the establishment of the initiative Beyond Compliance, which invites implant manufacturers on a voluntary basis to go beyond the requirements of the implant CE mark and enter a rigorous, ongoing monitoring process for newly-developed implants. The NJR supports the British Orthopaedic Association and the Medicines and Healthcare products Regulatory Agency, who are the joint leaders of this programme, by providing data and operational support. We are proud to be a part of this world-leading development.

In support of better cost-effectiveness of implant purchasing by Trusts, the NJR was commissioned by the Department of Health under the QIPP Orthopaedic

Chairman’s introductionLaurel Powers-Freeling



Procurement Group (see page 45) to look at pricing data across NHS Trusts and Local Health Boards in England and Wales; 35 units have been involved in the pilot study to date. By matching actual cost data with NJR data, a potential suite of tools will enable healthcare organisations to analyse and compare spend and usage of orthopaedic implant products. The goal is to develop a model that can be extended nationally.

NHS England recently announced through the ‘Everyone Counts’ initiative that outcome of surgery at individual consultant level would be published by the end of June 2013 for ten clinical areas, one of which is hip and knee, and which is supported by data from the NJR. At the same time, the NJR has also developed a surgeon and hospital profile system that has been used as the publication vehicle. The magnitude and complexity of this exercise for orthopaedics has relied on a huge amount of work and collaboration between the NJR and the British Orthopaedic Association, with support from the specialist societies, the British Association for Surgery of the Knee and the British Hip Society. Despite very tight deadlines, we were able to publish data on the new NJR system, which we intend to develop further in the coming year to provide surgeons and trusts with the ability to customise profiles that are made available to the public.

In June this year, the NJR hosted the 2nd Annual Congress for the International Society of Arthroplasty Registries (ISAR) in Stratford-upon-Avon, providing us with an opportunity to showcase our work and influence the development of future international cooperation. We look forward to the 3rd ISAR Congress in Boston, USA in 2014.

As we move from this year to next, the NJR has a number of new activities and plans that we believe will further support our stakeholders, including:

•Patient Implant Cards – we are undertaking a pilot study with the aim of introducing a patient implant card designed to improve online access to information for patients and also provide feedback to the NJR.

•NJR Research Fellows – due to the success of the NJR Research Fellows posts, the programme will continue, with one new Fellow now appointed

and with intentions to make a further appointment this year.

•NJR Communications – we have developed a new communications strategy for 2013/14, which has included the recent launch of NJR social media platforms, including Twitter, Facebook and our first eBulletin news service, with more innovations planned for next year.

•New Annual Report format – work is ongoing that will see NJR Annual Reporting data presented online, taking into account a stakeholder survey of preferences and views.

Finally, we will be holding a special celebration of the NJR’s ‘10th Birthday’ this September with a special stakeholder reception to launch this Annual Report.

....................................................................................

While I gave my thanks to colleagues at the beginning of this introduction, I would like to close by mentioning the members of the NJRSC who will be stepping-down during 2013/14, which include Professor Paul Gregg, Mick Borroff and Professor Alex MacGregor – all of whom have been on the Steering Committee since its inception. I would also like to thank Andrew Woodhead who has served on the NJRSC since 2007, and Dean Sleigh who stepped down in March 2013 and has served on the NJRSC since 2008. Each of them can rightly take pride in having built the NJR and in the importance of the work we do today.

Yours sincerely,

Laurel Powers-Freeling

Chairman, National Joint Registry Steering Committee


Foreword from the Chairman of the Editorial BoardThe 2013/14 year marks the 10th anniversary of the National Joint Registry. By 31 March 2013 the NJR held more than 1.4 million records and nearly 200,000 submissions were received on hip, knee, ankle, shoulder, and elbow replacements. The in-year compliance is over 90% and the overall compliance, since 2003, is 86.8%. It was interesting to note that 55% of joint replacement activity carried out in independent hospitals was funded by the NHS.

The previous trend in terms of the uncemented fixation continues and the use of metal-on-polyethylene and ceramic-on-ceramic bearings predominate. The use of the metal-on-metal articulation has declined to very low levels. The knee replacement trends continue very much as they have done over the lifespan of the registry with the posterior cruciate retaining bicondylar cemented knee being the procedure of choice. Despite higher observed revision probability with the unicondylar knees these have still maintained about 8% of the market.

An important change this year in Part Three of the report has been the use of the Kaplan-Meier survivorship estimates for all information in the tables instead of the Nelson-Aalen cumulative hazard used previously, although the latter technique has been used for the graphs. The details of this are explained in Part Three itself. It is also important to note that the data has not been fully risk adjusted. Instead it has been presented according to a combination of fixation attributes and in the larger groups also with different bearing attributes as we did last year. Instead of considering survival of a single component, both the stem and cup brand have been considered together and in the larger groups further broken down in relation to the bearing used within the brand companies. This allows a more realistic view on the effect of the ‘whole’ hip replacement. However, as the data has not been fully risk adjusted care needs to be taken interpreting the results and, as always, I would recommend looking at the upper and lower confidence intervals around the mean to ascertain whether any differences are likely to be statistically significant.

For the first time Patient Reported Outcome Measures are reported. This represents a major step forward looking at other factors apart from revision which may affect the outcome. It is still relatively early days both in terms of understanding how this data should be statistically analysed and how the findings should be incorporated. With such a large database the NJR is clearly having a larger influence on the evidence base. However, it will probably take another ten years before the full effects and benefits of bearing performance are fully appreciated.

The availability of new materials and a better understanding of the biomechanics of joints have resulted in many new innovations being available to orthopaedic surgeons. An important role of the NJR has been to maintain a close surveillance on the early adoption of new technologies and our implant performance Scrutiny Group regularly review clinical publications and results reported by international registries. It is important that this review of other data takes place because the numbers of any new product implanted in one country are often too small for any definitive decisions on performance to be made within the first couple of years following the initial implantations.

The planning for the 11th Annual Report is already underway and I would like to point out that the format of next year’s report is likely to be significantly different. We are intending to concentrate on providing online and interactive report features. The traditional printed report will be a much briefer summary and in this context the 10th Annual Report is likely to be last of the larger report formats.

Once again I would like to thank everybody who has contributed to the registry, not least to the patients for allowing their data to be recorded and to all surgeons for entering their data in to the NJR.

Martyn Porter

Chairman, Editorial Board

Executivesummary


Part 1: Annual progress

The 10th Annual Report of the National Joint Registry for England, Wales and Northern Ireland is the formal public report for the period 1 April 2012 to 31 March 2013 (Part One). Also included are statistics on joint replacement activity for the period 1 January to 31 December 2012 (Part Two) and survivorship and more detailed statistical analysis on hip and knee joint replacement surgery using data from 1 April 2003 to 31 December 2012 (Part Three). Part Four shows indicators for hip and knee joint replacement procedures by Trust and unit based on the 2012 calendar year.

The NJR began collecting data on hip and knee replacement operations on 1 April 2003. Data collection on ankle replacements began on 1 April 2010 and on shoulder and elbow replacements on 1 April 2012. Data collection in Northern Ireland began in February 2013. The total number of procedures recorded in the NJR exceeded 1.4 million records by 31 March 2013, with 2012/13 having the highest ever annual number of submissions at 196,403.

The NJR uses rates of compliance (case ascertainment), patient consent, and linkability (the ability to link a patient’s primary procedure to a revision procedure) as its key data quality indicators. Details of how these are calculated are included in the report. At 91%, 2012/13 saw the highest annual rate of consent recorded, whilst linkability remained constant at 96%.

The NJR Steering Committee and its sub-committees are vital to the running and development of the NJR. A key focus of the steering committee throughout the last year has been to review the NJR’s priorities and its governance and operating model, in recognition of the great increase in scope and responsibilities of the NJR since its formation in November 2002.

The report highlights the ongoing work of the Implant Performance Sub-committee, the Surgeon Outlier Sub-committee, the NJR Research Sub-committee, the

NJR Editorial Board, and the NJR Data Quality Group. The reports from the respective Chairman of the Implant Performance Sub-committee and the Surgeon Outlier Sub-committee outline how outlier analysis is undertaken and include the high level outcomes of the monitoring process for 2012/13.

The work of the NJR has continued to expand throughout 2012/13. In April 2012, details of shoulder and elbow joint replacement procedures were added to the data collection, Northern Ireland joined the NJR in February 2013, and the NJR began the next phase of its PROMs study: the follow up, at three years, of approximately 43,000 hip and knee replacement patients. The report also outlines two other major developments being supported by the NJR: Price Benchmarking and Beyond Compliance. Price Benchmarking is sponsored by the Department of Health and is currently in the second phase of its pilot. The service, when fully implemented, will provide a comparison of implant prices across NHS England and NHS Wales. Beyond Compliance is a voluntary, post-market surveillance process that goes beyond the normal, regulatory requirements for the introduction, to market, of new implants. Using a central data repository consisting of data from numerous sources, new implants can be more closely followed up with the intention of them being introduced to market in a more controlled fashion than has been possible previously.

The NJR has continued to increase its presence internationally and is a full member of both the International Society of Arthroplasty Registers (ISAR) and the International Consortium of Orthopaedic Registers (ICOR). The NJR recently hosted ISAR’s 2nd Annual Congress (June 2013).



Part Two of the NJR 10th Annual Report includes data on clinical activity – volumes and surgical technique, in relation to hip, knee and ankle procedures carried out in England and Wales between 1 January 2012 and 31 December 2012. It also includes information on elbow and shoulder prostheses between 1 April 2012 and 31 December 2012. To be included in the report all procedures must have been entered into the NJR by 28 February 2013.

During 2012 there were 413 orthopaedic units that were active and this included 240 NHS hospitals and 163 independent units. The remaining units were independent sector treatment centres. A total of 96% of units submitted at least one procedure carried out within the calendar year 2012 to the NJR. The average number of hip replacements submitted per unit was 218 and for knee replacement 235.

Just over 1% of activity in NHS hospitals is independently funded but in independent hospitals the majority of work (55%) is now funded by the NHS.

Hip replacement procedures

A total of 86,488 hip procedures were recorded on the NJR in 2012 which represented a 7.5% increase from last year. Of these 76,448 were primary and 10,040 were revision procedures. The ‘revision’ burden now stands at 12% of total hip activity compared to 11% in 2011. In terms of fixation of hip replacement in 2012 the trend was very similar to 2011 where cementless fixation predominates at 43% with a slight reduction in cemented hip replacement to 33% (compared to 36% last year) and a slight increase in the use of hybrid fixation at 20% (compared to 18% last year). The use of hip resurfacing has now fallen to 1% and large head metal-on-metal replacements to 2%. Patient characteristics have remained fairly constant with an average age of 68.7 years and a predominance of female patients (60%).

The proportion of patients within age ranges has remained virtually the same in the 10 years that the NJR has been recording data with about one third of patients being in the age range 70 to 79 and just over 1% being less than 40 years at the time of surgery. The average body mass index (BMI) increased very slightly to 28.7 compared to 28.6 in 2011.

The ASA distribution is identical to last year with only 15% being ASA grade 1 and the majority of patients being ASA grade 2. However, there were important differences in patients ASA grades between those treated within NHS hospitals compared to independent hospitals. For example, 21% of patients treated in NHS hospitals had an ASA grade 3 compared to just 7% in independent hospitals and patients with ASA grade 1 (fittest patients) were just 11% in the NHS and almost double (21%) in independent hospitals. These data would suggest that a much fitter cohort of patients are treated in independent hospitals which is important when comparing outcomes between these two sectors.

As previously noted, both the age and gender of the patient have strong associations with the type of replacement carried out. For example, in female patients less than 50 years of age about 68% were cementless replacements compared to just 21% in the age range between 80 and 89.

The most common diagnosis was osteoarthritis but again the age of the patient had a strong influence on the diagnosis and in young patients, as expected, there was a much higher incidence of patients with a diagnosis of avascular necrosis and hip dysplasia compared to the more elderly cohort of patients.

The surgical techniques were very similar to those recorded in 2011, the lateral position being used in 93% of cases and a slight increase in the use of the posterior approach to 61% compared to 59% last year.

Part 2: Clinical activity 2012


Minimally-invasive surgery (MIS) was recorded as being used in 5% and image-guided surgery was used very infrequently in just 0.3% of cases.

In terms of thromboprophylaxis a multi-modal regime was commonly used with low molecular weight Heparin being used in 73% of cases and TED stockings in 66%.

In 2012, 146 brands of femoral stem, 101 brands of acetabular cup and eight brands of resurfacing cup were used. Using the Orthopaedic Data Evaluation Panel (ODEP) ratings only about half of all femoral and acetabular components had an ODEP rating in primary arthroplasty. However, the components used with the full 10A benchmark rating was 88% for cemented stems, 69% for cementless stems, 34% in cemented cups, 3% for cementless cups and 63% for resurfacing cups.

In terms of brand choice the Exeter V40 stem was most commonly used in 66% of cemented hips and the contemporary cup used in about 34% of cases. A rapid rise of the Exeter rim fit cup introduced in 2010 was observed. This now has a market share of about 12%, obtained in a very short time period.

In regard to cementless fixation the Corail stem has maintained its position as the most commonly used stem in about 46% of cases and the Pinnacle socket in 33%. The use of resurfacing in 2012 fell to 1,075 compared to 1,883 in 2011. The Birmingham hip resurfacing is the most popular implant used.

The preference to use large diameter heads to improve stability continues with about 30% of femoral heads being 36 millimetres, another 30% being 32 millimetres and nearly 40% being 28 millimetres. Head sizes over 36 millimetres are now only rarely used as is the smaller head size of 22.25 millimetres.

In terms of bearing combinations the use of metal-on-polyethylene (this includes standard and cross link polyethylene) remains the most common selection in just under 60% of cases followed by a ceramic-on-ceramic articulation. There is a slight increase in the use of ceramic-on-polyethylene and the use of metal-on-metal articulation continues to fall.

There were 10,040 hip revision procedures recorded in 2012 of which 88% were single-stage revisions. Aseptic loosening was the most commonly recorded indication for revision surgery in 40%, infection in 12% that increased to 13% for adverse soft tissue reactions (1,330 cases). Patients undergoing revision surgery are less fit than patients undergoing primary replacement with one third of patients being graded as ASA grade 3 for staged revision surgery. NHS hospitals incurred most of the burden of revision operations – 83% compared to independent hospitals 15%. This differs to the activity of primary surgery where NHS hospitals carried out 69% of primary surgery compared to 27% in the independent sector. When the revision is carried out in a single operation both the cup and stem are removed in 45% of cases, the acetabular component only in 30% and the femoral stem only in 14%. The revision components used during single-stage hip revision is approximately equal between cemented and cementless (28% versus 29%) whereas on the acetabular side cementless components are used three times more frequently (58% versus 18%) than cemented components.

Knee replacement procedures

In 2012, 90,842 knee replacement procedures were entered into the NJR representing an increase of 7.3% compared to 2011. In these procedures 84,833 were primaries and 6,009 were revision procedures. The revision burden of knee replacement is just over 6.5% which is just over half of the revision burden of hip replacements. The type of knee replacements used has remained remarkably constant over the last three to four years with 86% being cemented total knee replacements, 8% being unicondylar replacements, 3% total knee replacements not using cement and only about 1% being patello-femoral replacements.

In terms of surgical technique a medial parapatellar approach was used in 93% of procedures. MIS was used in just 2% of total knee replacements but much more frequently in unicondylar replacements (46%). The patella was resurfaced in 38% of primary cemented knee replacements but in just 7% of cementless total knee replacements. As in hip replacements thromboprophylaxis tended to be multi-modal with low molecular weight Heparin being used in 72% of cases and TED stockings in 70%. The PFC



Sigma was the most commonly used total condylar knee replacement being used in just under 37% of cases. For the unicondylar replacement there was a slight decrease in the use of the Oxford which had just over 60% of the market share.

A total of 6,009 knee revision procedures were reported in 2012 representing an increase of 17% compared to 2011. The vast majority of these (78%) were single-stage revision operations. As in hip revisions, patients undergoing revision knee replacements tended to be less fit than patients undergoing primary replacement and 85% of the revisions were carried out within NHS hospitals compared to 69% of primaries indicating that it is the NHS that picks up a disproportionate amount of the knee revision burden. Indications for revision surgery were recorded as aseptic loosening in 32% of cases and infection in 22%.

Ankle replacement procedures

This is only the second full year of recording ankle replacements with data collection starting on 1 April 2010. The compliance has improved from 64% last year to 77%.

Of the ankle replacements recorded for the calendar year 2012 there were 590 ankle replacements including 540 primaries and 50 revisions. The majority, 86%, were funded by the NHS and the patient characteristics in terms of ASA and BMI were not dissimilar to that of patients undergoing hip and knee replacement. Unlike hip replacements male gender was recorded in 58% of cases and osteoarthritis was the most common diagnosis in 84% and inflammatory arthritis in 13%. Additional information is recorded on ankles including tibia-hindfoot alignment of 46% being in neutral position and the range of ankle dorsiflexion, 42% having dorsiflexion between five and 20 degrees and 54% having plantarflexion between five and 15 degrees.

In terms of surgical technique the anterior approach was the most common in 97% and in 11% Achilles tendon lengthening was carried out. Bone grafts were used in 15%.

For prophylaxis low molecular weight Heparin was used in 80%. 56% had TED stockings but there was

less reliance on calf or foot compression compared to hip and knee replacements.

The main implant used was the DePuy Mobility in 52% followed by the Zenith ankle replacement manufactured by Corin in 20%.

Of the 50 ankle revision procedures most, 46, were carried out on the NHS. The main indicators for revision were undiagnosed pain (36%), suspicion of infection (26%), aseptic loosening of the tibial component (18%) and aseptic loosening of the talar component (16%).

Elbow replacement procedures

This is the first year that we have reported on elbow replacement and shoulder replacement surgery with data collection starting on 1 April 2012 and therefore the reporting period is nine months rather than the full calendar year.

There were 288 elbow replacement procedures which include 214 primary and 74 revision procedures. Many of the revision procedures clearly relate to previous periods of implantation. 89% of the primaries were total replacements and 9% were radial head replacements. The indications for surgery were more variable compared to other procedures in this report with osteoarthritis only comprising 32%, inflammatory arthritis 33% and trauma or trauma sequelae comprising a further 37%. The average age of patients was 65 (female) and 67 (male). 89% were treated in the NHS.

The posterior approach was used in 89% of cases and humeral bone graft in 16%. 59% had low molecular weight Heparin and 54% TED stockings.

Of the 74 revision procedures, 50% were carried out for aseptic loosening, 18% for infection, 12% for instability and 19% for peri-prosthetic fracture. The Coonrad Morrey prosthesis manufactured by Zimmer had 45% of the market share.

Shoulder replacement procedures

Shoulder replacements are again reported for nine months of the calendar year 2012 for reasons explained under the elbow section.


A total of 2,225 shoulder replacement procedures were recorded including 1,968 primaries and 257 revisions. Of the primary procedures there was quite a diverse mix of prostheses with 27% being primary total replacements, 15% hemi-arthroplasty, 6% resurfacing, 22% hemi-resurfacing and 30%, or 597, reverse prostheses. Osteoarthritis was the primary diagnosis in 61% of cases but 24% of patients were reported to have cuff tear arthropathy. The mean age of female patients (73.2 years) was greater than that of male patients (68.8 years) and 72% of patients were female.

The most common surgical approach was the Delta pectoral approach in 75%. Humeral bone graft was used in 12%. A tenotomy of the long head of biceps was carried out in 45% of patients and the rotator cuff condition was described as normal in just 43%. 57% of patients received low molecular weight Heparin.

Of the 257 revision procedures, the indications for surgery were variable; just 14% for aseptic loosening, 30% were conversion of hemi to total and 25% were revision for cuff insufficiency.



Part Three of the 10th Annual Report describes the clinical outcomes represented by survivorship data and mortality in relation to hip and knee replacements carried out in England and Wales between 1 April 2003 and 31 December 2012. This represents nearly ten years of survivorship information.

It also includes for the first time pre- and post-operative Patient Reported Outcome Measures (PROMs) collected since April 2009.

The National Joint Registry contains over 1.4 million operations but because of exclusions in relation to patient identifiers, linkage issues and other causes, the survivorship analysis was based on 539,372 primary hips with 11,780 linked first revisions, 589,028 primary knees and 11,666 linked first revisions and 1,417 ankles with 9 linked first revisions.

This year we have used Kaplan-Meier estimates and the cumulative chance of revision of first implant or death of patient but we have continued to use Nelson-Aalen cumulative hazard estimates for the graphs. Details of these statistical methodologies are explained in the appendices to this report.

Hip replacement procedures

The data describes the number of patients and percentages of implant fixation combinations with those of bearing surface combinations and illustrates the change of usage of both fixation and bearing between 2003 and 2012 inclusive. This shows interesting changes over the years, for example in 2003, 55.3% of all hip replacements were metal-on-polyethylene cemented replacements but in 2012 this has nearly halved to just 28.6%. In comparison the metal-on-polyethylene uncemented hip replacement was used in just 6.2% of cases in 2003 and this has almost trebled to 17.8% in 2012. The ceramic-on-ceramic uncemented hip replacement has also shown a rapid increase from just 3.5% in 2003 to a nearly six fold increase to 19.2% in 2012. The use of metal-on-

metal resurfacing peaked at 10.8% in 2006 and was just 1.3% in 2012.

The unadjusted Kaplan-Meier survivorship estimates are presented for each of these fixation and bearing combinations within the report. The lowest revision rate at nine years was that of the ceramic-on-polyethylene cemented hip replacement with a cumulative probability of first revision of just 1.84% (95% CI of 1.51% to 2.24%). Considering all bearing combinations overall, cemented hip replacement had a cumulative percentage revision probability of 2.71% (2.57% to 2.87%) at nine years after operation compared to 6.71% (6.40% to 7.05%) with uncemented fixation, once again the ceramic-on-polyethylene bearing had the lowest revision rate within the uncemented fixation group. The hybrid and reversed hybrid groups were somewhere between the cemented and uncemented fixation groups with a nine-year revision probability of 3.42% (3.10% to 3.76%) for hybrids and 3.37% (2.52% to 4.33%) for reverse hybrids.

When a metal-on-metal articulation was used with cementless fixation the nine-year revision probability of a first implant was 17.66% (15.93% to 19.56%). This was similar to the metal-on-metal resurfacing which had a revision probability of 12.31% (11.62% to 13.04%) at nine years.

The number of revisions by indication for revision are presented per 1,000 patient-years for fixation and bearing, for example for dislocation/subluxation there were 0.89 (0.83-0.96) revisions per 1,000 patient-years with cemented fixation but this was just 0.43 (0.34 to 0.53) when metal-on-metal resurfacing was used. Soft tissue reaction was recorded in 0.02 (0.01 to 0.05) of cemented metal-on-polyethylene replacements compared to 3.55 (3.05 to 4.13) of metal-on-metal resurfacing and 5.50 (4.90 to 6.20) of metal-on-metal uncemented replacement. The revision rates following surgery were not linear, for example the revision rate for 1,000 patient-years within one

Part 3: Outcomes after joint replacement 2003 to 2012


year of surgery was 7.71 (7.47 to 7.96) but this fell to 4.60 (4.45 to 4.75) between one and three years from primary operation.

The Kaplan-Meier cumulative probabilities of a first prosthesis revision are listed for a large number of cup stem brand combinations. For example, the cemented Exeter V40 – Elite Plus Ogee socket combination had a revision probability after nine years of 1.57% (1.30% to 1.90%) and the uncemented Furlong HAC stem – CSF had a cumulative probability of first revision nine years after surgery of 2.97% (2.59% to 3.40%).

For the cup stem brand combinations with over 10,000 cases the brand combinations were further broken down to examine the effect of bearing surface, for example, the Exeter V40 Contemporary metal-on-polyethylene bearing had a nine-year first revision probability of 2.33% (2.00% to 2.70%) but when the ceramic-on-polyethylene bearing was used with the same brands the cumulative chance of revision after nine years was 1.87% (1.20% to 2.90%). The Corail Pinnacle group was interesting as the effect of the bearing could be clearly seen. Eight years post surgery, the chance of first revision was 5.89% (5.11% to 6.79%). However, within this group with a Corail Pinnacle combination, if a ceramic-on-polyethylene bearing was used the probability of first revision was just 1.84% (1.34% to 2.51%) whereas when a metal-on-metal bearing was used the cumulative probability was 11.10% (9.06% to 13.58%).

With resurfacing clear differences could be seen between the brands. Eight years after the primary surgery, the probability of first revision with the Birmingham hip (BHR) resurfacing was 6.61% (6.12% to 7.13%) compared to 29.69% (27.03% to 32.55%) when the ASR was used.

Cumulative revision probabilities were also considered as a function of head size and head material when used with a polyethylene liner. This allowed multiple comparisons, for example, when a metal head was used with a polyethylene liner contained in a metal shell, the revision probabilities were higher for the larger 44 millimetre head compared to the 28 millimetre head.

The cumulative probability of death at different times after the primary surgery is presented broken down by gender and age group. The risk of death within 90 days of surgery overall was 0.51% (0.50% to 0.53%). In female patients this ranged from 0.21% (0.16% to 0.27%) in patients less than 55 years to 1.31% (1.22% to 1.41%) in patients 80 years and above and at nine years after primary surgery the cumulative probability of death in male patients less than 55 years was 4.39% (3.88% to 4.96%) compared to 65.67% (63.62% to 67.72%) for patients aged 80 and above.

One of the in-depth studies, that of metal-on-metal hip resurfacing was published in The Lancet in October 2012. In this paper the effects of age, gender and femoral head size are considered and the best outcomes were observed in male patients aged 55 years with a head size of 54 millimetres where the revision rate at seven years was 2.47% (1.90% to 3.20%).

Knee replacement procedures

In comparison to hip replacements, the changes in fixation, constraint and type of knee replacement has not varied as much over the observation period 2003 to 2012. The use of cemented total replacements increased from 81.5% in 2003 to 86.9% in 2012 and within cemented groups the unconstrained (posterior-cruciate retaining) fixed knee increased from 53.3% in 2003 to 59.8% in 2012. Despite some concerns with higher revision rates seen amongst unicondylar replacements, the use of these remains fairly static between 8% and 9% and similarly for patello-femoral replacements (which are relatively low volume), the use of these ranged from just 1.0% in 2003 to 1.3 % in 2012.

It was reassuring that the most commonly used replacement, the all cemented total replacement unconstrained and fixed, had a low cumulative probability of first revision of just 2.90% (95% CI of 2.77% to 3.04%) at nine years. The cemented mobile constrained condylar knees had a revision probability of 4.48% (2.87% to 6.96%) at nine years. With uncemented and hybrid replacements the posterior-stabilised knees had a revision probability of 6.70% (5.15% to 8.70%) at nine years. As previously noted



unicondylar knees had a high revision probability of 11.57% (10.92% to 12.26%) at nine years and the patello-femoral replacement had a revision probability of 16.11% (14.09% to 18.39%) at the same time period.

The stated reasons for revision by fixation are described as revision rates per 1,000 patient-years. The revision rate was 1.10 (1.06 to 1.15) revisions for infection and for component size mismatch 0.73 (0.70 to 0.77). There was a further breakdown of reasons for revision by fixation and degree of constraint.

The revision probabilities are described up to nine years following surgery for the main brands; compared to hip replacement there was less variation in revision probability. For example, the PFC Sigma bicondylar knee had a cumulative revision probability of 2.45% (2.30% to 2.61%) at nine years and the Genesis 2 2.43% (2.11% to 2.79%). Some knees performed less well including the Kinemax with a revision probability of 4.30% (3.81% to 4.86%) at nine years and the Rotaglide Plus which had a revision probability of 5.45% (4.19% to 7.07%). When patello-femoral joints were considered the seven-year revision probability of the Avon knee was 10.94% (9.49% to 12.60%) but for the Journey PFJ Oxinium it was 17.52% (12.98% to 23.41%). There was also variation with unicondylar knees, for example the Zimmer unicompartmental knee had a revision probability of 5.27% (4.15% to 6.69%) at nine years compared to the Preservation which had a revision probability of 17.31% (14.43% to 20.68%).

When considering the type of constraint within the brand class there was generally low variation but there were some differences, for example within the Nexgen brand the cumulative revision probability with a cemented unconstrained fixed tibial insert was 2.44% (2.03% to 2.93%) at nine years compared to 3.62% (3.20% to 4.41%) when the Nexgen posterior-stabilised fixed insert was used.

The cumulative probability of patient death at different times after knee replacement had a similar pattern to that of hip replacement. For all cases the 90-day mortality probability was 0.36% (0.34% to 0.39%). At nine years this increased to 22.27% (21.95% to 22.59%). In female patients less than 55 years the

probability of death was 3.55% (2.88% to 4.37%) at nine years compared to 51.00% (49.55% to 52.46%) in patients 80 years or older.

Ankle replacement procedures

Because of the more recent inclusion of ankles and relatively small numbers, limited data are presented on ankle replacements. There were 1,417 primary operations in a population with a median age of 67 years, 57.2% of patients were male. Nearly all the ankle replacements were cementless. The Mobility brand was used in 56.5% of cases. There were only nine revisions recorded. Mortality was relatively low following ankle surgery with a 90-day cumulative mortality of 0.14% (0.04% to 0.58%) and a two-year cumulative probability of 1.40% (0.69% to 2.83%).

Patient Reported Outcome Measures (PROMs)

For the first time the NJR reports on PROMs. PROMs data, which is part of an NHS-funded initiative, is collected separately from the NJR. This collection has only been in action since April 2009 and relates to a pre-operative questionnaire and a follow-up questionnaire about six months following surgery. Data includes EQ-5D Index, EQ-5D Health Scale and Oxford Hip/Knee scores.

The original PROMs data file had 445,134 entries but for a variety of reasons a substantial proportion of these entries could not be matched to NJR data because of data quality issues, duplication and incomplete data.

Of the 124,136 PROMs entries linked to primary hip operations in the NJR, 99.7% of questionnaires were completed pre-operatively but only 75.6% post-operatively. For hip replacement surgery 85.6% of patients described themselves as being much better compared to before the operation, 10% reported having had a wound problem, 5.8% bleeding since the operation, 7.3% recorded they had been re-admitted to hospital since the operation and 2.1% declared they had had further surgery following the original operation.

In relation to change in EQ-5D, the median change following surgery was 0.380 (IQR 0.175 to 0.694) and for the patients treated with a cemented metal-


on-polyethylene hip replacement the median change was 0.413 (0.159 to 0.694) and this compared to metal-on-metal resurfacing where the median change was 0.309 (0.165 to 0.484). However, the median pre-operative score for resurfacing was higher (0.587) for metal-on-metal compared to metal-on-polyethylene cemented (0.293).

The overall median change in EQ-5D Health Scale score (VAS) was 9 (IQR -2 to 20). This tended to be lower for all cemented where the median was 6 (-5 to 20) compared to uncemented where the median was 10 (-1 to 22).

The median change in Oxford hip score was 21 (IQR 14 to 28) for all cases and the variation between fixation types of bearings was very low.

For knee replacement surgery 70.8% of patients described themselves as being much better compared to how they were before the operation, 13.4% described having had a wound problem, 7.9% bleeding, 9.6% having been re-admitted and 3.3% having further surgery.

The median change in EQ-5D Index for all knee primaries (with scores at both time points) was 0.275 (IQR 0.069 to 0.568). The median change was lower for patello-femoral replacement (0.105). The median change in EQ-5D Healthscale score (VAS) was 3 (-7 to 15) for all cases but 0 for patello-femoral replacement (-10 to 15). The median change in Oxford knee score for all cases was 16 (9 to 22) but again was lower for patello-femoral joints at 10 (4 to 18).

1.1 Introduction

Annual progressPart 1


1.1.1 The National Joint Registry

The National Joint Registry for England, Wales and Northern Ireland has collected hip and knee joint replacement data since 2003. The NJR has recorded data on ankle replacement surgery since April 2010 and from April 2012, data on shoulder and elbow joint replacement surgery. Northern Ireland has been submitting data since February 2013. The NJR is currently the largest register of its kind in the world, with over 1.4 million recorded procedures.

The NJR’s purpose and aims are set out in its strategic plan and are summarised below:

Mission statement:‘The purpose of the National Joint Registry for England, Wales and Northern Ireland is to collect high quality and relevant data about joint replacement surgery in order to provide an early warning of issues relating to patient safety.

In a continuous drive to improve the quality of outcomes and ensure the quality and cost effectiveness of joint replacement surgery, the NJR will monitor and report on outcomes, and support and enable related research.’

Strategic goals:

1. Monitor in real time the outcomes achieved by brand of prosthesis, hospital and surgeon, and highlight where these fall below an expected performance in order to allow prompt investigation and to support follow-up action

2. Inform patients, clinicians, providers and commissioners of healthcare, regulators and implant suppliers of the outcomes achieved in joint replacement surgery

3. Evidence variations in outcome achieved across surgical practice in order to inform best practice

4. Enhance patient awareness of joint replacement outcomes to better inform patient choice and patients’ quality of experience through engagement with patients and patient organisations

5. Support evidence-based purchasing of joint replacement implants for healthcare providers to support quality and cost effectiveness

6. Support suppliers in the routine post-market surveillance of implants and provide information to clinicians, patients, hospital management and the regulatory authorities

In July 2012, the NJR Steering Committee, along with invited stakeholders, held a one-day workshop to define the key activities necessary to support those aims and their relative priorities.

1.1.2 Management and funding

The NJR is managed by the Healthcare Quality Improvement Partnership (HQIP) under a contract with NHS England as part of the delivery of the National Clinical Audit and Patient Outcomes Programme (NCAPOP). HQIP support the work of the NJR Steering Committee and all its sub-committees. The NJR Steering Committee, which met four times in 2012/13, is responsible for overseeing the strategic direction and running of the NJR. Last year its status changed from that of an advisory non-departmental public body (ANDPB) to Departmental Expert Committee. Its members are currently appointed by the Department of Health (DH) Appointments Team following a formal recruitment process and the current list of members and their declarations are listed in Appendix 1. The Steering Committee has a lay Chairman, Ms Laurel Powers-Freeling.

There are currently six sub-committees which support the work of the NJR Steering Committee:

•The Editorial Board Chairman, Mr Martyn Porter

•The Implant Performance Sub-committee Chairman, Mr Keith Tucker

•The Surgeon Outliers Sub-committee Chairman, Professor Paul Gregg

•The Research Sub-committee Chairman, Professor Alex Macgregor

•The Regional Clinical Coordinators’ (RCC) Network Chairman, Mr Peter Howard

•The Data Quality Group Chairman, Professor Paul Gregg



In early 2013, to reflect its change in status, the Steering Committee started a review of the NJR’s governance and committee structure and composition. The outcomes of the review are included in Section 1.3.2 below.

The NJR services are delivered under three separate contracts:

•The NJR Centre, managed and staffed by Northgate Information Solutions (UK) Ltd. Northgate is responsible for the management and development of the NJR’s IT infrastructure, software applications, data management and reporting services. This work is complemented by the NJR Service Desk, a team who provide day-to-day information and support to stakeholders, and the NJR Regional Coordinators (RC), an eight-strong team providing on-site support to orthopaedic units in hospitals.

•The NJR statistical support, analysis and research team, based at the University of Bristol. The team is responsible for the delivery of statistical analyses of NJR data and data from other sources, and for developing the statistical methodologies for the identification of potential outlier performance.

Their role also includes ad hoc data analyses, in addition to those included in the NJR Annual Report, that are central to the work of the Implant Performance Group and the Surgeon Outliers Sub-committee.

•NJR Communications, managed by HQIP. This is a programme of stakeholder and multi-media communication to support the delivery of the strategic plan including the publication of the Public and Patient Guide to the NJR Annual Report. The HQIP communications team also support the Editorial Board and Regional Clinical Coordinators’ Network.

Currently the NJR is funded through a levy raised on the sale of hip, knee, ankle, elbow, and shoulder implants. HQIP manages the levy payment collection and holds the NJR budget on behalf of the Steering Committee. The funding model is being reviewed and is likely to change in financial year 2013/14.

1.1.3 Content of the 10th Annual Report

The format of this report is similar to the 9th Annual Report:

•Part One is a general outline of the work of the NJR for the financial year 1 April 2012 to 31 March 2013. In addition to summary statistics relating to the NJR’s key data quality indicators, this section includes a summary of the major activities undertaken by the NJR and individual reports on the work of the sub-committees.

•Part Two is a description of joint replacement activity reported to the NJR as having been carried out in the calendar year 1 January to 31 December 2012.

•Part Three provides an analysis of survivorship of hip, knee and ankle replacement procedures carried out between 1 April 2003 and 31 December 2012. Data from the Hospital Episodes Statistics (HES) service, Patient Episode Database for Wales (PEDW), and the English Patient Reported Outcomes Measures (PROMs) programme are also included in the analysis.

•Part Four provides a series of reports about clinical activity and outcomes at both Trust and unit level.

Part 11.2 Data completeness and quality



1.2.1 Key indicators

Whilst NHS hospitals in England and Wales have always been ‘expected’ to submit data to the NJR, it has always been mandatory for independent sector units in England and Wales since the registry started. However, the Standard NHS Contract for Acute Services was amended in April 2011 (Section 12.1.2) and now states that all providers shall participate in audits relevant to the service they provide within NCAPOP, of which the NJR is part. The submission of complete data to the NJR is, therefore, now mandatory for all NHS Trusts and Foundation Trusts within England. The Welsh Government has agreed that the NJR is mandatory for all NHS Wales hospitals and the Northern Ireland Health and Social Care Board has written NJR data entry into NHS Trust contracts, this includes all NHS-funded procedures.

Performance against the three indicators of data quality (compliance, consent, and linkability) has continued to improve year on year, although the provision of continual support to orthopaedic units is required to maintain and improve performance levels. These figures are available throughout the year from NJR StatsOnline on the NJR website.

Compliance

The compliance rate is the proportion of procedure records submitted to the NJR compared with the levy returns for the number of implants sold.1 It is impossible to establish a one to one link between a single levy and the use of the implant and this comparison is subject to a number of factors, such as variation in the procurement cycle throughout the year. It is often the case that more procedures are reported than levies are collected, leading to a positive (>100%) compliance rate, followed by periods where there are more levies raised than procedures reported. For individual NHS Trusts, compliance can also be measured against data held in the Hospital Episodes Statistics (HES) service and the Patient Episode Database for Wales (PEDW) service, though there are

likely to be minor variations between the two because of coding differences. This comparison does not include privately funded procedures that take place in the independent sector in England and Wales as this data is not submitted to either HES or PEDW. The overall compliance rate from 1 April 2003 to 31 March 2013 was 86.8%.

Consent

The consent rate compares the number of records submitted where the patient has agreed to their personal data being stored on the NJR database with the number of procedures recorded on the NJR.2 It is a requirement in England, Wales, and Northern Ireland that patients ‘opt in’ to have their personal data held by the NJR. Patient details are essential for linking patient procedures in order to monitor joint replacement procedure outcomes and it follows that, without high rates of patient consent, the NJR will not achieve its goals. Patients are known to rarely decline consent, and a number of units regularly achieve 100% consent rates. Failures to record positive consent are usually due to the lack of robust processes in hospitals which ensure that the completed consent form is available to the person entering the procedure details. The consent rate for 2012/13 was 91.0%.

1 For compliance analysis only, the number of procedures excludes the following procedures: re-operations other than revision; stage 1 of a 2-stage revision; excision arthroplasty; amputation; and conversion to arthrodesis. These are excluded because they do not include the implantation of a component attracting the levy.

2 Personal information includes NHS number, surname, date of birth and postcode.

Why are there sometimes more procedures reported than levies collected, leading to compliance rates greater than 100%?

•Bulk buying of implants in one year or at different times in the year

•Not all levies collected by the implant suppliers

•Not all revision procedures use a leviable component


Figure 1.1 Compliance, Consent, and Linkability Rates from 2003 to 2013.

Source: Procedures entered into the NJR 1 April 2003 to 31 March 2013 and levy submissions to NJR by implant suppliers.

2004/052003/04 2005/06 2006/07 2007/08 2008/09 2009/10

68.3

64.3

59.6

43.4

63.3

57.2

Compliance

Consent

Linkability

81.6

74.0

69.6

80.6

81.2

78.0

95.3

84.4

91.8

91.6

87.6

94.7

114.3

87.9

95.3

2010/11

106.8

89.0

95.8

2011/12 2012/13

90.3

90.5

96.0

91.0

91.0

95.6

Financial year

%

0

120

100

80

60

40

20

Compliance Consent Linkability

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Linkability

The linkability rate compares the number of records submitted with the patient’s NHS number with the number of procedures recorded on the NJR. The NHS number is required to link all primary and revision procedures relating to a single patient.3

The ability to link all operations relating to a single patient is vital in determining clinical outcomes. Operations are linked using the patient’s NHS number.

Low rates of linkability adversely affect the ability of the NJR to monitor clinical and implant performance.

Where the NHS number is missing, tracing is attempted using the NHS Demographics Batch Service. This relies on the patient’s name, date of birth and postcode being correctly entered. The linkability rate for 2012/13 was 95.6%.

3 NJR data is submitted for NHS number tracing and the ‘linkability’ figure includes NHS numbers that were traced subsequent to the operation details being submitted to the NJR.



1.2.2 Operation totals

By 31 March 2013, 1,456,756 hip, knee, ankle, elbow, and shoulder replacement procedures had been reported to the NJR. There were 196,403 procedures submitted in 2012/13.

Table 1.1 shows the total number of hip and knee procedures recorded on the NJR in England and

Wales each year from 2008/09 to 2012/13. As for the previous five years, the number of knee replacement procedures (98,288) exceeded the number of hip replacement procedures (94,044) in 2012/13 (51% and 49% as a proportion). Table 1.1 also records ankle procedures from April 2010 and elbow and shoulder procedures from April 2012. Northern Ireland’s joint replacement data is included from February 2013.

Source: Procedures entered into the NJR 1 April 2008 to 31 March 2013.©

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Table 1.1 Total joint replacement procedures entered into the NJR, 2008/09 to 2012/13, recorded by country in which the procedure took place.

2008/09 2009/10 2010/11 2011/12 2012/13England hip 71,845 74,676 82,077 83,787 88,830

England knee 75,971 79,173 86,581 87,378 92,698

England shoulder 2,881

England elbow 345

England ankle 423 518 679

Wales hip 4,900 3,919 4,004 4,533 5,144

Wales knee 5,651 4,611 4,506 5,099 5,557

Wales shoulder 110

Wales elbow 13

Wales ankle 25 40 36

Northern Ireland hip 70

Northern Ireland knee 33

Northern Ireland shoulder 5

Northern Ireland elbow 0

Northern Ireland ankle 2

Total procedures 158,367 162,379 177,616 181,355 196,403


Operation types

Table 1.2 below shows the number of procedures reported by type from 1 April 2008 to 31 March 2013. Primary operations make up 91.5% of all procedures

reported, whilst the proportion of revisions (less shoulders and elbows) has increased by 0.6% to 9.3% from 8.7% in 2011/12.

Source: Procedures entered into the NJR 1 April 2008 to 31 March 2013.

4 Re-operation information was not collected on the first version of the Minimum Dataset (MDSv1) from 1 April 2003 to 31 March 2004. It was included on MDSv2 from 1 April 2004 and removed from MDSv3 which came into use on 1 December 2007. However, some units are continuing to use MDSv2 which is why some re-operations continue to be reported. The figures are included for completeness only.

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Table 1.2 Total joint replacement procedures entered into the NJR, 2008/09 to 2012/13, recorded by procedure type.

2008/09 2009/10 2010/11 2011/12 2012/13Hip primary 69,342 70,268 76,927 78,405 82,837

Hip revision 7,327 8,245 9,117 9,914 11,207

Hip re-operation4 76 82 37 1 0

Knee primary 77,020 78,561 85,272 86,637 91,682

Knee revision 4,514 5,147 5,766 5,840 6,606

Knee re-operation4 88 76 49 0 0

Ankle primary 418 538 650

Ankle revision 30 20 67

Shoulder primary 2,666

Shoulder revision 330

Elbow primary 267

Elbow revision 91

158,367 162,379 177,616 181,355 196,403



Procedures by provider type

There are four types of organisations in England carrying out hip, knee, ankle, elbow, and shoulder joint replacement surgery:

•NHS hospitals

•NHS treatment centres

•Independent sector hospitals

•Independent sector treatment centres (ISTCs)

There are no NHS treatment centres or ISTCs in either Wales or Northern Ireland and as the numbers for Northern Ireland only cover a six week period, they are grouped together as a provider.

Table 1.3 shows the proportion of procedures by type of provider.

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Table 1.3 Proportion of reported procedures by type of provider, 2008/09 to 2012/13.

2008/09 2009/10 2010/11 2011/12 2012/13Hips

NHS hospitals69.4% 71.6% 71.7% 70.8% 71.2%

53,231 56,272 61,707 62,570 66,952

Independent hospitals26.1% 24.4% 24.3% 25.2% 25.5%

20,040 19,164 20,881 22,256 23,947

ISTCs4.5% 4.0% 4.1% 4.0% 3.3%

3,474 3,159 3,493 3,494 3,075

Northern Ireland- - - - 0.1%

- - - - 70

All NJR 76,745 78,595 86,081 88,320 94,044

Knees

NHS hospitals70.2% 72.5% 72.2% 70.6% 70.7%

57,270 60,707 65,781 65,330 69,501

Independent hospitals24.2% 22.5% 23.1% 24.8% 25.6%

19,773 18,859 21,044 22,898 25,135

ISTCs5.6% 5.0% 4.7% 4.6% 3.7%

4,579 4,218 4,262 4,249 3,619

Northern Ireland- - - - <1%

- - - - 33

All NJR 81,622 83,784 91,087 92,477 98,288

Ankles

NHS hospitals- - 79.0% 76.0% 78.2%

- - 354 424 561

Independent hospitals- - 17.6% 19.4% 18.3%

- - 79 108 131

ISTCs- - 3.3% 4.7% 3.2%

- - 15 26 23


- - - - 2

All NJR - - 448 558 717

Continued >


Source: Procedures entered into the NJR 1 April 2008 to 31 March 2013.

Further information is available on the NJR website under ‘NJR 10th Annual Report’.

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2008/09 2009/10 2010/11 2011/12 2012/13Shoulders

NHS hospitals- - - - 82.6%

- - - - 2,476

Independent hospitals- - - - 14.7%

- - - - 439

ISTCs- - - - 2.5%

- - - - 76


- - - - 5

All NJR - - - - 2,996

Elbows

NHS hospitals- - - - 94.1%

- - - - 337

Independent hospitals- - - - 5.6%

- - - - 20

ISTCs- - - - 0.3%

- - - - 1


- - - - 0

All NJR - - - - 358

Table 1.3 (continued)

Part 11.3 Work of the NJR Steering Committee and its Sub-committees


1.3.1 Introduction

This section highlights the work undertaken by the NJR Steering Committee and its sub-committees throughout 2012/13. The reports not only reflect the continually increasing requirements placed on the NJR by its numerous stakeholders but the commitment and efforts of the NJR Steering Committee members who receive no remuneration, other than travel and accommodation expenses, for their considerable effort.

The membership of the NJR Steering Committee and membership of and attendance at meetings for all sub-committees for 2012/13 can be found online (Appendix Four).

1.3.2 NJR Steering Committee

In July 2012, the NJR Steering Committee held a workshop with invited stakeholders to examine how the NJR governance and operating model should evolve to remain fit for the future. The four key components of the workshop were: agree the purpose of the NJR over the next ten years; agree and prioritise the activities needed to support the purpose; assess the capabilities necessary to deliver the activities and consider the committee structure necessary to support the delivery of those activities.

Having agreed the mission statement included at Section 1.1.1, the workshop agreed the following priorities:

•Improving data quality

•Improving data access, data availability and data linkage

•Supporting research - internal and external

•Effective stakeholder communications and patient and public engagement

•Extending the benefits of the NJR - new joints, new geographical areas

•Greater international collaboration as the largest arthroplasty register in the world

•Supporting cost effectiveness and value for money

•Outcomes reporting and identifying best and worst practice and

•Providing a ‘rapid response’ service - bespoke reactive analysis of NJR data

It is clear that, as the NJR has matured over its first ten years, the NJR’s governance structure and its resources, designed for a simpler set of activities and outputs, could not be sustained with an increasing work load, a growing list of strategic priorities, changes in the healthcare environment, greater stakeholder expectations, and rapidly increasing international interest and collaboration.

In order to ensure that appropriate focus on all areas of business was maintained, decisions could be made in a timely and efficient manner, representation included all major stakeholders, resource capacity was appropriate to the effort required, and that roles and responsibilities were clearly defined, the following updates to the NJR’s operating model were considered:

•The creation of a new NJR Executive Committee to provide strategic leadership and decision making in a more effective manner, and tasking the Steering Committee to handle operational matters

•The creation of a new medical advisory committee

•The appointment of a new post of NJR Medical Director

•Ensuring that the sub-committee structure is fit for purpose and can deliver the objectives

•Ensuring that the relationship between committees and activities is transparent

•Increasing committee capacity through the recruitment of new members and the involvement of NJR RCC Network in what has previously been steering committee and sub-committee business

•Ensuring patient involvement in steering committee and sub-committee business

•Supporting the NJR’s standing committee structure, by convening ad-hoc working groups to work on specific issues and areas of concern of NJR development, with clear direction, specified outcomes, timelines and budgets

•Ensuring that all committees and working groups have clear terms of reference, an agreed composition, and defined purposes and responsibility, and that members have clearly defined roles and terms of office

The work to define and agree the final operating model will continue in 2013/14 with the final operating model being submitted to DH for its consideration and



endorsement. Once that has been achieved, the final structure will reflect the interactions and relationships between the various committees and will include detailed terms of reference for the committees and their members.

1.3.3 NJR Editorial Board - Mr Martyn Porter, Chairman

The composition and role of the Editorial Board remains unchanged from 2011/12. Its main role is to ensure that the Annual Report is produced on time, for wider distribution at the British Orthopaedic Association (BOA) Congress in the autumn, and to ensure that it is reviewed in detail and quality assured. In 2013/14, to celebrate the 10th anniversary of the NJR, there will be an independent event to launch the report’s findings.

The overall publication process is managed by HQIP. Parts One and Two, focusing on annual progress and clinical activity, are managed by the NJR Centre (Northgate Information Solutions), particularly with the help of Mike Swanson and Claire Newell. Part Three, outcomes after joint replacement is produced by the University of Bristol team, particularly with the help of Professor Ashley Blom, Michèle Smith and Linda Hunt (statistical lead). Part Four, Trust- and unit-level activity is a joint contribution from the NJR Centre and the University of Bristol.

The Editorial Board meets five times a year and has several teleconferences with a significant part of the editorial work carried out by email. We meet shortly after the BOA Congress to discuss the response to the recently launched report, to consider feedback and start planning for the next report publication. We then have a teleconference in March to review the progress of the previous year’s special topics and to plan the special topics for the coming year. The meeting in April is to update the Editorial Board regarding the production of the Annual Report and consider the timelines and actions that need to be taken. In May we meet to review the early outputs of Parts One to Four and to consider the format, tables, content and accuracy. There are then two further review stages before we meet in early July to approve the content before formal sign off at the July NJR Steering Committee meeting.

The secondary roles of the Editorial Board include identification of special topics and in-depth studies. It is recognised that the timelines to produce the Annual Report are often very tight and more detailed work takes a longer period to obtain the necessary outputs. Recent in-depth topics have included analysis of resurfacing, metal-on-metal hip replacements and this year includes a study of mortality. There are plans to study infection and revision operations in more detail. All these studies are planned and monitored through the Research Sub-committee to prevent duplication, overlap and inconsistency.

NJR Fellowship Programme

The first two NJR Fellows, Mr Simon Jameson and Mr Paul Baker, who were appointed for one year, have worked with the Editorial Board and published a range of papers on aspects of both hip and knee replacement in peer review journals. They have also worked in collaboration with the University of Bristol but more often with their local mentors and academic supervisors in their places of routine clinical activity. They have both been extremely motivated and both presented and published their work which is listed in the appendices. A further update on the NJR Fellowship programme is included at 1.4.11.

Annual Report Development Strategy

It is important that the Editorial Board recognise the changes necessary with emerging technology. We have established a working group which will consider greater emphasis to online and, where possible, real time reporting and, possibly, a shorter hard copy of the report. We are also considering more interactive modes of obtaining information.

We are also considering holding a Research Day where the outputs and publications from the NJR can be presented and discussed in more detail.

Public and Patient Guide

In conjunction with the HQIP communications team and, in particular, Rebecca Beaumont, the Editorial Board oversees the production of the Public and Patient Guide which was first launched in 2011. We will continue to develop this important output and the 2012 edition included important patient-friendly developments (see 1.4.5).


BOA Congress

The Editorial Board also work with the British Orthopaedic Association where they provide at least one instructional session at the Annual Congress. In 2013/14, we will be fortunate to have three sessions as part of the programme.

1.3.4 Implant Performance Sub-committee - Mr Keith Tucker, Chairman

The Implant Performance Sub-committee essentially embraces two committees. The main committee includes the members of the Scrutiny Group together with representatives from the implant manufacturing industry. The composition of the Scrutiny Group includes representatives from the NJR Steering Committee, the Medicines and Healthcare products Regulatory Agency (MHRA), HQIP, Northgate Information Solutions and the University of Bristol.

It is the Scrutiny Group’s brief to analyse and assess the confidential data that relates to implants that have come under performance review (potential outliers). A performance review can be triggered by verbal or written communication, a paper or presentation at a surgical meeting or a report from another joint registry. Most commonly a review results from analysis of our own data where the Patient Time Incidence Rate (PTIR) has been found to be unacceptably high. The PTIR is the revision rate per 100 observed years and is calculated by the statistical team in Bristol from the data prepared by Northgate. The PTIR for every implant is measured twice yearly.

We are reviewing our methodology at present but essentially when an implant has a PTIR of twice the group PTIR (Level 1) a report is filed with the MHRA. When the PTIR is only 1.5 times the group PTIR, a warning letter is sent to the company (Level 2). Over the past year there have been two Level 1 reports and fourteen Level 2 reports.

Since this committee has been in existence we have picked up outlier performance which has involved ‘mix and match’. This is where components of a hip replacement are made by more than one manufacturer. Examples include a stem being made by Company A and the acetabular component by

Company B. There have not been any examples of outlier performance when the articulation has been ‘hard on soft’ (such as a metal or ceramic head articulating with a high density polyethylene cup or liner) but there have been two Level 1 reports and nine Level 2 reports for combinations which involve ‘hard on hard’ (such as metal-on-metal).

We keep a close watch on some, usually relatively new prostheses, where concern has been raised in other countries. For example, during the past year, there have been some concerns expressed by one manufacturer with regard to a femoral component which incorporates a modular neck – this was showing up as an outlier in the Australian Registry. We have looked carefully at all the NJR data for implants with modular necks and compared this to use in some other countries, but surgeons recorded on the NJR have not made a lot of use of modular necks prostheses in hip replacement.

Looking to the future, the committee feels it is time that we turned our attention to revision prostheses. The NJR has about 76,000 revisions logged into the database. Anecdotally we know that some revision procedures do better than others. The implants are often (but not always) extremely expensive. There are also issues about whether surgical experience and volume have a part to play in outcomes. In our view, a fully comprehensive assessment of these implants is now due.

My thanks go to all the committee for their dedication and hard work - it is one of the great strengths of the NJR that it has the ability to monitor device performance in this manner, to facilitate outlier device investigation by both the regulator and manufacturers. Thanks too must go to Melissa Wright (HQIP) for her organisation and note keeping.

1.3.5 Surgeon Outliers Sub-committee - Professor Paul Gregg, Chairman

The Outliers Sub-committee (surgical data) met three times in 2012/13. The committee’s role is to ensure that, at the earliest stage, concerns about potential outlier performance of units and surgeons is highlighted and communicated to those concerned.



It is important to emphasise that the identification of a potential outlier surgeon does not mean that a surgeon’s performance is poor as many other contributing factors may have influence, for example, type of implant used, case-mix and incomplete provision of data to the NJR. All of these factors have been seen to contribute to potential outlier performance in some cases.

The first Annual Clinical Reports to NHS Trusts, Local Health Boards and independent providers were sent out in September 2012 and the reports contained the following data:

•Compliance rate as a percentage

•Consent rate as a percentage

•Linkability rate as a percentage

•A ‘traffic light’ system indicating their performance against these indicators: green, amber, red

In addition:

•Unit mortality ratio (reported as Standardised Mortality Ratio (SMR) with a ‘traffic light’ system)

•Unit revision rate for hips and knees (reported as Standardised Revision Ratio (SRR) with a ‘traffic light’ system)

•Individual surgeon (anonymised) revision rates for hips and knees

In addition, the SRR’s are shown on funnel plots for all units and surgeons with individual funnel plots for all hips, cemented hips, uncemented hips, resurfacing/MoM hips, hybrid hips, all knee replacements, cemented knee replacements, uncemented knee replacements, unicondylar knee replacements and patello-femoral knee replacements.

In the event of a surgeon being identified as a ‘potential outlier’ (SRR > 99.8% control limit), a letter is sent to the surgeon six weeks before the Annual Clinical Report is sent, informing him/her of the situation and enclosing the data upon which the potential outlying status had been calculated. This is to allow the surgeon opportunity to validate the data which the NJR holds for them. Separate notification of the identity of a potential outlying surgeon is made to the CEO at the time of sending the Annual Clinical Report.

In the case of surgeons known to have retired, be on long-term sick leave, moved abroad or left the Trust or Local Health Board, a letter would also be sent to the CEO for notification.

For private units, letters are sent to the Group CEO who would forward the letter to the appropriate general manager.

Future reports will be sent out in April/May each year to coincide with the new financial year.

Six months after the dissemination of the Annual Clinical Reports, the data is scrutinised and if additional potential outlier units or surgeons are identified, the relevant CEO is informed six weeks after notifying the surgeon.

CEOs are asked to acknowledge receipt of the report and, if there is no response after a second communication, the Care Quality Commission (CQC in England or NHS Wales) is informed. The latter has only been necessary for two Trusts following the first distribution of Annual Clinical Reports.

Two CQC representatives attended one of the sub-committee meetings in order for the NJR to share with them our current approach to managing potential outlier units and surgeons. The CQC will continue to work with the NJR to determine how our data can form part of the CQC Quality Risk Profiles information and be used in their hospital inspection process in England.

In some cases, surgeons had been identified as potential outliers because of their use of specific prostheses known to have poor results and which, subsequently, have been removed from the market. It had been agreed that three years after a prosthesis has been removed from the market due to poor results, those cases would be removed from the database of all surgeons and their SRR re-calculated. In the three years interim, funnel plots would be shown with the withdrawn prosthesis in and a plot with the withdrawn prosthesis out.

The committee also noted for 2012/13 the difficulties encountered in an audit of Trusts to seek further clarification of the performance of the Pinnacle acetabular cup when used with a metal liner. Despite


a letter being sent to 13 Trusts in July 2012 by Sir Bruce Keogh, NHS Medical Director, instructing them to take part, only eight responded by March 2013 and only four of those had completed the data collection. The matter was escalated to the CQC to follow up on behalf of the NJR. The audit has now been completed for 12 of the 13 units and a report on the outcomes provided to the MHRA and NHS England.

After extensive discussions it has been agreed that, to give greater clarity on the sub-types of joint replacement, the next Annual Clinical Reports will show separate funnel plots for units and surgeons as follows:

Knees

•All types of knee replacements together

•Total knee replacement cemented

•Total knee replacement uncemented/hybrid

•Unicondylar knee replacement

•Patello-femoral knee replacement

Hips

•All types of hip replacement together

•Total hip replacement cemented

•Total hip replacement uncemented

•Hybrid and reverse hybrid total hip replacement

•Resurfacing and metal-on-metal total hip replacement

It is important to remember that the success and validity of this outlier process relies heavily on the diligence of Trusts, Local Health Boards, independent providers and surgeons entering all primary and revision procedures. It is the surgeon’s, independent provider’s, Local Health Board’s and Trust’s responsibility to make sure that all cases are registered and accurate. Participation in the NJR has been mandatory since April 2011 for NHS hospitals and since April 2003 for the independent sector. Surgeons are advised to check regularly with the NJR Clinician Feedback System to ensure the data held by NJR are accurate. This will become increasingly important with the impending publication of named surgeon implant

survivorship statistics, as part of NHS England’s transparency agenda.

Thanks are expressed to the members of the committee for their time and contribution to this important, but sometimes challenging, process. The Chair wishes to extend particular thanks to the significant amount of work undertaken by Mr Peter Howard in connection with many of the analyses.

1.3.6 NJR Research Sub-committee - Professor Alex MacGregor, Chairman

The Research Sub-committee’s remit is to maximise access to NJR for the wider research community whilst upholding the quality of research based on NJR data. The committee takes formal responsibility for the release of data for research through an impartial and objective protocol and has oversight of the use and reporting of NJR data by research groups.

During the period 2012/13, the committee sanctioned the release of data to six external research groups. These included data released for analysis that will inform the revised NICE guidance for total hip and surface replacement. The committee received an unprecedented number of expressions of interest for future project work from both the UK and overseas, some of which has been submitted for external funding. We encourage any researcher planning externally funded work with the NJR to discuss their proposals in confidence with the NJR in advance of submission. Full details of the NJR’s research data access policy and protocols, together with detailed guidance notes for applicants, can be found at www.njrcentre.org.uk.

The research profile of the NJR has continued to expand over the last year, with over 40 presentations to national and international scientific meetings. A total of 18 scientific papers have been published in peer reviewed literature for this reporting year, based on work carried out by the NJR statistical analysis team at the University of Bristol and by academic groups working on data releases that were sanctioned by the committee.



Notable publications in this period include a British Medical Journal (BMJ) paper outlining the most extensive contemporary analysis of the cost-effectiveness of cemented, cementless and hybrid prostheses for total hip replacement. Also published in the BMJ, an analysis using NJR-HES linked data of cancer risk in the seven years after metal-on-metal joint replacement provided the first registry based evidence of the absence of increased cancer risk following surgery. Findings published in the Lancet showed an inferior implant survivorship for metal-on-metal resurfacing in women when compared to other surgical options. This year also saw the first set of analyses to include NJR data linked to PROMs.

A full list of publications related to NJR data is included in Appendix Two. The redesigned research library section of our website catalogues all NJR research data releases with their progress reports, together with links to all publications related to NJR data.

1.3.7 NJR Data Quality Group - Professor Paul Gregg, Chairman

A Data Quality Sub-committee was established in 2012 and met once during this reporting year 2012/13.

Although there has been a gradual and progressive improvement in compliance, consent and linkability since the start of the registry, there was still concern about the compliance with the registration of both primary and revision joint replacement by some Trusts despite being made mandatory in April 2011. The terms of reference were to explore methods of improving data capture and quality.

It was decided to try and establish a named data quality person for each provider who would be responsible on an annual basis, for providing the numbers of procedures performed to the NJR for cross-checking and validation.

A letter was sent to provider CEOs explaining that, as part of their compliance with the NJR, a data quality process was being created and it was therefore being requested that they provide the name and contact details of their nominated data quality returns person. An instruction sheet was sent with the letter outlining what was required from the nominated person and providing advice regarding any coding issues they may come across. The NJR website would list each provider’s nominated person.

It is disappointing to report that only 55 responses were received from 151 letters which were sent to all Trusts in England, Welsh Local Health Boards, and private sector groups. Chase letters were sent to all CEOs of non-responding providers, with copies to Medical Directors, and failure to respond will lead to a third and final letter being sent to provider CEOs to state that any data from their units that appeared in the public domain would be un-validated as the NJR had not received a named representative. A list of providers that have not supplied a data quality representative will appear in future NJR Annual Reports.

In addition to the above, a data accuracy audit is being planned across 20 orthopaedic units under the direction of the Regional Clinical Coordinators (RCCs). A sample set of 30 patients (15 hips, 15 knees with 5 of each set being revisions) will be studied in each of the units. This study will look at the accuracy of data entry onto the NJR Minimum Dataset (MDS) form (comparing with notes, theatre logs etc.) and accuracy of transcription from the NJR MDS form to the database.

It should be recorded that three previous data accuracy studies have shown encouraging results for the accuracy of the main data fields.

I would like to thank the members of the sub-committee for their contributions and the RCC Network for undertaking the proposed audit of data accuracy.


1.3.8 NJR Regional Clinical Coordinators’ (RCC) Network – Mr Peter Howard, Chairman

As Chair of the Regional Clinical Co-ordinators Network since 2007, I am aware of the significant achievements this group has made in supporting the raising of the profile of the NJR to fellow clinicians and acting as the key link in communicating NJR activities to hospital managers and other relevant hospital staff.

Working with our respective Regional Coordinators this year, the Network has, as always, been keen to understand the specific concerns of individual hospitals in relation to their NJR responsibilities. Although there continue to be issues with some Trusts, there are clear improvements within this area.

The RCCs have been vital to understanding specific issues regarding data quality by initiating unit-level audits of NJR data. This work feeds into the strategic actions of the Data Quality Group and will become an ongoing function of the Network.

This year also saw a substantial review of the MDS. The RCCs were able to input into the list of proposed changes to the dataset and help create a priority group of actions to be implemented into the relevant NJR forms in the coming months.

Once again, the RCC Network has supported the development of the Patient and Public Guide to the Annual Report by ensuring key messages from the main report are distilled accurately to enable patients to be clear about the key outcomes of joint replacement surgery.

As my time as Chair of the RCC Network comes to an end, I would like to thank all of the surgeons who have put themselves forward for this role and their individual efforts in championing the NJR at a local level.

Part 11.4 Highlights


This section provides a brief summary of the work and activities undertaken by the NJR during 2012/13.

1.4.1 Geographic extension of the NJR

From February 2013, hospitals in Northern Ireland started to submit data to the NJR. Some system development was necessary to accommodate a patient identifier different to the NHS number used in NHS Trusts in England and Welsh Local Health Boards. The Healthcare Number (HCN) allocated to patients in Northern Ireland is retained and used if those patients subsequently receive treatment in either England or Wales. The NJR already has many HCN numbers recorded for patients who have had joint replacement surgery. This means that it will be possible to get a more accurate assessment of outcomes where patients may have had a primary joint replacement procedure in Northern Ireland and a subsequent revision in either England or Wales. It is hoped that the benefits that the NJR brings for patients, surgeons, and healthcare management will be recognised by independent providers.

It is hoped that units in both the Isle of Man and Jersey will start submitting data to the NJR in 2013/14.

1.4.2 Extension of the NJR: Elbows and shoulders

From 1 April 2012, the NJR started to collect data about elbow and shoulder joint replacement procedures. The project was supported by the British Elbow and Shoulder Society (BESS).

The NJR Steering Committee has also agreed to a two-year pilot in which PROMs, using Oxford Shoulder Scores, will be collected from patients who have undergone a shoulder replacement procedure at six months following surgery. Pre-operative Oxford Shoulder Scores are collected as part of the primary shoulder data set. The follow-up will be with NHS-funded patients only in England and Wales.

1.4.3 Beyond Compliance: ‘Protecting Patients, Supporting Innovation’

For a manufacturer to market a joint replacement in Europe, the device must have been awarded a CE mark (Conformité Européene). CE marks are categorised

according to the perceived risk inherent in the device. Until 2008 joint replacement implants were graded as Class 2b. Total hip, knee, and shoulder replacement have since been re-classified to Class 3. CE marks are awarded by Notified Bodies. Each European State has one or more Notified Body which is supervised by the appropriate competent authority in each country, e.g. the MHRA in the United Kingdom.

The CE Mark is “Compliance”. It is illegal for anyone to hinder the sale of a product with a CE mark. The CE mark is, to a very considerable extent, awarded on the basis of ‘Equivalence’. Until now manufacturers have sometimes claimed equivalence in more than two features of the design. Equivalence could have been claimed in the material, shape, lubrication system etc., whilst at the same time claiming the product is a new and important addition to the market. To obtain a Class 3 CE Mark, the manufacturer has also to outline a post-market surveillance plan. Despite CE regulations, devices have been introduced into the market that have proven to be poor. Even with NJR, ODEP, MHRA and the CE Mark, there are examples of implants falling short of expectations. This has frustrated many for a considerable period.

Mr Peter Kay, during his time in office as BOA President, developed the concept of Beyond Compliance. Implicit in Beyond Compliance is the invitation to a manufacturer to go beyond the demands of the CE mark and enter into a process that will offer greater rigour and organisation than that currently available through the CE process. It is proposed that Beyond Compliance, whilst remaining an entirely voluntary process, could be used with all new implants and modifications to established devices.

Beyond Compliance embraces two main features and is governed by a Steering Committee. The first feature is an Advisory Group service and the second, a very sophisticated post-CE mark online surveillance service. ODEP has been asked to take the lead with Beyond Compliance and the panel agreed to set up the advisory service and the monitoring process last year at the invitation of the BOA and MHRA. NHS Supply Chain is responsible for the administrative organisation of the process.

The Advisory Group’s first duty is to look at the detailed product file provided by the manufacturer. The Advisory



Group will then assess the level of residual risk there might be with this product. The manufacturer’s post-marketing surveillance plan, including post-market clinical follow-up studies, will also be reviewed. With the manufacturer, the group will discuss and agree the rate at which the device could enter the market and add any other comments they think appropriate. Following that decision there will also be agreement on a plan for post-market clinical follow-up, which will be monitored with the implanting surgeons and manufacturer representatives.

Any implant selected for the process is notified to the NJR Centre which will then create a record for the implant in a central data repository. When the record of a procedure is submitted to the NJR in the normal way, the system will automatically recognise a Beyond Compliance device and copy the procedure details to that central repository. The repository will

also receive details of those procedures where the device has been revised.

The NJR Centre will also be able to add procedure level data from HES, PEDW, and the NHS England national PROMs programme. Surgeons will be able to upload additional data such as x-rays, operation notes and video. Suppliers will also be able to upload pre-CE Mark data and results from follow-up studies.

Not only will surgeons, suppliers, and Advisory Group members be able to access all the data relating to a specific implant, a number of automated reports will also be available, enabling them to monitor the performance of that implant. Additionally, there will be a number of additional services, such as providing suppliers with the ability to undertake follow-up studies with patients. The flow of data and information is shown in the figure below:

Figure 1.2 Beyond Compliance data flow.

Surgeons

NJR Centre

Hospitals

SuppliersAdvisory Group

Reports and Additional Services

Central Data Repository

Operation NotesOperation Video

X-Rays

Pre-CE Mark DataBibliography

Follow-Up Study Data

NJR Procedure DataNJR Primary/Revision Linked Data

HES, PEDW, PROMs

© N

atio

nal J

oint

Reg

istr

y 20

13


Should the results of a device going through the Beyond Compliance process prove to be unsatisfactory, the MHRA will be informed immediately.

Through this project, NJR data will be used to assist in the monitoring of new devices with a view to detecting problems earlier, if they occur, and to help promote good practice with a system of sophisticated post-market surveillance. Presently, with the involvement of NJR, the development of this project is a world first. Our progress to date has stimulated discussion for the use of a Beyond Compliance system for other devices such as breast implants and heart valves.

Please visit www.beyondcompliance.co.uk or contact Mr Keith Tucker for further details.

It is appropriate to acknowledge the enthusiasm and huge amount of preparatory work that Northgate Information Solutions have put into this project.

1.4.4 Publication of consultant-level data

In December 2012, the NHS England CEO, Sir David Nicholson, announced plans for nine surgical specialties and one medical specialty to start publishing consultant-level activity and outcomes information by June 2013. Orthopaedics was one of the specialties included and the NJR will be used as the source of outcomes data for hip and knee joint replacement and will provide a web-based portal for the publication of this information. The NJR is working closely with the lead specialty association British Orthopaedic Association in their discussions with NHS England and HQIP to ensure that the requirements are understood and in order to obtain consent from those consultant surgeons registered with the NJR to publish their data. The data will be made available at www.njrsurgeonhospitalprofile.org.uk.

1.4.5 Patient-focused initiatives

A second edition of the NJR’s Public and Patient Guide to the Annual Report was published in 2012/13 with notable improvements in content and design as well as a choice of online formats - a standard PDF

or interactive version. These ideas and suggestions were taken forward from the workshops at the Patient Focus conference in 2012 and came to fruition through the newly established NJR Patient Network. The Public and Patient Guide has again been awarded the Information Standard logo, a quality mark for evidence-based information supported by the Department of Health.

The NJR Patient Network has grown over the year, meeting twice to share views and to get to know the NJR and its work in more detail. Members have helped to shape the recently revised patient information leaflet and new poster for hospital waiting areas and are currently involved in the development of a patient implant card pilot project. The NJR would like to thank all members for their thoughts, comments and time spent contributing to the registry’s progress.

The Network is a significant development for the registry and the group will be a firm feature in the NJR’s structure and work programme in the future. All of the registry’s patient-focused initiatives continue to be supported and championed at NJR Steering Committee through patient representatives Mary Cowern and Sue Musson.

1.4.6 NJR Feedback Services: Updates

NJR Clinician Feedback

The Steering Committee agreed to a project to implement further reports in NJR Clinician Feedback following the preparation of a set of prioritised requirements by the RCC Network. These high level requirements to be delivered are:

•A plot track for individual surgeons on the Patient Time Incidence Rate report (PTIR) enabling surgeons to identify either improving or worsening outcomes. The PTIR report will also be able to be run as ‘Lead Surgeon’ enabling either trainee surgeons to assess outcomes where they were the lead surgeon or enabling consultant surgeons to separate those procedures where they were the lead surgeon from those procedures where a trainee was the lead surgeon.



•The current Revision Rate reports will be updated to include revision rates at five and seven years. As for the PTIR report, the Revision Rate report will be extended to include ‘Lead Surgeon’ in addition to ‘Consultant in Charge’.

•Surgeons will be provided with further information about their patients whose primary procedures have been revised by another surgeon and, potentially, in another hospital. The reasons for revision and time to latest endpoint will be provided along with sufficient information for the primary surgeon to identify the patient and, if necessary, review patient notes. Surgeons will also be able to download and print the primary procedure details submitted to the NJR for those patients.

•Surgeons will also be provided with an Annual Summary report for the purposes of the revalidation process, very similar to the Annual Clinical Report.

NJR Management Feedback

•NJR Management Feedback is used to produce the Annual Clinical Report which was sent to units for the first time in September 2012. The report is available as a download from NJR Management Feedback and is accessible by anyone in the unit authorised to do so by senior management.

NJR Supplier Feedback

•NJR Supplier Feedback is a unique, procedure-level online data reporting system to enable manufacturers to perform post-marketing surveillance on their range of implants. Improvements to the Supplier Feedback system are being considered to broaden reporting to revision hips and knees as well as shoulder, elbow and ankle joints. Linkage to PROMs data for primary hips and knees is planned, along with the development of additional online analysis tools.

1.4.7 Proposed changes to the Minimum Dataset

The NJR Steering Committee has also approved the development of the Minimum Dataset to the next version, MDSv6. The changes are not major and

reflect, for example, recent developments in chemical thromboprophylaxis, the need to carry out different types of analyses, removing inconsistencies between the data forms, and the requirement to improve data quality by removing ambiguity and changing system defaults. The development will take place later in 2013/14 once the changes have been approved by the NHS Information Standards Board.

1.4.8 Price Benchmarking

Quality, Innovation, Production, and Protection (QIPP) is a large transformational programme for the NHS which aims to improve the quality of care provided by the NHS whilst, at the same time, making up to £20 billion of efficiency savings by 2014/15 which will be invested in frontline care. QIPP Procurement is a workstream of the QIPP programme and aims to help NHS provider Trusts reduce and optimise non-pay expenditure without compromising quality of patient treatment and care.

Orthopaedic joint replacement implants represent relatively high cost and high volume procurement within this category and are, therefore, subject to particular focus. Orthopaedic implants are purchased locally or regionally across England and Wales. Each purchasing authority negotiates pricing with suppliers based upon local conditions and purchase volumes. As a result of this local procurement model, there are variations in pricing for orthopaedic implants across NHS England and NHS Wales. With funding from the Department of Health, the Price Benchmarking project aims to highlight this price variation in England and Wales. Following a successful pilot in 2012/13 with three purchasing authorities, the pilot project was widened to other authorities and will continue to expand in 2013/14. Early indications are that there are, in some instances, significant price variations for some prostheses and that the volume of purchases does not necessarily attract appropriate discounts. This information will become more widely available in the latter stages of the project roll out via an online reporting tool.


1.4.9 International developments

The NJR is regularly approached and asked to take part in a conference or symposium to support greater international collaboration and we are keen to share our experiences across the globe.

International Society of Arthroplasty Registers (ISAR)

The NJR was certainly not the first joint registry. The Scandinavians, in particular, were many years ahead with Australia becoming an important member some 13 years ago. New Zealand was not long following and there are now about 18 countries with national joint registries in varying stages of development. The USA has a relatively embryonic national registry but also has a number of registries which tend to be regional. Italy has three registries and a national registry project.

ISAR was set up in 2004 essentially between the Scandinavian and Australian registries. The NJR joined two years ago and are now full members. The idea behind the foundation was to encourage registries to communicate with each other and form data linkages – we know that there is much to learn from each other.

ISAR had its first Congress in Bergen during May 2012 and, following its success, the management board asked the NJR to host ISAR 2013 in the UK. It is a great honour to showcase the NJR’s progress and developments, welcome a plethora of experience and, of course, have access to Continuing Professional Development (CPD) on one’s own doorstep. The ISAR working group chose Stratford-upon-Avon as the host town, knowing it would produce an excellent ambience for the meeting.

The current President of ISAR is Göran Garellick and Mr Martyn Porter will be President 2014/15 following the American Academy of Orthopaedic Surgeons (AAOS) meeting in February 2014.

International Consortium of Orthopaedic Registries (ICOR)

The ICOR initiative was launched in 2011, essentially as a response to the problems of metal-on-metal hip replacement in the US. It was promoted by the US Food and Drugs Administration (FDA) and launched

with an inaugural conference at their headquarters in Silver Springs, Maryland. The meeting was attended by representatives of most national joint registries. Since then ICOR has promoted several collaborative audits and reports. The NJR is represented on the ICOR committee by Keith Tucker.

The US FDA and the European Commission are driving the Unique Device Identifier (UDI) initiative which the NJR is fully supporting. Eventually all implants will have a UDI (usually entrenched in their bar-code) which will relate to an internationally agreed component database.

ICOR grant bursaries for research associated with registry data and are willing to fund travelling fellowships. For more information, contact Art Sedrakyan whose details can be found on the ICOR website (www.icor-initiative.org).

1.4.10 Patient Reported Outcomes Measures (PROMs)

The NJR reported the results from its first PROMs survey in the 2nd Annual Report in 2005. This study was carried out in a group of 20,000 patients who had previously undergone replacement of a hip or knee joint. The NJR initiated a second more extensive one year follow-up PROMs programme in 2011. In order to be eligible for the study, patients had to have completed a pre-operative questionnaire for the NHS England national PROMs programme and have consented to have their personal details held by the NJR. Over a six-month period, 50,000 questionnaires were sent to patients, with approximately 42,500 being returned completed. With about 1,500 patients being lost to follow-up since the start of the programme, approximately 41,000 Year Three follow-up questionnaires will be despatched over a six-month period which began in March 2013. It is intended to undertake a further follow-up project at five years following surgery.

The data from the Year One follow-up is currently being examined and will be linked to both pre- and post-operative data from the NHS England PROMs programme, NJR data and HES data. The team from the University of Bristol, along with Steering Committee member Professor Alex MacGregor, will undertake the analysis of the data.



1.4.11 NJR Fellowships

Following the excellent work undertaken by the previous two NJR Fellows, the NJR advertised the availability of another Fellowship in the latter half of 2012. Following interview, Mr Jeya Palan has been appointed and is due to start his Fellowship in April 2013. His work will be directed by the NJR Research Sub-committee and he will be supported by the team at the University of Bristol looking at issues in relation to unicompartmental knee replacement in addition to revision hip and knee replacements. Another NJR Fellowship will be advertised later in 2013.

1.4.12 Orthopaedic Data Evaluation Panel (ODEP) overview

The ODEP group was set up to monitor NICE guidance on primary hip implants in 2002 and hip resurfacing in 2004. Although ODEP is independent from the NJR, its Chairman Keith Tucker is also a member of the NJR Steering Committee and the NJR provides data to facilitate the monitoring process. The NJR also uses ODEP outputs in a number of published reports. The panel provides an ongoing assessment of hip implants to benchmark both hip femoral stems and hip acetabular cups against the NICE guidance, providing a benchmark rating for implant survivorship and submitted data quality. The ODEP rating is now a commonly used benchmark not only in the UK but globally. A full list of products submitted to the panel and their individual ratings can be found at www.odep.org.uk.

The group is hosted by NHS Supply Chain and members, listed below, volunteer their time and expertise:

•Keith Tucker – Chairman of ODEP - Consultant orthopaedic surgeon from Norwich

•Peter Kay – Consultant orthopaedic surgeon, Wrightington, Wigan and Leigh NHS Foundation Trust.

•Philip Lewis – NHS Supply Chain

•Martin Pickford – Northgate, orthopaedic advisor to the NJR

•Andy Smallwood – Procurement Wales

•Evert Smith – Consultant orthopaedic surgeon, North Bristol NHS Trust

•Ian Stockley – Consultant orthopaedic surgeon, Sheffield Teaching Hospitals NHS Foundation Trust

The panel has recently started the assessment of required criteria for the evaluation of knee implants which will follow a similar process of data submission and evaluation to the hip products. In order to gain the expert knowledge required for this field we have recruited the following members:

•Colin Esler – Consultant orthopaedic surgeon, University Hospitals of Leicester NHS Trust

•Richard Parkinson – Consultant orthopaedic surgeon, Wirral University Teaching Hospital NHS Foundation Trust

•Andrew Porteous – Consultant orthopaedic surgeon, North Bristol NHS Trust

•Andrew Toms – Consultant orthopaedic surgeon, Royal Devon and Exeter NHS Foundation Trust

•Timothy Wilton – Consultant orthopaedic surgeon, Derby Hospitals NHS Foundation Trust

The panel members accept data submissions for hips bi-annually in spring and autumn with monthly meetings arranged to discuss and review improvements to the process scheduled throughout the year.

The year 2012 saw a marked increase in the level of activity of the panel with the numbers of submissions being provided for benchmark reaching 108 and the start of three major activities:

•Initiation of a full review of the hip benchmarking process

•Introduction of a benchmarking process for knees

•Formation of the Beyond Compliance Advisory Group (see 1.4.3)

Plans for 2013/14 will see the full launch of the revised hip process, submissions from industry to gain a knee benchmark and the completion of the pilot phase of the Beyond Compliance initiative. In addition, improvements to access of information with the launch of a new website and, in recognition of the importance placed on ODEP, introducing further programme support.

1.5 Finance

Part 1



1.5.1 Income and expenditure 2012/13

The NJR is self financing, funded by a levy raised on the sale of hip, knee, ankle, shoulder, and elbow implants to NHS and independent healthcare providers in England, Wales, and Northern Ireland (the latter from February 2013). The rate of the levy is recommended by the NJR Steering Committee for approval by the Department of Health (DH), and is subject to a Memorandum of Understanding between the DH, Welsh Government, Health and Social Care Board Northern Ireland, Independent Healthcare Advisory Services and the Association of British Healthcare Industries (ABHI) Orthopaedics Special Interest Section.

The levy was set at £20.00 per joint from 1 April 2012 to 31 March 2013. Levy income in 2012/13 was £3,292,579 (2011/12: £3,131,630). Expenditure for the same period was £2,512,741 (2011/12: £2,831,850).

Total expenditure for members’ expenses during 2012/13 was £8,337 (2011/12: £26,069).

Below are some of the 2012/13 costs associated with the major NJR project areas:

•Shoulder PROMs £46,750 (total cost of project £116,950)

•Hospital Management Feedback £14,950 (total cost of project £49,950)

•Geographical extension of the NJR £39,083 (total cost of project £146,750)

•Clinician Feedback Phase Two £70,500 (total cost of project £141,650)

•Price Benchmarking Phase One £49,705 (total cost of project £49,705)

The NJR’s financial results are included in the audited accounts of HQIP (Healthcare Quality Improvement Partnership) which manages the registry. The full audited accounts are available on HQIP’s website from September 2013 (www.hqip.org.uk), and also from the Charity Commission, and Companies House.


Laurel Powers-Freeling Chairman (from April 2011)

Professor Paul Gregg Vice ChairmanActing Chairman (October 2009 to March 2011)Orthopaedic Surgeon (from October 2002)

Mr Mick Borroff Orthopaedic device industry (from October 2002)

Mary Cowern Patient Representative. Patient group – Arthritis Care (from October 2006)

Dr Jean-Jacques de Gorter Independent healthcare sector (from October 2011)

Professor Alex MacGregor Public health and epidemiology (from October 2002)

Sue Musson Patient representative (from October 2011)

Carolyn Naisby Practitioner with special interest in orthopaedics (from July 2006)

Mr Martyn Porter Orthopaedic surgeon (from January 2003)

Dean Sleigh Orthopaedic device industry (from April 2008. Resigned in February 2013)

Mr Keith Tucker Orthopaedic surgeon (from May 2007)

Andrew Woodhead NHS Trust management (from January 2007)

A1.2 Membership from April 2012

Members are appointed as posts become vacant.

Appendix 1 NJR Steering Committee 2012/13

A1.1 NJR Steering Committee – Composition

As a department expert committee, the composition of the NJRSC by category is:

•Chairman 1

•Orthopaedic surgeons 3

•Patient representatives 2

•Implant manufacturer/supplier industry 2

•Public health/epidemiology 1

•NHS organisation management 1

•Independent healthcare provider 1

•Practitioner with special interest in orthopaedic care who is a GP, nurse or allied 1 health professional (physiotherapist or occupational therapist)



Laurel Powers-Freeling No interests to declare

Professor Paul Gregg Emeritus Consultant Orthopaedic Surgeon, James Cook University Hospital, Middlesbrough, Professor of Orthopaedic Surgical Science, Orthopaedic Advisor for Ramsay Healthcare

Mick Borroff Chair, ABHI Orthopaedics Special Interest Section Employed by DePuy International Ltd, manufacturer of orthopaedic prostheses

Mary Cowern Wales Director for the UK charity Arthritis Care

Dr Jean-Jacques de Gorter Director of Clinical Services, Spire Healthcare

Professor Alex MacGregor Professor of Genetic Epidemiology, University of East Anglia Consultant Rheumatologist, Norfolk and Norwich University Hospital NHS Trust

Sue Musson Managing Director, Firecracker Projects Limited (supplying management consultancy to NHS organisations) Non-Executive Director, Bridgewater Community NHS Trust

Carolyn Naisby Consultant Physiotherapist, City Hospitals Sunderland NHS Foundation Trust

Mr Martyn Porter Consultant Orthopaedic Surgeon, Wrightington, Wigan and Leigh NHS Trust (orthopaedic unit has received financial support from DePuy International for clinical and RSA studies for Elite Plus femoral stem and C-Stem). Has acted as a consultant to DePuy International in relation to the development of a hip femoral stem (C-Stem AMT) and received royalties on this hip stem

Mr Dean Sleigh ABHI Council member, ABHI Orthopaedics Special Interest Section

Mr Keith Tucker Consultant orthopaedic surgeon, NorwichRoyalties received from Johnson & Johnson Orthopaedics more than five years ago for contribution to design of hip prostheses (all royalties paid into an orthopaedic charity)

Andrew Woodhead Head of Mergers and Acquisitions, NHS London (until 31 March 2012)Managing Director - Andrew Woodhead Consulting Ltd (from Oct 2012)Associate Consultant - Deloitte (from Oct 2012) Associate Consultant - Verita (from Nov 2012)Trustee - Guideposts Charity (from July 2013)

Mr Peter Howard Chairman of the NJR Regional Clinical Coordinators’ Network

Dr Crina Cacou Senior Medical Device Specialist, MHRA

Andy Smallwood Procurement Wales

Elaine Young National Development Lead, HQIP

Robin Burgess Chief Executive, HQIP

Robin Rice Welsh Government

A1.3 Observers

The following have regularly attended NJR Steering Committee meetings as observers:

A1.4 Members’ declarations of interest


Appendix 2 List of papers, publications and research requests using NJR data

This appendix provides details of published analyses and data releases that have been sanctioned by the NJR Research Sub-committee between April 2012 and March 2013. NJR data is available for research purposes following approval by the NJR Research Sub-committee. For further details please visit the NJR website at www.njrcentre.org.uk.

Published papers (April 2012 to March 2013)

Factors Influencing Revision Risk Following 15,740 Single-Brand Hybrid Hip Arthroplasties: A Cohort Study From a National Joint RegistryJameson SS, Mason JM, Baker PN, Jettoo P, Deehan DJ, Reed MR. J Arthroplasty. 2013 Mar 21. pii: S0883-5403(13)00108-3. doi: 10.1016/j.arth.2012.11.021.

Cemented, cementless and hybrid prostheses for total hip replacement: a cost-effectiveness analysisPennington M, Grieve R, Sekhon JS, Gregg PJ, Black N, van der Meulen JH. BMJ. 2013 Feb 27;346:f1026. doi: 10.1136/bmj.f1026.

Mid-term survival following primary hinged total knee replacement is good irrespective of the indication for surgeryBaker P, Critchley R, Gray A, Jameson S, Gregg P, Port A, Deehan D. Knee Surg Sports Traumatol Arthrosc. 2012 Dec 14.

Mid-term equivalent survival of medial and lateral unicondylar knee replacement: an analysis of data from a National Joint RegistryBaker PN, Jameson SS, Deehan DJ, Gregg PJ, Porter M, Tucker K. J Bone Joint Surg Br. 2012 Dec;94(12):1641-8. doi: 10.1302/0301-620X.94B12.29416.

The design of the acetabular component and size of the femoral head influence the risk of revision following 34,721 single-brand cemented hip replacements: a retrospective cohort study of medium-term data from a National Joint RegistryJameson SS, Baker PN, Mason J, Gregg PJ, Brewster N, Deehan DJ, Reed MR. J Bone Joint Surg Br. 2012 Dec;94(12):1611-7. doi: 10.1302/0301-620X.94B12.30040.

Failure rates of metal-on-metal hip resurfacings: analysis of data from the National Joint Registry for England and WalesSmith AJ, Dieppe P, Howard PW, Blom AW; National Joint Registry for England and Wales. Lancet. 2012 Nov 17;380(9855):1759-66. doi: 10.1016/S0140-6736(12)60989-1.

Patient and implant survival following 4323 total hip replacements for acute femoral neck fracture: a retrospective cohort study using National Joint Registry dataJameson SS, Kyle J, Baker PN, Mason J, Deehan DJ, McMurtry IA, Reed MR. J Bone Joint Surg Br. 2012 Nov;94(11):1557-66. doi: 10.1302/0301-620X.94B11.29689.



Appendix 2 List of papers, publications and research requests using NJR data

Revision following patello-femoral arthoplastyBaker PN, Refaie R, Gregg P, Deehan D. Knee Surg Sports Traumatol Arthrosc. 2012 Oct;20(10):2047-53.

Revision for unexplained pain following unicompartmental and total knee replacementBaker PN, Petheram T, Avery PJ, Gregg PJ, Deehan DJ. J Bone Joint Surg Am. 2012 Sep 5;94(17):e126.

The association between body mass index and the outcomes of total knee arthroplastyBaker P, Petheram T, Jameson S, Reed M, Gregg P, Deehan D. J Bone Joint Surg Am. 2012 Aug 15;94(16):1501-8.

Reason for revision influences early patient outcomes after aseptic knee revisionBaker P, Cowling P, Kurtz S, Jameson S, Gregg P, Deehan D. Clin Orthop Relat Res. 2012 Aug;470(8):2244-52. doi: 10.1007/s11999-012-2278-7.

The effect of surgical factors on early patient-reported outcome measures (PROMs) following total knee replacementBaker PN, Deehan DJ, Lees D, Jameson S, Avery PJ, Gregg PJ, Reed MR. J Bone Joint Surg Br. 2012 Aug;94(8):1058-66. doi: 10.1302/0301-620X.94B8.28786.

The effect of aspirin and low molecular weight heparin on venous thromboembolism after knee replacement: A non-randomised comparison using National Joint Registry data Jameson SS, Baker PN, Charman SC, Deehan DJ, Reed MR, Gregg PJ, van der Meulen JH. J Bone Joint Surg Br. 2012 Jul;94(7):914-8.

Comparison of patient-reported outcome measures following total and unicondylar knee replacement Baker PN, Petheram T, Jameson SS, Avery PJ, Reed MR, Gregg PJ, Deehan DJ. J Bone Joint Surg Br.2012 Jul;94(7):919-27.

Patient Reported Outcome Measures after revision of the infected Total Knee Replacement: Do patients prefer single or two-stage revision? Baker P, Petheram TG, Kurtz S, Konttinen YT, Gregg P, Deehan D. Knee Surg Sports Traumatol Arthrosc. 2012 June 13.

Independent predictors of revision following metal-on-metal hip resurfacing: A retrospective cohort study using National Joint Registry data Jameson SS, Baker PN, Mason J, Porter ML, Deehan DJ, Reed MR. J Bone Joint Surg Br. 2012 Jun;94(6):746-54.

Risk of cancer in first seven years after metal-on-metal hip replacement compared with other bearings and general population: Linkage study between the National Joint Registry for England and Wales and hospital episode statisticsSmith AJ, Dieppe P, Porter M, Blom AW; National Joint Registry of England and Wales. BMJ. 2012 Apr 3;344:e2383. doi: 10.1136/bmj.e2383.

Total hip replacement for the treatment of acute femoral neck fractures: results from the National Joint Registry of England and Wales at 3-5 years after surgery Stafford GH, Charman SC, Borroff MJ, Newell C, Tucker JK. Ann R Coll Surg Engl. 2012 Apr;94(3):193-8. doi: 10.1308/003588412X13171221589720.


Approved requests for NJR data for research (April 2012 to March 2013)

Rate of venous Thromboembolism in total ankle arthroplasty Zaidi R Royal National Orthopaedic Hospital NHS Trust, Stanmore February 2013

Does the type of venous thromboembolism (VTE) chemoprophylaxis influence the rate of revision for infection following primary hip and knee replacement?Baker P Health Education North East January 2013

Total hip replacement and surface replacement for the treatment of pain resulting from end stage arthritis of the hip (Review of technology appraisal guidance 2 and 44)Clarke A Warwick Medical School, University of Warwick December 2012

Understanding failure in unicompartmental knee arthroplastyMurray DW Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford November 2012

Revision rates by prosthesis type: parametric survival analysis to inform a model of cost-effectivenessDanielson V Johnson & Johnson Medical November 2012



Appendix 3Additional information on the NJR websitewww.njrcentre.org.ukThe following information will also be available on the NJR website:

1. NJR 10th Annual Report - Parts One, Two, Three and Four (annual progress 2012/13, clinical activity 2012, implant survivorship 2003 to 2012, and Trust- and unit-level activity and outcomes 2012)

2. NJR 10th Annual Report - Part One: Annual Progress 2012/13 – Welsh Language

3. NJR 10th Annual Report - NJR Steering Committee and Sub-committee composition and attendance 2012/13

4. NJR 10th Annual Report - NJR Steering Committee Terms of Reference

5. NJR 10th Annual Report - NJR Regional Clinical Coordinators’ Terms of Reference

6. NJR 10th Annual Report - Prostheses Data

7. NJR 10th Annual Report - Tables and Figures

8. NJR 10th Annual Report - Public and Patient Guide

2.1 Introduction

Part 2Clinical activity 2012



This section summarises the number of hip, knee and ankle replacement procedures undertaken in England and Wales between 1 January and 31 December 2012 and entered into the NJR by 28 February 2013. Details of elbow and shoulder procedures submitted between 1 April and 31 December 2012 and submitted into the NJR by 28 February 2013 are also included. The information is summarised according to the type of hospital or treatment centre, procedure type and patient characteristics.

2.1.1 Hospitals and treatment centres participating in the NJR

A total of 413 orthopaedic units were open and of these 398 (96%) submitted at least one hip, knee, ankle, elbow or shoulder procedure to the NJR (Table 2.1). During the life of the NJR there has been a trend showing a greater proportion of all hip replacements being performed in larger centres. However, in 2012 the proportion of large volume centres has remained constant but the percentage of medium sized centres (200-299) has increased by 3% (Figure 2.1).

On average, 218 hip replacements and 235 knee replacements were recorded per orthopaedic unit over the year, although the numbers varied from 1 to 1,490 procedures for any one joint type. Compared with previous years, there was a decrease in the number of units performing more than 400 knee procedures (Table 2.2) but a large increase in the number of units performing 300-400 knee procedures. Most units performing ankle procedures perform less than 5 in a year but there are four units doing larger volumes.

The nine months of recording elbow and shoulder replacements show that most units do less than 5 elbow procedures in nine months whereas more than half the units do more than 5 shoulder procedures in nine months.


Table 2.1 Total number of hospitals and treatment centres in England and Wales able to participate in the NJR and the proportion actually participating in 2012.

Total number of units Number of units submitting Proportion participatingTotal 413 398 96%

NHS hospitals 240 225 94%

England 222 207 93%

Wales 18 18 100%

Independent hospitals 163 163 100%

England 157 157 100%

Wales 6 6 100%

ISTC 10 10 100%

England 10 10 100%

Wales - - -

Table 2.2 Number of participating hospitals, according to number of procedures performed during 2012.

Total number of

hospitals

Number of procedures

<50 50 - 99 100 - 199 200 - 299 300 - 399 400+Hip procedures

Hospitals entering replacements 396 48 68 109 73 55 43

Hospitals entering primary replacements 396 57 70 119 77 41 32

Knee procedures



Total number of

hospitals


<5 5 - 9 10 - 14 15 - 19 20 - 24 25+Ankle procedures



Elbow procedures



Shoulder procedures



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Note: Elbow and Shoulder data for nine months only.



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Hip procedures

0%

100%

80%

60%

40%

20%

Per

cent

age

of h

osp

itals

Knee procedures

Year

400+

300 - 399 200 - 299 100 - 199 50 - 99 <50Number of hospitalsTotal hip procedures

4%8%

18%31%21%19%

393

63,948

2005

7%8%

14%29%22%20%

399

66,703

2006

9%10%

18%25%23%15%

391

74,878

2007

10%9%

17%31%17%15%

394

78,183

2008

8%12%

17%31%18%13%

395

78,918

2009

7%

13%27%23%28%

392

53,306

2004

3%

2010

10%11%

19%27%19%15%

400

81,623

2012

11%14%

18%28%17%12%

396

86,488

2011

11%14%

16%29%18%12%

398

84,892

0%

100%

80%

60%

40%

20%

Per

cent

age

of h

osp

itals

Year

400+ 300 - 399

200 - 299 100 - 199

50 - 99 <50Number of hospitalsTotal kneeprocedures

5%8%

14%33%

20%19%

391

64,042

2005

8%9%

12%24%

25%22%

398

66,207

2006

12%11%

14%25%

19%19%

389

78,106

2007

13%10%

15%31%

15%15%

390

82,477

2008

12%14%

17%29%

15%14%

393

84,148

2009

4%

11%25%

24%32%

393

48,937

2004

4%

2010

14%12%

17%26%

18%13%

392

86,974

2012

15%16%

17%30%

12%11%

386

90,842

2011

16%10%

18%29%

14%11%

392

89,837

Figure 2.1 Percentage of participating hospitals by number of procedures per annum, 2004 to 2012.

2.2 Hip replacement procedures 2012

Part 2



The total number of hip procedures entered into the NJR during 2012 was 86,488, an increase of 7% over 2011. Of these, 76,448 were primary and 10,040 were revision procedures. The revision ‘burden’ increased on the 2011 levels by 1% to 12%.

Table 2.3 shows that 93% of patients at independent hospitals and ISTCs were graded as fit and healthy or with mild disease according to the ASA system, compared with 78% at NHS units.

Nearly all procedures (94%) undertaken at ISTCs were primary procedures. The percentage of primary hip

resurfacings has decreased again this year to 1% of all primary procedures. The percentage of resurfacing procedures done in Independent hospitals (3%) is triple that of NHS hospitals (1%), as shown in Figure 2.2. Independent units and ISTCs perform more cementless hip primary procedures than NHS hospitals.

At NHS hospitals, revision procedures account for 14% of all procedures. In comparison, the revision burden at independent hospitals is 7%.

5 Bilaterals will only be counted as a bilateral if they are entered under the same operation during data entry. If the two procedures are recorded under two different operations they will be counted as two unilateral procedures. Therefore, the count of bilaterals is likely to be an underestimate.

Table 2.3 Procedure details, according to type of provider for hip procedures in 2012.

NHS hospitalsIndependent

hospitals ISTC Total

No. % No. % No. % No. %Total hip procedures 61,044 71% 22,415 26% 3,029 4% 86,488 Patient physical status

P1 - fit and healthy 6,977 11% 4,703 21% 381 13% 12,061 14%

P2 - mild disease not incapacitating 40,955 67% 16,139 72% 2,421 80% 59,515 69%

P3 - incapacitating systemic disease 12,565 21% 1,541 7% 227 7% 14,333 17%

P4 and P5 547 <1% 32 <1% - 0% 579 <1%

Procedure type

Primary procedures 52,675 69% 20,927 27% 2,846 4% 76,448 88%Primary total prosthetic replacement using cement

18,756 36% 5,614 27% 946 33% 25,316 33%

Primary total prosthetic replacement not using cement

21,985 42% 10,566 50% 1,592 56% 34,143 45%

Primary total prosthetic replacement not classified elsewhere (e.g. hybrid)

11,399 22% 4,203 20% 305 11% 15,907 21%

Primary resurfacing arthroplasty of joint 535 1% 544 3% 3 <1% 1,082 1%

Revision procedures 8,369 83% 1,488 15% 183 2% 10,040 12%

Hip single-stage revision 7,236 86% 1,405 94% 171 93% 8,812 88%

Hip stage one of two-stage revision 514 6% 39 3% 7 4% 560 6%

Hip stage two of two-stage revision 563 7% 43 3% 5 3% 611 6%

Hip excision arthroplasty 56 <1% 1 <1% 0 0% 57 <1%

Bilateral or unilateral5

Bilateral 214 <1% 152 <1% 2 <1% 368 <1%

Unilateral 60,830 100% 22,263 100% 3,027 100% 86,120 100%

Funding

Independent 697 1% 10,078 45% 5 <1% 10,780 12%

NHS 60,347 99% 12,337 55% 3,024 100% 75,708 88%

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Figure 2.2 Primary hip procedures by type of provider 2012.

2.2.1 Primary total hip replacement procedures (THR) 2012

Of the 76,448 primary hip replacement procedures undertaken in 2012, 33% were cemented THRs, 43% were cementless, 1% were hip resurfacing procedures and 2% were large head metal-on-metal (LHMoM) THRs (Figure 2.3). For the first time the number of operations for the current reporting year available for this report is greater than the previous year. Normally, this is not the case as not all procedures performed in the reporting year are submitted in time to be reported in the Annual Report. It is too soon to tell whether this is due to an increase in activity, an increase in compliance, more timely submissions or a combination of these factors.

The ratio between cemented and cementless

procedures has continued to change in 2012. In 2011, there was a 5% difference and in 2012 this increased to 10% more cementless procedures than cemented procedures being carried out. There has been an increase in the percentage of hybrid (standard and reverse hybrid) procedures performed. There has also been a significant decrease in the percentage of resurfacing procedures and in procedures where a large metal head is used with a resurfacing cup (LHMoM). This decline is thought to have resulted from the well publicised voluntary recall of one brand of resurfacing device (ASR – DePuy) and ongoing concerns regarding the safety of LHMoM procedures as reflected in MHRA guidance and follow-up.

In 2012, 15% of hybrid procedures were reverse hybrid (cementless stem, cemented socket) and 85% were standard hybrid (cemented stem, cementless socket).

0%

20%

40%

60%

80%

100%

Type of provider

Per

cent

age

of p

roce

dur

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pe

Cemented 36% 27% 33%

Cementless 42% 50% 56%

Hybrid 22% 20% 11%

Resurfacing 1% 3% <1%

52,675 20,927 2,846

NHS hospitals

Independent hospitals ISTCs


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Figure 2.3 Type of primary hip replacement procedures undertaken between 2005 and 2012.

2.2.1.1 Patient characteristics

Age and gender were included for those patients who gave consent for their personal identifiers to be entered into the NJR and where consent was ‘Not recorded’ (a total of 96%). The average age was 67.4 years, 0.2 years more than last year. Approximately 60% of the patients were female (Table 2.5) which is the same as 2011. On average, female patients were older than male patients at the time of their primary hip replacement (69.7 years and 67.2 years respectively, Table 2.5). Patients undergoing a resurfacing procedure were the youngest, at an average age of 53.4 years (Table 2.5). Seven times as many males have a resurfacing procedure compared with females.

According to the ASA system, 15% of patients undergoing a primary hip replacement in 2012 were graded as fit and healthy prior to surgery, compared with 37% in 2003. Figure 2.6 shows the changes in ASA grade over ten years. Patient BMI6 has increased over the past eight years from 27.4 to 28.7, as shown in Figure 2.7. Females undergoing THR have a consistently lower mean BMI than males; the converse is the case for TKR (Figure 2.22). Figure 2.7 shows that there has been an increase in the number of patients with a BMI of between 30 and 39 and a decrease in the number of patients with BMI between 20 and 24. The single largest indication recorded for surgery was osteoarthritis, recorded in 92% of procedures (Table 2.4). Figure 2.5 shows that the percentage of patients within the age group bands has not changed

0%

10%

20%

30%

40%

50%

60%

Year

Per

cent

age

of p

roce

dur

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pe

Cemented

Cementless

Hybrid

Resurfacing

Large head metal- on-metal (≥36mm)


54%

22%

12%

9%

3%

56,454

2005

46%

25%

14%

10%

6%

59,967

2006

43%

27%

14%

9%

7%

67,321

2007

38%

32%

15%

8%

8%

70,559

2008

36%

37%

15%

6%

6%

70,908

2009

36%

41%

16%

3%

5%

73,006

2010

36%

41%

18%

2%

3%

75,460

2011

33%

43%

20%

1%

2%

76,448

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6 BMI: 20-24 normal, 25-29 overweight, 30-39 obese, 40+ morbidly obese.


significantly since 2003, suggesting that the increase in BMI and reduction in fitness of patients is not due to an ageing patient cohort. However, only 16% of entries in 2005 had BMI data entered (BMI was not collected as

part of MDSv1) and, while this has increased to 67% in 2012, all BMI data has to be viewed with caution as surgeons may be more likely to enter BMI data when the BMI is high, introducing an element of bias.

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Table 2.4 Patient characteristics for primary hip replacement procedures in 2012, according to procedure type.

Primary total prosthetic

replacement using cement


replacement not using cement


replacement not classified elsewhere

(e.g. hybrid)

Primary resurfacing

arthroplasty of joint Total

No. % No. % No. % No. % No. %

Total hip primaries 25,316 33% 34,143 45% 15,907 21% 1,082 1% 76,448

Patient physical status

P1 - fit and healthy 2,433 10% 6,145 18% 2,011 13% 503 46% 11,092 15%P2 - mild disease not incapacitating

17,730 70% 23,860 70% 11,064 70% 545 50% 53,199 70%

P3 - incapacitating systemic disease

4,975 20% 4,019 12% 2,717 17% 34 3% 11,745 15%

P4 and P5 178 <1% 119 <1% 115 <1% 0 0% 412 <1%

BMI

Number with BMI data 17,084 67% 22,694 66% 10,775 68% 747 69% 51,300 67%

Average 28.35 29.08 28.54 28.09 28.71

SD 5.20 5.34 5.35 4.32 5.29

Indications for surgery

Osteoarthritis 23,123 91% 31,837 93% 14,192 89% 1,036 96% 70,188 92%

Avascular necrosis 570 2% 828 2% 486 3% 11 1% 1,895 2%

Fractured neck of femur 1,035 4% 645 2% 759 5% 1 0% 2,440 3%Congenital dislocation/Dysplasia of the hip

171 <1% 758 2% 254 2% 28 3% 1,211 2%

Inflammatory arthropathy 340 1% 409 1% 262 2% 10 <1% 1,021 1%

Failed hemiarthroplasty 60 <1% 45 <1% 67 <1% 0 0% 172 <1%

Trauma - chronic 370 1% 333 <1% 264 2% 15 1% 982 1%Previous surgery - non trauma related

47 <1% 142 <1% 60 <1% 1 <1% 250 <1%

Previous arthrodesis 16 <1% 14 <1% 10 <1% 0 0% 40 <1%

Previous infection 22 <1% 25 <1% 17 <1% 3 <1% 67 <1%

Other 379 1% 386 1% 288 2% 18 2% 1,071 1%

Side

Bilateral 42 <1% 228 <1% 80 <1% 14 1% 364 <1%

Left, unilateral 11,273 45% 15,487 45% 7,215 45% 529 49% 34,504 45%

Right, unilateral 14,001 55% 18,428 54% 8,612 54% 539 50% 41,580 54%



Table 2.5 Age and gender for primary hip replacement patients in 2012.


replacement using cement




replacement not classified elsewhere

(e.g. hybrid)

Primary resurfacing


No. % No. % No. % No. % No. %Total hip primaries

25,316 33% 34,143 45% 15,907 21% 1,082 1% 76,448

Total hip primaries with patient data

24,570 97% 32,827 96% 15,290 96% 958 89% 73,645 96%

Average age 73.1 65.2 70.0 53.4 68.7

SD 9.6 11.4 11.0 9.6 11.4Interquartile range

67.6 – 79.8 58.4 – 73.2 63.9 – 77.7 47.5 – 59.9 62.2 – 76.9

Average age by gender

Female 16,162 66% 18,176 55% 9,682 63% 120 13% 44,140 60%

Average 73.66 65.77 70.75 52.69 69.70


68.2 - 80.3 59.0 - 73.7 64.7 - 78.4 47.9 - 58.6 63.4 - 77.7

Male 8,408 34% 14,651 45% 5,608 37% 838 87% 29,505 40%

Average 72.14 64.48 68.75 53.52 67.20


66.5 - 78.9 57.7 - 72.5 62.4 - 76.1 47.4 - 60.2 60.4 - 75.6

Age group by gender

Female

<30 years 20 <1% 118 <1% 30 <1% 3 3% 171 <1%

30 - 39 years 63 <1% 287 2% 67 <1% 8 7% 425 <1%

40 - 49 years 204 1% 1,176 6% 306 3% 32 27% 1,718 4%

50 - 59 years 983 6% 3,390 19% 1,001 10% 53 44% 5,427 12%

60 - 69 years 3,777 23% 6,523 36% 2,838 29% 22 18% 13,160 30%

70 - 79 years 6,864 42% 5,051 28% 3,561 37% 1 <1% 15,477 35%

80 - 89 years 3,972 25% 1,558 9% 1,729 18% 1 <1% 7,260 16%

90+ 279 2% 73 <1% 150 2% 0 0% 502 1%

Male

<30 years 12 <1% 116 <1% 30 <1% 11 1% 169 <1%

30 - 39 years 39 <1% 298 2% 61 1% 52 6% 450 2%

40 - 49 years 182 2% 1,146 8% 261 5% 220 26% 1,809 6%

50 - 59 years 595 7% 3,013 21% 761 14% 339 40% 4,708 16%

60 - 69 years 2,278 27% 5,309 36% 1,708 30% 189 23% 9,484 32%

70 - 79 years 3,569 42% 3,761 26% 2,001 36% 24 3% 9,355 32%

80 - 89 years 1,638 19% 976 7% 752 13% 3 <1% 3,369 11%

90+ 95 1% 32 <1% 34 <1% 0 0% 161 <1%

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Table 2.6 Indications for hip primary procedure based on age groups.

Indication

<30 years30-39 years

40-49 years

50-59 years

60-69 years

70-79 years

80-89 years 90+

No. % No. % No. % No. % No. % No. % No. % No. %

Total hip primaries by age group

340 875 3,527 10,135 22,644 24,832 10,629 663

Osteoarthritis 150 44% 552 63% 2,996 85% 9,348 92% 21,219 94% 23,227 94% 9,756 92% 567 86%Avascular necrosis

81 24% 155 18% 237 7% 314 3% 394 2% 363 1% 245 2% 34 5%

Fractured neck of femur

4 1% 6 <1% 27 <1% 180 2% 598 3% 895 4% 450 4% 31 5%

Congenital dislocation/Dysplasia of the hip

75 22% 182 21% 333 9% 272 3% 194 <1% 68 <1% 17 <1% 1 <1%

Inflammatory arthropathy

31 9% 33 4% 100 3% 164 2% 312 1% 249 1% 94 <1% 8 1%

Failed hemi-arthroplasty

2 <1% 10 1% 7 <1% 20 <1% 43 <1% 67 <1% 16 <1% 0 0%

Trauma - chronic

12 4% 26 3% 81 2% 148 1% 236 1% 226 <1% 175 2% 27 4%

Previous surgery, non trauma related

23 7% 41 5% 58 2% 46 <1% 31 <1% 27 <1% 8 <1% 1 <1%

Previous arthrodesis

5 1% 1 <1% 4 <1% 5 <1% 12 <1% 6 <1% 5 <1% 1 <1%

Previous infection

8 2% 10 1% 7 <1% 9 <1% 13 <1% 14 <1% 4 <1% 0 0%

Indication other

41 12% 63 7% 128 4% 146 1% 215 <1% 248 1% 142 1% 23 3%

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Figure 2.4 Age and gender for primary hip replacement patients in 2012.

Resurfacing 2%

Hybrid 18%

Cementless 69%

Cemented 12%

Female

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

roce

dur

es

<30Age group

171 2%

16%

68%

15%30-39

4252%

18%

68%

12%40-49

1,718<1%

18%

62%

18%50-59

5,427<1%

22%

50%

29%60-69

13,160<1%

23%

33%

44%70-79

15,477<1%

24%

21%

55%80-89

7,2600%

30%

15%

56%90+

502Number of patients

Resurfacing 7%

Hybrid 18%

Cementless 69%

Cemented 7%

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

roce

dur

es

<30Age group

16912%

14%

66%

9%30-39

45012%

14%

63%

10%40-49

1,8097%

16%

64%

13%50-59

4,7082%

18%

56%

24%60-69

9,484<1%

21%

40%

38%70-79

9,355<1%

22%

29%

49%80-89

3,3690%

21%

20%

59%90+


Male

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Figure 2.5 Age for primary hip replacement patients between 2003 and 2012.

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

atie

nts

in

each

age

ban

d

50-5940-4930-39<30

90+80-8970-79

16%4%1%

2003

<1%

14,557

<1%13%33%31%

15%5%1%

2004

<1%

28,222

<1%13%33%31%60-69

Number ofpatients

Year

16%5%1%

2005

<1%

40,370

<1%13%34%31%

15%5%1%

2006

<1%

47,687

<1%13%34%30%

15%5%1%

2007

<1%

60,637

<1%13%34%31%

15%5%1%

2008

<1%

66,892

<1%13%34%30%

14%5%1%

2009

<1%

67,729

<1%14%34%30%

14%5%1%

2010

<1%

69,900

<1%14%34%30%

14%5%1%

2012

<1%

73,645

<1%14%34%31%

14%5%1%

2011

<1%

72,537

<1%14%34%31%

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Figure 2.6 ASA grades for primary hip replacement patients between 2003 and 2012.

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

atie

nts

P4 and P5P3P2P1

<1%9%

53%

2003

37%

26,435

<1%11%57%

2004

31%

48,061

<1%13%60%

2005

26%

57,594

<1%13%63%

2006

23%

59,967

<1%13%66%

2007

20%

67,322

<1%13%69%

2008

18%

70,559

<1%14%69%

2009

17%

70,908

<1%15%69%

2010

16%

73,006

<1%15%70%

2012

15%

76,448

<1%15%70%

2011

15%

75,461Number ofpatients

Year

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2.2.1.2 Surgical techniques

The surgical techniques used in procedures in 2012 are summarised in Table 2.7. Patients were mainly positioned laterally. The lateral position was used more frequently in hybrid and resurfacing procedures than in cemented and cementless procedures. As would be expected, the most frequently used incision approach was posterior for all procedure types, though for cemented procedure types there were nearly as

many procedures performed where a lateral (including Hardinge) approach was used.

The reduction in the use of cemented stems (from 77% in 2004 to 51% in 2012) and also in the use of cemented cups (from 56% to 36%) is consistent with the reduction seen in the overall number of cemented procedures and a corresponding increase in hybrid and cementless surgery. The change in 2012 appears to have been mainly caused by the rapid decline

Figure 2.7 BMI for primary hip replacement patients between 2004 and 2012.

25

26

27

28

30

29

BM

I

Per

cent

age

of p

atie

nts

0%

60%

50%

40%

30%

20%

10%

Year 2004 2005 2006 2007 2008 2010 2011

BMI 30-34

BMI 15-19

BMI 20-24

BMI 25-29

Average BMI- all patients

BMI 35-39

BMI 40-44

BMI 45+

2009

Average BMI- female

Average BMI- male

27.36

3%

27%

40%

21%

6%

2%

<1%

27.29

27.71

17%

5,919

27.47

3%

27%

40%

21%

6%

2%

<1%

27.15

27.87

16%

9,002

27.67

3%

25%

40%

21%

7%

2%

<1%

27.53

27.94

18%

10,473

27.91

3%

24%

40%

23%

8%

2%

<1%

27.77

28.16

21%

14,237

28.31

2%

21%

41%

25%

8%

2%

<1%

28.12

28.62

48%

33,842

28.43

2%

21%

40%

25%

9%

2%

<1%

28.22

28.72

56%

39,431

28.53

2%

20%

40%

25%

9%

2%

<1%

28.31

28.83

60%

43,679

28.60

2%

20%

40%

26%

9%

2%

<1%

28.40

28.92

64%

48,345

2012

28.71

2%

19%

40%

26%

10%

3%

<1%

28.49

29.04

67%

51,300

Percentage of prwith BMI

with BMI

ocedures


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in metal-on-metal procedures rather than a switch from one type of conventional hip replacement to another since 2004 (Figure 2.3). The relative usage of different types of bone cement is shown in Figure 2.8 and shows that the use of antibiotic cement has

increased from 73% in 2004 to 89% in 2012. Use of minimally-invasive surgery was greatest in cementless procedures, although it was used in less than 5% of all procedures (Table 2.7) which is the same as 2011.

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Table 2.7 Surgical technique for primary hip replacement patients in 2012.

Primary total

prosthetic replacement

using cement




replacement not classified

elsewhere (e.g. hybrid)

Primary resurfacing


No. % No. % No. % No. % No. %Total hip primaries

25,316 33% 34,143 45% 15,907 21% 1,082 1% 76,448

Patient position

Lateral 22,965 91% 31,864 93% 15,303 96% 1,077 100% 71,209 93%Supine 2,351 9% 2,279 7% 604 4% 5 <1% 5,239 7%

Incision Lateral (inc. Hardinge)

10,131 40% 10,878 32% 4,092 26% 133 12% 25,234 33%

Posterior 13,731 54% 21,185 62% 11,157 70% 916 85% 46,989 61%Trochanteric osteotomy

310 1% 26 <1% 11 <1% 13 1% 360 <1%

Other 1,144 5% 2,054 6% 647 4% 20 2% 3,865 5%

Minimally-invasive surgery

Yes 478 2% 2,884 8% 365 2% 14 1% 3,741 5%No 24,838 98% 31,259 92% 15,542 98% 1,068 99% 72,707 95%

Image-guided surgery

Yes 32 <1% 158 <1% 31 <1% 33 3% 254 <1%No 25,284 100% 33,985 100% 15,876 100% 1,049 97% 76,194 100%

Bone graft used - femur

Yes 173 <1% 400 1% 44 <1% 13 1% 630 <1%No 25,143 99% 33,743 99% 15,863 100% 1,069 99% 75,818 99%

Bone graft used - acetabular

Yes 1,014 4% 1,321 4% 841 5% 79 7% 3,255 4%No 24,302 96% 32,822 96% 15,066 95% 1,003 93% 73,193 96%


2.2.1.3 Thromboprophylaxis

Patients may receive more than one chemical and more than one mechanical thromboprophylaxis method. The most frequently prescribed chemical method of thromboprophylaxis for hip replacement patients was low molecular weight Heparin (LMWH), at 73%, and the most used mechanical method was TED stockings

(66%), (Table 2.8). There has been a marked decrease over the past years in the use of aspirin, 20% in 2009 to 8% in 2012. Direct thrombin inhibitor is now used in 13% of hip primary procedures and the use of ‘other chemical’ has gone up from 7% in 2009 to 13% in 2012. The number of procedures for which both chemical and mechanical methods were prescribed has continued to rise from 63% in 2007 to 92% in 2012.

Figure 2.8 Bone cement types for primary hip replacement procedures undertaken between 2004 and 2012.


0%

50%

40%

30%

20%

10%

60%

70%

80%

90%

Year

Per

cent

age

of p

roce

dur

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Antibiotic-loadedhigh viscosity

Antibiotic-loadedmedium viscosity

Antibiotic-loadedlow viscosity

High viscosity

Medium viscosity

Low viscosity

34,497

62%

2004

6%

5%

7%

19%

<1%

40,473

65%

2005

7%

4%

6%

17%

<1%

40,544

65%

2006

8%

3%

6%

18%

<1%

44,334

65%

2007

9%

3%

5%

17%

<1%

43,362

68%

2008

9%

3%

5%

15%

<1%

41,108

74%

2010

10%

2%

4%

11%

<1%

43,789

79%

2012

9%

1%

2%

8%

<1%

43,359

77%

2011

9%

1%

3%

9%

<1%

41,514

70%

10%

2%

5%

13%

<1%

2009

using cement

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2.2.1.4 Untoward intra-operative events

Untoward intra-operative events were reported in 1.3% of procedures (Table 2.9). Of the 999 untoward events reported, a decrease of 9 events compared with 2011, 33% were attributed to calcar crack.

As would be expected, this occurred more often in cementless than in cemented hips. Furthermore, 16% were trochanteric fractures, also more common in cementless procedures. 36% of events were of ‘other’ description.

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Table 2.8 Thromboprophylaxis regime for primary hip replacement patients, prescribed at time of operation.

Total

No. %

Total hip primaries 76,448

Aspirin 6,124 8%

Low molecular weight Heparin (LMWH) 55,713 73%

Pentasaccharide 1,148 2%Warfarin 557 <1%

Direct thrombin inhibitor 10,203 13%Other chemical 9,583 13%

No chemical 2,143 3%Foot pump 20,159 26%

Intermittent calf compression 33,052 43%TED stockings 50,713 66%

Other mechanical 2,272 3%No mechanical 3,679 5%

Both mechanical and chemical 70,700 92%Neither mechanical nor chemical 36 <1%

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Table 2.9 Reported untoward intra-operative events for primary hip replacement patients in 2012, according to procedure type.

Primary total


using cement






Primary resurfacing


No. No. No. No. No.

Total hip primaries 25,316 34,143 15,907 1,082 76,448

Event specified 273 517 206 3 999

Calcar crack 28 239 61 0 328

Pelvic penetration 44 24 19 0 87

Shaft fracture 13 22 11 0 46

Shaft penetration 6 14 1 0 21

Trochanteric fracture 56 61 39 0 156

Other 126 157 75 3 361


2.2.1.5 Hip primary components

This section outlines in more detail the trends in brand usage for hips. For a full listing of brands used in 2012, please visit the NJR website at www.njrcentre.org.uk. This section also includes an analysis of usage according to National Institute for Health and Care Excellence (NICE) guidelines, as interpreted by the Orthopaedic Data Evaluation Panel (ODEP).

2.2.1.5.1 Compliance with ODEP and NICE guidelines

In 2012, 101 brands of acetabular cup, 8 brands of resurfacing cup and 146 brands of femoral stem were used in primary and revision procedures and recorded on the NJR. This is a decrease in the number of brands of acetabular cup and stem in use compared with 2011.

The 2nd NJR Annual Report in 20047 gave a full description of the NICE guidance on the selection of prostheses for primary THRs and metal-on-metal hip resurfacing arthroplasty. It also described the establishment of ODEP. Its remit is to provide an independent assessment of clinical evidence, submitted by suppliers, on the compliance of their implants for THR and hip resurfacing against NICE benchmarks for safety and effectiveness. ODEP produced detailed criteria for this guidance which is currently under review as part of a complete overhaul of the system.

The ODEP committee have reviewed suppliers’ clinical data submissions and ODEP ratings have been given to 69 brands of femoral stem (50% of those available) and 49 brands of acetabular cup (49%) used in primary procedures. However, there are 39 brands of acetabular cup (39%) and 46 brands of femoral stem (33%) currently being used in England and Wales for which no data has yet been submitted to ODEP. It should be noted however that some of this usage relates to stems designed for revision surgery being used in primary procedures for unspecified reasons. Revision brands are not covered by NICE guidance

nor the ODEP process. The latest listings for brands currently being used in England and Wales can be seen on the ODEP website:

www.odep.org.uk

Analysis of primary procedures shows that the use of products meeting the full 10 year (10A) benchmark, as recommended by NICE, is as follows:

•Cemented stems 88% (using 14 brands out of 47 recorded on the NJR)

•Cementless stems 69% (17 brands out of 91)

•Cemented cups 34% (10 brands out of 43)

•Cementless cups 3% (7 brands out of 57)

•Resurfacing cups 63% (1 brand out of 9)

These percentages are based on the latest ODEP ratings from clinical outcomes data already submitted to the ODEP committee and published in February 2013. Manufacturers are expected to submit additional data to progress through the ratings and this will result in these percentages changing in the future.

Comparison with the 2011 figures shows that use of cemented and cementless stems achieving the 10-year benchmark has not changed significantly. Usage of cementless stems achieving the 10-year benchmark is 69% (a decrease of 3% on last year). However, the percentage for cementless cups achieving 10-year benchmark was 3%.

2.2.1.5.2 Hip brand usage in primary procedures

Figures 2.9 to 2.13 show historical trends in the usage of the most popular brands of cemented stems, cemented cups, cementless stems, cementless cups and hip resurfacing cups.

Figure 2.9 shows that the market is dominated by polished collarless tapered stems, with the Exeter V40 having a market share of more than 66% and the CPT stem continuing to consolidate its position in second place.

7 See pages 86 to 92 of the 2nd NJR Annual Report, available on the NJR website www.njrcentre.org.uk.



Figure 2.9 Top five cemented hip stem brands, trends 2003 to 2012.

Figure 2.10 Top five cemented hip cup brands, trends 2003 to 2012.

2004

31,844

2003

18,944Number ofcomponents used

2005

35,608

2006

34,140

2007

35,912

2008

34,004

2009

32,983

2010

33,898

2012

38,406

2011

36,222

Year

0%

70%

60%

50%

40%

30%

20%

10%

Per

cent

age

of p

roce

dur

es

Exeter V40

CPTC-Stem AMTCemented Stem

C-Stem Cemented Stem

Charnley Cemented Stem

2004

25,540

2003


2005

27,870

2006

25,648

2007

27,051

2008

25,335

2009

24,048

2010

24,276

2012

26,975

2011

25,826

Year

0%

40%

30%

35%

25%

20%

15%

10%

5%Per

cent

age

of p

roce

dur

es

ContemporaryElite PlusOgee

Elite Plus Cemented Cup

MarathonExeter Rim�t

The trend for cemented cups (Figure 2.10) continues to show that sales of different brands are in line with the popularity of the stem manufacturer. The only

significant change being a proportion of Exeter stem users switching from the Contemporary to the Exeter Rimfit cup, both manufactured by Stryker.

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The relative sales of cementless stem brands (Figure 2.11) are very similar to the previous year, with press-fit HA coated stems continuing to dominate the

market. The Corail prosthesis continues to maintain its position as market leader.

Figure 2.11 Top five cementless hip stem brands, trends 2003 to 2012.

2004

10,771

2003


2005

15,163

2006

18,551

2007

23,698

2008

29,411

2009

32,323

2010

34,921

2012

36,808

2011

35,885

Year

0%

50%

40%

30%

20%

10%

Per

cent

age

of p

roce

dur

es

CorailFurlongHAC Stem

Accolade TaperlocCementless Stem

M/L TaperCementless

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The cementless stem market share has again reflected the sales of the corresponding cementless cups from the same manufacturers, which means that the Pinnacle cup from DePuy has retained its position as the market leader (Figure 2.12) despite appearing to lose some share to other brands, notably the

Exceed ABT from Biomet. More information on the other brands used can be found in the document ‘Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2012’ which can be downloaded from the NJR website.

Figure 2.12 Top five cementless hip cup brands, trends 2003 to 2012.

2004

16,417

2003


2005

21,186

2006

24,175

2007

28,826

2008

34,367

2009

39,392

2010

44,296

2012

47,656

2011

46,554

Year

0%

40%

30%

35%

25%

15%

20%

5%

10%

Per

cent

age

of p

roce

dur

es

Pinnacle Trident TrilogyExceed ABT CSF Plus

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Figure 2.13 Top five resurfacing head brands, trends 2003 to 2012.

2004

5,031

2003


2005

6,230

2006

6,502

2007

6,701

2008

5,798

2009

4,358

2010

2,689

2012

1,075

2011

1,883

Year

0%

90%

80%

70%

60%

50%

40%

30%

20%

10%Per

cent

age

of p

roce

dur

es

BHR ResurfacingHead

Adept ResurfacingHead

Cormet 2000Resurfacing Head

Recap ResurfacingHead

AccisResurfacingHead

2.2.1.5.3 Trends in head size use

Figure 2.14 shows the relative usage of different femoral head sizes (for all femoral heads used in conjunction with a femoral stem) each year since the inception of the NJR. It is immediately clear that there has been a gradual increase in the use of larger head sizes (36mm diameter and above). However, between 2010 and 2012 this had been reversed slightly. This trend accurately reflects the trends in usage of LHMoM prostheses during the lifetime of the NJR.

2.2.1.5.4 Trends in hip articulation

Figure 2.15 shows the change in hip articulation types since the inception of the NJR. Only those procedures where complete articulation surfaces can be derived are included. The most interesting observation being the huge rise in the use of ceramic-on-ceramic bearings, from small numbers in 2003 to over 17,000 in 2012, though this has remained steady over the past year. This growth would appear to have been mainly at the expense of metal-on-metal bearings.

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Figure 2.13 shows the sales evolution of brands of hip resurfacing prostheses in the English and Welsh markets. It is evident that the previous trend towards a decline in the usage of the original brands has continued to reverse. The market share of the BHR brand increased significantly during the course of

2012, at the expense of all other brands reflecting its clinical performance when measured against most of its competitors. However, it should be noted that this is against a background of an ongoing decline in the overall volume of resurfacing hip replacement.



Figure 2.14 Femoral head size, trends 2003 to 2012.

Figure 2.15 Hip articulation, trends 2003 to 2012.

2004

36,137

2003

18,889Number of modularheads components used

2005

45,078

2006

48,497

2007

56,472

2008

61,674

2009

63,875

2010

67,853

2012

74,176

2011

71,247

Year

0%

100%

80%

60%

40%

20%

Per

cent

age

of p

roce

dur

es

22.25mm 26mm 28mm

36mm 38-44mm 46+mm

30mm 32mm 34mm

2004

46,566

2003

25,344Number of procedureswith hip articulationdetails

2005

55,748

2006

58,293

2007

65,629

2008

68,878

2009

69,457

2010

71,450

2011

73,844

2012

75,897

Year

0

45,000

50,000

40,000

35,000

30,000

25,000

20,000

15,000

10,000

5,000

Num

ber

of p

roce

dur

es

Metal-on-poly

Ceramic-on-ceramic

Ceramic-on-poly

Metal-on-metal

Ceramic-on-metal

Metal-on-ceramic*

* This combination is contra-indicated

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2.2.2 Hip revision procedures 2012

A total of 10,040 hip revision procedures were reported in 2012, an increase of 1,401 compared with 2011. Table 2.10 shows that of these, 8,812 (88%) were single-stage revision procedures, 560 (6%) were stage one of a two-stage process, 611 (6%) procedures were stage two of a two-stage revision and 57 (<1%) were excision arthroplasty procedures. Infection as an indication for revision has increased to 12% of the total.


Table 2.10 summarises patient characteristics for the 10,040 hip revision procedures undertaken in 2012. Compared with 2011, the patient demographics have largely remained unchanged, though there was a slight increase in the average age in each procedure type

(with the exception of excision arthroplasty). However, the percentage of patients who were graded as being fit and healthy prior to surgery has decreased from 26% in 2003 to 10% in 2012.

Aseptic loosening has continued its decrease as a reason for revision compared with previous years. Adverse soft tissue reaction was noted for 13% of all revision procedures (Table 2.10). However, this option was added in July 2009 so it is not possible to tell if this increase is actual or due to a delay in the usage of the new MDS H2 data forms. More than one indication for revision may be given.



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Table 2.10 Patient characteristics for hip revision procedures in 2012, according to procedure type.

Hip single-

stage revision

Hip stage one of two-stage

revision

Hip stage two of two-stage

revision Hip excision arthroplasty

Total revision procedures

No. % No. % No. % No. % No. %

Total revision procedures 8,812 88% 560 6% 611 6% 57 <1% 10,040

Number with patient data 8,475 96% 551 98% 599 98% 51 89% 9,676 96%

Average age 70.0 69.5 68.9 71.3 69.8

SD 12.0 11.3 11.4 13.2 12.0

Interquartile range62.8 -

78.663.0 -

77.663.4 -

77.365.6 -

80.262.9 -

78.4Gender

Female 4,926 58% 269 49% 275 46% 27 53% 5,497 57%

Male 3,549 42% 282 51% 324 54% 24 47% 4,179 43%


P1 - fit and healthy 894 10% 28 5% 45 7% 2 4% 969 10%P2 - mild disease not incapacitating

5,604 64% 330 59% 362 59% 20 35% 6,316 63%


2,180 25% 186 33% 194 32% 28 49% 2,588 26%

P4 and P5 134 2% 16 3% 10 2% 7 12% 167 2%


Aseptic loosening 3,881 44% 62 11% 54 9% 11 19% 4,008 40%

Lysis 1,227 14% 44 8% 32 5% 8 14% 1,311 13%

Pain 2,219 25% 72 13% 51 8% 9 16% 2,351 23%

Dislocation/subluxation 1,207 14% 22 4% 19 3% 9 16% 1,257 13%

Periprosthetic fracture 797 9% 15 3% 27 4% 1 2% 840 8%

Infection 288 3% 455 81% 443 73% 36 63% 1,222 12%

Malalignment 450 5% 6 1% 4 <1% 0 0% 460 5%

Fractured acetabulum 97 1% 3 <1% 0 0% 1 2% 101 1%

Fractured stem 151 2% 4 <1% 3 <1% 0 0% 158 2%

Fractured femoral head 28 <1% 0 0% 0 0% 0 0% 28 <1%

Incorrect sizing head/socket 61 <1% 0 0% 0 0% 1 2% 62 <1%Wear of acetabular component

1,177 13% 12 2% 10 2% 0 0% 1,199 12%

Dissociation of liner 133 2% 7 1% 16 3% 2 4% 158 2%

Adverse soft tissue reaction 1,286 15% 25 4% 19 3% 0 0% 1,330 13%

Other 819 9% 19 3% 57 9% 4 7% 899 9%

Side

Bilateral 4 <1% 0 0% 0 0% 0 0% 4 <1%

Left, unilateral 4,078 46% 285 51% 303 50% 26 46% 4,692 47%

Right, unilateral 4,730 54% 275 49% 308 50% 31 54% 5,344 53%


2.2.2.2 Components removed and components used

Both the acetabular and femoral components were removed in approximately half of all revision procedures (Table 2.12). However, comparison of the different types of revision procedures indicates that both

components were more likely to be removed during a two-stage revision process than during a single-stage revision. This is expected since the majority of two-stage revisions are carried out for reasons of infection, where all components are routinely removed. The components used during single-stage revision procedures are shown in Table 2.13.

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Table 2.11 Indication for surgery for hip revision procedures 2008 to 2012.

2008 2009 2010 2011 2012 Total

No. % No. % No. % No. % No. % No. %Indications for single-stage revisionNumber of procedures 6,421 17% 6,610 18% 7,375 20% 8,201 22% 8,812 24%

37,419

Aseptic loosening 3,809 59% 3,654 55% 3,700 50% 3,776 46% 3,881 44% 18,820 50%

Pain 1,746 27% 2,032 31% 2,000 27% 2,114 26% 2,219 25% 10,111 27%

Lysis 1,108 17% 997 15% 1,104 15% 1,112 14% 1,227 14% 5,548 15%Adverse soft tissue reaction to particle debris

1 <1% 86 1% 410 6% 982 12% 1,286 15% 2,765 7%

Infection 173 3% 192 3% 236 3% 264 3% 288 3% 1,153 3%

Indications for stage one of a two-stage revisionNumber of procedures 456 17% 554 21% 529 20% 549 21% 560 21% 2,648 Infection 366 80% 440 79% 422 80% 448 82% 455 81% 2,131 80%

Pain 87 19% 103 19% 110 21% 78 14% 72 13% 450 17%

Aseptic loosening 89 20% 84 15% 72 14% 56 10% 62 11% 363 14%

Lysis 58 13% 50 9% 52 10% 43 8% 44 8% 247 9%

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Table 2.12 Components removed during hip revision procedures in 2012.

Hip single-stage

revision Hip stage one of a two-stage revision

Hip excision arthroplasty Total

No. % No. % No. % No. %

Total 8,812 560 57 9,429

Both cup and stem 3,986 45% 470 84% 40 70% 4,496 48%Acetabular cup only 2,662 30% 23 4% 3 5% 2,688 29%

Femoral stem only 1,275 14% 31 6% 10 18% 1,316 14%Neither cup nor stem 889 10% 36 6% 4 7% 929 10%



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Table 2.13 Components used during single-stage hip revision procedures in 2012.

Hip single-stage revision

Number of procedures %

Total 8,812

Femoral prosthesis

Cemented 2,482 28%Cementless 2,569 29%

Not revised 3,761 43%

Acetabular prosthesis

Cemented 1,569 18%Cementless 5,090 58%

Not revised 2,153 24%

2.3 Knee replacement procedures 2012

Part 2



The total number of knee replacement procedures entered into the NJR during 2012 was 90,842, an increase of 7.3% compared with 2011. Of the 90,842 procedures submitted, 84,833 were primary procedures and 6,009 were revision procedures. Table 2.14 summarises the patient characteristics and details of knee replacement procedures according to type of provider.

As a percentage of their activity, ISTCs performed more unicondylar knee replacement procedures (Figure 2.16) than any other type of provider and NHS hospitals performed more cemented bicondylar knee procedures than any other provider. The revision procedures undertaken at NHS hospitals comprised 85% of all revision procedures performed.

8 Bilaterals will only be counted as a bilateral if they are entered under the same single operation during data entry. If the two procedures are recorded under two different operations they will be counted as two unilateral procedures. Therefore, the count of bilaterals is likely to be an underestimate.

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Table 2.14 Procedure details, according to type of provider for knee procedures in 2012.

NHS hospitalsIndependent

hospitals ISTC TotalNo. % No. % No. % No. %

Total knee procedures 63,679 70% 23,501 26% 3,662 4% 90,842


P1 - fit and healthy 5,320 8% 3,873 16% 369 10% 9,562 11%P2 - mild disease not incapacitating

45,825 72% 17,784 76% 3,015 82% 66,624 73%


12,217 19% 1,829 8% 276 8% 14,322 16%

P4 and P5 317 <1% 15 <1% 2 <1% 334 <1%

Procedure type

Primary procedures 58,556 69% 22,749 27% 3,528 4% 84,833 93%Total prosthetic replacement using cement

51,703 88% 18,597 82% 3,040 86% 73,340 86%

Total prosthetic replacement not using cement

1,823 3% 887 4% 1 <1% 2,711 3%

Hybrid total knee 335 <1% 103 <1% 8 <1% 446 <1%

Patello-femoral replacement 815 1% 420 2% 36 1% 1,271 1%

Unicondylar knee replacement 3,880 7% 2,742 12% 443 13% 7,065 8%

Revision procedures 5,123 85% 752 13% 134 2% 6,009 7%

Knee single-stage revision 3,900 76% 657 87% 118 88% 4,675 78%Knee stage one of two-stage revision

548 11% 42 6% 11 8% 601 10%

Knee stage two of two-stage revision

649 13% 52 7% 5 4% 706 12%

Knee conversion to arthrodesis 20 <1% 1 <1% 0 0% 21 <1%

Amputation 6 <1% 0 0% 0 0% 6 <1%

Bilateral or unilateral8

Bilateral 668 1% 374 2% 46 1% 1,088 1%

Unilateral 63,011 99% 23,127 98% 3,616 99% 89,754 99%

Funding

Independent 511 <1% 8,995 38% 16 <1% 9,522 10%

NHS 63,168 99% 14,506 62% 3,646 100% 81,320 90%


Figure 2.16 Primary knee procedures by type of provider 2012.

0%

20%

40%

60%

80%

100%

Type of provider

Per

cent

age

of p

roce

dur

e ty

pe

Cemented

Cementless

Hybrid

Unicondylar

Patello-femoral

88%

3%

<1%

7%

1%

58,556

NHS hospitals

82%

4%

<1%

12%

2%

22,749

Independenthospitals

86%

<1%

<1%

13%

1%

3,528

ISTCs


2.3.1 Primary knee replacement procedures 2012

Of the 84,883 primary knee replacements undertaken in 2012, 76,497 (90%) were bicondylar procedures (TKR), 7,065 (8%) were unicondylar knee replacements and 1,271 (1%) were patello-femoral replacements (Table 2.15). Compared with previous years, these proportions have largely remained the same (Figure 2.17) though there has been a slight increase in cemented TKR at the expense of cementless TKR over the past four years. Figure 2.18 is based on total condylar knee

replacements where the meniscal implant has been specified. The usage of unconstrained fixed implants has increased gradually over the past six years at the expense of unconstrained mobile constructs. Figure 2.19 shows that the usage of fixed constraint implants has increased since 2006.

The single largest indication recorded for surgery was osteoarthritis, recorded in 98% of all primary procedures (Table 2.15). All other indications were recorded at 1% or less.

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Table 2.15 Patient characteristics for primary knee replacement procedures in 2012, according to procedure type.

Primary total


using cement


replacement not using

cement




Patello-femoral

replacementUnicondylar replacement Total

No. % No. % No. % No. % No. % No. %

Total knee primaries 73,340 86% 2,711 3% 446 <1% 1,271 1% 7,065 8% 84,833


P1 - fit and healthy 6,881 9% 280 10% 46 10% 309 24% 1,574 22% 9,090 11%P2 - mild disease not incapacitating

54,368 74% 2,092 77% 324 73% 864 68% 4,947 70% 62,595 74%


11,840 16% 333 12% 74 17% 97 8% 536 8% 12,880 15%

P4 and P5 251 <1% 6 <1% 2 <1% 1 <1% 8 <1% 268 <1%

BMINumber with BMI data

51,084 70% 1,577 58% 306 69% 865 68% 5,282 75% 59,114 70%

Average 30.92 31.02 31.25 30.02 30.00 30.83

SD 5.54 5.13 5.35 5.17 4.81 5.47


Osteoarthritis 71,384 97% 2,683 99% 428 96% 1,238 97% 6,987 99% 82,720 98%

Avascular necrosis 223 <1% 3 <1% 3 <1% 3 <1% 55 <1% 287 <1%Inflammatory arthropathy

500 <1% 11 <1% 2 <1% 2 <1% 4 <1% 519 <1%

Previous infection 64 <1% 2 <1% 0 0% 0 0% 1 <1% 67 <1%

Rheumatoid arthritis 1,108 2% 15 <1% 4 <1% 1 <1% 5 <1% 1,133 1%

Previous trauma 413 <1% 9 <1% 8 2% 5 <1% 25 <1% 460 <1%

Other 507 <1% 9 <1% 9 2% 32 3% 45 <1% 602 <1%

Side

Bilateral 667 <1% 24 <1% 7 2% 90 7% 292 4% 1,080 1%

Left, unilateral 34,293 47% 1,269 47% 203 46% 504 40% 3,373 48% 39,642 47%

Right, unilateral 38,380 52% 1,418 52% 236 53% 677 53% 3,400 48% 44,111 52%


Figure 2.17 Type of primary knee replacement procedures undertaken between 2006 and 2012.

0%

20%

40%

60%

80%

100%

Year

Per

cent

age

of p

roce

dur

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TKR using cement

TKR not usingcement

TKR Hybrid

Patello-femoral

UnicondylarNumber of procedures

83%

7%

1%

1%

8%

62,430

2006

83%

6%

1%

1%

8%

73,767

2007

83%

6%

1%

1%

8%

77,754

2008

83%

6%

1%

1%

8%

79,071

2009

85%

5%

<1%

1%

8%

81,427

2010

86%

4%

<1%

1%

8%

84,230

2011

86%

3%

<1%

1%

8%

84,833

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Figure 2.18 Implant constraint for bicondylar primary knee replacement procedures between 2006 and 2012.

0%

20%

40%

60%

80%

Year

Per

cent

age

of p

roce

dur

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Constrainedcondylar

Posteriorstabilised, �xed

Posteriorstabilised, mobile

Unconstrained,�xed

Unconstrained,mobile

Hinged/linked


<1%

24%

2%

62%

11%

<1%

54,968

<1%

24%

2%

63%

11%

<1%

64,884

<1%

24%

2%

64%

10%

<1%

68,502

<1%

25%

2%

65%

8%

<1%

69,852

<1%

25%

2%

66%

7%

<1%

71,956

<1%

25%

1%

67%

6%

<1%

74,787

<1%

23%

1%

70%

5%

<1%

76,140

2006 2007 2008 2009 2010 2011 2012

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Figure 2.19 Bearing type for unicondylar implant used in primary knee replacement procedures undertaken between 2006 and 2012.

0%

10%

20%

30%

40%

50%

60%

70%

80%

Year

Per

cent

age

of p

roce

dur

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Fixed

Mobile

Number of procedures*

25%

75%

5,723

23%

77%

6,639

24%

76%

7,017

26%

74%

7,105

30%

70%

7,460

31%

69%

7,260

36%

64%

7,095

2006 2007 2008 2009 2010 2011 2012

* This is the number of procedures using a unicondylar meniscal implant regardless of patient procedure selected


According to the ASA grade system, 11% of patients undergoing a primary knee replacement procedure were graded as fit and healthy (Table 2.15).

The average age of patients was 69.3 years and 57% were female. Patients undergoing a patello-femoral replacement were the youngest, at an average age of 59.7 years and 73% of these were female (Table 2.16). On average, female patients were of a similar age to male patients at the time of their primary knee replacement (69.5 years and 68.9 years respectively), see Table 2.16. However, female patients were, on average, older than male patients for cementless, cemented and hybrid procedures but younger for patello-femoral and unicondylar procedures.

Figure 2.21 shows the trend in ASA grade over the past ten years. Since 2003, similar to the data trend for total hip replacement, there has been a reduction in the

number of patients assessed as being fit and healthy at the time of operation and an increase in P2 and P3 status of patients. Figure 2.22 shows the increase in BMI9 over the past nine years for patients having primary knee procedures. This figure has progressively increased from 29.2 to 30.8 over the period. There has been a slight decrease in BMI for female patients whereas the BMI of male patients has continued to increase. It also shows that there has been a steady increase in the number of patients within the BMI range 30 to 34 and 35 to 39 and a decrease within the ranges 20 to 24 and 25 to 29. The average knee replacement patient in 2012, by BMI measurement, was clinically obese. It is interesting to note that the profile of Figure 2.22 is significantly different to the equivalent chart for hips, Figure 2.7.

However, only 16% of entries in 2004 had BMI data entered and while this has increased to 70% in 2012 all BMI data has to be viewed with caution as surgeons may be more likely to enter BMI data when the BMI is high, introducing an element of bias.

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9 BMI: 20-24 normal, 25-29 overweight, 30-39 obese, 40+ morbidly obese.



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Table 2.16 Age and gender for primary knee replacement patients in 2012.

Primary total


using cement



cement




Patello-femoral


No. % No. % No. % No. % No. % No. %

Total knee primaries 73,340 86% 2,711 3% 446 <1% 1,271 1% 7,065 8% 84,833 Total knee primaries with patient data

71,022 97% 2,674 99% 429 96% 1,207 95% 6,659 94% 81,991 97%

Average Age 70.01 68.51 68.24 59.74 63.59 69.30

SD 9.36 9.51 10.57 11.74 9.92 9.68

Interquartile Range 63.9 -

76.862.0 -

75.661.1 -

75.951.3 -

67.856.5 -

70.263.0 -

76.3 Average age by gender

Female 41,007 58% 1,318 49% 215 50% 888 74% 3,064 46% 46,492 57%

Average age 70.26 68.91 68.60 59.05 62.95 69.50

SD 9.49 9.66 11.34 11.60 10.13 9.87


77.262.1 -

76.360.0 -

76.750.6 -

67.155.6 -

70.063.0 -

76.7 Male 30,015 42% 1,356 51% 214 50% 319 26% 3,595 54% 35,499 43%

Average age 69.69 68.15 67.98 61.64 64.16 68.90

SD 9.18 9.35 9.80 11.98 9.72 9.45


76.261.9 -

75.161.9 -

74.953.7 -

69.357.3 -

70.063.0 -

75.7Age group by gender

Female

<30 years 16 <1% 1 <1% 0 0% 2 <1% 3 <1% 22 <1 %

30 - 39 years 60 <1% 1 <1% 1 <1% 27 3% 15 <1% 104 <1 %

40 - 49 years 805 2% 38 3% 11 5% 170 19% 307 10% 1,331 3%

50 - 59 years 5,025 12% 192 15% 39 18% 296 33% 887 29% 6,439 14%

60 - 69 years 13,503 33% 464 35% 66 31% 226 25% 1,083 35% 15,342 33%

70 - 79 years 15,145 37% 455 35% 61 28% 127 14% 622 20% 16,410 35%

80 - 89 years 6,187 15% 163 12% 33 15% 40 5% 146 5% 6,569 14%

90+ 266 <1% 4 <1% 4 2% 0 0% 1 <1% 275 <1%

Male

<30 years 6 <1% 0 0% 0 0% 2 <1% 0 0% 8 <1%

30 - 39 years 36 <1% 1 <1% 2 <1% 6 2% 16 <1% 61 <1%

40 - 49 years 653 2% 44 3% 6 3% 43 13% 248 7% 994 3%

50 - 59 years 3,665 12% 209 15% 28 13% 98 31% 922 26% 4,922 14%

60 - 69 years 10,756 36% 508 37% 91 43% 94 29% 1,449 40% 12,898 36%

70 - 79 years 11,023 37% 456 34% 63 29% 54 17% 767 21% 12,363 35%

80 - 89 years 3,737 12% 136 10% 24 11% 19 6% 187 5% 4,103 12%

90+ 139 <1% 2 <1% 0 0% 3 <1% 6 <1% 150 <1%


Figure 2.20 Age and gender for primary knee replacement patients in 2012.

Patello-femoral

TKR hybrid

TKR not usingcement

TKR using cement

Female

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

roce

dur

es

Age group

Unicondylar9%

0%

5%

73%<30

14%

22

30-39

26%

<1%

<1%

58%

14%

104

40-49

13%

<1%

3%

60%

23%

1,331

50-59

5%

<1%

3%

78%

14%

6,439

60-69

1%

<1%

3%

88%

7%

15,342

70-79

<1%

<1%

3%

92%

4%

16,410

80-89

<1%

1%

2%

94%

2%

6,569

90+

0%

1%

1%

97%

<1%


Male

Patello-femoral

TKR hybrid

TKR not usingcement

TKR using cement

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

roce

dur

es

Age group

Unicondylar25%

0%

0%

75%<30

0%

8

30-39

10%

3%

2%

59%

26%

61

40-49

4%

<1%

4%

66%

25%

994

50-59

2%

<1%

4%

74%

19%

4,922

60-69

<1%

<1%

4%

83%

11%

12,898

70-79

<1%

<1%

4%

89%

6%

12,363

80-89

<1%

<1%

3%

91%

5%

4,103

90+

2%

0%

1%

93%

4%


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Figure 2.21 ASA grades for primary knee replacement patients between 2003 and 2012.

0%

20%

40%

60%

80%

100%

Per

cent

age

of p

roce

dur

es

P4 and P5P3P2P1

<1%10%58%

2003

31%

24,665

<1%13%62%

2004

25%

46,596

<1%14%65%

2005

20%

60,767

<1%14%68%

2006

17%

62,430

<1%14%71%

2007

15%

73,767

<1%13%73%

2008

13%

77,754

<1%15%72%

2009

13%

79,071

<1%15%73%

2010

12%

81,427

<1%15%74%

2012

11%

84,833

<1%15%73%

2011

11%

84,230Number ofprocedures

Year

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Figure 2.22 BMI for primary knee replacement patients between 2004 and 2012.

25

32

30

31

29

28

27

26

BM

I

Per

cent

age

of p

atie

nts

0%

35%

30%

20%

25%

50%

40%

45%

10%

5%

15%

Percentage of prwith BMI

with BMI

ocedures


Year

BMI 30-34

BMI 15-19

BMI 20-24

BMI 25-29

Average BMI- all patients

BMI 35-39

BMI 40-44

BMI 45+

Average BMI- female

Average BMI- male

2004

29.25

1%

17%

38%

28%

11%

3%

1%

30.01

28.77

16%

5,509

2005

29.45

1%

14%

40%

29%

12%

3%

1%

29.96

28.91

15%

9,101

2006

29.53

1%

15%

38%

29%

11%

3%

1%

29.97

28.96

17%

10,579

2007

29.85

<1%

14%

37%

30%

13%

4%

1%

30.32

29.25

22%

16,110

2008

30.28

<1%

12%

36%

31%

14%

4%

1%

30.73

29.69

49%

38,207

2009

30.54

<1%

11%

36%

32%

15%

5%

2%

31.04

29.88

57%

45,200

2010

30.66

<1%

10%

35%

32%

15%

5%

2%

31.16

30.03

61%

49,930

2011

30.81

<1%

10%

35%

32%

16%

5%

2%

31.34

30.14

66%

55,409

2012

30.83

<1%

10%

34%

33%

16%

5%

2%

31.29

30.23

70%

59,114


The most common surgical approach was the medial parapatellar, used in 93% of procedures (Table 2.17). Minimally-invasive surgery (MIS) was used in 46% of unicondylar knee replacement procedures, reflecting the popularity of the Oxford Partial Knee, but was used in only 2% of all other types of knee replacement intervention. For cemented knee procedures, 38% had the patella replaced at the time of the primary procedure whereas only 7% of patellas were replaced during primary cementless knee procedures.

Compared with previous years, the surgical techniques used in primary knee replacements have largely remained unchanged. However, there has been an increase in the use of MIS in unicondylar knee replacements, from 37% in 2004 to 46% in 2012.

The use of bone cement in primary knee procedures is summarised in Figure 2.23.

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Table 2.17 Characteristics of surgical practice for primary knee replacement procedures in 2012, according to procedure type.

Primary total


using cement



cement




Patello-femoral replacement

Unicondylar replacement Total

No. % No. % No. % No. % No. % No. %Total knee primaries

73,340 86% 2,711 3% 446 <1% 1,271 1% 7,065 8% 84,833

Surgical approachLateral parapatellar

590 <1% 20 <1% 8 2% 14 1% 242 3% 874 1%

Medial parapatellar

68,359 93% 2,583 95% 352 79% 1,178 93% 6,193 88% 78,665 93%

Mid-Vastus 2,317 3% 54 2% 19 4% 35 3% 268 4% 2,693 3%

Sub-Vastus 1,281 2% 10 <1% 64 14% 22 2% 209 3% 1,586 2%

Other 793 1% 44 2% 3 <1% 22 2% 153 2% 1,015 1%

PatellaPatella implanted

27,819 38% 190 7% 123 28% 1,231 97% 60 1% 29,423 35%

Patella not implanted

45,521 62% 2,521 93% 323 72% 40 3% 7,005 99% 55,410 65%

Minimally-invasive surgery

Yes 1,750 2% 99 4% 7 2% 158 12% 3,222 46% 5,236 6%

No 71,590 98% 2,612 96% 439 98% 1,113 88% 3,843 54% 79,597 94%


Yes 2,169 3% 206 8% 25 6% 3 <1% 67 1% 2,470 3%

No 71,171 97% 2,505 92% 421 94% 1,268 100% 6,998 99% 82,363 97%

Bone graft used - femur

Yes 521 <1% 15 <1% 3 <1% 0 0% 22 <1% 561 <1%

No 72,819 99% 2,696 99% 443 99% 1,271 100% 7,043 100% 84,272 99%

Bone graft used - tibia

Yes 267 <1% 12 <1% 4 <1% 1 <1% 7 <1% 291 <1%

No 73,073 100% 2,699 100% 442 99% 1,270 100% 7,058 100% 84,542 100%


Figure 2.23 Bone cement types for primary knee replacement procedures undertaken between 2003 and 2012.


0%

50%

40%

30%

20%

10%

60%

70%

80%

90%

Year

Per

cent

age

of p

roce

dur

es

Antibiotic-loadedhigh viscosity

Antibiotic-loadedmedium viscosity

Antibiotic-loadedlow viscosity

High viscosity

Medium viscosity

Low viscosity

36,472

84%

2004

3%

3%

7%

4%

<1%

18,396

82%

2003

3%

2%

6%

6%

<1%

50,062

86%

2005

3%

3%

4%

3%

<1%

52,656

87%

2006

2%

2%

5%

4%

<1%

64,584

89%

2007

3%

1%

4%

3%

<1%

69,710

91%

2008

2%

<1%

4%

2%

<1%

75,702

91%

2010

3%

<1%

3%

2%

<1%

80,164

95%

2012

3%

<1%

<1%

1%

0%

78,929

94%

2011

2%

<1%

2%

2%

<1%

71,979

91%

2%

<1%

4%

3%

<1%

2009

using cement


Table 2.18 shows that the most frequently prescribed chemical method of thromboprophylaxis for knee replacement patients was LMWH (72%), while TED stockings were the most used mechanical method (70%). Compared with previous years, there has been an increase in the prescription of a combined chemical and mechanical regime, from 49% in 2004

to 92% in 2012. There has been a marked decrease over the past two years in the use of aspirin (from 20% in 2009 to 8% in 2012). Direct thrombin inhibitor is now used in 13% of knee primary procedures and the use of ‘other chemical’ has gone up from 7% in 2009 to 12% in 2012. This change was also seen in hip primary procedures. Less than 1% of patients had neither mechanical nor chemical-prescribed thromboprophylaxis.

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Table 2.19 shows that untoward intra-operative events were rare, reported in less than 1% of knee procedures. There were fewer instances reported in 2012 compared to 2011.

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Table 2.18 Thromboprophylaxis regime for primary knee replacement patients, prescribed at time of operation.

Total

No. %

Totals 84,833

Aspirin 6,568 8%

Low molecular weight Heparin 61,347 72%

Pentasaccharide 1,265 1%

Warfarin 559 <1%

Direct thrombin inhibitor 10,731 13%

Other chemical (all) 10,039 12%

No chemical 3,118 4%

Foot pump 22,482 27%

Intermittent calf compression 36,027 42%

TED stockings 59,351 70%

Other 1,177 1%

No mechanical 3,867 5%

Both mechanical and chemical 77,926 92%

Neither mechanical nor chemical 47 <1%


2.3.1.5 Knee primary components

Figure 2.24 shows the leading brands of total condylar knees in England and Wales. The PFC Sigma knee,

marketed by DePuy, continues to dominate the market. The Triathlon, Genesis 2 and Vanguard appear to be increasing in popularity.

Figure 2.24 Top five total condylar knee brands, trends 2003 to 2012.

2004

40,866

2003


2005

53,573

2006

54,849

2007

64,841

2008

68,348

2009

69,467

2010

71,543

2012

75,961

2011

74,544

Year

0%

40%

30%

20%

10%

Per

cent

age

of p

roce

dur

es

PFC Sigma Bicondylar Knee Nexgen Triathlon Genesis 2 Vanguard

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Table 2.19 Reported untoward intra-operative events for primary knee replacement patients in 2012, according to procedure type.

Primary total


using cement



cement




Patello-femoral


No. No. No. No. No. No.

Total knee primaries 73,340 2,711 446 1,271 7,065 84,833 Number of procedures with no events specified

72,829 2,703 442 1,263 7,041 84,278

Total specified 511 8 4 8 24 555

Fracture 128 1 2 2 10 143

Patella tendon avulsion 26 0 0 0 3 29

Ligament injury 60 0 0 0 3 63

Other 297 7 2 6 8 320



The brand usage for patello-femoral prostheses are shown in Figure 2.26 and the equivalent graph for

highly constrained and hinged revision knees is shown in Figure 2.27.

Likewise, the market for unicondylar knees is dominated by one product, the Oxford Partial Knee (Figure 2.25). The market share of the Oxford Partial has decreased gradually since 2003 and the Sigma HP, still relatively new to the market, and the Zimmer Uni continue to be the next most used brands of unicondylar knee system.

More information on the other brands used can be found in the document ‘Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2012’ which can be downloaded from the NJR website.

Figure 2.25 Top five unicondylar knee brands, trends 2003 to 2012.

2004

4,261

2003


2005

5,439

2006

5,750

2007

6,659

2008

7,083

2009

7,181

2010

7,458

2012

7,078

2011

7,269

Year

0%

60%

70%

80%

50%

40%

30%

20%

10%Per

cent

age

of p

roce

dur

es

Oxford Partial Knee AMC/UniglideSigma HP Triathlon UniZimmer Uni

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Figure 2.26 Top five patello-femoral knee brands, trends 2003 to 2012.

2004

503

2003

267Number ofcomponents used

2005

673

2006

728

2007

1,017

2008

1,155

2009

1,200

2010

1,255

2012

1,210

2011

1,320

Year

0%

60%

70%

80%

50%

40%

30%

20%

10%Per

cent

age

of p

roce

dur

es

Avon Sigma HP Journey PFJ OxiniumZimmer PFJ FPV

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Figure 2.27 Top five fixed hinged knee brands, trends 2003 to 2012.

2004

129

2003

70Number ofcomponents used

2005

195

2006

213

2007

262

2008

282

2009

307

2010

305

2012

294

2011

306

Year

0%

60%

50%

40%

30%

20%

10%

Per

cent

age

of p

roce

dur

es

Endo RotatingHinge

MRHNexgen HingeType

RT-Plus Noiles

2.3.2 Knee revision procedures 2012

A total of 6,009 knee revision procedures were reported, an increase of 17% on 2011. Of these, 4,675 (78%) were single-stage revision procedures, 601 (10%) were stage one of a two-stage revision

and 706 (12%) were stage two of a two-stage revision (Table 2.20). A further 27 procedures were recorded, comprising 21 conversions of previous knee replacements to arthrodesis and six knee amputations. Compared with previous years, there has been no change in the types of revision procedures carried out.

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The mean age of knee revision patients was 69 years (Table 2.20). The average has decreased by 0.5 years compared with 2011. There were more female (52%) than male patients (48%) which is similar to 2011. Aseptic loosening was the most common indication for

single-stage revision (38%) and infection was the most common indication for two-stage revision, conversion to arthrodesis and amputation.

Compared with previous years, the patient characteristics described above have largely remained the same.

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Table 2.20 Patient characteristics for knee revision procedures in 2012, according to procedure type.

Knee single-

stage revision

Knee stage one of two-stage

revision

Knee stage two of two-

stage revision

Knee conversion to

arthrodesisKnee

Amputation Total

No. % No. % No. % No. % No. % No. %

Total 4,675 78% 601 10% 706 12% 21 <1% 6 <1% 6,009

Total with patient data 4,546 97% 583 97% 687 97% 19 90% 6 100% 5,841 97%

Average age 68.76 69.74 69.87 71.71 70.62 68.97

SD 10.47 10.28 9.49 9.80 12.25 10.64


76.3363.41 -

77.2063.60 -

77.1267.55 -

76.9668.53 -

78.4562 .09 -

76.48

Gender

Female 2,466 54% 242 42% 295 43% 10 53% 5 83% 3,018 52%

Male 2,080 46% 341 58% 392 57% 9 47% 1 17% 2,823 48%


P1 - fit and healthy 408 9% 31 5% 33 5% 0 0% 0 0% 472 8%

P2 - mild disease not incapacitating 3,217 69% 366 61% 434 61% 10 48% 2 33% 4,029 67%

P3 - incapacitating systemic disease 1,005 21% 192 32% 230 33% 11 52% 4 67% 1,442 24%

P4 and P5 45 1% 12 2% 9 1% 0 0% 0 0% 66 1%


Aseptic loosening 1,778 38% 69 11% 84 12% 1 5% 0 0% 1,932 32%

Pain 846 18% 27 4% 31 4% 2 10% 0 0% 906 15%

Lysis 405 9% 59 10% 40 6% 1 5% 0 0% 505 8%

Wear of polyethylene component 563 12% 14 2% 14 2% 0 0% 0 0% 591 10%

Instability 792 17% 24 4% 31 4% 2 10% 0 0% 849 14%

Infection 255 5% 512 85% 541 77% 14 67% 4 67% 1,326 22%

Malalignment 368 8% 7 1% 9 1% 0 0% 0 0% 384 6%

Stiffness 297 6% 12 2% 9 1% 2 10% 0 0% 320 5%

Progressive arthritis remaining 540 12% 3 <1% 10 1% 0 0% 0 0% 553 9%

Dislocation/subluxation 188 4% 5 <1% 14 2% 0 0% 0 0% 207 3%

Periprosthetic fracture 187 4% 8 1% 4 <1% 1 5% 0 0% 200 3%

Component dissociation 86 2% 2 <1% 4 <1% 0 0% 0 0% 92 2%

Implant fracture 49 1% 2 <1% 2 <1% 0 0% 0 0% 53 <1%

Other 493 11% 24 4% 54 8% 2 10% 4 67% 577 10%

Side

Bilateral 8 <1% 0 0% 0 0% 0 0% 0 0% 8 <1%

Left, unilateral 2,168 46% 299 50% 347 49% 13 62% 2 33% 2,829 47%

Right, unilateral 2,499 53% 302 50% 359 51% 8 38% 4 67% 3,172 53%

Part 22.4 Ankle replacement procedures 2012


The NJR started recording primary and revision total ankle replacements on 1 April 2010. By reviewing submitted procedures against ankle levy submissions, we have calculated compliance of ankle joint NJR submissions to be 77%, which is improving on previous years but further work is required.

A total of 590 ankle replacement proformas, comprising 540 primary and 50 revision procedures carried out between 1 January and 31 December 2012, were submitted to the NJR by 28 February 2013. Due to the small number collected so far the procedures tables in this section are displayed at a summary level only. Of all the ankle procedures carried out 86% were funded by the NHS. 84% of patients were classified as P1 – fit and healthy (15%) or P2 – had mild disease not incapacitating (69%). (Table 2.21)

2.4.1 Primary ankle replacement procedures 2012

Of the 540 primary procedures, 414 (77%) were performed in the NHS, 107 (20%) in the independent sector and 19 (3%) in ISTCs. Almost all of the primary

procedures performed were reported as being uncemented but the use of cement was reported in five cases, three of which pertained to a hybrid procedure.


The average age of female patients was 64.7 years whereas the average age for a male patient was 68.8 years. 58% of patients were male (Table 2.22). The BMI average was 29.0, which is higher than for hip primary procedures but lower than knee primary procedures. No bilateral procedures were submitted to the NJR and 55% of procedures were performed on the right ankle. 84% of patients had their procedure performed due to osteoarthritis and 13% due to inflammatory arthritis. The pre-operative range of movement and degrees of deformity can be seen in Table 2.21.



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Table 2.21 Patient characteristics for primary ankle replacement procedures in 2012.

Primary proceduresNo. %

Total ankle primaries 540


P1 - fit and healthy 81 15%

P2 - mild disease not incapacitating 371 69%

P3 - incapacitating systemic disease 87 16%

P4 and P5 1 <1%


Osteoarthritis 455 84%

Rheumatoid arthritis 56 10%

Other inflammatory arthropathy 17 3%

Other 20 4%

Tibia-hindfoot alignment

Physiological neutral 247 46%

5-15° Varus 126 23%

16-30° Varus 26 5%

>30° Varus 2 <1%

5-15° Valgus 71 13%

16-30° Valgus 15 3%

>30° Valgus 3 <1%

Not available 50 9%Pre-operative range of movementankle dorsiflexion5-20° 229 42%

Neutral 208 39%

Fixed equinus 54 10%

Not available 49 9%Pre-operative range of movementankle plantarflexion5-15° 292 54%

16-45° 185 34%

Not available 63 12%



Table 2.23 details the surgical technique used during ankle primary procedures. Additional ankle related procedures were performed in 36% of procedures.

Achilles tendon lengthening was performed in 11% of procedures and subtalar joint fusion in 6%. Bone graft was used in 15% of procedures.

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Table 2.22 Age and gender for primary ankle replacement patients in 2012.

Primary procedures

No. %


Total ankle primaries with patient data 519 96%

Female age 218 42%

Average 64.7

SD 12.1

Interquartile range 57.2 - 73.3

Male age 301 58%

Average 68.8

SD 9.4


Female age groups

<45 years 18 8%

45 - 54 years 27 12%

55 - 64 years 51 23%

65 - 74 years 79 36%

75 - 84 years 40 18%

>85 years 3 1%

Male age groups

<45 years 6 2%

45 - 54 years 20 7%

55 - 64 years 64 21%

65 - 74 years 130 43%

75 - 84 years 75 25%

>85 years 6 2%



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Table 2.23 Characteristics of surgical practice for primary ankle replacement procedures in 2012.

Primary procedures

No. %


Incision

Anterior 523 97%

Anterolateral 8 1%

Lateral (transfibular) 2 <1%

Other 7 1%

Associated procedures at time of surgery

Subtalar joint fusion 30 6%

Talonavicular fusion 19 4%

Calcaneal displacement osteotomy 17 3%

Achilles tendon lengthening 59 11%

Fusion distal tibiofibular joint 1 <1%

Fibula osteotomy 3 <1%

Medial malleolar osteotomy 4 <1%

Lateral ligament reconstruction 4 <1%

Medial ligament reconstruction 2 <1%

Other 77 14%

None 348 64%


Yes 6 1%

No 534 99%

Bone graft used

Yes 79 15%

No 461 85%



In 4% of procedures an untoward intra-operative event was reported. Of those reported the most common

was ‘Fracture of the medial malleolus’ which occurred in 15 primary procedures (3%).


Table 2.24 shows that 80% of primary ankle replacement procedures used both chemical and mechanical thromboprophylaxis regimes and

only 2% used neither mechanical nor chemical regimes. LMWH was the most popular chemical thromboprophylaxis regime used in 80% of total ankle replacement (TAR) procedures.

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Table 2.24 Thromboprophylaxis regime for primary ankle replacement patients, prescribed at time of operation.

Total

No. %


Aspirin 26 5%

Low molecular weight Heparin 430 80%

Pentasaccharide 0 0%

Warfarin 8 1%

Direct thrombin inhibitor 16 3%

Other chemical 62 11%

No chemical 32 6%

Foot pump 70 13%

Intermittent calf compression 154 29%

TED stockings 303 56%

Other mechanical 17 3%

No mechanical 87 16%

Both mechanical and chemical 432 80%

Neither mechanical nor chemical 11 2%

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Table 2.25 Reported untoward intra-operative events for primary ankle replacement patients in 2012.


Total events specified 24

Fracture of medial malleolus 15

Fracture of lateral malleolus 2

Fracture (other) 3

Ligament Injury 0

Other 4



2.4.1.5 Ankle primary components

The DePuy Mobility ankle prosthesis was used in 52% of all primary procedures recorded in 2012. The next most commonly used prosthesis was Corin’s Zenith ankle replacement at 20% followed by MatOrtho’s BOX prosthesis at 8%. More information on the other brands used can be found in the document ‘Prostheses used in hip, knee, ankle, elbow and

shoulder replacement procedures 2012’ which can be downloaded from the NJR website.

2.4.2 Ankle revision procedures 2012

Of the 50 revision procedures, 46 were performed in the NHS (92%). 66% were single-stage revisions and 22% were conversion to arthrodesis.


The average age for a patient having a revision procedure was 64.7 years. Only 12% were fit and healthy and 24% had severe systemic disease (P3). 36% of revisions were for undiagnosed pain and 20% due to infection – low suspicion.

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Table 2.26 Details for ankle revision procedures in 2012.

Procedure type Patient procedure No.

50

Single-stage revision Prosthetic replacement not classified elsewhere (e.g. hybrid) 4

Single-stage revision Prosthetic replacement not using cement 29

Stage one of two-stage revision 2

Stage two of two-stage revision Prosthetic replacement not classified elsewhere (e.g. hybrid) 1

Stage two of two-stage revision Prosthetic replacement not using cement 2

Stage two of two-stage revision Prosthetic replacement using cement 1

Conversion to arthrodesis Conversion to ankle fusion (subtalar joint not fused) 3

Conversion to arthrodesis Conversion to ankle & subtalar fusion (not using ttc nail) 4

Conversion to arthrodesis Conversion to ankle & subtalar fusion (using ttc nail) 4


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Table 2.27 Patient characteristics for ankle revision procedures in 2012.

Revision procedures

No. %

Total 50





P4 and P5 0 0%


Infection high suspicion 3 6%

Infection low suspicion 10 20%

Aseptic loosening - tibial 9 18%

Aseptic loosening - talar 8 16%

Lysis - tibia 4 8%

Lysis - talus 2 4%

Malalignment 9 18%

Implant fracture - tibia 1 2%

Implant fracture - talar 1 2%

Implant fracture - meniscal 5 10%

Wear of polyethylene component 6 12%

Meniscal insert dislocation 0 0%

Component migration/dissociation 2 4%

Pain (undiagnosed) 18 36%

Stiffness 4 8%

Soft tissue impingement 3 6%

Other 6 12%

Side

Bilateral 0 0%

Left, unilateral 21 42%

Right, unilateral 29 58%

2.5 Elbow replacement procedures 2012

Part 2


The NJR started recording primary and revision elbow replacements on 1 April 2012. This Annual Report therefore deals with nine months of operation data (1 April to 31 December 2012).

A total of 288 elbow replacement procedures, comprising 214 primary and 74 revision procedures carried out between 1 April and 31 December 2012, were submitted to the NJR by 28 February 2013. Due to the small number collected so far the procedures tables in this section are displayed at a summary level only.

2.5.1 Primary elbow replacement procedures 2012 (nine months)

Of the 214 primary procedures, 200 (93%) were performed in the NHS, and the remaining in the

independent sector. 88% of the primary procedures were total elbow replacement procedures and 9% were radial head replacements only (Table 2.28). Primary procedures were mainly performed due to other inflammatory arthropathy (33%) and osteoarthritis (32%).


The average age of female patients was 66.9 years whereas the average age for a male patient was 65.6 years. 67% of patients were female (Table 2.29). 83% of patients were right handed and 3% were ambidextrous. Table 2.29 shows that 54% have ASA grade of P2 and 34% have P3 – incapacitating systemic disease.

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Table 2.28 Details for primary elbow procedures in 2012 (nine months).

Primary procedures

No. %

Total elbow primaries 214

Procedure type

Primary radial head replacement 20 9%

Primary total prosthetic replacement 188 88%

Primary lateral resurfacing 6 3%

Primary indications

Osteoarthritis 69 32%


Essex Lopresti 0 0%

Avascular necrosis 0 0%

Acute trauma 50 23%

Trauma sequelae 29 14%

Failed hemiarthroplasty 1 <1%

Other 7 3%

Side

Left 119 56%

Right 95 44%

Organisation type

NHS - England 190 89%

NHS - Wales 10 5%

Independent 14 7%

Funding

Independent 12 6%

NHS 202 94%



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Table 2.29 Patient characteristics for primary elbow replacement procedures in 2012 (nine months).

Primary procedures

No. %

Total elbow primaries 214





P4 and P5 1 <1%

Handedness

Ambidextrous 6 3%

Left 31 14%

Right 177 83%

Total elbow primaries with patient data 196 92%

Female age 131 67%

Average 66.9

SD 14.7


Male age 65 33%

Average 65.6

SD 13.9


Age groups 196

<45 years 18 9%

45 - 54 years 20 10%

55 - 64 years 40 20%

65 - 74 years 61 31%

75 - 84 years 41 21%

>85 years 16 8%


Table 2.30 details the surgical technique used during elbow primary procedures. 89% of elbow procedures were performed using a posterior approach and less than 1% used image-guided surgery. 16% of replacements required humeral bone grafting but

less than 1% required an ulnar bone graft. 8% of procedures resulted in an untoward intra-operative event with fracture of the humerus occurring in 39% of these and shaft penetration of the ulna in 33%.


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Table 2.30 Characteristics of surgical practice for primary elbow replacement procedures in 2012 (nine months).

Primary procedures

No. %

Total 214

Incision

Kocher 24 11%

Posterior 190 89%


Yes 2 <1%

No 212 99%

Humeral bone graft used

Yes 34 16%

No 180 84%

Ulnar bone graft used

Yes 2 <1%

No 212 99%

Untoward intra-operative events

Procedures with none specified 198

Procedures with events specified 16 7%

No. of events specified 18

Shaft penetration humerus 1 6%

Shaft penetration ulna 6 33%

Fracture humerus 7 39%

Fracture ulna 1 6%

Nerve injury 0 0%

Vascular injury 0 0%

Other 3 17%


Table 2.31 shows that 90% of elbow replacement procedures used mechanical methods and 66% used chemical methods; 60% of primary procedures used

both chemical and mechanical thromboprophylaxis regimes. 4% used neither mechanical nor chemical regimes. LMWH was the most popular chemical thromboprophylaxis regime used in 59% of procedures.



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Table 2.31 Thromboprophylaxis regime for primary elbow replacement patients, prescribed at time of operation.

Total no. of primary procedures

No. %

Total 214

Aspirin 1 <1%

Low molecular weight Heparin 126 59%

Pentasaccharide 0 0%

Warfarin 1 <1%

Direct thrombin inhibitor 2 <1%


No chemical 73 34%

Foot pump 50 23%


TED stockings 116 54%

Other mechanical 3 1%


Both mechanical and chemical 129 60%


2.5.2 Elbow revision procedures 2012

Of the 74 revision procedures, 74% were single-stage revisions (Table 2.32). Aseptic loosening accounted for 50% of the reasons for revision.

67% of the patients were female and their average age was 65.3. The average age for male patients undergoing revision was 63.9.


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Table 2.32 Details for elbow revision procedures in 2012 (nine months).

Procedure type Patient procedure No. %

Total 74

Single-stage revision Revision to lateral resurfacing 1 1%

Single-stage revision Revision total prosthetic replacement 54 73%

Stage one of two-stage revision 6 8%

Stage two of two-stage revision Revision total prosthetic replacement 10 14%

Excision arthroplasty 3 4%


Aseptic loosening 37 50%

Infection 13 18%

Instability 9 12%

Periprosthetic fracture 14 19%

Other 15 20%

Side

Left 32 43%

Right 42 57%

Total elbow revision procedures with patient data 73 99%

Female age 49 67%

Average 65.3

SD 13.6


Male age 24 33%

Average 63.9

SD 13.1


2.5.3 Elbow components used in primary and revision procedures

The Zimmer Coonrad Morrey had 45% of the market share in total elbow replacement prostheses used in primary and revision procedures. For procedures

where only the radial head was replaced, the most used brand was the Anatomic Radial head manufactured by Acumed. More information on the other brands used can be found in the document ‘Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2012’ which can be downloaded from the NJR website.

2.6 Shoulder replacement procedures 2012

Part 2


The NJR started recording primary and revision shoulder replacements on 1 April 2012. This Annual Report therefore deals with nine months of operation data (1 April to 31 December 2012).

A total of 2,225 shoulder replacement procedures, comprising 1,968 primary and 257 revision procedures carried out between 1 April and 31 December 2012, were submitted to the NJR by 28 February 2013. Due to the small number collected so far the procedures tables in this section are displayed at a summary level only.

2.6.1 Primary shoulder replacement procedures 2012 (nine months)

Of the 1,968 primary procedures, 1,630 (83%) were performed in the NHS sector and the remaining in the

independent sector. The most frequently performed primary procedure was the reverse polarity total shoulder replacement at 597 (30%) followed by the standard polarity total shoulder replacement with 525 (27%) procedures (Table 2.33). Primary procedures were mainly performed due to osteoarthritis (61%) and cuff tear arthropathy (24%).


The average age of female patients was 73.2 years whereas the average age for a male patient was 68.8 years. 72% of patients were female (Table 2.34). 84% of patients were right handed and 4% were ambidextrous. Table 2.34 shows that 62% had ASA grade of P2 and 28% have P3 – incapacitating systemic disease.

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Table 2.33 Details for primary shoulder procedures in 2012 (nine months).

Primary procedures

No. %

Total shoulder primaries 1,968

Procedure type

Primary total prosthetic replacement 525 27%

Primary hemi-arthroplasty of joint 296 15%

Primary resurfacing arthroplasty of joint 122 6%

Primary resurfacing hemi-arthoplasty of joint 428 22%

Primary reverse polarity total prosthetic replacement 597 30%

Primary indications

Osteoarthritis 1,202 61%

Cuff tear arthropathy 470 24%


Avascular necrosis 81 4%

Acute trauma 92 5%

Trauma sequelae 111 6%

Other 54 3%

Side

Left 921 47%

Right 1,047 53%

Organisation type

NHS - England 1,567 80%

NHS - Wales 63 3%

Independent 289 15%

ISTC 49 2%

Funding

Independent 151 8%

NHS 1,817 92%



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Table 2.34 Patient characteristics for primary shoulder replacement procedures in 2012 (nine months).

Primary procedures

No. %

Total shoulder primaries 1,968



P2 - mild disease not incapacitating 1,214 62%


P4 and P5 23 1%

Previous surgery (not arthroplasty)

None 1,623 82%

Cuff repair 85 4%

Excision ACJ 31 2%

Stabilisation 28 1%

Subacromial decompression 132 7%

Other 134 7%

Handedness

Ambidextrous 69 4%

Left 254 13%

Right 1,645 84%

Total shoulder primaries with patient data 1,894 96%

Female age 1,359 72%

Average 73.2

SD 9.3


Male age 535 28%

Average 68.8

SD 11.3


Age groups 1,894

<45 years 38 2%

45 - 54 years 93 5%

55 - 64 years 256 14%

65 - 74 years 688 36%

75 - 84 years 698 37%

>85 years 121 6%


Table 2.35 details the surgical technique used during shoulder primary procedures. 75% of shoulder procedures were performed using a delto-pectoral approach and less than 1% used image-guided surgery. 12% of replacements required humeral bone

graft and 4% required glenoid bone graft. Long head biceps tenotomy was required in 45% of procedures and 43% had normal rotator cuff condition. 2% of procedures resulted in an untoward intra-operative event with vascular injury occurring in 44% of these.


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Table 2.35 Characteristics of surgical practice for primary shoulder replacement procedures in 2012 (nine months).

Primary procedures

No. %

Total 1,968

Approach

Deltoid detachment 11 1%

Deltoid split 112 6%

Delto-pectoral 1,474 75%

Posterior 9 <1%

Superior (MacKenzie) 362 18%


Yes 2 <1%

No 1,966 100%

Humeral bone graft used

Yes 243 12%

No 1,725 88%

Glenoid bone graft used

Yes 79 4%

No 1,889 96%

Soft tissues

Long head biceps tenotomy 882 45%

Rotator cuff condition

Normal 848 43%

Attenuated 470 24%

Absent/torn 590 30%

Repaired 60 3%

Untoward intra-operative events

Procedures with none specified 1,920

Procedures with events specified 48 2%

No. of events specified 48

Shaft penetration 1 2%

Fracture humerus 15 31%

Fracture glenoid 10 21%

Nerve injury 0 0%

Vascular injury 21 44%

Other 1 2%


Table 2.36 shows that 93% of shoulder replacement procedures used mechanical methods and 65% used chemical methods; 61% of primary procedures used both chemical and mechanical thromboprophylaxis

regimes. 4% used neither mechanical nor chemical regimes. LMWH was the most popular chemical thromboprophylaxis regime used in 57% of procedures and TED stockings, the most popular mechanical thromboprophylaxis, were used in 60% of procedures.



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Table 2.36 Thromboprophylaxis regime for primary shoulder replacement patients, prescribed at time of operation.

Total no. of primary procedures

No. %

Total 1,968

Aspirin 52 3%

Low molecular weight Heparin 1,118 57%

Pentasaccharide 7 <1%

Warfarin 22 1%

Direct thrombin inhibitor 35 2%


No chemical 695 35%

Foot pump 376 19%


TED stockings 1,180 60%

Other mechanical 18 <1%


Both mechanical and chemical 1,202 61%


2.6.2 Shoulder components used in primary procedures

The Delta Xtend reverse shoulder from DePuy had 22% of the total shoulder replacement market for primary procedures. The Copeland shoulder system from Biomet has 27% of market share for primary resurfacing. More information on the other brands used can be found in the document ‘Prostheses used in hip, knee, ankle, elbow and shoulder replacement procedures 2012’ which can be downloaded from the NJR website.

2.6.3 Shoulder revision procedures 2012 (nine months)

Of the 257 revision procedures, 86% were single-stage revisions (Table 2.37). Conversion from a hemi to a total was the cause for 30% of revision procedures performed. 68% of the patients were female and their average age was 69.9. The average age for male patients undergoing revision was 68.5.


Table 2.37 Details for shoulder revision procedures in 2012 (nine months).

Procedure type Patient procedure No. %

Total 257

Single-stage revision Revision hemi-arthroplasty of joint 27 11%

Single-stage revision Revision resurfacing arthoplasty of joint 13 5%

Single-stage revisionRevision resurfacing hemi-arthoplasty of joint

9 4%

Single-stage revisionRevision reverse polarity total prosthetic replacement

109 42%

Single-stage revision Revision total prosthetic replacement 63 25%

Stage one of two-stage revision 14 5%

Stage two of two-stage revision Revision hemi-arthroplasty of joint 4 2%

Stage two of two-stage revision Revision resurfacing arthoplasty of joint 1 <1%

Stage two of two-stage revisionRevision reverse polarity total prosthetic replacement

11 4%

Stage two of two-stage revision Revision total prosthetic replacement 6 2%


Aseptic loosening 36 14%

Conversion hemi to total 77 30%

Conversion total to hemi 1 <1%

Cuff insufficiency 65 25%

Infection 25 10%

Instability 34 13%

Periprosthetic fracture 11 4%

Other 60 23%

Side

Left 128 50%

Right 129 50%

Total shoulder revision procedures with patient data 241 94%

Female age 164 68%

Average 69.9

SD 9.1


Male age 77 32%

Average 68.5

SD 10.3


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3.1 Summary of data sources and linkage

Outcomes after joint replacement 2003 to 2012

Part 3


The outcome analyses have been based on all patients with at least one primary joint replacement carried out between 1 April 2003 and 31 December 2012, inclusive, and whose record had been submitted to the NJR by the end of February 2013.

Documentation of implant survivorship and mortality require a person-level identifier to relate operations carried out on the same individual. Starting with a total of 1,419,738 NJR source file records, around 12.9% were lost because no suitable person-level identifier was found. In around half of these (48.7%), the patient had declined to give consent for details to be held, the remainder being attributable to tracing and linkage difficulties. A person-level identifier was available for 95.9% of operations from 2008 to 2012 but, in earlier years, the proportion had been much lower, for example, it was 58.9% in 2004. The implication of this is that the subset of patients with longer follow-up may be less representative than those patients with shorter follow-up.

Amongst the patients with person-level identifiers, 4.7% had solely revision operations recorded within the time frame, i.e. they had no primary operation record in the NJR. This was either because the primary had taken place at an earlier point in time (before the NJR data collection period began in 2003) or it had not been included for other reasons; these cases were excluded. This left 945,196 patients with at least one record of a primary joint replacement within the NJR, i.e. hips, knees, ankles, elbows or shoulders.

At the joint level, some further revisions were excluded if they could not be matched to primary joint replacements. For example, if a primary operation was recorded only for one side and there was a documented revision for the other side, the latter was excluded.

The resulting data sets are shown in Table 3.1. Shoulder and elbow replacements are not shown here but will be included in a later Report. Separate sets of analyses have been carried out for hips, knees and ankles, although the numbers for the latter are still quite small.

Table 3.2 opposite shows the composition of the three data sets. Of the 478,730 patients with primary hip operations 12.6% had operations documented for both hips; likewise 19.5% of the 499,015 patients with knee operations had operations on both sides.

Implant survivorship is later described with respect to the lifetime of the primary joint only, i.e. we have looked only at time to first revision, not the time from a revision

operation to any subsequent one. Table 3.2 shows the number of subsequent revision procedures and these numbers are small.

The unit of observation for all sets of survivorship analysis has been taken as the individual primary joint replacement. A patient with left and right replacements of a particular type, therefore, will have two entries, and an assumption is made that the survivorship of a

Table 3.1 Summary description of datasets used for survivorship analysis.

NJR dataSummary of data All NJR procedure-level data restructured to person-level

Time period 1 April 2003 – 31 December 2012

Data exclusions- Excludes data where patient-level identifier is not present- Excludes patients where no primary operation is recorded in the NJR- Excludes any revisions after the first revision

Number of primary operations 539,372 hips; 589,028 knees; 1,417 ankles

Number of revisions linked to a primary operationNJR identified primary-linked first revisions:11,780 hips; 11,666 knees; 9 ankles©

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replacement on one side is independent of the other. In practice it would be difficult to validate this, particularly given that some patients had had prior replacements not recorded in the NJR. Risk factors such as age are recorded at the time of primary operation and will therefore be different for the two procedures unless the two operations are performed at the same time.

A further complication is that patients may have more than one type of implant.

Figure 3.1 shows the overlap amongst patients in the dataset. For example, 443,190 patients had only hip operations in the data base, 35,422 had both hip and knee replacements and a further 24 had hip, knee and ankles. We stress this is only the composition within the NJR; ankle operations have only recently been included and so the figures are not generalisable.

Figure 3.1 Patients with hip, knee and ankle primary operations within the survivorship data sets.

Table 3.2 Composition of person-level datasets for survivorship analysis.

Hips Knees Ankles

Number Number Number

Number of patients 478,730 499,015 1,388

Number (%) of patients with only one primary joint operation 418,088 (87.3%) 409,002 (82.0%) 1,359 (97.9%)Number (%) of patients with different operation dates for left and right sides of the same primary joint

57,550 (12.0%) 82,440 (16.5%) 27 (1.9%)

Number (%) of patients with bilateral operations (both sides of the same primary joint replaced at the same time)

3,092 (0.6%) 7,573 (1.5%) 2 (0.1%)

Total number of primary joints 539,372 589,028 1,417

Number with at least one revision operation linked to the primary 11,780 11,666 9

Number with more than one revision procedure 1,524 1,821 0

HIPS ANKLES

KNEES463,368

443,190 1,069

35,422 201

94

24

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Part 33.2 Outcomes after primary hip replacement



This section looks at revision and mortality for all primary hip operations performed between 1 April 2003 and 31 December 2012. Patients operated on at the beginning of the registry therefore had a potential for nearly 10 years follow up.

Details of the patient cohort are given in Tables 3.1 and 3.2 of the preceding section; a total of 539,372 hips were included.

Methodological note

Survival analyses have been used throughout this section, first looking at the need for revision and then looking at mortality. For revision, only the first revision has been considered here. The majority of implants did not require revision and survival analysis made use of the information that was available on them, i.e. that they had not been revised up to the end of the follow up period (the end of 2012) or prior to their death; these observations were regarded as being ‘censored’ at those times. For mortality, the event was death, censoring only those cases that were still alive at the end of 2012 (and not for any revision procedure).

The survival tables below show ‘Kaplan-Meier’ estimates of the cumulative chance (probability) of revision, or death, at different times from the primary operation. This is instead of the Nelson-Aalen estimates of ‘cumulative hazard’ used in earlier annual reports, a change that brings us more into line with other registries. Please see the Annexe to Survival Analysis at the end of the chapter for a fuller explanation of the change. Where rates are

very small, the cumulative probability and cumulative hazard are numerically very similar, but with more extended follow up, they have started to diverge.

Cumulative hazard estimates have continued to be used for graphs that compare the survival experiences of different sub-groups. Although either Kaplan-Meier or cumulative hazards could be used for visual comparison, the latter have some advantage - again see our Annexe.

The cumulative hazard plots now also include tables of the numbers at risk at each anniversary. These are particularly useful where a particular group has appeared to ‘plateau’ it may simply be because the number of cases fell so low that the occurrence of further revisions/deaths became unlikely.

All the Kaplan-Meier estimates shown have been multiplied by 100, therefore estimate cumulative percentage probability.

In the case of revisions, no attempt has been made to adjust for the competing risk of death.

Terminology note

The six main categories of bearing surfaces for hip replacements are ceramic-on-ceramic (CoC), ceramic-on-metal (CoM), ceramic-on-polyethylene (CoP), metal-on-metal (MoM), metal-on-polyethylene (MoP) and resurfacing procedures. The metal-on-metal group in this section refers

to patients with a stemmed prosthesis and metal bearing surfaces (a monobloc metal acetabular cup or a metal acetabular cup with a metal liner). Although they have metal-on-metal bearing surfaces, resurfacing procedures, which have a surface replacement femoral prosthesis combined with a metal acetabular cup, are treated as a separate category.


Table 3.3 Numbers (%) of primary hip replacements by fixation and, within each fixation sub-group, by bearing surface.

Fixation Number (%)Bearing surface within

fixation groupNumber (%)

All cases 539,372 (100.0%) 539,372 (100.0%)

All cemented 201,580 (37.4%)

MoPMoMCoP

Others/unsure

178,077 (33.0%)1,229 (0.2%)

17,202 (3.2%)5,072 (0.9%)

All uncemented 205,317 (38.1%)

MoPMoMCoPCoCCoM

Others/unsure

74,762 (13.9%)28,367 (5.3%)27,964 (5.2%)

67,922 (12.6%)2,017 (0.4%)4,285 (0.8%)

All hybrid 84,671 (15.7%)

MoPMoMCoPCoC

Others/unsure

55,585 (10.3%)2,297 (0.4%)9,720 (1.8%)

15,239 (2.8%)1,830 (0.3%)

All reverse hybrid 12,296 (2.3%)MoPCoP

Others/unsure

8,397 (1.6%)3,816 (0.7%)

83 (<0.1%)All resurfacing 35,470 (6.6%) (MoM) 35,470 (6.6%)

Unsure 38 (<0.1%) Unsure 38 (<0.1%)

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3.2.1 Overview of primary hip surgery

Table 3.3 below shows the breakdown of cases by method of fixation and, within each fixation sub-group, by bearing surface.

The most commonly used type overall remained cemented metal-on-polyethylene (33%).



Table 3.4 shows the distribution of fixation/bearing surface groups for each year of primary operation.

The percentage of cemented metal-on-polyethylene, the most popular type of implant, has been falling with

time whereas the percentages of both the uncemented and hybrid metal-on-polyethylene have been increasing.

The proportions of metal-on-metal and resurfacing implants have been falling since 2008.

Table 3.4 Percentage of primary hip replacements performed each year by type of hip fixation and constraint.

Fixation/bearing

Percentage of hip replacements by year of primary operation2003

n=14,410

2004n=

27,974

2005n=

40,125

2006n=

47,455

2007n=

60,375

2008n=

66,586

2009n=

67,384

2010n=

69,649

2011n=

72,248

2012n=

73,166All cemented 60.5 54.2 48.6 42.8 39.8 34.3 31.9 31.4 32.4 33.2

Cemented by bearing surface:

MoP 55.3 49.0 43.9 38.4 35.7 30.4 28.2 27.2 27.6 28.6

MoM 0.2 0.4 0.4 0.4 0.4 0.4 0.1 0.1 0.1 0.1

CoP 3.0 3.5 3.1 3.0 2.6 2.7 2.9 3.3 3.5 4.1

Others/unsure 2.0 1.3 1.2 1.0 1.1 0.9 0.6 0.9 1.2 0.4

All uncemented 16.8 21.4 25.6 30.0 33.3 39.3 43.1 45.7 44.9 44.8

Uncemented by bearing surface:

MoP 6.2 9.0 9.8 10.3 10.8 13.1 15.1 16.9 17.1 17.8

MoM 1.3 2.2 5.4 8.3 10.3 10.9 8.0 3.2 0.5 0.1

CoP 5.0 5.1 5.1 4.3 4.0 3.9 4.7 5.6 6.1 7.3

CoC 3.5 4.2 4.4 6.2 7.3 10.1 13.6 18.1 20.1 19.2

CoM 0.0 <0.05 <0.05 <0.05 0.1 0.4 0.9 1.0 0.4 0.1

Others/unsure 0.9 0.8 0.9 0.9 0.9 1.0 0.9 0.9 0.7 0.3

All hybrid 12.3 13.3 14.1 15.2 15.0 15.1 15.8 16.2 17.2 17.6

Hybrid by bearing surface:

MoP 8.2 9.1 9.2 9.7 9.8 9.7 10.4 10.8 11.5 11.5

MoM 0.7 0.5 0.5 0.7 0.8 0.9 0.4 0.2 0.1 <0.05

CoP 1.6 1.5 1.2 1.3 1.1 1.4 1.8 2.0 2.3 3.1

CoC 1.2 1.9 2.7 3.2 2.9 2.7 2.9 3.0 3.1 2.8

Others/unsure 0.7 0.4 0.5 0.5 0.4 0.4 0.3 0.3 0.3 0.1

All reverse hybrid 0.6 0.9 1.1 1.2 1.8 2.5 2.7 2.8 3.1 3.1

Reverse hybrid by bearing surface:

MoP 0.4 0.6 0.7 0.8 1.1 1.7 1.9 1.9 2.2 2.0

CoP 0.3 0.2 0.3 0.3 0.6 0.7 0.8 0.9 0.9 1.1

Others/unsure <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05All resurfacing (MoM)

9.8 10.2 10.7 10.8 10.2 8.8 6.5 3.8 2.5 1.3

All types 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

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The primary operations were carried out by a total of 2,772 consultant surgeons across 456 units. The median number of primary procedures per consultant was 64, inter-quartile range (IQR) 10-244 and the median number of procedures per unit was 910.5, IQR 419.5-1677.

Table 3.5 below shows the distributions of consultant surgeon and unit caseloads for each type of fixation; consultants and units with fewer than 10 cases in the database have been excluded (683 of 2,772 consultant surgeons and 11 of 456 units).

The table shows, for each fixation type, the percentage of surgeons or units that carried out

procedures of that type, together with the median and IQR of the number of procedures they carried out.

Surgeons performing cemented THR carried out a median of 43 operations over the period they were observed with IQR 13 to 126 procedures. This means that 25% of surgeons performed fewer than 13 cemented hip replacements and 25% more than 126. Additionally, 10% of surgeons carrying out cemented hip replacements had performed between 782 and 1,390 procedures (not shown in table). Similarly, the surgeons with the highest 10% of caseloads performing uncemented THR carried out between 917 and 2,614 procedures over the period of observation.

Table 3.5 Distribution of consultant surgeon and unit caseload for each fixation type.

Fixation

Number of procedures carried out by consultant surgeons (n=2,089):

Number of procedures carried out by units (n=445):

% performing this fixation

type Median (IQR)


type Median (IQR)Cemented 95.2 43 (13-126) 99.6 252 (83-645)

Uncemented 84.4 38 (8-147) 98.0 296 (120.5-622.5)

Hybrids 71.3 11 (3-50) 94.6 69 (14-208)

Reverse hybrids 36.6 2 (1-8.5) 74.4 6 (2-25)

Resurfacing 37.2 12 (2-46) 88.1 46 (14.5-107)© N

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The median age at operation was 69 (IQR 61-76; range 7-105) years.10

Table 3.6 gives the breakdown of ages by fixation and by the main bearing surfaces within each fixation

sub-group. On the whole, resurfacing and ceramic-on-ceramic bearings tended to be used in younger patients although the age ranges were wide.

10 15 ages were 0 and assumed missing.



© N

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13*IQR=inter-quartile range; **Excludes all sub-groups with ‘other/unsure’ bearing surfaces, ***The bearing surface for the 7 year old was other or unsure so not shown in sub groups presented.

Table 3.6 Age (in years) at primary hip replacement, by fixation and main bearing surface.

FixationBy bearing surface within

fixation group**Median (IQR*; range) of ages Minimum age Maximum age

All cases 69 (61-76) 7 105

All cemented 74 (68-79) 7*** 103

Cemented and

MoP 74 (69-79) 15 103

MoM 65 (58-73) 25 98

CoP 65 (59-71) 16 101

All uncemented 65 (58-72) 9 105

Uncemented and

MoP 71 (65-77) 14 101

MoM 64 (57-70) 13 105

CoP 65 (59-71) 13 100

CoC 61 (53-67) 9 100

CoM 63 (56-69) 20 92

All hybrid 70 (62-76) 12 100

Hybrid and

MoP 73 (67-78) 12 100

MoM 63 (56-71) 15 93

CoP 65 (59-72) 16 96

CoC 60 (54-66) 13 92

All reverse hybrid 71 (64-77) 13 100

Reverse hybrid and

MoP 73 (68-78) 13 100

CoP 64 (59-70) 16 94

All resurfacing 55 (49-60) 12 95

Resurfacing and

MoM 55 (49-60) 12 95

3.2.2 Revisions after primary hip surgery

Table 3.7 shows Kaplan-Meier estimates of the cumulative percentage probability of first revision, for any cause, for all cases combined and then subdivided by fixation and bearing surface within each fixation group. Estimates are shown, together with 95% Confidence Intervals (95% CI), at 30 and 90 days after the primary operation and at each anniversary up to the ninth year. These do not adjust for other factors such as age and gender.

At time points where the estimates are shown in italics, fewer than 100 cases remained at risk; if the numbers at risk are small, revisions, as they occur, may appear to have greater impact on the failure rate estimates, i.e. the step upwards may appear steeper.

Amongst the cemented hips, the revision rate at nine years

was highest for metal-on-metal. This is further exemplified by Figure 3.2, where the cumulative hazard for the three bearing surface groups are plotted together. The shaded bands in these figures indicate point-wise 95% CIs for the estimates.

A similar picture exists for uncemented hips, see Figure 3.3, namely that the metal-on-metal revision rates were the highest, higher even than those for resurfacing.

Amongst the hybrid hips, again the revision rates for metal-on-metal were highest – see Figure 3.4.

For the cumulative hazard curves for metal-on-metal in Figures 3.2 to 3.4, the tangents appeared to increase over the 9 years of follow up, suggesting that the hazard rate (the rate of revision amongst the unrevised cases) increased with time from primary operation.


*Incl

udin

g th

e 38

with

uns

ure

fixat

ion/

bear

ing

surfa

ce; *

* W

ide

CIs

bec

ause

bas

ed o

n a

smal

l gro

up s

ize

(n=

83)

Tab

le 3

.7 K

apla

n-M

eier

est

imat

es o

f the

cum

ulat

ive

perc

enta

ge p

roba

bilit

y of

firs

t rev

isio

n (9

5% C

I), a

t diff

eren

t tim

es a

fter

the

prim

ary

oper

atio

n,

for

each

fixa

tion/

bear

ing

surfa

ce s

ub-g

roup

. For

the

estim

ates

in b

lue

italic

s, fe

wer

than

100

cas

es r

emai

n at

ris

k.

Fixa

tion/

bea

ring

typ

es30

day

s90

day

s1

year

2 ye

ars

3 ye

ars

4 ye

ars

5 ye

ars

6 ye

ars

7 ye

ars

8 ye

ars

9 ye

ars

All

case

s*0.

24

(0.2

3-0.

25)

0.40

(0.3

8-0.

42)

0.75

(0

.72-

0.77

)1.

20

(1.1

7-1.

23)

1.66

(1.6

2-1.

69)

2.15

(2.1

1-2.

20)

2.75

(2.6

9-2.

81)

3.38

(3.3

1-3.

45)

3.97

(3.8

8-4.

05)

4.53

(4.4

2-4.

63)

5.06

(4.9

2-5.

21)

All

cem

ente

d0.

12(0

.11-

0.14

)0.

22

(0.2

0-0.

24)

0.44

(0

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0.47

)0.

74

(0.7

0-0.

78)

1.01

(0

.97-

1.06

)1.

24(1

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1.30

)1.

52(1

.45-

1.58

)1.

79(1

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1.87

)2.

09(2

.00-

2.18

)2.

41(2

.29-

2.52

)2.

71(2

.57-

2.87

)C

emen

ted

by

bea

ring

sur

face

:

MoP

0.13

(0.1

1-0.

14)

0.23

(0

.20-

0.25

)0.

45(0

.42-

0.48

)0.

74(0

.70-

0.79

)1.

01(0

.96-

1.06

)1.

24(1

.18-

1.30

)1.

50(1

.43-

1.57

)1.

75(1

.67-

1.83

)2.

02(1

.92-

2.11

)2.

33(2

.22-

2.46

)2.

62(2

.47-

2.78

)

MoM

0.16

(0.0

4-0.

65)

0.24

(0.0

8-0.

76)

0.67

(0.3

3-1.

33)

1.65

(1.0

6-2.

58)

2.87

(2.0

4-4.

04)

4.39

(3.3

1-5.

80)

6.32

(4.9

4-8.

08)

9.20

(7.3

2-11

.52)

12.4

3(9

.93-

15.5

1)14

.38

(11.

40-1

8.06

)21

.43

(15.

41-2

9.36

)

CoP

0.07

(0.0

4-0.

12)

0.14

(0.0

9-0.

20)

0.35

(0.2

7-0.

45)

0.64

(0.5

2-0.

78)

0.88

(0.7

3-1.

06)

1.02

(0.8

5-1.

21)

1.21

(1.0

2-1.

45)

1.41

(1.1

8-1.

68)

1.67

(1.3

9-2.

01)

1.84

(1.5

1-2.

24)

1.84

(1.5

1-2.

24)

Oth

ers/

unsu

re0.

18(0

.09-

0.34

)0.

24(0

.14-

0.42

)0.

51(0

.34-

0.75

)0.

75(0

.54-

1.04

)1.

05(0

.78-

1.42

)1.

20(0

.90-

1.60

)1.

60(1

.22-

2.10

)2.

18(1

.68-

2.84

)2.

55(1

.96-

3.32

)2.

83(2

.15-

3.72

)3.

24(2

.30-

4.57

)

All

unce

men

ted

0.36

(0

.34-

0.39

)0.

55

(0.5

2-0.

58)

0.99

(0.9

5-1.

03)

1.56

(1

.50-

1.62

)2.

19(2

.12-

2.26

)2.

88(2

.79-

2.98

)3.

76(3

.65-

3.88

) 4.

77(4

.62-

4.92

)5.

59(5

.30-

5.68

)6.

23(5

.99-

6.48

)6.

71(6

.40-

7.05

)U

ncem

ente

d b

y b

eari

ng s

urfa

ce:

MoP

0.42

(0.3

7-0.

47)

0.62

(0.5

6-0.

68)

1.06

(0

.98-

1.14

)1.

51(1

.42-

1.61

)1.

93(1

.82-

2.05

)2.

19(2

.07-

2.32

)2.

50(2

.35-

2.65

)2.

92(2

.74-

3.11

)3.

21(3

.00-

3.43

)3.

80(3

.48-

4.14

)4.

30(3

.82-

4.84

)

MoM

0.31

(0.2

6-0.

39)

0.48

(0.4

1-0.

57)

1.02

(0.9

1-1.

14)

1.99

(1.8

4-2.

17)

3.38

(3.1

7-3.

60)

5.24

(4.9

7-5.

52)

7.65

(7.3

0-8.

02)

10.6

5(1

0.16

-11.

16)

13.0

4(1

2.39

-13.

72)

15.5

5(1

4.57

-16.

59)

17.6

6(1

5.93

-19.

56)

CoP

0.30

(0.2

4-0.

37)

0.47

(0.4

0-0.

56)

0.81

(0.7

1-0.

93)

1.17

(1.0

4-1.

32)

1.55

(1.3

9-1.

72)

1.86

(1.6

8-2.

07)

2.16

(1.9

5-2.

40)

2.40

(2.1

6-2.

66)

2.66

(2.3

9-2.

97)

2.89

(2.5

6-3.

25)

3.03

(2.6

5-3.

45)

CoC

0.34

(0.2

9-0.

38)

0.53

(0.4

8-0.

59)

0.96

(0.8

9-1.

04)

1.50

(1.4

0-1.

60)

1.87

(1.7

6-2.

00)

2.20

(2.0

6-2.

34)

2.58

(2.4

1-2.

76)

2.96

(2.7

4-3.

19)

3.41

(3.1

2-3.

72)

3.85

(3.4

6-4.

27)

4.08

(3.5

9-4.

64)

CoM

0.15

(0.0

5-0.

46)

0.20

(0.0

7-0.

53)

0.65

(0.3

8-1.

12)

1.47

(1.0

1-2.

12)

2.94

(2.1

9-3.

95)

4.15

(3.0

6-5.

62)

5.51

(3.5

9-8.

42)

5.51

(3.5

9-8.

42)

5.51

(3.5

9-8.

42)

5.51

(3.5

9-8.

42)

-

Oth

ers/

unsu

re0.

77(0

.55-

1.08

) 0.

87(0

.63-

1.19

)1.

25(0

.96-

1.64

)1.

70(1

.35-

2.15

)2.

18(1

.76-

2.69

)2.

63(2

.14-

3.21

)3.

31(2

.72-

4.02

)4.

08(3

.35-

4.96

)4.

28(3

.51-

5.21

)4.

96(3

.93-

6.26

)5.

75(4

.36-

7.57

)

All

hyb

rid

s0.

22(0

.19-

0.26

)0.

36 (0

.32-

0.40

)0.

65

(0.5

9-0.

71)

0.98

(0

.91-

1.05

)1.

23(1

.15-

1.31

)1.

54(1

.44-

1.64

)1.

88(1

.77-

2.00

)2.

27(2

.13-

2.42

)2.

66(2

.49-

2.85

)2.

99(2

.77-

3.22

)3.

42(3

.10-

3.76

)H

ybri

ds

by

bea

ring

sur

face

:

MoP

0.24

(0.2

0-0.

28)

0.38

(0.3

3-0.

44)

0.69

(0.6

2-0.

77)

1.02

(0.9

3-1.

11)

1.23

(1.1

3-1.

34)

1.46

(1.3

5-1.

59)

1.78

(1.6

5-1.

93)

2.08

(1.9

1-2.

25)

2.35

(2.1

6-2.

57)

2.65

(2.4

0-2.

93)

2.99

(2.6

6-3.

37)

MoM

0.35

(0.1

7-0.

70)

0.44

(0.2

3-0.

81)

0.66

(0.4

0-1.

09)

1.60

(1.1

6-2.

21)

2.98

(2.3

4-3.

78)

4.68

(3.8

5-5.

69)

6.29

(5.2

7-7.

51)

9.34

(7.8

7-11

.06)

12.6

7(1

0.64

-15.

06)

13.9

2(1

1.61

-16.

63)

14.8

6(1

2.05

-18.

25)

CoP

0.11

(0.0

6-0.

21)

0.22

(0.1

4-0.

34)

0.47

(0.3

5-0.

64)

0.69

(0.5

3-0.

90)

0.93

(0.7

3-1.

18)

1.14

(0.9

0-1.

44)

1.37

(1.0

8-1.

73)

1.52

(1.1

9-1.

94)

1.75

(1.3

5-2.

27)

1.97

(1.5

0-2.

60)

2.72

(1.8

8-3.

95)

CoC

0.22

(0.1

6-0.

31)

0.32

(0.2

4-0.

42)

0.54

(0.4

3-0.

67)

0.86

(0.7

2-1.

03)

0.99

(0.8

4-1.

18)

1.27

(1.0

8-1.

50)

1.44

(1.2

3-1.

70)

1.67

(1.4

1-1.

97)

1.87

(1.5

8-2.

26)

2.12

(1.7

3-2.

60)

2.34

(1.8

1-3.

02)

Oth

ers/

unsu

re0.

22

(0.0

8-0.

58)

0.55

(0.3

0-1.

02)

1.12

(0.7

2-1.

73)

1.37

(0.9

2-2.

03)

1.58

(1.0

8-2.

30)

1.85

(1.2

9-2.

65)

2.06

(1.4

4-2.

92)

2.49

(1.7

5-3.

53)

2.93

(2.0

4-4.

21)

3.39

(2.2

5-5.

10)

4.07

(2.5

4-6.

50)

All

reve

rse

hyb

rid

s0.

16(0

.10-

0.24

)0.

31(0

.23-

0.43

)0.

76

(0.6

1-0.

93)

1.11

(0

.92-

1.33

)1.

48

(1.2

5-1.

75)

1.76

(1.4

9-2.

08)

2.13

(1.7

8-2.

53)

2.46

(2.0

4-2.

96)

2.99

(2.4

1-3.

72)

3.31

(2.5

2-4.

33)

3.31

(2.5

2-4.

33)

Res

erve

hyb

rid

s b

y b

eari

ng s

urfa

ce:

MoP

0.18

(0.1

1-0.

30)

0.35

(0.2

4-0.

50)

0.81

(0.6

3-1.

03)

1.13

(0.9

1-1.

40)

1.42

(1.1

6-1.

74)

1.71

(1.4

0-2.

10)

2.20

(1.7

7-2.

72)

2.55

(2.0

2-3.

20)

3.02

(2.3

2-3.

91)

3.02

(2.3

2-3.

91)

3.02

(2.3

2-3.

91)

CoP

0.11

(0.0

4-0.

28)

0.21

(0.1

1-0.

43)

0.63

(0.4

2-0.

96)

1.01

(0.7

1-1.

43)

1.54

(1.1

3-2.

10)

1.79

(1.3

3-2.

42)

1.94

(1.4

1-2.

65)

2.11

(1.5

2-2.

92)

2.80

(1.8

3-4.

26)

3.67

(2.0

9-6.

40)

3.67

(2.0

9-6.

40)

Oth

ers/

unsu

re**

0.00

1.23

(0.1

7-8.

44)

1.23

(0.1

7-8.

44)

2.61

(0.6

6-10

.04)

4.10

(1.3

4-12

.24)

4.10

(1.3

4-12

.24)

4.10

(1.3

4-12

.24)

7.94

(2.6

5-22

.50)

7.94

(2.6

5-22

.50)

7.94

(2.6

5-22

.50)

7.94

(2.6

5-22

.50)

All

resu

rfac

ing

(Mo

M)

0.25

(0.2

0-0.

31)

0.66

(0.5

8-0.

75)

1.27

(1.1

6-1.

39)

2.18

(2.0

3-2.

34)

3.14

(2.9

6-3.

33)

4.39

(4.1

7-4.

63)

5.82

(5.5

5-6.

10)

7.32

(7.0

0-7.

65)

9.02

(8.6

3-9.

43)

10.5

4(1

0.05

-11.

05)

12.3

1(1

1.62

-13.

04)

© National Joint Registry 2013



Figure 3.2 Comparison of cumulative hazard of first revision for cemented hips with different bearing surfaces (with 95% CI).

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9

Years since primary surger

Numbers at risk

y

Cum

ulat

ive

haza

rd x

100

1 2 3 4 5 6 7 98Cemented MoP

Cemented MoM

Cemented CoP

178,077

1,229

17,202

152,981

1,151

14,022

130,206

1,072

11,325

108,931

1,002

8,961

88,203

880

6,984

67,448

612

5,172

47,008

397

3,652

30,708

216

2,319

16,134

96

1,164

5,594

15

344

© N

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Figure 3.3 Comparison of cumulative hazard of first hip revision for uncemented hips with different bearing surfaces (with 95% CI).

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9

Years since primary surgery

Cum

ulat

ive

haza

rd x

100

Uncemented MoP

Uncemented MoM

Uncemented CoP

74,762

28,367

27,964

67,922

2,017

35,470

60,095

27,716

22,234

53,029

1,942

33,989

47,032

26,841

17,670

38,276

1,621

31,820

34,874

24,022

13,639

25,689

921

28,841

24,669

18,424

10,443

16,673

310

24,276

16,385

11,517

7,877

10,147

53

18,459

10,371

5,880

5,538

5,918

10

12,547

6,010

2,476

3,617

3,134

1

7,759

2,689

648

1,832

1,512

1

3,881

670

142

602

445

0

1,273

Uncemented CoC

Uncemented CoM

Resurfacing

Numbers at risk

© N

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Figure 3.4 Comparison of cumulative hazard of a first hip revision for hybrid (not including reverse hybrid) hips with different bearing surfaces (with 95% CI).

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

Hybrid MoP

Hybrid MoM

Hybrid CoP

55,585

2,297

9,720

15,239

45,908

2,247

7,357

13,020

37,004

2,145

5,673

10,672

29,075

1,951

4,295

8,584

21,909

1,627

3,092

6,592

15,596

1,073

2,189

4,802

10,122

610

1,559

3,104

6,095

338

993

1,690

2,957

190

548

671

911

79

187

163Hybrid CoC

Numbers at risk

© N

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Table 3.8 shows the revision rates for each case, for all cases and broken down by fixation and, within each fixation group, by bearing surface. In the initial years of the formation of the registry, adverse soft tissue reaction was not included in the clinical assessment forms. Therefore, there were fewer ‘patient-years at risk’ for this reason.

The main reasons for revision were pain and aseptic loosening; resurfacing seemed to have the highest incidence of each, with uncemented hips a close

contender. Resurfacings also appeared to have the highest incidence of adverse soft tissue reactions. The incidence of dislocation/subluxation, however, was lowest for resurfacings.

After further subdivision by bearing surface, amongst the cemented, uncemented and hybrid fixation groups, the metal-on-metal sub-groups had the highest incidences of pain and aseptic loosening and also appeared to have the highest incidences of adverse soft tissue reactions.

Methodological note

The previous section looked at revisions for any reason. A number of reasons may be associated with any revision; for example, pain and osteolysis. This means the reasons are not mutually exclusive and therefore cannot be regarded as representing ‘competing risks’. Here we have calculated incidence rates for each reason using patient-

time incidence rates (PTIRs); the total number of revisions for that reason has been divided by the total of the individual patient-years at risk. The figures shown are the numbers per 1,000 years at risk. This method is appropriate if the hazard rate (the rate at which revisions occur in the unrevised cases) remains constant. The latter is explored further later in this section.

3.2.3 Revisions for different causes after primary hip surgery



*Including the 38 with unknown fixation/bearing. **Based on a small group size (n=83), therefore estimates are unreliable.

Table 3.8 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded reason for first hip revision. Rates shown are for all revised cases and by fixation and bearing surface.

Fixation/bearing types

Patient-years at risk

(x1,000)

Number of revisions per 1,000 patient-years for:

PainDislocation/ subluxation Infection

Aseptic loosening Lysis

Periprosthetic fracture

Implant fracture

All cases* 2,026.41.37

(1.32-1.42)1.03

(0.99-1.08)0.83

(0.80-0.88)1.44

(1.39-1.49)0.29

(0.27-0.31)0.64

(0.61-0.68)0.17

(0.15-0.19)

All Cemented 824.50.48

(0.44-0.53)0.89

(0.83-0.96)0.79

(0.73-0.85)0.93

(0.87-1.00)0.18

(0.15-0.21)0.30

(0.27-0.34)0.06

(0.05-0.08)


MoP 735.10.45

(0.40-0.50)0.92

(0.85-0.99)0.78

(0.72-0.84)0.93

(0.86-1.00)0.17

(0.15-0.21)0.31

(0.27-0.35)0.05

(0.04-0.07)

MoM 6.14.13

(2.79-6.11)0.83

(0.34-1.99)1.16

(0.55-2.43)4.13

(2.79-6.11)1.65

(0.89-3.07)1.16

(0.55-2.43)0.83

(0.34-2.00)

CoP 62.40.43

(0.30-0.63)0.69

(0.51-0.93)0.87

(0.66-1.13)0.67

(0.50-0.91)0.11

(0.05-0.24)0.10

(0.04-0.21)0.05

(0.02-0.15)

Others/unsure 20.90.62

(0.36-1.07)0.62

(0.36-1.07)0.96

(0.62-1.48)0.91

(0.58-1.43)0.14

(0.05-0.45)0.34

(0.16-0.70)0.24

(0.10-0.58)All uncemented

680.81.85

(1.75-1.95)1.29

(1.21-1.38)0.97

(0.89-1.04)1.94

(1.84-2.05)0.31

(0.27-0.35)0.82

(0.75-0.89)0.28

(0.24-0.32)


MoP 239.60.99

(0.87-1.12)1.62

(1.47-1.79)0.89

(0.78-1.02)1.53

(1.38-1.70)0.20

(0.15-0.27)1.01

(0.89-1.15)0.12

(0.08-0.17)

MoM 132.15.32

(4.94-5.73)1.10

(0.93-1.29)1.60

(1.40-1.83)3.44

(3.14-3.77)0.82

(0.68-0.99)0.64

(0.51-0.79)0.16

(0.10-0.24)

CoP 97.20.76

(0.61-0.96)1.20

(1.00-1.44)0.64

(0.50-0.82)1.44

(1.22-1.70)0.16

(0.10-0.27)0.51

(0.39-0.68)0.14

(0.09-0.24)

CoC 188.21.10

(0.96-1.26)1.05

(0.92-1.21)0.80

(0.68-0.94)1.64

(1.46-1.83)0.13

(0.09-0.19)0.83

(0.71-0.97)0.63

(0.53-0.76)

CoM 5.92.37

(1.40-4.00)1.19

(0.57-2.49)1.52

(0.79-2.93)2.71

(1.66-4.42)0.68

(0.25-1.80)0.34

(0.08-1.35)0.17

(0.02-1.20)


(0.95-2.07)1.34

(0.90-2.00)0.56

(0.30-1.04)2.13

(1.55-2.93)0.50

(0.26-0.97)1.18

(0.77-1.80)0.39

(0.19-0.82)

All hybrid 304.00.73

(0.64-0.84)1.19

(1.07-1.32)0.74

(0.65-0.84)0.83

(0.73-0.94)0.25

(0.20-0.31)0.65

(0.56-0.75)0.12

(0.08-0.16)

Hybrids by bearing surface:

MoP 196.90.52

(0.43-0.63)1.35

(1.20-1.52)0.77

(0.66-0.91)0.80

(0.69-0.94)0.23

(0.17-0.31)0.68

(0.57-0.80)0.09

(0.06-0.15)

MoM 11.44.54

(3.46-5.96)1.84

(1.20-2.82)0.96

(0.53-1.74)2.97

(2.12-4.16)1.49

(0.92-2.39)1.66

(1.06-2.60)0.17

(0.04-0.70)

CoP 30.60.62

(0.40-0.97)0.98

(0.69-1.40)0.65

(0.42-1.01)0.52

(0.32-0.85)0.13

(0.05-0.35)0.46

(0.27-0.77)0.03

(0.005-0.23)

CoC 56.90.69

(0.50-0.94)0.65

(0.47-0.90)0.55

(0.38-0.78)0.65

(0.47-0.90)0.11

(0.05-0.23)0.47

(0.33-0.69)0.25

(0.15-0.42)


(0.74-2.41)0.85

(0.41-1.78)1.34

(0.74-2.41)0.85

(0.41-1.78)0.49

(0.18-1.29)0.49

(0.18-1.29)0

All reverse hybrid

36.2 0.86

(0.60-1.22)1.19

(0.88-1.60)1.08

(0.79-1.48)1.38

(1.05-1.82)0.11

(0.04-0.29)0.61

(0.40-0.92)0.08

(0.03-0.26)

Reverse hybrids by bearing surface:

MoP 24.60.57

(0.34-0.96)1.30

(0.92-1.84)1.14

(0.79-1.65)1.22

(0.85-1.75)0.08

(0.02-0.33)0.69

(0.43-1.11)0.08

(0.02-0.33)

CoP 11.31.51

(0.94-2.43)0.98

(0.54-1.76)0.98

(0.54-1.76)1.60

(1.01-2.54)0.18

(0.04-0.71)0.44

(0.18-1.07)0.09

(0.01-0.63)Others/unsure**

0.3 0 0 06.26

(1.57-25.03)0 0 0

All Resurfacing (MoM)

180.64.78

(4.47-5.11)0.43

(0.34-0.53)0.65

(0.55-0.78)2.92

(2.68-3.18)0.82

(0.70-0.97)1.57

(1.39-1.76)0.35

(0.28-0.45)

© N

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Continued >



Fixation/bearing types

Patient-years at risk (x1,000)


Patient-years at risk (x1,000)

Adversesoft tissuereaction***Implant failure

Head/socket mismatch Malalignment

Other indication

All cases* 2,026.400.28

(0.26-0.31)0.06

(0.05-0.07)0.50

(0.47-0.53)0.66

(0.63-0.70)797.5

0.68 (0.63-0.74)

All Cemented 824.50.11

(0.09-0.14)0.03

(0.02-0.04)0.27

(0.24-0.31)0.19

(0.16-0.22)260.4

0.04 (0.02-0.07)


MoP 735.10.10

(0.08-0.13)0.03

(0.02-0.04)0.28

(0.24-0.32)0.17

(0.14-0.20)227.6

0.02 (0.01-0.05)

MoM 6.11.16

(0.55-2.43)0.17

(0.02-1.20)0.33

(0.08-1.32)2.97

(1.87-4.72)1.6

3.10 (1.30-7.40)

CoP 62.40.14

(0.08-0.28)0.02

(0.002-0.11)0.22

(0.13-0.38)0.14

(0.08-0.28)24.4 0


(0.02-0.38)0

0.24 (0.10-0.58)

0.24 (0.10-0.58)

6.8 0

All uncemented 680.80.50

(0.45-0.55)0.10

(0.08-0.13)0.72

(0.66-0.78)0.96

(0.89-1.03)340.5

1.02 (0.91-1.13)


MoP 239.60.43

(0.35-0.52)0.09

(0.06-0.13)0.71

(0.61-0.83)0.46

(0.38-0.55)120.0

0.18 (0.12-0.28)

MoM 132.10.95

(0.79-1.13)0.09

(0.05-0.16)0.95

(0.80-1.14)2.57

(2.31-2.86)51.7

5.50 (4.90-6.20)

CoP 97.20.35

(0.25-0.49)0.09

(0.05-0.18)0.54

(0.41-0.70)0.55

(0.42-0.71)38.8

0.10 (0.04-0.27)

CoC 188.20.35

(0.28-0.45)0.12

(0.08-0.18)0.63

(0.53-0.76)0.72

(0.61-0.85)117.1

0.19 (0.12-0.29)

CoM 5.90.68

(0.25-1.80)0.17

(0.02-1.20)1.19

(0.57-2.49)0.85

(0.35-2.03)5.6

1.60 (0.84-3.10)


(0.15-0.75)0.17

(0.05-0.52)0.73

(0.42-1.25)0.56

(0.30-1.04)7.4

0.67 (0.28-1.60)

All hybrid 304.00.24

(0.19-0.31)0.03

(0.01-0.05)0.40

(0.33-0.48)0.34

(0.28-0.41)128.6

0.14 (0.09-0.22)


MoP 196.90.24

(0.18-0.32)0.03

(0.01-0.06)0.42

(0.34-0.52)0.23

(0.17-0.31)84.2

0.04 (0.01-0.11)

MoM 11.40.35

(0.13-0.93)0.17

(0.04-0.70)0.96

(0.53-1.74)2.62

(1.83-3.75)3.5

3.70 (2.10-6.30)

CoP 30.60.20

(0.09-0.44)0

0.16 (0.07-0.39)

0.29 (0.15-0.57)

14.4 0

CoC 56.90.23

(0.13-0.39)0.02

(0.00(2)-0.12)0.37

(0.24-0.57)0.30

(0.19-0.48)23.5

0.09 (0.02-0.34)


(0.12-1.13)0

0.24 (0.06-0.97)

0.36 (0.12-1.13)

3.0 0

All reverse hybrid 36.2 0.14

(0.06-0.33)0.06

(0.01-0.22)0.41

(0.25-0.69)0.39

(0.23-0.65)20.4 0


MoP 24.60.12

(0.04-0.38)0.08

(0.02-0.33)0.45

(0.25-0.81)0.37

(0.19-0.70)13.8 0

CoP 11.30.18

(0.04-0.71)0

0.36 (0.13-0.95)

0.36 (0.13-0.95)

6.4 0

Others/unsure** 0.3 0 0 03.13

(0.44-22.00)0.1 0

All Resurfacing (MoM)

180.60.36

(0.28-0.46)0.12

(0.08-0.18)0.93

(0.80-1.08)2.27

(2.06-2.50)47.6

3.55 (3.05-4.13)

*Including the 38 with unknown fixation/bearing. **Based on a small group size (n=83), therefore estimates are unreliable. ***This reason was not asked in the early versions of the clinical assessment forms MDSv1 and MDSv2 for joint replacement/revision surgery and hence, for this reason, there are fewer patient-years at risk.

© N

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Table 3.9 illustrates how the risk of revision (for any reason) changed with time from primary operation.

The number of revisions per 1,000 patient-years was calculated for different periods after the primary operation, within the first year from primary operation, and between 1-3, 3-5, 5-7 and 7+ years after surgery.

Note the maximum follow-up for any implant was 9.75 years.

The rate was higher initially, with a small decrease between one and three years, after which the rate began to rise. The rates were less reliable after seven years because there were fewer patient-years at risk.

Table 3.9 Revision rates, expressed as numbers per 1,000 patient-years, for any reason, according to time interval from primary operation.

Time from primary operation Patient-years at risk (x1,000) Revision rate per 1,000 patient-years (95% CI)

<1 year 497.6 7.71 (7.47-7.96)

1-3 years 756.8 4.60 (4.45-4.75)

3-5 years 469.0 5.51 (5.30-5.72)

5-7 years 227.8 6.36 (6.04-6.69)

>7 years* 75.1 5.75 (5.23-6.32)

*current maximum observed follow up is 9.75 years

In Table 3.10 the breakdown of Table 3.9 has been repeated, this time showing separate breakdowns for each reason. There were trends of increasing risk of pain and aseptic loosening with time. Risk of

subluxation/dislocation, infection and periprosthetic fracture were highest early on, then fell. Incidence of adverse soft tissue reaction seemed to increase with time.

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Table 3.10 Revision rates (95% CI), expressed as numbers per 1,000 patient-years, for each reason, by time interval from primary operation.

Time from primary operation

Patient-years

at risk (x1,000)





Implant fracture

<1 year 497.60.85

(0.77-0.94)2.32

(2.19-2.45)1.28

(1.18-1.38)1.28

(1.18-1.38)0.10

(0.07-0.13)1.49

(1.38-1.60)0.27

(0.22-0.31)

1-3 years 756.81.25

(1.17-1.33)0.66

(0.61-0.72)0.87

(0.80-0.93)1.38

(1.30-1.47)0.21

(0.18-0.25)0.29

(0.26-0.33)0.14

(0.12-0.17)

3-5 years 469.01.77

(1.66-1.90)0.55

(0.48-0.62)0.58

(0.51-0.65)1.48

(1.38-1.60)0.40

(0.34-0.46)0.39

(0.34-0.46)0.12

(0.09-0.16)

5-7 years 227.8 1.96

(1.79-2.15)0.58

(0.48-0.68)0.44

(0.36-0.53)1.75

(1.59-1.93)0.56

(0.47-0.66)0.54

(0.46-0.65)0.17

(0.12-0.23)>7 years***

75.1 1.72

(1.44-2.04)0.75

(0.57-0.97)0.39

(0.27-0.56)1.88

(1.59-2.21)0.84

(0.65-1.07)0.48

(0.35-0.66)0.15

(0.08-0.26)

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Continued >


Time from primary operation

Patient-years at risk

(x1,000)

Number of revisions per 1,000 patient-years for: Patient-years at risk

(x1,000)

Adverse soft tissue reaction**

Implant failure

Head/socket mismatch Malalignment

Other indication

<1 year 497.60.26

(0.22-0.31)0.12

(0.10-0.16)0.91

(0.83-0.99)0.81

(0.74-0.90)301.0

0.10 (0.07-0.15)

1-3 years 756.80.16

(0.13-0.19)0.05

(0.03-0.07)0.40

(0.36-0.45)0.57

(0.52-0.63)376.3

0.71 (0.63-0.80)

3-5 years 469.00.36

(0.31-0.42)0.03

(0.01-0.05)0.35

(0.30-0.41)0.69

(0.62-0.77)116.2

2.04 (1.80-2.32)

5-7 years 227.8 0.51

(0.42-0.61)0.03

(0.01-0.06)0.31

(0.25-0.39)0.61

(0.52-0.73)3.4

2.36 (1.18-4.72)

>7 years*** 75.1 0.52

(0.38-0.71)0.04

(0.01-0.12)0.39

(0.27-0.56)0.48

(0.35-0.66)0.6

1.80 (0.25-1.30)


*Includes the 38 with unknown fixation/bearing. ** This reason was not asked in the early versions of the clinical assessment forms MDSv1 and MDSv2 for joint replacement/revision surgery and hence, for these reasons, there are fewer patient-years at risk. ***Current maximum observed follow up is 9.75 years.

Note on dislocations/subluxation: There were 2097 first revisions performed where dislocations/subluxation was given as a reason (out of all 539,372 operations); in 1,361 of these (64.9%) dislocation/subluxation was the only given reason. From tables 3.9-3.10 above, revisions due to dislocation/subluxation were more common in uncemented and hybrid/reverse hybrid hips than cemented hips and were more common within the first year after primary operation.

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3.2.4 Revisions after primary hip surgery for the main stem-cup brand combinations

Table 3.11 show Kaplan-Meier estimates of the cumulative percentage probability of revision (for any reason) for the main stem-cup brands.

As in our previous reports, we have only included those stem-cup combinations with more than 2,500 procedures in the case of cemented, uncemented, hybrid and reverse hybrid hips, and more than 1,000 in the case of resurfacings.

The figures in italics were at time points where fewer than 100 cases remained at risk.

Note it is possible that these sub-groups may differ in composition with respect to other factors that might influence revision, such as age and gender; no attempt here has been made to adjust for such factors.

Some further subdivisions by bearing type, however, are shown in the table that immediately follows, Table 3.12.



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Table 3.11 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) at different times after the primary operation, for cup-stem brand combinations with large group sizes (>2,500 or >1,000 in the case of resurfacings). Blue italics indicate that fewer than 100 cases remain at risk.

Stem/cup brand

No. of patients

Cumulative percentage probability of first revision (95% CI) at time shown if time since primary operation is:

1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 yearsCemented:

Charnley Cemented Stem/ Charnley Ogee

9,0990.37

(0.26-0.52)0.85

(0.67-1.061.18

(0.97-1.44)1.46

(1.22-1.75)1.84

(1.56-2.17)2.16

(1.84-2.54)2.48

(2.12-2.91)2.92

(2.48-3.45)3.17

(2.66-3.78)

Charnley Cemented Stem/ Charnley Cemented Cup

10,3070.29

(0.20-0.41)0.58

(0.45-0.76)0.80

(0.64-1.01)1.03

(0.85-1.27)1.34

(1.12-1.61)1.64

(1.38-1.94)1.88

(1.59-2.23)2.33

(1.96-2.75)2.49

(2.09-2.96)

C-Stem Cemented/Elite Plus Ogee

3,7490.44

(0.27-0.73)0.70

(0.47-1.04)0.90

(0.63-1.29)1.07

(0.76-1.49)1.17

(0.84-1.62)1.28

(0.93-1.77)1.55

(1.11-2.16)1.97

(1.38-2.81)1.97

(1.38-2.81)

Stanmore Modular Stem/ Stanmore-Arcom Cup

4,1350.38

(0.23-0.63)0.58

(0.38-0.89)0.98

(0.69-1.38)1.10

(0.79-1.54)1.45

(1.05-1.98)1.61

(1.17-2.21)1.61

(1.17-2.21)1.61

(1.17-2.21)1.61

(1.17-2.21)

CPT/ZCA 8,2340.69

(0.53-0.90)0.94

(0.74-1.18)1.22

(0.99-1.51)1.50

(1.22-1.84)1.92

(1.58-2.33)2.31

(1.90-2.81)2.73

(2.22-3.36)2.88

(2.31-3.58)2.88

(2.31-3.58)Exeter V40/Contemporary

55,6560.43

(0.38-0.49)0.71

(0.63-0.78)0.93

(0.85-1.03)1.14

(1.04-1.26)1.39

(1.26-1.52)1.65

(1.51-1.82)1.84

(1.66-2.03)2.11

(1.88-2.37)2.30

(1.99-2.64)Exeter V40/Elite Plus Ogee

17,2610.29

(0.22-0.39)0.51

(0.41-0.63)0.74

(0.61-0.89)0.86

(0.72-1.03)1.04

(0.87-1.24)1.31

(1.11-1.56)1.50

(1.26-1.79)1.57

(1.30-1.90)1.57

(1.30-1.90)Exeter V40/Exeter Duration

13,7810.58

(0.47-0.73)0.91

(0.76-1.09)1.20

(1.02-1.42)1.51

(1.30-1.76)1.74

(1.51-2.01)2.12

(1.84-2.44)2.54

(2.22-2.94)3.07

(2.61-3.60)3.23

(2.73-3.82)

Exeter V40/ Elite Plus Cemented Cup

6,1240.43

(0.29-0.64)0.69

(0.50-0.95)0.88

(0.65-1.18)0.95

(0.71-1.28)0.99

(0.74-1.33)1.14

(0.83-1.56)1.33

(0.95-1.85)1.50

(1.03-2.16)1.50

(1.03-2.16)

Exeter V40/Exeter Rimfit

4,0240.67

(0.42-1.05)0.91

(0.55-1.51)- - - - - - -

C-Stem AMT Cemented Stem/ Elite Plus Cemented Cup

2,6580.44

(0.24-0.79)0.54

(0.31-0.92)0.75

(0.45-1.25)0.92

(0.57-1.49)1.12

(0.70-1.78)1.12

(0.70-1.78)- - -

Uncemented:

Accolade/Trident

16,9400.97

(0.83-1.13)1.62

(1.43-1.85)2.18

(1.94-2.46)2.60

(2.31-2.93)3.22

(2.83-3.67)3.55

(3.05-4.12)3.88

(3.12-4.81)3.88

(3.12-4.81)3.88

(3.12-4.81)Corail/Duraloc Cementless Cup

4,0230.72

(0.50-1.04)1.21

(0.92-1.61)1.66

(1.30-2.12)1.88

(1.49-2.37)2.28

(1.83-2.83)2.64

(2.13-3.27)3.11

(2.51-3.84)3.78

(3.02-4.73)4.66

(3.51-6.17)

Corail/Pinnacle 67,7240.82

(0.75-0.89)1.32

(1.23-1.42)1.86

(1.74-1.98)2.49

(2.34-2.65)3.14

(2.94-3.34)4.03

(3.75-4.33)4.89

(4.48-5.34)5.89

(5.11-6.79)8.07

(5.70-11.36)Corail/ASR Resurfacing Cup

2,5971.00

(0.68-1.47)3.29

(2.67-4.05)7.47

(6.52-8.56)14.25

(12.94-15.69)23.28

(21.56-25.12)33.82

(31.50-36.26)39.04

(36.12-42.10)43.30

(38.30-48.66)-

Furlong HAC Stem/CSF

14,8520.91

(0.77-1.08)1.30

(1.12-1.50)1.61

(1.42-1.84)1.85

(1.63-2.09)2.02

(1.79-2.27)2.27

(2.01-2.55)2.58

(2.29-2.91)2.89

(2.54-3.28)2.97

(2.59-3.40)

Continued >


Stem/cup brand

No. of patients


1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 yearsFurlong HAC Stem/CSF Plus

11,3911.10

(0.92-1.31)1.54

(1.32-1.81)1.70

(1.46-1.99)1.87

(1.58-2.21)2.01

(1.63-2.47)2.01

(1.63-2.47)- - -

SL-Plus Cementless Stem/ EP/Fit Plus

4,1861.27

(0.97-1.67)2.22

(1.78-2.70)2.85

(2.37-3.43)3.37

(2.83-4.01)4.26

(3.59-5.04)4.69

(3.92-5.60)5.49

(4.45-6.76)5.75

(4.62-7.14)5.75

(4.62-7.14)

Taperloc Cementless Stem/Exceed ABT

9,8931.15

(0.95-1.39)1.44

(1.21-1.73)1.70

(1.42-2.04)1.93

(1.59-2.34)2.34

(1.85-2.96)2.72

(2.06-3.59)- - -

Hybrid:

CPT/Trilogy 8,9870.83

(0.66-1.05)1.11

(0.90-1.37)1.21

(0.99-1.49)1.62

(1.33-1.97)1.94

(1.60-2.35)2.26

(1.85-2.75)2.48

(2.01-3.04)2.63

(2.10-3.29)3.04

(2.19-4.21)Exeter V40/ Pinnacle

2,8030.48

(0.27-0.85)0.79

(0.50-1.26)1.02

(0.66-1.59)1.13

(0.73-1.75)1.29

(0.82-2.03)1.68

(0.95-2.98)1.68

(0.95-2.98)1.68

(0.95-2.98)-

Exeter V40/ Trident

28,3670.59

(0.51-0.69)0.90

(0.79-1.03)1.09

(0.96-1.24)1.25

(1.10-1.41)1.48

(1.30-1.67)1.73

(1.51-1.97)2.06

(1.75-2.42)2.31

(1.91-2.80)2.65

(1.96-3.58)Exeter V40/ Trilogy

10,3750.57

(0.44-0.73)0.80

(0.64-1.00)1.02

(0.83-1.25)1.20

(0.98-1.45)1.38

(1.13-1.67)1.64

(1.35-1.99)1.80

(1.47-2.20)2.12

(1.66-2.71)2.30

(1.75-3.01)

Reverse hybrid:

Corail/ Elite Plus Cemented Cup

2,5590.54

(0.31-0.93)0.93

(0.60-1.42)1.26

(0.85-1.86)1.52

(1.04-2.21)2.04

(1.36-3.04)2.04

(1.36-3.04)2.04

(1.36-3.04)2.04

(1.36-3.04)-

Corail/Marathon

3,1400.38

(0.20-0.70)0.65

(0.39-1.09)0.93

(0.57-1.53)0.93

(0.57-1.53)0.93

(0.57-1.53)- - - -

Resurfacing:

Adept Resurfacing Cup

3,2931.23

(0.90-1.67)1.85

(1.44-2.39)2.57

(2.06-3.20)3.54

(2.90-4.31)5.00

(4.13-6.03)6.67

(5.45-8.15)8.70

(6.91-10.93)8.70

(6.91-10.93)-

ASR Resurfacing Cup

3,0261.59

(1.20-2.10)3.44

(2.85-4.16)5.91

(5.12-6.81)9.44

(8.44-10.55)13.71

(12.48-15.05)18.57

(17.06-20.19)24.07

(22.18-26.11)29.69

(27.03-32.55)36.40

(30.94-42.48)

BHR Resurfacing Cup

18,2801.05

(0.92-1.21)1.66

(1.49-1.86)2.38

(2.17-2.62)3.15

(2.89-3.43)3.85

(3.56-4.17)4.69

(4.35-5.06)5.61

(5.21-6.04)6.61

(6.12-7.13)8.11

(7.40-8.88)

Cormet 2000 Resurfacing Cup

3,6291.44

(1.10-1.88)2.67

(2.19-3.25)3.55

(2.99-4.21)5.27

(4.57-6.07)7.39

(6.52-8.36)8.96

(7.96-10.08)11.41

(10.14-12.83)13.85

(12.23-15.65)16.34

(14.19-18.78)

Durom Resurfacing Cup

1,6601.40

(0.93-2.10)2.78

(2.08-3.70)3.83

(2.99-4.90)4.69

(3.74-5.87)5.89

(4.79-7.24)7.08

(5.80-8.63)9.45

(7.74-11.53)9.80

(7.99-12.01)9.80

(7.99-12.01)

Recap Magnum

1.6801.85

(1.31-2.63)2.77

(2.07-3.69)3.56

(2.75-4.60)4.36

(3.43-5.55)6.04

(4.78-7.62)7.43

(5.83-9.45)8.66

(6.51-11.49)8.66

(6.51-11.49)-

Conserve Plus Resurfacing Cup

1,3201.98

(1.35-2.89)3.62

(2.73-4.78)5.03

(3.96-6.38)6.83

(5.54-8.41)8.23

(6.74-10.02)10.12

(8.28-12.36)10.63

(8.59-13.11)12.22

(8.93-16.62)12.22

(8.93-16.62)


The cemented, uncemented and hybrid stem-cup brand sub-groups with more than 10,000 procedures in the preceding table (Table 3.11) have been further divided by bearing surface.

Table 3.12 shows the estimated cumulative percentage probabilities for the resulting fixation/bearing sub-groups in which there were more than 1,000 procedures.

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Table 3.12 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) at different times after the primary operation for cup-stem brand combinations with large group sizes (>10,000) with further subdivision by main bearing surface (provided the sub-group size >1,000). Blue italics indicate that fewer than 100 cases remain at risk.

Stem/cup brand

Bearing surface

No. of patients


1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 yearsCemented:

Exeter V40/Contemporary

MoP 51,9120.42

(0.36-0.48)0.70

(0.63-0.78)0.92

(0.83-1.02)1.14

(1.03-1.25)1.39

(1.26-1.52)1.65

(1.49-1.82)1.83

(1.65-2.03)2.12

(1.88-2.40)2.33

(2.00-2.70)

CoP 3,2980.48

(0.29-0.80)0.68

(0.44-1.06)1.05

(0.71-1.54)1.18

(0.81-1.71)1.30

(0.88-1.92)1.63

(1.07-2.46)1.87

(1.20-2.90)1.87

(1.20-2.90)1.87

(1.20-2.90)Exeter V40/Elite Plus Ogee

MoP 16,0260.30

(0.23-0.40)0.50

(0.40-0.63)0.73

(0.60-0.90)0.85

(0.70-1.02)1.02

(0.85-1.22)1.27

(1.06-1.52)1.47

(1.22-1.77)1.55

(1.27-1.89)1.55

(1.27-1.89)

CoP 1,0420.21

(0.05-0.85)0.68

(0.31-1.51)0.96

(0.48-1.92)1.14

(0.59-2.20)1.41

(0.74-2.71)1.41

(0.74-2.71)1.41

(0.74-2.71)1.41

(0.74-2.71)1.41

(0.74-2.71)

Uncemented:

Accolade/Trident

MoP 8,2810.97

(0.77-1.21)1.56

(1.29-1.88)2.25

(1.89-2.66)2.71

(2.28-3.23)3.24

(2.63-3.98)3.39

(2.73-4.20)3.39

(2.73-4.20)3.39

(2.73-4.20)-

CoP 2,1710.85

(0.52-1.39)1.83

(1.25-2.67)2.22

(1.53-3.22)2.79

(1.86-4.20)3.43

(2.26-5.21)3.43

(2.26-5.21)3.43

(2.26-5.21)3.43

(2.26-5.21)3.43

(2.26-5.21)

CoC 6,3191.02

(0.80-1.31)1.69

(1.38-2.07)2.16

(1.79-2.60)2.49

(2.07-2.99)3.16

(2.61-3.83)3.60

(2.89-4.47)4.10

(3.02-5.57)4.10

(3.02-5.57)4.10

(3.02-5.57)Corail/Pinnacle

MoP 23,9490.86

(0.75-0.99)1.21

(1.07-1.37)1.47

(1.30-1.66)1.69

(1.50-1.92)1.82

(1.60-2.08)2.19

(1.89-2.55)2.41

(2.03-2.87)2.62

(2.10-3.29)2.62

(2.10-3.29)

MoM 11,7110.83

(0.68-1.01)1.55

(1.34-1.79)2.38

(2.12-2.68)3.51

(3.18-3.89)4.84

(4.41-5.32)6.51

(5.91-7.17)8.45

(7.52-9.50)11.10

(9.06-13.58)19.89

(11.37-33.48)

CoP 6,1340.65

(0.47-0.89)0.96

(0.72-1.28)1.25

(0.94-1.66)1.60

(1.19-2.14)1.84

(1.34-2.51)1.84

(1.34-2.51)1.84

(1.34-2.51)1.84

(1.34-2.51)-

CoC 23,4960.83

(0.72-0.96)1.37

(1.21-1.55)1.83

(1.63-2.05)2.26

(2.01-2.54)2.53

(2.23-2.86)2.91

(2.50-3.39)3.05

(2.57-3.62)3.05

(2.57-3.62)-

CoM 1,7420.46

(0.23-0.93)1.28

(0.83-1.95)2.86

(2.07-3.95)3.72

(2.64-5.22)5.06

(2.85-8.90)5.06

(2.85-8.90)5.06

(2.85-8.90)5.06

(2.85-8.90)-

Furlong HAC Stem/CSF

MoP 6,7290.98

(0.77-1.25)1.41

(1.14-1.73)1.82

(1.51-2.19)2.05

(1.71-2.44)2.23

(1.87-2.65)2.76

(2.32-3.27)2.91

(2.45-3.46)3.48

(2.84-4.26)3.48

(2.84-4.26)

CoP 6,2280.74

(0.55-0.98)1.07

(0.84-1.37)1.28

(1.02-1.60)1.53

(1.24-1.89)1.63

(1.33-2.00)1.68

(1.37-2.06)1.93

(1.57-2.37)1.99

(1.62-2.45)2.13

(1.69-2.68)

CoC 1,6081.25

(0.81-1.93)1.70

(1.17-2.47)2.03

(1.44-2.85)2.30

(1.66-3.18)2.59

(1.90-3.51)2.68

(1.98-3.63)3.70

(2.74-4.98)4.44

(3.25-6.06)4.44

(3.25-6.06)Furlong HAC Stem/CSF Plus

MoP 2,6261.35

(0.97-1.89)1.73

(1.27-2.35)1.87

(1.38-2.52)2.40

(1.70-3.40)3.02

(1.86-4.89)- - - -

CoP 1,2811.11

(0.64-1.91)1.58

(0.98-2.55)1.73

(1.08-2.76)1.73

(1.08-2.76)1.73

(1.08-2.76)- - - -

CoC 7,4221.00

(0.79-1.27)1.47

(1.20-1.81)1.65

(1.35-2.01)1.70

(1.39-2.09)1.70

(1.39-2.09)1.70

(1.39-2.09)- - -

Hybrid:

Exeter V40/ Trident

MoP 15,1130.64

(0.52-0.78)0.98

(0.82-1.17)1.18

(1.00-1.40)1.30

(1.10-1.54)1.50

(1.26-1.78)1.68

(1.39-2.04)2.18

(1.66-2.86)2.36

(1.76-3.17)2.36

(1.76-3.17)

CoP 3,3010.55

(0.33-0.89)0.77

(0.50-1.18)1.02

(0.68-1.52)1.02

(0.68-1.52)1.68

(1.00-2.80)1.68

(1.00-2.80)2.16

(1.19-3.90)2.16

(1.19-3.90)2.16

(1.19-3.90)

CoC 9,3750.53

(0.40-0.70)0.82

(0.65-1.04)0.99

(0.80-1.23)1.19

(0.97-1.47)1.42

(1.16-1.74)1.74

(1.41-2.14)1.98

(1.57-2.49)2.31

(1.74-3.07)2.89

(1.84-4.53)Exeter V40/ Trilogy

MoP 8,2100.54

(0.40-0.73)0.75

(0.58-0.97)0.96

(0.76-1.22)1.10

(0.88-1.39)1.33

(1.07-1.67)1.61

(1.28-2.01)1.75

(1.38-2.21)2.07

(1.54-2.76)2.07

(1.54-2.76)CoP 1,876 0.55

(0.29-1.01)0.79

(0.47-1.34)1.08

(0.68-1.72)1.42

(0.93-2.17)1.42

(0.93-2.17)1.69

(1.11-2.55)1.93

(1.24-2.98)2.32

(1.42-3.77)2.32

(1.42-3.77)

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3.2.5 Revisions after primary hip surgery: Effect of head sizes for polyethylene liners

Four sub-groups were identified with polyethylene liners,

i. metal-on-polyethylene monobloc-cup (n=185,027)

ii. (metal-on-polyethylene - metal shell with polyethylene liners (n=129,152)

iii. ceramic-on-polyethylene – polyethylene monobloc-cup (n=20,841)

iv. ceramic-on-polyethylene - metal shell with polyethylene liners (n=37,278)

The Graphs (i)-(iv) in Figure 3.5 show the respective cumulative hazards broken down by head size. The same scale has been used for all graphs to facilitate comparison between them. Only head sizes where there were more than 500 procedures are shown.

A Cox ‘proportional hazards’ regression analysis was performed to compare the head sizes in each case. The most frequently used head size, 28mm, was used as the baseline for comparison in each analysis.

In the case of (i), metal-on-polyethylene monobloc-cup, there were significant differences between the five head sizes shown (P<0.001). Rates of revision for 22.25mm head size did not differ significantly from the baseline of 28mm heads (Hazard rate ratio (HRR) 1.05 (95% CI 0.95-1.17) P=0.31). Revision rates for 26mm heads were significantly lower (0.80 (0.69-0.93) P=0.003) than for 28mm heads and rates for both 32mm and 36mm were higher (1.19 (1.02-1.40) P=0.031 & 2.08 (1.27-3.41) P=0.004, respectively).

For (ii) metal-on-polyethylene with metal shell/polyethylene liner, the differences between the head sizes were not significant overall (P=0.055), however the revision rates were higher for 44mm heads than the baseline 28mm heads (HRR 1.84, 95% CI 1.17-2.90, P=0.008) whereas other head sizes did not differ significantly (minimum P=0.14).

For the other groups, (iii) and (iv), there were no significant differences amongst the sets of head sizes shown (P=0.69, P=0.15, respectively), although there were too few cases for larger head sizes to make worthwhile comparisons.



Figure 3.5 (i) Comparison of the cumulative hazard for revision for different head sizes for metal-on-polyethylene monobloc cup. (NB only head sizes where n>500 are shown)

6

5

4

3

2

1

0

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

y

Head size 22.5mm

Head size 26mm

Head size 28mm

29,582

16,642

120,152

16,784

1,331

27,420

15,416

103,028

11,586

746

25,021

14,049

86,715

7,925

393

22,410

12,742

71,059

5,258

165

19,585

10,951

55,970

3,317

30

16,573

8,990

40,629

2,056

3

13,107

6,943

26,182

1,172

0

9,701

4,945

15,606

639

0

5,922

2,772

7,224

291

0

2,312

965

2,260

78

0

Head size 32mm

Head size 36mm

Numbers at risk

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(ii) Comparison of the cumulative hazard for revision for different head sizes for metal-on-polyethylene with metal shell/polyethylene liners. (NB only head sizes where n>500 are shown)

6

5

4

3

2

1

0

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

y

Head size 22.5mm

Head size 26mm

Head size 28mm

850

737

68,789

32,691

22,394

2,928

698

722

680

60,999

23,357

16,227

2,462

571

608

615

52,854

16,037

10,769

1,923

452

527

534

44,150

10,190

6,272

1,382

320

474

464

35,350

5,840

2,997

838

193

404

386

26,202

3,051

1,317

286

58

333

298

17,662

1,512

476

25

2

239

208

10,739

614

171

10

1

139

108

5,039

219

66

5

1

45

23

1,462

20

14

1

0

Head size 32mm

Head size 36mm

Head size 40mm

Head size 44mm

Numbers at risk

© N

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Figure 3.5



(iii) Comparison of the cumulative hazard for revision for different head sizes for ceramic-on-polyethylene with polyethylene monobloc cup. (NB only head sizes where n>500 are shown)

6

5

4

3

2

1

0

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

y

Head size 22.25mm

Head size 28mm

Head size 32mm

2,314

15,115

3,073

2,082

12,558

2,074

1,814

10,310

1,339

1,599

8,134

829

1,376

6,259

447

1,104

4,506

210

801

3,040

120

485

1,958

62

190

1,032

23

0

364

9

Numbers at risk

© N

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Figure 3.5


6

5

4

3

2

1

0

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

y

Head size 28mm

Head size 32mm

Head size 36mm

18,790

11,265

6,883

16,743

8,077

4,229

14,724

5,591

2,657

12,686

3,497

1,524

10,569

2,096

711

8,443

1,184

313

6,161

725

120

4,125

406

21

2,199

151

0

748

37

0

Numbers at risk

© N

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(iv) Comparison of the cumulative hazard for revision for different head sizes for ceramic-on-polyethylene with metal shell/polyethylene liners. (NB only head sizes where n>500 are shown)

Figure 3.5

3.2.6 Mortality after primary hip surgery

This section describes the mortality of the cohort up to nine years from primary operation, according to gender and age group. Deaths were updated at the end of February 2013 using data from the Patient Demographic Service. Two hundred cases were excluded because the NHS number was not traceable and therefore no death date could be ascertained. A further three were excluded because of uncertainty in gender (n=1) and age (n=2), leaving 539,169, with a total of 42,805 reported deaths. Amongst these were 3,091 bilateral operations, with the left and right side operated on the same day; here the second of the two has been excluded, leaving 536,078 procedures and 42,655 deaths.

Table 3.13 shows Kaplan-Meier estimates of cumulative percentage mortality at 30 days, 90 days and at each anniversary up to the ninth, for all cases and by age and gender.

Note the cases were not ‘censored’ when further revision surgery was undertaken. Such surgery may have contributed to the overall mortality as shown here. The impact of this has not been quantified.




Tab

le 3

.13

Kap

lan-

Mei

er e

stim

ates

of t

he c

umul

ativ

e pe

rcen

tage

mor

talit

y (9

5% C

I), a

t diff

eren

t tim

es a

fter

prim

ary

hip

oper

atio

n, fo

r al

l cas

es a

nd b

y ag

e/ge

nder

.

No

. of

pat

ient

s

Cum

ulat

ive

per

cent

age

pro

bab

ility

of

first

rev

isio

n (9

5% C

I) at

tim

e sh

ow

n if

time

sinc

e p

rim

ary

op

erat

ion

is:

30 d

ays

90 d

ays

1 ye

ar2

year

s3

year

s4

year

s5

year

s6

year

s7

year

s8

year

s9

year

sA

ll ca

ses

536,

078

0.25

(0.2

4-0.

260.

51(0

.50-

0.53

)1.

52(1

.49-

1.56

)3.

06(3

.01-

3.11

)4.

93(4

.86-

5.00

)7.

15(7

.06-

7.23

)9.

54(9

.43-

9.64

)12

.17

(12.

05-1

2.30

)14

.97

(14.

82-1

5.13

)18

.14

(17.

94-1

8.35

)21

.41

(21.

11-2

1.71

)

By

gen

der

and

ag

e g

roup

Mal

es:

<55

ye

ars

32,5

650.

08

(0.0

6-0.

12)

0.16

(0

.12-

0.21

)0.

49

(0.4

2-0.

57)

0.87

(0

.77-

0.98

)1.

28

(1.1

5-1.

43)

1.70

(1

.54-

1.87

)2.

08

(1.8

9-2.

28)

2.64

(2

.40-

2.89

)3.

23

(2.9

3-3.

55)

3.76

(3

.39-

4.17

)4.

39

(3.8

8-4.

96)

55-

59

year

s22

,505

0.05

(0

.03-

0.09

)0.

17

(0.1

2-0.

23)

0.57

(0

.48-

0.68

)1.

05

(0.9

2-1.

20)

1.78

(1

.60-

1.99

)2.

62

(2.3

8-2.

89)

3.19

(2

.91-

3.49

)3.

84

(3.5

1-4.

20)

4.78

(4

.37-

5.24

)5.

97

(5.4

2-6.

58)

7.02

(6

.27-

7.86

)60

-64

year

s33

,235

0.13

(0

.09-

0.17

)0.

25

(0.2

0-0.

31)

0.87

(0

.77-

0.97

)1.

71

(1.5

7-1.

87)

2.71

(2

.52-

2.92

)3.

85

(3.6

0-4.

10)

4.87

(4

.58-

5.18

)6.

21

(5.8

5-6.

60)

7.27

(6

.83-

7.73

)8.

81

(8.2

3-9.

44)

10.2

2 (9

.42-

11.0

9)65

-69

year

s36

,818

0.20

(0

.16-

0.25

)0.

41

(0.3

5-0.

48)

1.16

(1

.06-

1.28

)2.

27

(2.1

2-2.

44)

3.72

(3

.50-

3.95

)5.

26

(4.9

9-5.

55)

7.03

(6

.70-

7.38

)8.

94

(8.5

3-9.

37)

11.2

9 (1

0.77

-11.

84)

14.0

3 (1

3.34

-14.

76)

16.5

2 (1

5.58

-17.

52)

70-7

4 ye

ars

38,1

360.

23

(0.1

9-0.

29)

0.50

(0

.44-

0.58

)1.

69

(1.5

7-1.

83)

3.52

(3

.33-

3.73

)5.

77

(5.5

1-6.

04)

8.41

(8

.08-

8.76

)11

.05

(10.

64-1

1.47

)14

.00

(13.

51-1

4.52

)17

.23

(16.

61-1

7.87

)21

.34

(20.

51-2

2.21

)25

.18

(24.

00-2

6.40

)75

-79

year

s30

,152

0.47

(0

.39-

0.55

)0.

84

(0.7

4-0.

95)

2.63

(2

.45-

2.83

)5.

38

(5.1

1-5.

67)

9.06

(8

.69-

9.44

)12

.93

(12.

47-1

3.41

)17

.55

(16.

97-1

8.15

)22

.94

(22.

21-2

3.70

)28

.15

(27.

24-2

9.07

)34

.49

(33.

30-3

5.72

)41

.92

(40.

13-4

3.76

)80

+

year

s22

,579

1.18

(1

.05-

1.33

)2.

18

(1.9

9-2.

38)

5.58

(5

.28-

5.90

)10

.85

(10.

41-1

1.30

)17

.16

(16.

60-1

7.75

)24

.90

(24.

19-2

5.62

)32

.76

(31.

91-3

3.62

)41

.01

(40.

01-4

2.03

)49

.14

(47.

94-5

0.35

)57

.38

(55.

89-5

8.89

)65

.67

(63.

62-6

7.72

)

Fem

ales

:

<55

ye

ars

31,9

390.

06

(0.0

4-0.

090.

21

(0.1

6-0.

27)

0.68

(0

.59-

0.77

)1.

10

(0.9

9-1.

23)

1.61

(1

.46-

1.77

)2.

01

(1.8

4-2.

20)

2.33

(2

.13-

2.54

)2.

79

(2.5

6-3.

05)

3.31

(3

.02-

3.63

)3.

81

(3.4

4-4.

22)

4.29

(3

.79-

4.86

) 5

5- 5

9 ye

ars

26,0

830.

09

(0.0

6-0.

14)

0.20

(0

.15-

0.26

)0.

63

(0.5

4-0.

74)

1.20

(1

.06-

1.35

)1.

69

(1.5

2-1.

87)

2.37

(2

.16-

2.60

)3.

04

(2.7

9-3.

32)

3.77

(3

.46-

4.10

)4.

60

(4.2

2-5.

01)

5.39

(4

.91-

5.92

)6.

31

(5.6

2-7.

07)

60-6

4 ye

ars

41,4

320.

08

(0.0

6-0.

11)

0.17

(0

.14-

0.22

)0.

61

(0.5

3-0.

69)

1.26

(1

.15-

1.38

)1.

99

(1.8

4-2.

14)

2.85

(2

.66-

3.05

)3.

79

(3.5

5-4.

04)

4.65

(4

.37-

4.96

)5.

77

(5.4

0-6.

16)

7.02

(6

.54-

7.54

)7.

97

(7.3

4-8.

65)

65-6

9 ye

ars

53,0

920.

09

(0.0

7-0.

12)

0.23

(0

.19-

0.28

)0.

77

(0.7

0-0.

85)

1.59

(1

.48-

1.71

)2.

57

(2.4

2-2.

73)

3.73

(3

.54-

3.93

)5.

02

(4.7

8-5.

27)

6.39

(6

.09-

6.69

)7.

92

(7.5

5-8.

31)

9.68

(9

.19-

10.1

9)11

.75

(11.

03-1

2.51

)70

-74

year

s59

,720

0.14

(0

.12-

0.18

)0.

32

(0.2

8-0.

37)

1.02

(0

.94-

1.11

)2.

22

(2.1

0-2.

35)

3.61

(3

.45-

3.79

)5.

38

(5.1

6-5.

61)

7.50

(7

.22-

7.79

)9.

78

(9.4

3-10

.13)

12.3

0 (1

1.86

-12.

76)

15.1

5 (1

4.58

-15.

75)

18.5

4 (1

7.70

-19.

41)

75-7

9 ye

ars

53,6

080.

28

(0.2

4-0.

33)

0.53

(0

.47-

0.59

)1.

64

(1.5

3-1.

76)

3.56

(3

.40-

3.74

)5.

83

(5.6

1-6.

06)

8.64

(8

.35-

8.94

)11

.89

(11.

53-1

2.26

)15

.40

(14.

95-1

5.86

)19

.21

(18.

65-1

9.79

)23

.75

(23.

00-2

4.52

)29

.13

(27.

99-3

0.30

)80

+

year

s54

,214

0.59

(0

.53-

0.66

)1.

31

(1.2

2-1.

41)

3.60

(3

.44-

3.77

)7.

16

(6.9

3-7.

40)

11.6

3 (1

1.32

-11.

94)

17.2

6 (1

6.87

-17.

66)

23.3

6 (2

2.88

-23.

85)

30.1

7 (2

9.58

-30.

77)

37.3

5 (3

6.62

-38.

08)

45.0

7 (4

4.14

-46.

01)

52.1

6 (5

0.87

-53.

47)


3.2.7 In-depth study: Metal-on-metal hip resurfacing

Since the last annual report we have examined metal-on-metal hip resurfacing in greater depth. A research paper comparing the failure rates of metal-on-metal hip resurfacings with alternative forms of hip replacement was published in the Lancet in November 2012.

Smith AJ, Dieppe P, Howard PW, Blom AW; National Joint Registry for England and Wales. Failure rates of metal-on-metal hip resurfacings: Analysis of data from the National Joint Registry for England and Wales. Lancet. 2012 Nov 17;380(9855):1759-66

We have analysed data from the NJR to test the following hypotheses: larger head size is related to higher failure rates; metal-on-metal has significantly worse results in women; and hip resurfacing gives better implant survivorship than stemmed THR in younger patients.

Methods

Analysis was based on 434,560 THRs between April 2003 and September 2011 where patient-identifiers are present that allow revisions to be linked to primary operations (81.8% of 531,247 operations). These operations were performed in 447 units under the care of 2,584 consultant surgeons.

The analysis estimated all-cause revision rates. The unit of analysis was implant (rather than patient) so bilateral procedures were included (2,645). We have compared revision rates for three types of bearing surface: resurfacing, ceramic-on-ceramic, and metal-on-polyethylene. A range of commonly used head sizes were compared for the resurfacing and ceramic-on-ceramic groups whereas the most commonly used head size of 28mm (Table 1) was been chosen for the metal-on-polyethylene group. A confounding variable was the fixation of the implant. We have addressed this by reporting ceramic-on-ceramic results for uncemented fixation as this was most commonly used (45,099/57,748, 78.1%) while for metal-on-polyethylene, results were shown separately for cemented, uncemented and hybrid fixations.

There were substantial differences between the bearing groups in terms of patient characteristics. To reduce the effects of confounding, analysis was based on the large majority with an American Society of Anaesthesiologists (ASA) grade of 1 or 2 at time of primary surgery and those whose surgery was undertaken for osteoarthritis only (Table 1). The now-withdrawn ASR implants (2,829, 8.9% of the total) were excluded from the resurfacing analysis so as not to distort the results. Furthermore, sensitivity analysis confirmed that the results for the newer technologies of resurfacing and ceramic-on-ceramic were not distorted by a ‘learning curve’ effect of less experienced surgeons (see web appendix published in Lancet).

Multivariable analysis has been used to adjust for patient age and ASA grade and to measure the effect of head size. As head size and gender were highly correlated, separate models were estimated for men and women to avoid multicollinearity. Separate models were also specified for the different bearing groups.

Flexible parametric survival models that estimate the cumulative incidence of revision in the presence of the competing risk of death were used. Standard survival analysis treats death simply as censored information but this has been shown to overestimate revision rates. In all models, head size, age and ASA grade were selected as predictors of revision and age and ASA grade were predictors of the competing risk of death. The effect of age was allowed to differ for the main and competing risks. These models produce hazard ratios, which are a measure of relative risk (averaged over time). To illustrate the absolute effect of these factors, the models have been used to predict revision rates for a typical patient by estimating the covariate-adjusted cumulative incidence function in the presence of competing risks.

One resurfacing brand, the Birmingham Hip Resurfacing system (BHR), was used in more than half of cases giving large enough numbers to repeat the multivariable analysis approach for the BHR cases alone (15,386/26,199, 58.9%). This enabled the potentially confounding influence of different brand effects to be removed. We have compared the BHR with the most commonly used alternatives in each group: the Exeter V40 Contemporary metal-on-



polyethylene 28mm cemented THR (23,906/69,569, 34.4%) and the Corail Pinnacle 36mm ceramic-on-ceramic uncemented THR (9,604/18,370, 52.3%).

The reasons for revision across all groups were also examined by dividing the number of revisions for each reason by the total person time at risk of revision (per 1,000 patient-years). This was equivalent to a person-time incidence rate and 95% confidence intervals have been estimated assuming a Poisson distribution.

Results

Overall, 7.4% (31,932/434,560) of THRs were resurfacing procedures. Annual numbers in England and Wales reached a peak of 6,650 operations in 2007 but thereafter fell to around 2,000 in 2011. Resurfacing patients were most commonly aged 59 years while the median age was 55. Overall, 78.4% of patients were aged 45-65 years and 69.1% of resurfacings were undertaken on men (Table L1).

Unadjusted analysis suggested that revision rates for resurfacing procedures were higher than for stemmed THR (five-year revision rate of 5.2% (95% CI 4.9-5.5%) compared with 2.8% (95% CI 2.7-2.9%). However, this overall rate disguised differences according to gender (Figure L1). In women, 8.5% of resurfacings had been revised by five years (95% CI 7.8-9.2%) compared with 3.6% in men (95% CI 3.3-3.9%). A head size of between 46mm and 54mm was used for 92.1% (20342/22076) of male resurfacing patients while 76.5% (7541/9856) of females had a head size of 42-46mm. Just 1% (98/9,856) of women received the larger head sizes above 50mm. In total, 15 resurfacing brands were used.

The multivariable models for resurfacing procedures confirmed that head size was an independent predictor of revision for both men (hazard ratio 0.951, 95% CI 0.945-0.978, p<0.0005 per unit increase in head size) and women (hazard ratio 0.921, 95% CI 0.892-0.951, p<0.0005) indicating that smaller head sizes were more likely to be revised. These hazard ratios can be broadly interpreted as each 1mm increase in head size being associated with a 5-8% reduction in the hazard (the risk of revision at a particular point in time). Age was a significant predictor

of the competing risk of death but not of revision for either men or women. ASA grade was a significant predictor of revision for men only (hazard ratio 1.267, 95% CI 1.042-1.540, p=0.018) indicating that patients with ASA grade 2 were more likely to be revised than those with ASA grade 1.

Predicted revision rates from these models illustrate the absolute effect of head size. For a 55-year-old man, the five-year revision rate with a 46mm head was 4.1% compared with 2.6% for a 54mm head (Table L2). Resurfacing revision rates for women were much higher than for men (five-year revision rate of 8.3% with a 42mm head size) (Table L3). This was true even with the same head size: a 55-year-old woman had a five-year revision rate of 6.1% with a 46mm head size compared with 4.1% for a 55-year-old man. Only 0.4% (35/9,856) of women had a head size of 54mm or above associated with the lowest revision rates in men.

Resurfacing procedures with a large head size (54mm or greater) resulted in revision rates which were not significantly worse than those of other common surgical options (Table L2). In men, a 54mm resurfacing head had a five-year revision rate of 2.6% compared with 2.1% for an uncemented 40mm ceramic-on-ceramic prosthesis and 1.9% for a cemented 28mm metal-on-polyethylene articulation. However, the smaller resurfacing head sizes compared less well. Key results are illustrated in Figure L2. Overall, just 23% (5,085/22,076) of male resurfacings used the 54mm or larger head size that had the lowest revision rates.

In women, resurfacing, even with larger heads, offered significantly poorer implant survivorship than all other common surgical options (Table L3). In 55-year-old women, a 46mm resurfacing procedure had a fiveyear revision rate of 6.1% compared with 2.5% for a 36mm ceramic-on-ceramic prosthesis and 1.5% for a cemented 28mm metal-on-polyethylene articulation (Figure L3).

Generally, the BHR had better implant survivorship than other resurfacing brands. Unadjusted analysis for all male patients shows a five-year revision rate of 2.4% (95% CI 2.1-2.7%) for the BHR compared with 8.1% (95% CI 6.7-9.8%) for the now-withdrawn ASR


Figure L1 Cumulative hazard of revision after resurfacing by gender (with 95% CI).


Female

Male

2%

4%

6%

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14%

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and 4.2% (95% CI 3.7-4.9%) for other resurfacing brands. The equivalent five-year revision rates in women were more than twice as high for all brands (5.8% (95% CI 5.1-6.6%) for the BHR, 21.0% (95% CI 17.7-24.9%) for the ASR and 9.2% (95% CI 8.1-10.5%) for other brands). However, the multivariable models indicated that in men aged 55, the BHR with the 54mm head size did not demonstrate better implant survivorship than the Exeter/Contemporary or the Corail/Pinnacle and had considerably worse implant survivorship in women (Table L4).

Resurfacings were most commonly revised for pain, periprosthetic fracture, and aseptic loosening (Table L5). Revision for periprosthetic fracture was up to eight times more common in resurfacing than in other surgical options. Revisions for pain in women were up to 10 times higher with resurfacing than with other surgical options and revisions for aseptic loosening were up to four times higher. Revisions for dislocation in resurfacing were lower than other options in men.



Figure L2 Estimated cumulative incidence of revision for 55-year-old male by prosthesis type.

Figure L3 Estimated cumulative incidence of revision for 55-year-old female by prosthesis type.


Resurfacing 46mm

Resurfacing 52mm

Resurfacing 48mm

Resurfacing 50mm

Resurfacing 54mm

Uncemented ceramic-on-ceramic 40mm

Cemented metal-on-polyethylene 28mm0

1%

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Resurfacing 42mm

Uncemented ceramic-on-ceramic 36mm

Resurfacing 44mm

Resurfacing 46mm

Cemented metal-on-polyethylene 28mm0

1%2%3%4%5%6%7%8%9%

10%11%12%

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Table L1 Description of comparison groups: number of cases (percentage of total).

Bearing surface

Resurfacing (N=31,932)Ceramic-on-ceramic

(N=57,748) Metal-on-polyethylene

(N=226,165)Head sizeLess than 28mm 0 (0.0%) 0 (0.0%) 22,140 (9.9%)28mm 0 (0.0%) 12,274 (21.3%) 154,305 (68.2%)30-34mm 0 (0.0%) 18,680 (32.3% 30,059 (13.3%)36-40mm 577 (1.8%) 26,339 (46.0%) 16,113 (7.2%)42mm 2,107 (6.6%) 0 (0.0%) 0 (0.0%)44mm 2,032 (6.4%) 0 (0.0%) 349 (0.2%)46mm 5,626 (17.6%) 0 (0.0%) 0 (0.0%)48mm 3,735 (11.7%) 0 (0.0%) 0 (0.0%)50mm 8,905 (27.9%) 0 (0.0%) 0 (0.0%)52mm 3,397 (10.6%) 0 (0.0%) 0 (0.0%)54mm 4,054 (12.7%) 0 (0.0%) 0 (0.0%)56-62mm 1,066 (3.3%) 0 (0.0%) 0 (0.0%)Unknown size 379 (1.2%) 455 (0.8%) 3,199 (1.4%)Age (mean age in years) 54.1 59.6 72.7Aged less than 40 years 1,934 (6.1%) 2,874 (5.0%) 558 (0.3%)Aged 40-49 6,877 (21.5%) 6,065 (10.5%) 1,929 (0.9%)Aged 50-59 14,067 (44.1%) 16,877 (29.2%) 12,451 (5.5%)Aged 60-69 8,229 (25.8%) 22,918 (39.7%) 58,865 (26.0%)Aged 70 or over 825 (2.6%) 9,014 (15.6%) 152,362 (67.4%)GenderMale 22,076 (69.1%) 25,290 (43.8%) 78,891 (34.9%)Female 9,856 (30.9%) 32,458 (56.2%) 147,274 (65.1%)ASA grade1 - fit and healthy 15,613 (48.9%) 16,048 (27.8%) 29,320 (13.0%)2 - mild systemic disease that does not limit activity

15,336 (48.0%) 37,196 (64.4%) 157,492 (69.6%)

3 - systemic disease that limits activity but is not incapacitating

947 (3.0%) 4,385 (7.6%) 37,764 (16.7%)

4/5 - incapacitating, life-threatening systemic disease/not expected to survive 24 hours without an operation

36 (0.1%) 119 (0.2%) 1589 (0.7%)

DiagnosisOsteoarthritis only 29,550 (92.5%) 50,626 (87.7%) 208,173 (92.0%)Other 2,382 (7.5%) 7,122 (12.3%) 17,992 (8.0%)Total (% of all THR) 31,932 (7.4%) 57,748 (13.3%) 226,165 (52.0%)Multivariable model samplesTotal in model 26,119 (81.8%) 36,009 (62.4%) 115,574 (51.1%)Number of surgeons 698 (27.0%) 1,202 (46.5%) 2,144 (83.0%)Number of units 372 (83.2%) 397 (88.8%) 434 (97.1%)Numbers followed up by yearLess than 1 year 1,681 (6.4%) 9,034 (25.1%) 14,871 (12.9%)1 - < 2 years 2,692 (10.3%) 8,868 (24.6%) 16,967 (14.7%)2 - < 3 years 3,708 (14.2%) 6,419 (17.8%) 17,257 (14.9%)3 - < 4 years 4,457 (17.1%) 4,577 (12.7%) 17,852 (15.4%)4 - < 5 years 4,335 (16.6%) 2,940 (8.2%) 16,906 (14.6%)5 - < 6 years 3,653 (14.0%) 1,980 (5.5%) 13,218 (11.4%)6 - < 7 years 2,835 (10.9%) 1,182 (3.3%) 10,265 (8.9%)7 or more years 2,756 (10.6%) 1,008 (2.8%) 8,237 (7.1%)

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Note: among the full sample of hip replacements (N=434,560), there are other bearing surfaces which are not shown in this table: 46,290 ceramic-on-polyethylene (10.7% of the total), 31,171 stemmed metal-on-metal (7.2% of total), 2,430 other combinations (0.6%), and 38,824 unknown bearings (8.9%).



Table L2 Predicted revision rates for 55-year-old males by prosthesis and head size (95% CI).

Type/head size Year 1 Year 3 Year 5 Year 7

Resurfacing 46mm 1.57 (1.26-1.95) 2.81 (2.31-3.42) 4.05 (3.34-4.90) 5.23 (4.29-6.38)

48mm 1.40 (1.17-1.68) 2.52 (2.15-2.94) 3.63 (3.12-4.21) 4.69 (3.99-5.51)

50mm 1.26 (1.06-1.48) 2.25 (1.96-2.58) 3.25 (2.85-3.70) 4.20 (3.65-4.84)

52mm 1.12 (0.94-1.34) 2.02 (1.74-2.34) 2.91 (2.52-3.35) 3.77 (3.23-4.38)

54mm 1.00 (0.82-1.23) 1.80 (1.50-2.17) 2.60 (2.18-3.11) 3.37 (2.80-4.06)

Ceramic-on-ceramic

Uncemented 28mm 1.24 (0.92-1.68) 2.46 (1.87-3.22) 3.41 (2.64-4.40) 4.08 (3.14-5.28)

Uncemented 32mm 1.05 (0.84-1.30) 2.07 (1.72-2.50) 2.88 (2.39-3.47) 3.45 (2.81-4.23)

Uncemented 36mm 0.88 (0.71-1.10) 1.75 (1.43-2.14) 2.43 (1.96-3.02) 2.91 (2.28-3.71)

Uncemented 40mm 0.74 (0.55-1.01) 1.48 (1.09-2.00) 2.05 (1.49-2.83) 2.46 (1.73-3.47)

Metal-on-polyethylene

Cemented 28mm 0.56 (0.43-0.73) 1.28 (1.00-1.64) 1.91 (1.50-2.44) 2.40 (1.87-3.06)

Hybrid 28mm 1.26 (0.83-1.92) 2.19 (1.48-3.24) 3.21 (2.20-4.67) 4.10 (2.80-5.97)

Uncemented 28mm 1.41 (1.03-1.93) 2.57 (1.92-3.42) 3.48 (2.63-4.59) 4.18 (3.14-5.56)

Table L3 Predicted revision rates for 55-year-old females by prosthesis and head size (95% CI).


Resurfacing 42mm 1.81 (1.47-2.24) 5.09 (4.33-5.97) 8.33 (7.18-9.65) 11.67 (10.00-13.58)

44mm 1.54 (1.26-1.88) 4.33 (3.75-4.99) 7.11 (6.24-8.09) 9.99 (8.71-11.43)

46mm 1.31 (1.07-1.60) 3.69 (3.17-4.28) 6.07 (5.28-6.95) 8.54 (7.39-9.85)

Ceramic-on-ceramic

Uncemented 28mm 0.87 (0.68-1.12) 1.87 (1.50-2.33) 2.63 (2.12-3.25) 3.31 (2.63-4.17)

Uncemented 32mm 0.84 (0.69-1.01) 1.81 (1.53-2.13) 2.54 (2.15-3.01) 3.20 (2.62-3.92)

Uncemented 36mm 0.81 (0.65-1.02) 1.75 (1.41-2.17) 2.46 (1.95-3.09) 3.10 (2.38-4.03)

Metal-on-polyethylene

Cemented 28mm 0.60 (0.32-1.10) 1.12 (0.62-2.01) 1.47 (0.82-2.60) 1.81 (0.99-3.28)

Hybrid 28mm 0.70 (0.49-1.02) 1.23 (0.87-1.73) 1.82 (1.30-2.53) 2.48 (1.77-3.47)

Uncemented 28mm 0.81 (0.60-1.07) 1.46 (1.12-1.91) 1.94 (1.49-2.53) 2.25 (1.71-2.95)

Note: results are estimated from multivariable competing risks flexible parametric survival models based on 18,375 resurfacing cases, 16,136 uncemented ceramic-on-ceramic cases, and for 28mm metal-on-polyethylene: 22,407 cemented, 6,634 hybrid and 9,352 uncemented cases. Results are based on an ASA grade of 2.

Note: results are estimated from multivariable competing risks flexible parametric survival models based on 7,744 resurfacing cases, 19,873 uncemented ceramic-on-ceramic cases, and for 28mm metal-on-polyethylene: 47,162 cemented, 13,383 hybrid and 16,636 uncemented cases. Results are based on an ASA grade of 2.

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Table L4 Comparison of most commonly used brands; predicted revision rates for 55-year old patients (95% CI).


Males aged 55 BHR 46mm 1.52 (1.12-2.05) 2.48 (1.87-3.28) 3.43 (2.61-4.50) 4.32 (3.26-5.70)

BHR 50mm 1.15 (0.92-1.43) 1.87 (1.54-2.28) 2.60 (2.15-3.12) 3.27 (2.69-3.97)

BHR 54mm 0.86 (0.65-1.15) 1.41 (1.09-1.84) 1.96 (1.52-2.52) 2.47 (1.90-3.20)Uncemented Corail /Pinnacle ceramic-on-ceramic 36mm

0.93 (0.65-1.35) 1.90 (1.36-2.64) 2.52 (1.72-3.67) -

Cemented Exeter V40/ Contemporary metal-on-polyethylene 28mm

0.53 (0.28-1.02) 1.00 (0.54-1.86) 1.31 (0.71-2.41) 1.61 (0.86-3.02)

Females aged 55

BHR 42mm 2.01 (1.52-2.66) 5.02 (4.03-6.25) 8.23 (6.73-10.04) 11.76 (9.59-14.36)

BHR 46mm 1.20 (0.91-1.57) 3.00 (2.43-3.71) 4.96 (4.08-6.00) 7.14 (5.86-8.67)Uncemented Corail/Pinnacle ceramic-on-ceramic 36mm

0.63 (0.42-0.94) 1.53 (1.07-2.20) 2.00 (1.35-2.95) -

Cemented Exeter V40/ Contemporary metal-on-polyethylene 28mm

0.42 (0.25-0.71) 0.87 (0.54-1.41) 1.38 (0.86-2.20) 1.94 (1.18-3.17)

Note: results are estimated from multivariable competing risks flexible parametric survival models based on 10,889 male and 4,497 female BHR resurfacing cases, 5,389 male and 4,213 female Corail Pinnacle 36mm ceramic-on-ceramic cases and 7,857 male and 16,049 female cases for the Exeter/Contemporary. Results are based on an ASA grade of 2. Seven-year revision rates cannot be estimated for the Corail/Pinnacle ceramic-on-ceramic 36mm as this has only been in use in England and Wales since 2005.

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Table L5 Reasons for revision (95% CI), expressed as incidence per 1,000 patient-years, by articulation and fixation.

Resurfacing

Uncemented ceramic-on-

ceramic

Uncemented metal-on-

polyethylene 28mm

Hybrid11 metal-on-polyethylene

28mm

Cemented metal-on-polyethylene

28mm

Males Aseptic loosening 1.42 (1.17-1.72) 1.80 (1.42-2.27) 1.88 (1.48-2.41) 0.73 (0.47-1.14) 0.75 (0.58-0.97)

Dislocation/subluxation 0.18 (0.10-0.31) 1.13 (0.84-1.52) 1.56 (1.19-2.04) 1.77 (1.32-2.36) 0.75 (0.58-0.97)

Implant failure 0.07 (0.03-0.16) 0.46 (0.29-0.73) 0.35 (0.20-0.62) 0.12 (0.04-0.37) 0.10 (0.05-0.20)

Implant fracture 0.29 (0.19-0.44) 0.62 (0.41-0.92) 0.03 (0.00-0.21) 0.15 (0.06-0.41) 0.05 (0.02-0.13)

Incorrect sizing 0.03 (0.01-0.11) 0.05 (0.01-0.21) 0.03 (0.00-0.21) 0.00 - 0.00 -

Infection 0.55 (0.40-0.75) 1.13 (0.84-1.52) 1.12 (0.81-1.54) 1.15 (0.80-1.65) 1.09 (0.88-1.34)

Lysis 0.25 (0.16-0.39) 0.08 (0.02-0.24) 0.29 (0.16-0.55) 0.19 (0.08-0.46) 0.24 (0.15-0.37)

Malalignment 0.64 (0.48-0.86) 0.59 (0.39-0.89) 0.68 (0.45-1.02) 0.27 (0.13-0.56) 0.21 (0.13-0.34)

Other 1.12 (0.90-1.39) 0.69 (0.48-1.01) 0.18 (0.08-0.39) 0.31 (0.15-0.61) 0.15 (0.09-0.26)

Pain 1.70 (1.42-2.02) 1.13 (0.84-1.52) 1.00 (0.72-1.40) 0.77 (0.50-1.19) 0.46 (0.34-0.64)

Periprosthetic fracture 1.54 (1.28-1.86) 0.64 (0.43-0.95) 0.38 (0.22-0.66) 0.69 (0.44-1.10) 0.51 (0.38-0.70)

Person time (years) 73,143.3 38,917.4 33,959.7 26,061.9 79,971.8

Number revised 457 255 185 128 267

Number of operations 18,375 16,136 9,352 6,634 22,407

Females

Aseptic loosening 3.73 (3.14-4.43) 1.25 (0.97-1.61) 1.17 (0.92-1.49) 0.83 (0.61-1.12) 0.75 (0.63-0.90)

Dislocation/subluxation 0.77 (0.53-1.13) 1.09 (0.83-1.42) 1.72 (1.41-2.10) 1.38 (1.09-1.75) 0.81 (0.69-0.96)

Implant failure 0.37 (0.22-0.64) 0.41 (0.26-0.64) 0.21 (0.12-0.38) 0.28 (0.16-0.47) 0.05 (0.03-0.10)

Implant fracture 0.32 (0.17-0.57) 0.66 (0.46-0.93) 0.05 (0.02-0.17) 0.06 (0.02-0.18) 0.03 (0.01-0.07)

Incorrect sizing 0.09 (0.03-0.27) 0.12 (0.06-0.27) 0.05 (0.02-0.17) 0.02 (0.00-0.14) 0.01 (0.00-0.05)

Infection 0.63 (0.42-0.96) 0.41 (0.26-0.64) 0.39 (0.26-0.59) 0.32 (0.19-0.52) 0.56 (0.46-0.69)

Lysis 0.86 (0.60-1.23) 0.12 (0.06-0.27) 0.07 (0.03-0.19) 0.18 (0.09-0.34) 0.14 (0.10-0.21)

Malalignment 1.15 (0.84-1.56) 0.78 (0.57-1.07) 0.82 (0.61-1.09) 0.47 (0.32-0.71) 0.30 (0.23-0.39)

Other 2.78 (2.28-3.40) 0.74 (0.53-1.02) 0.41 (0.27-0.62) 0.18 (0.09-0.34) 0.17 (0.12-0.25)

Pain 5.28 (4.57-6.10) 1.00 (0.76-1.33) 0.68 (0.49-0.93) 0.51 (0.35-0.75) 0.41 (0.33-0.52)

Periprosthetic fracture 1.61 (1.24-2.09) 0.94 (0.71-1.26) 0.55 (0.39-0.78) 0.32 (0.19-0.52) 0.19 (0.14-0.27)

Person time (years) 34,859.4 48,806.1 56,259.4 50,637.5 167,174.5

Number revised 477 274 248 167 411

Number of operations 7,744 19,873 16,636 13,383 47,162

11 Not including reverse hybrid

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3.2.8 Conclusions

This year’s report confirms many of the trends shown in previous years. Once again we stress that implant survivorship alone is an incomplete measure of outcome. Implant survivorship gives little indication of satisfaction, relief of pain, improvement in function and greater participation in society. Readers should also understand that each year more data are available and thus analysis can give a more accurate picture. Each year’s analysis thus supersedes the previous analyses and may, in places, appear contradictory with previous reports from a smaller dataset. Furthermore, the data are imperfect and rely on accurate and comprehensive reporting by surgeons. Some fields, such as body mass index (BMI), were not initially reported but we are encouraged that in 2012 over 60% of entries included BMI data. We would urge surgeons to complete all fields in the NJR forms in order to allow meaningful analysis. This year we have analysed survivorship for metal-on-polyethylene bearings by head size for the first time. We have not attempted to sub-classify polyethylene as what constitutes so called third generation polyethylene is not clearly defined. This analysis shows that there appears to be an association between increased implant failure and larger head sizes.

We note that metal-on-metal stemmed hip replacement and hip resurfacing have virtually ceased with fewer than one in one thousand hip replacements performed in 2012 belonging to each of these classes of implant. The failure rates in these classes continue to be markedly higher than the alternatives. Other bearing surfaces continue to have very low failure rates regardless of fixation, especially for ceramic-on-polyethylene bearings.

As we now have more data, we have been able to extend brand analysis to more stem/cup combinations. Brand analysis of stem/cup combinations shows higher unadjusted failure rates with uncemented stem/cup combinations than with hybrid or all cemented combinations. The best survivorship at nine years is achieved with all-cemented components.

The in-depth analysis of hip resurfacing highlights the high failure rate, particularly amongst women. It also demonstrates that failure rate is related to both gender and head size, with smaller femoral heads and female gender independently associated with higher rates of implant revision. In men with the largest head sizes the failure rates are not significantly worse than alternatives. Only 23% of men who have undergone resurfacing in England and Wales have these larger femoral heads.

Mortality in the first 30 or 90 days after surgery remains very low, which is reassuring. However, mortality at nine years after hip replacement is high in those over the age of 75 suggesting than long-term implant survivorship is unlikely to be important in this age group.

Part 33.3 Outcomes after primary knee replacement


In the period 2003 to 2012 589,028 knees were replaced for the first time. The knee is made up of three compartments: medial, lateral and patello femoral compartments; when a ‘total’ knee replacement (TKR) is implanted two out of the three compartments are always replaced (medial and lateral) and the patella is resurfaced if the surgeon considers this to be of benefit to the patient. If a single compartment is replaced then the term ‘unicompartmental’ is applied to the implant (UKR). The medial, lateral or patello-femoral compartments can be replaced independently, if clinically appropriate.

There is variation in the constraint of the tibial insert depending on whether the posterior cruciate ligament is preserved (cruciate retaining CR) or sacrificed (posterior-stabilised, PS) at the time of surgery. Additional constraint may be necessary to allow the

implant to deal with additional ligament deficiency or bone loss, where a constrained condylar (CCK) or hinged knee would be used, even in a primary situation. The tibial construct may be modular with a metallic tibial tray and a polyethylene insert or non-modular being constructed of polyethylene alone. In recent years all-polyethylene tibial components have increased in popularity so as to contain costs of the implant.

The tibial insert may be mobile or remain in a fixed position on the tibial tray. This also applies to medial and lateral unicompartmental knees. Many brands of total knee implant exist in fixed and mobile forms with CR or PS constraint.

The method of fixation used to secure the vast majority of knee replacements in place is cement (83.4% from table 3.14), unlike hip replacements.

Terminology note

Both total and partial knee replacement procedures are discussed in this section. At present, the NJR does not distinguish between medial and lateral unicondylar knee replacements during the data collection process. In addition, there are other possible knee designs, such as combinations of unicondylar and patello-femoral

replacements, but these are not reported on here as numbers are too small.

With regard to the use of the phrase ‘constraint’ here, for brevity, total knee replacements are termed unconstrained (instead of posterior cruciate-retaining) or posterior-stabilised (instead of posterior cruciate-stabilised).

3.3.1 Overview of primary knee surgery

Table 3.14 shows the proportion of all kinds of primary knee operations performed, broken down by fixation method and bearing type. The vast majority of replacements were of the total knee joint with an all cemented implant being the most common fixation method used (83.4% of all primary knee operations were total replacements using all cemented components). Nearly 9% of all primary operations were unicondylar and, of the remaining total knee replaced joints, 6.5% were either all uncemented or a hybrid type (made up of both cemented and uncemented parts).

Over half of all operations (54%) were total knee replacements which were all cemented, unconstrained and fixed, followed by 21% which were all cemented,

posterior-stabilised and fixed. A number of primary operations could not be classified according to their bearing/constraint (approximately 2.5%).

Table 3.15 shows the annual change in usage of primary knee replacement. Overall, over 80% of all primaries utilised an all cemented fixation method and, since 2003, the share of all implant replacements of this type has increased by some 5%. The main decline in type of primary surgery has been in the use of all uncemented and hybrid total knee replacements over time. Each approximately has halved in terms of proportion of implants of this type now used compared to figures for 2003. There has also been a steady increase in use of all cemented all polyethylene tibial implants (2.1% of primary surgeries in 2012 compared to less than half a percent of all primary surgeries between 2003 and 2005).



Table 3.14 Numbers and percentages of primary knee replacements by fixation method and bearing type.

Type of primary knee operation Number of primary knee operations Percentage of totalFixation method Bearing Type

Total knee replacement

All cemented 490,939 83.4

Cemented and

unconstrained, fixed 317,914 54.0

unconstrained, mobile 25,931 4.4

posterior-stabilised, fixed 123,162 20.9

posterior-stabilised, mobile 8,276 1.4

constrained condylar 2,173 0.4

all polyethylene tibia 6,124 1.0

bearing type unknown 7,359 1.3

All uncemented 31,382 5.3

All hybrid 7,307 1.2

Uncemented/hybrid and

unconstrained, fixed 18,865 3.2

unconstrained, mobile 16,502 2.8

posterior stabilised, fixed 2,479 0.4

other constraint 350 0.06

bearing type unknown 493 0.08

Unicompartmental knee replacement

All unicondylar 51,474 8.7

Unicondylar and

fixed 13,763 2.3

mobile 36,982 6.3

bearing type unknown 729 0.1

All patello-femoral 7,881 1.3

Knee type unknown 45 0.01

All types 589,028 100.0©

Nat

iona

l Joi

nt R

egis

try

2013


Table 3.15 Percentage of primary knee replacements performed each year by method of fixation and, within each fixation group, by bearing type.

Percentage of knee replacements each year by fixation and bearing type

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012Total knee replacement

All cemented 81.5 80.8 81.7 81.4 81.9 81.9 82.7 84.0 85.6 86.9

Cemented and

unconstrained, fixed 53.3 53.0 53.0 50.7 50.5 51.4 53.1 54.5 56.6 59.8unconstrained, mobile

4.0 4.2 5.2 6.3 6.3 5.6 4.6 3.9 2.8 2.3

posterior-stabilised, fixed

20.8 20.6 19.8 20.1 20.4 21.0 21.4 21.7 21.6 20.6

posterior-stabilised, mobile

0.9 1.1 1.6 1.9 1.7 1.4 1.4 1.4 1.2 1.1

constrained condylar 0.4 0.5 0.4 0.3 0.3 0.3 0.3 0.4 0.4 0.5

all polyethylene tibia 0.3 0.2 0.4 0.6 0.9 0.9 0.7 1.0 1.7 2.1bearing type unknown

1.8 1.3 1.4 1.6 1.8 1.4 1.2 1.1 1.2 0.6

All uncemented 6.7 6.6 6.2 6.5 6.5 6.2 5.7 4.7 4.1 3.3

All hybrid 2.8 2.8 2.4 1.7 1.4 1.4 1.2 0.9 0.5 0.4

Uncemented/hybrid and

unconstrained, fixed 4.9 4.7 4.3 4.0 4.1 4.0 3.7 2.7 1.9 1.4

unconstrained, mobile 3.5 3.7 3.3 3.2 3.1 3.1 2.7 2.6 2.4 2.1posterior stabilised, fixed

0.9 0.7 0.6 0.7 0.5 0.4 0.4 0.3 0.2 0.2

other constraint 0.0 0.0 0.2 0.2 0.1 0.1 0.0 0.0 0.0 0.0bearing type unknown

0.3 0.3 0.2 0.2 0.1 0.1 0.1 0.0 0.0 0.0


All unicondylar 8.0 8.7 8.6 9.2 8.8 9.1 9.0 9.0 8.4 8.1

Unicondylar and

fixed 1.4 1.8 2.1 2.3 2.0 2.1 2.2 2.6 2.6 2.9

mobile 6.5 6.7 6.5 6.8 6.7 6.8 6.6 6.2 5.8 5.2bearing type unknown

0.2 0.2 0.1 0.2 0.1 0.2 0.2 0.1 0.1 0.0

All patello-femoral 1.0 1.0 1.0 1.1 1.4 1.5 1.5 1.4 1.5 1.3

Knee type unknown 0.2 0.01

All types 13,512 27,697 41,846 49,459 66,587 73,806 75,494 78,061 81,032 81,534

© N

atio

nal J

oint

Reg

istr

y 20

13



2,722 consultant surgeons carried out at least one type of primary knee arthroplasty between 2003 and 2012. The median number of primary operations performed by a surgeon was 107 (IQR 21 to 315) over the whole period. The total number of surgical units in which at least one primary knee operation was carried out in the time period was 448. The median number of operations performed in a unit was 954 (IQR 460 to 1825).

Table 3.16 summarises the key features of the distribution of primary operations carried out by surgeons and units in terms of the proportions who performed each type of procedure and the median and IQR of the number of procedures they carried out. Surgeons and units who performed fewer than 10

operations over the whole period were excluded (i.e. 475 surgeons and 15 units, respectively).

Surgeons performing cemented TKR carried out a median of 137 operations of this type over the whole period they were observed with an IQR of 47 to 316 procedures. This means that 25% of surgeons had a caseload of fewer than 47 cemented total knee replacements over the time and 25% of surgeons carried out more than 316 procedures. The 10% of surgeons with the highest caseload completed between 517 and 2,599 all cemented primary TKRs (not shown in table 3.16). The majority of surgeons and units carried out very few, if any, uncemented and hybrid TKRs.

Table 3.16 Distribution of consultant surgeon and unit caseload12 for each fixation type.

Distribution of primary knee operations by fixation type performed by

(i) Consultant Surgeons (n=2,247) (ii) Surgical Units (n=433)% performing

this fixation type Median IQR


type Median IQRTotal knee replacement

All cemented 99.7 137 (47-316) 100.0 838 (390-1591)

All uncemented 26.6 6 (1-41) 64.0 16 (2-77)

All hybrid 29.5 2 (1-5) 71.4 4 (2-14)


All unicondylar 57.2 13 (3-43) 97.7 69 (25-148)

All patello-femoral 30.7 5 (2-13) 82.7 11 (4-27)

© N

atio

nal J

oint

Reg

istr

y 20

13

12 Only surgeons or units with at least 10 primary operations recorded in the NJR are presented in the tables. The total count of surgeons who had performed any knee operation between 2003 and 2012 is 2,722. Of these, 475 have performed fewer than 10 operations over this period. Excluding these from reported results leaves 2,247 surgeons. The total count of units who had performed any knee operation between 2003 and 2012 is 448. Of these, 15 have performed fewer than 10 operations over this period. Excluding these from reported results leaves 433 units.

Table 3.17 shows the age distribution of patients undergoing a first replacement of their knee joint. The median age of a person receiving a cemented total knee replacement was 70 years (with an inter-quartile range of 64 to 77 years). However, for unicompartmental primary knee surgery, patients were typically 6 (unicondylar) and 11 years younger

(patello-femoral). The 99th percentile of patient age for all types of surgery ranged between 85 and 88 years, indicating that surgery was rarely undertaken in a person aged 90 or older, although the maximum age of a patient who underwent primary surgery over the nine year period was aged 102 years.


Table 3.17 Age (in years) at primary operation13 for different types of knee replacement; by fixation and bearing type.

Fixation Bearing TypeMedian (IQR)14

of ages Minimum age15 Maximum ageTotal knee replacement

All cemented 70 (64-77) 14 102

Cemented and

unconstrained, fixed 70 (64-77) 16 101

unconstrained, mobile 69 (62-75) 23 97

posterior-stabilised, fixed 71 (64-77) 15 102

posterior-stabilised, mobile 65 (59-73) 22 95

constrained, condylar 72 (63-79) 20 96

all polyethylene tibia 75 (70-79) 25 96

bearing type unknown 70 (63-77) 14 99

All uncemented 69 (62-75) 20 101

All hybrid 69 (62-76) 23 96

Hybrid and

unconstrained, fixed 69 (62-76) 24 99

unconstrained, mobile 69 (62-76) 25 101

posterior-stabilised, fixed 66 (59-74) 20 93

other bearing type 65 (57-73) 33 95



All unicondylar 64 (57-70) 18 100

Unicondylar and

fixed 63 (56-70) 18 100

mobile 64 (58-71) 23 100


All patello-femoral 59 (51-68) 1 93

Fixation unknown 69 (59-77) 43 85

All types 70 (63-76) 1 102

© N

atio

nal J

oint

Reg

istr

y 20

13

13 Ages at primary operation excluding those 19 cases where age was recorded as zero years. Based on a total of 589,009 joints.14 The interquartile range (IQR) shows the age range of the middle 50% of patients arranged in order of their age at time of primary knee operation.15 The lowest age excluding 19 cases where age was recorded as zero years. The patello-femoral joint replacement in a one year old in the table above

certainly represents a data input error.



3.3.2 Revisions after primary knee surgery

Table 3.18 shows Kaplan-Meier estimates of the cumulative percentage probability of first revision, for any cause, for all cases combined and then subdivided by knee types. Estimates are shown, together with 95% Confidence Intervals (95% CIs), at 30 and 90 days after the primary operation and at each anniversary up to the 9th.

These estimates are not adjusted for other factors such as age and gender and these will be looked at in the future. The unicondylar and patello-femoral replacements seem to have done particularly badly

but are generally used in younger patients. This may be a function of milder disease in these patients, or the desire to delay a total knee replacement for as long as possible. Younger patients too may be more active which puts more strain on their implants.

Figure 3.6 compares the cumulative hazard of a first revision for the main types of primary knee replacement surgery over time. Patello-femoral and unicompartmental knee replacements were revised much earlier than total knee replacements. All curves increase in a reasonably linear fashion as time increases, indicating that the hazard rate was, by and large, constant over time.


Tab

le 3

.18

Kap

lan-

Mei

er e

stim

ates

of t

he c

umul

ativ

e pe

rcen

tage

pro

babi

lity

of fi

rst r

evis

ion

(95%

CI)

at s

peci

fied

times

afte

r pr

imar

y kn

ee

repl

acem

ent,

by fi

xatio

n an

d be

arin

g ty

pe.

Cum

ulat

ive

per

cent

age

pro

bab

ility

of

a fir

st r

evis

ion

(95%

CI)

at t

ime

sho

wn

if tim

e el

apse

d s

ince

pri

mar

y o

per

atio

n is

:

Fix

atio

n/b

eari

ng t

ype

30

day

s90

day

s1

year

2 ye

ars

3 ye

ars

4 ye

ars

5 ye

ars

6 ye

ars

7 ye

ars

8 ye

ars

9 ye

ars

Tota

l kne

e re

pla

cem

ent

All

cem

ente

d0.

03

(0.0

3-0.

04)

0.07

(0

.07-

0.08

)0.

38

(0.3

6-0.

40)

0.96

(0

.93-

0.99

)1.

45

(1.4

1-1.

49)

1.81

(1

.76-

1.85

)2.

11

(2.0

6-2.

16)

2.36

(2

.31-

2.42

)2.

63

(2.5

6-2.

70)

2.88

(2

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2.97

)3.

12

(3.0

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24)

Cem

ente

d an

d

unco

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aine

d, fi

xed

0.02

(0

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)0.

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(0.0

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07)

0.33

(0

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0.35

)0.

88

(0.8

4-0.

92)

1.33

(1

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1.38

)1.

66

(1.6

1-1.

71)

1.92

(1

.86-

1.99

)2.

19

(2.1

2-2.

26)

2.44

(2

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2.53

)2.

71

(2.6

0-2.

81)

2.90

(2

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3.04

)un

cons

trai

ned,

m

obile

0.09

(0

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0.13

)0.

13

(0.0

9-0.

18)

0.51

(0

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0.60

)1.

22

(1.0

9-1.

37)

1.84

(1

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2.03

)2.

35

(2.1

5-2.

57)

2.65

(2

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2.89

)2.

89(2

.65-

3.16

)3.

14

(2.8

6-3.

44)

3.31

(2

.99-

3.66

)3.

78

(3.2

4-4.

40)

post

erio

r-st

abilis

ed,

fixed

0.04

(0

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0.05

)0.

08

(0.0

7-0.

10)

0.43

(0

.39-

0.47

)1.

03

(0.9

7-1.

09)

1.53

(1

.45-

1.61

)1.

89

(1.8

0-1.

99)

2.28

(2

.18-

2.40

)2.

52

(2.4

0-2.

64)

2.79

(2

.65-

2.94

)3.

06

(2.8

9-3.

24)

3.32

(3

.08-

3.58

)po

ster

ior-

stab

ilised

, m

obile

0.07

(0

.03-

0.16

)0.

13

(0.0

7-0.

24)

0.68

(0

.52-

0.89

)1.

56

(1.2

9-1.

87)

2.22

(1

.89-

2.60

)2.

73

(2.3

5-3.

17)

3.08

(2

.66-

3.56

)3.

53

(3.0

4-4.

09)

3.84

(3

.28-

4.49

)3.

84

(3.2

8-4.

49)

5.01

(3

.55-

7.06

)

cons

trai

ned

cond

ylar

0.14

(0

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0.43

)0.

47

(0.2

5-0.

87)

1.02

(0

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1.58

)1.

85

(1.3

0-2.

61)

2.56

(1

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3.51

)3.

04

(2.2

4-4.

13)

3.35

(2

.47-

4.54

)3.

35

(2.4

7-4.

54)

3.65

(2

.64-

5.04

)4.

48

(2.8

7-6.

96)

4.48

(2

.87-

6.96

)

all p

olye

thyl

ene

tibia

00.

10

(0.0

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23)

0.39

(0

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0.61

)0.

93

(0.6

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27)

1.48

(1

.12-

1.95

)1.

74

(1.3

3-2.

27)

2.29

(1

.76-

2.98

)2.

41

(1.8

4-3.

15)

2.64

(1

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3.55

)2.

64

(1.9

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55)

2.64

(1

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3.55

)be

arin

g ty

pe

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own

0.01

(0

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0.20

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19

(0.1

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32)

0.63

(0

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0.85

)1.

56

(1.2

9-1.

89)

2.27

(1

.92-

2.68

)2.

80

(2.4

0-3.

27)

3.27

(2.8

1-3.

80)

3.40

(2

.92-

3.96

)3.

80

(3.2

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47)

3.92

(3

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4.64

)4.

36

(3.3

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60)

All

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men

ted

0.04

(0

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)0.

12

(0.0

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(1.3

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65)

2.11

(1.9

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2.50

(2.3

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70)

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(2

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)3.

16

(2.9

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41)

3.47

(3

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3.77

)3.

69

(3.3

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02)

4.03

(3.6

1-4.

50)

All

hyb

rid

0.03

(0

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0.11

)0.

07

(0.0

3-0.

17)

0.54

(0

.39-

0.74

)1.

31

(1.0

6-1.

61)

1.75

(1

.46-

2.10

)2.

00

(1.6

9-2.

38)

2.32

(1

.96-

2.73

)2.

55

(2.1

6-3.

00)

2.93

(2

.48-

3.46

)3.

11

(2.6

2-3.

68)

3.44

(2

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4.39

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Unc

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(0.0

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13)

0.59

(0

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0.71

)1.

47

(1.3

0-1.

66)

1.96

(1

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2.18

)2.

22

(2.0

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46)

2.51

(2.2

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2.66

(2

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2.95

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02

(2.7

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(2

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unco

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(0.0

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0.15

(0

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76)

1.38

(1

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1.59

)2.

01

(1.7

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26)

2.42

(2

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2.71

)2.

79

(2.5

0-3.

11)

3.13

(2

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)3.

38

(3.0

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79)

3.50

(3

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3.94

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75

(3.2

4-4.

32)

post

erio

r st

abilis

ed,

fixed

0.04

(0

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0.29

)0.

08

(0.0

2-0.

32)

0.42

(0

.23-

0.78

)1.

80

(1.3

2-2.

44)

2.63

(2

.03-

3.40

)3.

31

(2.6

1-4.

19)

4.11

(3

.28-

5.15

)4.

65

(3.7

2-5.

80)

5.25

(4

.18-

6.57

)6.

70

(5.1

5-8.

70)

6.70

(5

.15-

8.70

)

othe

r co

nstr

aint

0

00.

31

(0.0

4-2.

18)

2.23

(1

.07-

4.62

)2.

88

(1.5

1-5.

47)

3.22

(1

.74-

5.90

)3.

22

(1.7

4-5.

90)

4.28

(2

.42-

7.53

)4.

28

(2.4

2-7.

53)

4.28

(2

.42-

7.53

)4.

28

(2.4

2-7.

53)

bear

ing

type

un

know

n0.

20

(0.0

3-1.

43)

0.20

(0

.03-

1.43

)0.

82

(0.3

1-2.

17)

1.24

(0

.56-

2.74

)2.

41

(1.3

4-4.

32)

2.91

(1

.70-

4.97

)3.

20

(1.9

0-5.

36)

3.95

(2

.41-

6.45

)4.

47

(2.7

4-7.

28)

4.47

(2

.74-

7.28

)4.

47

(2.7

4-7.

28)


Con

tinue

d >



Cum

ulat

ive

per

cent

age

pro

bab

ility

of

a fir

st r

evis

ion

(95%

CI)

at t

ime

sho

wn

if tim

e el

apse

d s

ince

pri

mar

y o

per

atio

n is

:

Fix

atio

n/b

eari

ng t

ype

30

day

s90

day

s1

year

2 ye

ars

3 ye

ars

4 ye

ars

5 ye

ars

6 ye

ars

7 ye

ars

8 ye

ars

9 ye

ars

Uni

com

par

tmen

tal k

nee

rep

lace

men

t

All

unic

ond

ylar

0.05

(0

.03-

0.07

)0.

15

(0.1

2-0.

19)

1.22

(1

.13-

1.32

)3.

12

(2.9

6-3.

29)

4.59

(4

.39-

4.80

)5.

87(5

.64-

6.12

)7.

06

(6.7

8-7.

34)

8.22

(7

.89-

8.56

)9.

40(9

.00-

9.81

)10

.63

(10.

13-1

1.15

)11

.57

(10.

92-1

2.26

)

Uni

cond

ylar

and

fixed

0.05

(0

.02-

0.11

)0.

10

(0.0

6-0.

17)

0.89

(0

.74-

1.07

)3.

01

(2.7

0-3.

34)

4.70

(4

.29-

5.14

)6.

22

(5.7

3-6.

76)

7.41

(6

.83-

8.02

)8.

37

(7.7

1-9.

07)

9.28

(8

.52-

10.1

1)9.

74

(8.8

9-10

.67)

10.7

2 (9

.34-

12.2

9)

mob

ile

0.05

(0

.03-

0.08

)0.

17

(0.1

3-0.

22)

1.35

(1

.23-

1.47

)3.

20

(3.0

1-3.

40)

4.59

(4

.36-

4.84

)5.

82

(5.5

5-6.

11)

7.02

(6

.70-

7.35

)8.

24

(7.8

6-8.

64)

9.50

(9

.04-

9.99

)10

.94

(10.

35-1

1.56

)11

.86

(11.

11-1

2.65

)be

arin

g ty

pe

unkn

own

00.

14

(0.0

2-0.

97)

0.84

(0

.38-

1.86

)1.

43

(0.7

7-2.

65)

3.17

(2

.05-

4.89

)3.

81

(2.5

3-5.

71)

4.14

(2

.76-

6.18

)5.

41

(3.6

1-8.

09)

6.07

(4

.00-

9.17

)7.

22

(4.5

2-11

.42)

9.11

(5

.27-

15.5

0)

All

pat

ello

-fem

ora

l0

0.05

(0

.02-

0.14

)1.

09

(0.8

7-1.

36)

3.22

(2

.81-

3.68

)5.

50

(4.9

4-6.

12)

7.43

(6

.74-

8.19

)9.

69

(8.8

3-10

.62)

10.8

1 (9

.85-

11.8

6)12

.88

(11.

65-1

4.23

)14

.75

(13.

15-1

6.52

)16

.11

(14.

09-1

8.39

)

Oth

ers/

unkn

ow

n0

00

00

00

02.

63

(0.3

7-17

.25)

2.63

(0

.37-

17.2

5)0

All

typ

es0.

03

(0.0

3-0.

04)

0.08

(0

.07-

0.09

)0.

48

(0.4

6-0.

49)

1.22

(1

.19-

1.25

)1.

83

(1.7

9-1.

87)

2.29

(2.2

4-2.

34)

2.70

(2

.65-

2.76

)3.

05

(2.9

9-3.

12)

3.43

(3

.36-

3.50

)3.

79

(3.7

0-3.

88)

4.12

(4

.00-

4.24

)


Tab

le 3

.18

(con

tinue

d)


Figure 3.6 Cumulative hazard (x100) of a first revision for different types of primary knee replacement at increasing years after the primary surgery (with 95% CI).

22

20

18

16

14

12

10

8

6

4

2

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

Cemented

Uncemented

Hybrid

490,939

31,382

7,307

7,881

51,474

413,315

28,199

6,845

6,679

44,107

337,600

24,441

6,295

5,361

36,376

267,439

20,415

5,471

4,181

28,915

202,689

15,975

4,508

3,071

21,999

142,760

11,425

3,504

2,028

15,428

91,079

7,320

2,595

1,202

9,918

54,676

4,369

1,778

712

5,825

25,627

2,142

896

335

2,762

7,913

670

280

105

828

Patello-femoral

Unicondylar

Numbers at risk

© N

atio

nal J

oint

Reg

istr

y 20

13

Figure 3.7 compares the cumulative hazard of a first revision of a prosthesis for different bearing types of cemented TKR. There is no marked separation of the cumulative hazard curves for any of the types of bearing shown and the confidence intervals for each type overlap. This strongly suggests that the different bearing types by and large have similar cumulative

hazard of the need of revision surgery. However, the curvature of the hazard curves of each type over time indicates that the hazard rate changes over time with the risk of needing a revision of the implant in earlier years (up to five years after surgery) being higher than later times after surgery.



Figure 3.7 Comparison of the cumulative hazard (x100) of a knee prosthesis first revision for different bearing types at increasing years after the primary surgery when the primary arthroplasty method of fixation was cemented only (with 95% CI).

8

7

6

5

4

3

2

1

0 1 2 3 4 5 6 7 8 9


Cum

ulat

ive

haza

rd x

100

y

PS mobile

C cond

PT

8,276

2,173

6,124

25,931

123,162

317,914

7,359

7,257

1,661

4,356

23,743

104,490

265,085

6,723

6,147

1,294

2,973

21,054

85,328

215,218

5,586

4,958

956

2,147

17,676

67,223

169,856

4,623

3,854

730

1,588

14,007

50,491

128,326

3,693

2,812

537

976

9,881

35,159

90,705

2,690

1,782

335

465

5,945

22,327

58,653

1,572

942

214

211

3,151

13,414

35,853

891

352

106

84

1,279

6,469

16,905

432

104

25

30

378

1,986

5,226

164

UC mobile

PS �xed

UC �xed

Unknown

Numbers at risk

© N

atio

nal J

oint

Reg

istr

y 20

13Key: UC fixed=unconstrained and fixed, UC mobile= unconstrained and mobile, PS fixed=posterior-stabilised and fixed, PS mobile=posterior-stabilised and mobile, C cond=constrained and condylar, PT=polyethylene tibia.

3.3.3 Revisions for different causes after primary knee surgery

Methodological note

The previous section looked at revisions for any reason. For any revision, a number of reasons may be related to the first revision of the implant. The reasons are not mutually exclusive of each other. Incidence rates for each reason have been calculated

using patient–time incidence rates; the total number of revisions for that reason divided by the total number of individual patient-years at risk. The figures are given as the numbers of revisions for that reason per 1,000 years at risk. This method is appropriate if the hazard rate remains constant.

Table 3.19 shows the revision rates for each reason recorded on the clinical assessment forms for joint replacement/revision surgery for all cases and then

subdivided by fixation type and whether the primary procedure was a TKR or an UKR. Table 3.20 shows these first knee revision rates for each reason


by fixation/bearing type. In earlier versions of the clinical assessment forms recording the type of joint replacement or revision operation to be undertaken and reasons for this, both ‘stiffness’ and ‘arthritis’ were not originally included as options for indicating the need for revising the implant. Therefore, for these reasons for revision, there are fewer years at which patients are at risk specifically for these categories.

The main reasons for revision were pain, aseptic loosening and infection in a primary TKR. Pain and aseptic loosening were also primary reasons given for revision of an UKR (and amongst the highest incidence rates for revision) alongside implant instability and failure and dislocation. Progression of arthritis was a key reason for revision of both unicondylar and patello-femoral UKRs.

Table 3.19 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded reason for first knee revision. Rates shown are for all revised cases and by fixation type.

Patient-years

at risk (x1,000)





Implant fracture

All cases* 2173.51.18

(1.14-1.23)0.23

(0.21-0.25)1.10

(1.06-1.15)1.41

(1.36-1.46)0.25

(0.23-0.28)0.14

(0.12-0.15)0.02

(0.02-0.03)By fixation:

Cemented 1,800.00.78

(0.74-0.82)0.14

(0.12-0.16)1.16

(1.11-1.21)1.05

(1.01-1.10)0.23

(0.21-0.26)0.11

(0.10-0.13)0.02

(0.01-0.02)

Uncemented 130.81.30

(1.12-1.51)0.30

(0.22-0.41)0.90

(0.75-1.08)2.01

(1.78-2.27)0.28

(0.20-0.38)0.15

(0.10-0.24)0.07

(0.04-0.13)

Hybrid 35.90.95

(0.68-1.33)0.20

(0.09-0.41)1.23

(0.91-1.65)1.23

(0.91-1.65)0.25

(0.13-0.48)0.08

(0.03-0.26)0.06

(0.01-0.22)

Unicondylar 191.8 4.16

(3.88-4.46)0.93

(0.81-1.08)0.76

(0.64-0.89)4.29

(4.01-4.59)0.48

(0.39-0.59)0.33

(0.26-0.43)0.05

(0.02-0.09)

Patello-femoral 27.6 6.37

(5.50-7.38)1.01

(0.70-1.47)0.36

(0.19-0.67)2.24

(1.75-2.88)0.07

(0.02-0.29)0.25

(0.12-0.53)0.11

(0.04-0.34)

Patient-years

at risk (x1,000)

Number of revisions per 1,000 patient-years for: Patient-years

at risk (x1,000) Stiffness**

Patient-years

at risk (x1,000)

Arthritis***

Implant failure

Component size

mismatch MalalignmentOther

indication

All cases* 2173.50.27

(0.25-0.29)0.73

(0.70-0.77)0.44

(0.41-0.47)0.64

(0.61-0.68)2000.0

0.39 (0.36-0.42)

893.10.42

(0.38-0.46)By fixation:

Cemented 1,800.00.17

(0.15-0.19)0.67

(0.63-0.70)0.37

(0.34-0.40)0.42

(0.39-0.45)1700.0

0.39 (0.36-0.42)

744.10.16

(0.14-0.20)

Uncemented 130.80.23

(0.16-0.33)0.93

(0.78-1.11)0.58

(0.46-0.73)0.50

(0.39-0.63)119.2

0.53 (0.41-0.68)

46.30.22

(0.12-0.40)

Hybrid 35.90.33

(0.19-0.59)0.84

(0.58-1.20)0.39

(0.23-0.66)0.25

(0.13-0.48)30.9

0.36 (0.20-0.64)

9.7 0

Unicondylar 191.81.06

(0.92-1.21)1.14

(1.00-1.30)0.80

(0.69-0.94)2.37

(2.16-2.60)178.1

0.29 (0.22-0.38)

12.72.27

(1.96-2.63)Patello-femoral

27.61.73

(1.31-2.31)1.09

(0.76-1.55)1.85

(1.40-2.43)4.05

(3.37-4.88)25.9

0.66 (0.41-1.06)

80.24.81

(3.74-6.18)


*Including the one case with bearing type unknown. **This reason was not asked in the earliest version of the clinical assessment form MDSv1 for joint replacement or revision surgery. Therefore, there are fewer patient-years at risk. ***This reason was not asked in the early versions of the clinical assessment forms MDSv1 and MDSv2 for joint replacement/revision surgery and hence, for these reasons, there are fewer patient-years at risk.

© N

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nal J

oint

Reg

istr

y 20

13©

Nat

iona

l Joi

nt R

egis

try

2013



Table 3.20 Revision rates (95% CI), expressed as number of revisions per 1,000 patient-years, for each recorded reason for first knee revision. Rates shown are for each fixation/bearing surface sub-group.

By fixation/bearing

Patient-years

at risk (x1,000)





Implant fracture

Total knee replacement

Cementedunconstrained, fixed

1,100.00.76

(0.71-0.81)0.13

(0.11-0.15)1.05

(0.99-1.11)0.93

(0.87-0.99)0.21

(0.18-0.24)0.08

(0.07-0.10)0.02

(0.01-0.03)unconstrained, mobile

110.21.09

(0.91-1.30)0.24

(0.16-0.35)1.23

(1.04-1.46)1.35

(0.58-1.43)0.35

(0.26-0.48)0.15

(0.10-0.25)0.01

(0.00-0.06)posterior-stabilised, fixed

448.50.68

(0.61-0.76)0.13

(0.10-0.17)1.38

(1.27-1.49)1.24

(1.14-1.34)0.26

(0.21-0.31)0.16

(0.13-0.20)0.01

(0.00-0.02)posterior-stabilised, mobile

32.31.30

(0.96-1.76)0.28

(0.14-0.54)1.14

(0.83-1.58)1.18

(0.86-1.62)0.31

(0.17-0.57)0.28

(0.14-0.54)0.09

(0.03-0.29)constrained, condylar

6.90.58

(0.22-1.54)0.58

(0.22-1.50)3.61

(2.44-5.35)1.45

(0.78-2.69)0.43

(0.14-1.34)0.43

(0.14-1.34)0

all polyethylene tibia

15.80.63

(0.34-1.18)0.32

(0.13-0.76)1.39

(0.92-2.11)0.89

(0.52-1.49)0.25

(0.09-0.67)0.13

(0.03-0.51)0

Bearing type unknown

30.11.30

(0.95-1.77)0.17

(0.07-0.40)1.46

(1.09-1.97)1.70

(1.29-2.23)0.23

(0.11-0.49)0.13

(0.05-0.35)0.07

(0.02-0.27)

Uncemented/Hybridunconstrained, fixed

83.90.98

(0.79-1.21)0.17

(0.10-0.40)1.00

(0.81-1.24)1.79

(1.52-2.10)0.20

(0.13-0.33)0.10

(0.05-0.19)0.05


67.01.37

(1.12-1.68)0.37

(0.25-0.55)0.92

(0.72-1.19)1.85

(1.55-2.21)0.33

(0.22-0.50)0.19

(0.11-0.33)0.09


11.31.96

(1.29-2.97)0.62

(0.30-1.30)1.16

(0.67-1.99)2.13

(1.43-3.18)0.36

(0.13-0.95)0.18

(0.04-0.71)0

other constraint 1.83.26

(1.46-7.25)0

0.54 (0.08-3.85)

0 0 0 0


2.70.74

(0.19-2.96)0

0.74 (0.19-2.96)

3.33 (1.73-6.40)

0.74 (0.19-2.96)

00.37

(0.05-2.6)


Unicondylar

fixed 46.44.96

(4.35-5.64)0.13

(0.06-0.29)0.90

(0.67-1.22)4.70

(4.11-5.36)0.43

(0.28-0.67)0.32

(0.19-0.54)0.06

(0.02-0.20)

mobile 142.23.91

(3.60-4.25)1.21

(1.04-1.40)0.71

(0.58-0.86)4.20

(3.88-4.56)0.51

(0.40-0.64)0.34

(0.26-0.46)0.04

(0.01-0.08)Bearing type unknown

3.23.77

(2.14-6.63)0.31

(0.04-2.23)0.63

(0.16-2.51)2.20

(1.05-4.61)0 0

0.31 (0.04-2.20)

Patello-femoral

27.66.37

(5.50-7.38)1.00

(0.70-1.50)0.36

(0.19-0.67)2.24

(1.75-2.88)0.07

(0.02-0.29)0.25

(0.12-0.53)0.11

(0.04-0.34)Others/unknown

0.3 0 0 02.92

(0.41-20.76)0 0 0

© N

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13

Blue italic estimates based on a small group size (n<30), therefore estimates are unreliable. *This reason was not asked in the earliest version of the clinical assessment form MDSv1 for joint replacement or revision surgery. Therefore, there are fewer patient-years at risk. **This reason was not asked in the early versions of the clinical assessment forms MDSv1 and MDSv2 for joint replacement/revision surgery and hence, for these reasons, there are fewer patient-years at risk.

Continued >



By fixation/bearing

Patient-years

at risk (x1,000)

Number of revisions per 1,000 patient-years for: Patient-

years at risk

(x1,000) Stiffness*

Patient-years

at risk (x1,000) Arthritis**

Implant failure

Component size

mismatch MalalignmentOther

indicationCementedunconstrained, fixed

1,100.00.14

(0.12-0.16)0.62

(0.58-0.67)0.38

(0.34-0.42)0.42

(0.38-0.46)1,100.0

0.38 (0.35-0.42)

477.2 0.14


110.20.28

(0.20-0.40)1.06

(0.89-1.27)0.48

(0.37-0.63)0.44

(0.34-0.59)103.9

0.56 (0.43-0.72)

40.80.10


448.50.19

(0.16-0.24)0.64

(0.57-0.72)0.34

(0.29-0.39)0.35

(0.30-0.41)414.0

0.31 (0.26-0.37)

191.00.21

(0.15-0.29)posterior-stabilised, mobile

32.30.28

(0.14-0.54)1.21

(0.88-1.65)0.25

(0.12-0.49)1.08

(0.78-1.51)30.9

0.97 (0.68-1.39)

12.40.16

(0.04-0.64)

constrained, condylar

6.90.43

(0.14-1.34)1.01

(0.48-2.12)0.14

(0.02-1.03)0.29

(0.07-1.16)6.4

0.31 (0.08-1.25)

2.7 0


15.80.25

(0.09-0.67)0.57

(0.30-1.09)0.25

(0.09-0.67)0.70

(0.39-1.26)15.4

0.39 (0.17-0.87)

9.50.21

(0.05-0.84)bearing type unknown

30.10.27

(0.13-0.53)0.70

(0.45-1.07)0.37

(0.20-0.66)0.76

(0.51-1.15)27.5

0.33 (0.17-0.63)

10.60.38

(0.14-1.00)

Uncemented/Hybridunconstrained, fixed

83.90.24

(0.15-0.37)0.85

(0.67-1.07)0.44

(0.32-0.61)0.41

(0.29-0.57)75.2

0.44 (0.31-0.62)

29.60.07


67.00.27

(0.17-0.43)0.85

(0.66-1.10)0.58

(0.43-0.79)0.34

(0.23-0.52)60.9

0.43 (0.29-0.63)

22.20.36


11.30.18

(0.04-0.71)1.33

(0.80-2.21)1.16

(0.67-1.99)1.16

(0.67-1.99)10.1

0.99 (0.53-1.84)

3.4 0

other constraint 3.30.54

(0.08-3.85)2.17

(0.81-5.78)0

0.54 (0.08-3.85)

1.81.10

(0.28-4.40)0.3 0


2.70.37

(0.05-2.63)1.85

(0.77-4.45)0.37

(0.05-2.63)1.11

(0.36-3.44)2.1

1.40 (0.45-4.33)

0.5 0


Unicondylar

fixed 46.40.82

(0.60-1.13)0.93

(0.69-1.25)0.80

(0.58-1.10)1.94

(1.58-2.38)43.9

0.41 (0.26-0.65)

21.12.84

(2.21-3.66)

mobile 142.21.14

(0.98-1.33)1.20

(1.03-1.40)0.82

(0.68-0.98)2.53

(2.28-2.81)131.3

0.25 (0.18-0.35)

57.82.08

(1.74-2.48)Bearing type unknown

3.20.94

(0.30-2.92)1.26

(0.47-3.35)0.31

(0.04-2.23)1.26

(1.05-4.61)3.0 0 1.3

1.56 (0.39-6.22)

Patello-femoral

27.61.74

(1.31-2.31)1.09

(0.76-1.55)1.85

(1.40-2.43)4.05

(3.37-4.88)25.9

0.66 (0.41-1.06)

12.74.81

(3.74-6.18)Other/unknown

0.32.92

(0.41-21.00)0 0 0 0.3 0 -

Blue italic estimates based on a small group size (n<30), therefore estimates are unreliable. *This reason was not asked in the earliest version of the clinical assessment form MDSv1 for joint replacement or revision surgery. Therefore, there are fewer patient-years at risk. **This reason was not asked in the early versions of the clinical assessment forms MDSv1 and MDSv2 for joint replacement/revision surgery and hence, for these reasons, there are fewer patient-years at risk.

© N

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nal J

oint

Reg

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3.3.4 Revisions after primary knee surgery by main brands for TKR and UKR

Tables 3.21 and 3.22 show the Kaplan-Meier estimates of the cumulative percentage probability of first revision (for any reason) of a primary TKR (table 3.21) and primary UKR (table 3.22) by implant brand. We have only included those brands that have been used in a primary knee procedure in 1,000 or more operations. Figures in blue indicate those time points

where fewer than 100 primary knee joint replacements remain at risk. No attempt has been made to adjust for other factors that may influence the chance of revision so the figures are unadjusted probabilities.

Table 3.23 shows Kaplan-Meier estimates of the cumulative percentage probability of first revision of a primary TKR or primary UKR by implant brand and bearing type for those brands/bearing types which were implanted on at least 1,000 occasions.


Table 3.21 Kaplan-Meier estimated cumulative percentage probability of first revision (95% CI) of a primary total knee replacement by main type of implant brand at the indicated number of years after primary operation.16

Brand17

Number of knee

joints

Cumulative percentage probability of a first revision (95% CI) at time shown if time elapsed since primary operation is

1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 yearsAdvance MP

5,2580.29

(0.17-0.49)1.20

(0.91-1.58)1.62

(1.27-2.06)1.98

(1.58-2.48)2.22

(1.78-2.77)2.94

(2.33-3.71)3.17

(2.50-4.01)3.42

(2.63-4.45)3.98

(2.79-5.66)

AGC 53,4400.28

(0.24-0.33)0.92

(0.83-1.01)1.38

(1.28-1.50)1.74

(1.62-1.88)1.97

(1.83-2.11)2.30

(2.14-2.47)2.54

(2.35-2.74)2.85

(2.62-3.11)3.12

(2.83-3.45)

Columbus 4,3190.45

(0.28-0.72)1.54

(1.16-2.04)2.07

(1.60-2.66)2.52

(1.97-3.23)2.88

(2.23-3.73)3.29

(2.48-4.37)4.37

(2.58-7.35)4.37

(2.58-7.35)-

E-Motion Bicondylar Knee

2,0010.69

(0.40-1.19)1.55

(1.05-2.27)2.54

(1.84-3.50)2.64

(1.92-3.62)2.79

(2.03-3.83)3.55

(2.41-5.22)3.55

(2.41-5.22)3.55

(2.41-5.22)3.55

(2.41-5.22)

Endoplus Bicondylar Knee

13,8330.70

(0.57-0.86)1.34

(1.16-1.55)1.81

(1.59-2.05)2.18

(1.94-2.45)2.44

(2.17-2.74)2.68

(2.38-3.02)2.85

(2.53-3.23)3.00

(2.58-3.48)3.00

(2.58-3.48)

Genesis 2 30,0100.42

(0.35-0.51)0.96

(0.84-1.10)1.39

(1.23-1.56)1.84

(1.64-2.06)2.07

(1.85-2.32)2.27

(2.01-2.56)2.34

(2.07-2.66)2.43

(2.11-2.79)2.43

(2.11-2.79)

Genesis 2 Oxinium

4,8320.55

(0.37-0.82)1.35

(1.03-1.77)2.25

(1.80-2.82)2.69

(2.17-3.34)3.37

(2.71-4.19)3.75

(2.99-4.71)4.50

(3.51-5.77)4.82

(3.69-6.29)4.82

(3.69-6.29)Insall-Burstein 2

2,0580.30

(0.13-0.66)0.90

(0.57-1.43)1.58

(1.11-2.24)2.17

(1.61-2.93)2.69

(2.04-3.53)3.08

(2.36-4.00)3.45

(2.67-4.46)3.79

(2.91-4.93)3.79

(2.91-4.93)

Kinemax 10,8620.24

(0.16-0.35)1.03

(0.86-1.25)1.76

(1.52-2.03)2.21

(1.95-2.51)2.67

(2.37-3.00)3.00

(2.68-3.36)3.49

(3.13-3.89)3.91

(3.50-4.37)4.30

(3.81-4.86)

LCS 2,0380.64

(0.37-1.10)1.09

(0.72-1.65)1.75

(1.26-2.43)2.06

(1.52-2.79)2.33

(1.75-3.10)2.39

(1.80-3.16)2.61

(1.99-3.43)2.74

(2.10-3.58)2.94

(2.25-3.83)LCS Complete

18,2350.47

(0.38-0.56)1.13

(0.98-1.31)1.70

(1.50-1.93)2.25

(2.01-2.53)2.64

(2.35-2.96)2.88

(2.56-3.24)3.12

(2.73-3.56)3.12

(2.73-3.56)-

Maxim 2,1240.30

(0.13-0.66)0.93

(0.59-1.47)1.63

(1.14-2.32)2.02

(1.46-2.80)2.33

(1.71-3.18)2.33

(1.71-3.18)3.02

(2.18-4.19)3.33

(2.35-4.72)5.05

(3.00-8.46)

MRK 5,5340.27

(0.16-0.45)0.76

(0.55-1.06)1.32

(1.01-1.71)1.63

(1.28-2.08)1.73

(1.36-2.21)1.83

(1.42-2.36)1.83

(1.42-2.36)3.33

(1.74-6.31)3.33

(1.74-6.31)Natural Knee II

2,5380.33

(0.17-0.67)0.88

(0.57-1.37)1.32

(0.91-1.91)1.76

(1.26-2.45)2.21

(1.62-3.01)2.66

(1.96-3.61)2.80

(2.06-3.79)2.80

(2.06-3.79)2.80

(2.06-3.79)

Nexgen 73,9660.37

(0.33-0.42)0.88

(0.81-0.96)1.38

(1.28-1.48)1.74

(1.63-1.87)2.16

(2.03-2.31)2.47

(2.31-2.64)2.75

(2.56-2.95)3.06

(2.82-3.32)3.26

(2.96-3.60)

Opetrak 2,2320.73

(0.44-1.20)2.14

(1.57-2.91)2.56

(1.92-3.41)3.26

(2.49-4.27)3.74

(2.87-4.87)4.09

(3.12-5.35)4.62

(3.33-6.39)5.43

(3.63-8.10)5.43

(3.63-8.10)PFC Sigma Bicondylar Knee

187,7280.36

(0.34-0.39)0.87

(0.82-0.91)1.28

(1.22-1.34)1.55

(1.49-1.62)1.81

(1.73-1.89)1.96

(1.88-2.05)2.14

(2.04-2.24)2.30

(2.19-2.42)2.45

(2.30-2.61)

Profix 3,9410.36

(0.22-0.61)0.98

(0.71-1.36)1.22

(0.91-1.63)1.52

(1.17-1.98)1.81

(1.41-2.33)2.28

(1.78-2.91)2.36

(1.84-3.01)2.36

(1.84-3.01)2.94

(1.90-4.53)

Rotaglide 1,0670.21

(0.05-0.84)0.58

(0.24-1.40)1.62

(0.92-2.85)2.01

(1.18-3.41)2.59

(1.55-4.30)3.08

(1.81-5.21)3.80

(2.15-6.66)3.80

(2.15-6.66)3.80

(2.15-6.66)

Rotaglide + 2,1080.57

(0.33-1.01)1.85

(1.35-2.53)2.79

(2.15-3.61)3.40

(2.69-4.31)3.66

(2.91-4.60)4.12

(3.30-5.14)4.62

(3.71-5.74)4.74

(3.81-5.90)5.45

(4.19-7.07)

Scorpio 34,1850.40

(0.34-0.47)1.17

(1.06-1.30)1.71

(1.57-1.86)2.08

(1.92-2.26)2.43

(2.25-2.63)2.70

(2.49-2.92)3.13

(2.87-3.40)3.26

(2.98-3.56)3.53

(3.13-3.97)

Triathlon 29,7660.44

(0.36-0.53)1.07

(0.94-1.22)1.54

(1.36-1.74)1.84

(1.62-2.10)1.93

(1.69-2.21)2.11

(1.78-2.50)2.98

(1.89-4.69)2.98

(1.89-4.69)-

Vanguard 17,0980.35

(0.26-0.46)0.95

(0.77-1.16)1.57

(1.30-1.89)2.04

(1.68-2.48)2.36

(1.92-2.91)2.56

(2.00-3.26)3.41

(2.02-5.70)3.41

(2.02-5.70)-

16 Estimates in blue indicate that fewer than 100 cases remain at risk at the time shown. 17 Brands shown have been used in at least 1,000 primary total knee replacement operations.

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Table 3.22 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) of a primary unicompartmental knee replacement by main type of implant brand at the indicated number of years after primary operation.18

Brand19

Number of knee

joints


1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 years

Patello-femoral

Avon 3,7940.76

(0.52-1.11)2.35

(1.89-2.93)4.01

(3.37-4.76)5.58

(4.79-6.50)7.68

(6.69-8.82)8.51

(7.42-9.75)10.94

(9.49-12.60)12.53

(10.72-14.61)13.88

(11.61-16.56)

FPV 1,2270.89

(0.48-1.65)4.16

(3.06-5.64)6.35

(4.88-8.23)8.74

(6.80-11.21)9.16

(7.09-11.78)9.16

(7.09-11.78)9.16

(7.09-11.78)- -

Journey PFJ Oxinium

1,0641.98

(1.26-3.08)4.60

(3.39-6.23)8.20

(6.43-10.43)9.69

(7.68-12.19)13.89

(11.08-17.34)17.52

(12.98-23.41)17.52

(12.98-23.41)- -

Unicondylar

AMC/Uniglide 2,2792.58

(1.99-3.35)5.18

(4.28-6.26)6.98

(5.89-8.26)8.36

(7.12-9.81)9.07

(7.73-10.63)10.57

(8.94-12.48)11.78

(9.75-14.19)11.78

(9.75-14.19)11.78

(9.75-14.19)

MG Unicondylar 2,3610.89

(0.58-1.37)2.53

(1.97-3.25)3.83

(3.12-4.70)4.72

(3.92-5.69)5.71

(4.80-6.79)6.64

(5.62-7.84)7.03

(5.93-8.32)7.23

(6.08-8.59)7.23

(6.08-8.59)Oxford Partial Knee

35,9471.18

(1.07-1.30)2.91

(2.73-3.10)4.25

(4.03-4.50)5.43

(5.16-5.71)6.61

(6.30-6.95)7.82

(7.44-8.21)9.10

(8.63-9.58)10.52

(9.92-11.15)11.49

(10.72-12.31)

Preservation 1,5092.26

(1.62-3.15)4.86

(3.89-6.08)7.53

(6.29-8.99)9.57

(8.17-11.20)11.13

(9.60-12.89)12.55

(10.88-14.46)13.85

(12.00-15.97)15.08

(13.00-17.46)17.31

(14.43-20.68)

Sigma HP 3,1421.04

(0.72-1.50)3.17

(2.47-4.06)4.96

(3.84-6.41)6.51

(4.66-9.05)6.51

(4.66-9.05)- - - -

Zimmer Unicompartment

3,7340.52

(0.32-0.85)2.11

(1.62-2.76)3.36

(2.67-4.24)4.69

(3.74-5.87)5.27

(4.15-6.69)5.27

(4.15-6.69)5.27

(4.15-6.69)5.27

(4.15-6.69)5.27

(4.15-6.69)

18 Estimates in blue indicate that fewer than 100 cases remain at risk at the time shown. 19 Brands shown have been used in at least 1,000 primary unicompartmental knee replacement operations.

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Table 3.23 Kaplan-Meier estimates of the cumulative percentage probability of first revision (95% CI) of a total knee replacement at the indicated number of years after primary operation, by main implant brands and type of fixation and constraint20.

Brand 21No. of joints



Advance MPcemented unconstrained, fixed

5,1890.30

(0.18-0.50)1.22

(0.93-1.60)1.61

(1.27-2.06)1.98

(1.58-2.49)2.23

(1.78-2.78)2.96

(2.34-3.73)3.18

(2.51-4.04)3.45

(2.64-4.49)4.03

(2.80-5.76)

AGC

cemented unconstrained, fixed

50,1600.25

(0.21-0.30)0.85

(0.76-0.94)1.32

(1.21-1.43)1.68

(1.55-1.82)1.90

(1.76-2.05)2.24

(2.07-2.41)2.45

(2.26-2.66)2.78

(2.53-3.04)3.07

(2.76-3.41)

Uncemented/hybrid unconstrained, fixed

2,0511.14

(0.76-1.72)2.51

(1.90-3.31)2.91

(2.25-3.77)3.42

(2.66-4.39)3.54

(2.76-4.54)3.99

(3.09-5.14)4.26

(3.25-5.57)4.26

(3.25-5.57)4.26

(3.25-5.57)

Columbus


4,0510.39

(0.23-0.67)1.39

(1.02-1.89)1.85

(1.40-2.45)2.29

(1.74-3.00)2.68

(2.02-3.57)3.14

(2.29-4.30)4.38

(2.41-7.91)4.38

(2.41-7.91)-

E-Motion Bicondylar Knee

Uncemented/hybrid unconstrained, mobile

1,4160.89

(0.51-1.56)1.50

(0.95-2.34)2.08

(1.41-3.08)2.20

(1.50-3.23)2.37

(1.61-3.47)3.26

(2.04-5.20)3.26

(2.04-5.20)- -

Endoplus Bicondylar Knee


7,4400.75

(0.58-0.97)1.43

(1.18-1.72)1.84

(1.56-2.18)2.21

(1.89-2.59)2.48

(2.12-2.91)2.72

(2.31-3.20)3.05

(2.55-3.65)3.05

(2.55-3.65)3.05

(2.55-3.65)

cemented unconstrained, mobile

4,2350.55

(0.37-0.83)1.11

(0.83-1.48)1.56

(1.22-1.99)1.91

(1.53-2.40)2.19

(1.76-2.71)2.41

(1.95-2.97)2.47

(2.00-3.05)2.47

(2.00-3.05)2.47

(2.00-3.05)

Uncemented/hybrid unconstrained, mobile

1,4460.66

(0.34-1.26)1.14

(0.69-1.89)1.90

(1.27-2.86)2.51

(1.73-3.64)2.65

(1.84-3.83)2.86

(1.98-4.14)2.86

(1.98-4.14)4.23

(2.15-8.26)4.23

(2.15-8.26)

Genesis 2

cemented uncons-trained, fixed

21,9350.32

(0.25-0.41)0.81

(0.69-0.96)1.18

(1.02-1.38)1.62

(1.40-1.87)1.85

(1.60-2.14)2.11

(1.81-2.45)2.16

(1.85-2.53)2.27

(1.90-2.71)2.27

(1.90-2.71)

cemented posterior stabilised, fixed

6,7360.79

(0.59-1.05)1.48

(1.18-1.85)2.02

(1.64-2.49)2.54

(2.08-3.10)2.80

(2.27-3.46)2.80

(2.27-3.46)2.80

(2.27-3.46)2.80

(2.27-3.46)2.80

(2.27-3.46)

Genesis 2 Oxinium


3,2590.47

(0.28-0.79)1.03

(0.71-1.50)1.93

(1.44-2.58)2.25

(1.70-2.97)3.04

(2.31-3.99)3.35

(2.53-4.42)3.73

(2.80-4.96)4.08

(2.99-5.57)4.08

(2.99-5.57)

Insall-Burstein 2


1,8690.33

(0.15-0.72)0.66

(0.38-1.16)1.35

(0.91-2.01)2.01

(1.44-2.78)2.43

(1.79-3.29)2.68

(2.00-3.60)3.10

(2.33-4.13)3.48

(2.59-4.67)3.48

(2.59-4.67)

Kinemax

Cemented uncons-trained, fixed

10,6560.25

(0.17-0.36)1.05

(0.88-1.27)1.78

(1.54-2.05)2.22

(1.95-2.53)2.69

(2.39-3.03)3.03

(2.71-3.40)3.51

(3.14-3.92)3.94

(3.52-4.40)4.28

(3.79-4.83)

LCS

Uncemented/hybrid uncons-trained, mobile

1,3560.74

(0.40-1.38)1.12

(0.67-1.85)1.80

(1.21-2.67)2.11

(1.46-3.04)2.35

(1.66-3.32)2.35

(1.66-3.32)2.43

(1.72-3.42)2.43

(1.72-3.42)2.43

(1.72-3.42)

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Continued >






LCS Complete

cemented unconstrained, mobile

8,0650.39

(0.28-0.56)0.93

(0.73-1.18)1.56

(1.28-1.89)2.31

(1.94-2.74)2.77

(2.33-3.29)3.07

(2.57-3.66)3.37

(2.74-4.15)3.37

(2.74-4.15)-

Uncemented/hybrid uncons-trained, mobile

10,0490.54

(0.41-0.71)1.32

(1.09-1.58)1.84

(1.57-2.17)2.21

(1.89-2.56)2.53

(2.17-2.96)2.75

(2.34-3.22)2.95

(2.48-3.52)2.95

(2.48-3.52)-

Maxim


1,3150.08

(0.01-0.57)0.59

(0.28-1.23)1.33

(0.80-2.19)1.75

(1.12-2.74)2.12

(1.40-3.22)2.12

(1.40-3.22)2.85

(1.87-4.35)3.30

(2.10-5.16)4.51

(2.43-8.29)

MRK


5,4390.27

(0.16-0.46)0.78

(0.56-1.08)1.34

(1.03-1.73)1.65

(1.30-2.11)1.76

(1.38-2.25)1.86

(1.44-2.39)1.86

(1.44-2.39)3.38

(1.77-6.41)3.38

(1.77-6.41)

Natural Knee II


2,3940.36

(0.18-0.71)0.94

(0.61-1.46)1.41

(0.97-2.04)1.75

(1.24-2.46)2.14

(1.55-2.95)2.37

(1.72-3.25)2.37

(1.72-3.25)2.37

(1.72-3.25)2.37

(1.72-3.25)

Nexgen


29,3770.25

(0.20-0.32)0.66

(0.57-0.78)1.10

(0.96-1.25)1.41

(1.24-1.59)1.65

(1.46-1.87)2.00

(1.75-2.28)2.18

(1.88-2.52)2.44

(2.03-2.93)2.44

(2.03-2.93)

posterior stabilised, fixed

36,6510.43

(0.37-0.51)0.94

(0.84-1.05)1.44

(1.30-1.58)1.84

(1.68-2.02)2.37

(2.17-2.58)2.65

(2.43-2.89)2.99

(2.73-3.28)3.38

(3.04-3.76)3.62

(3.20-4.11)Uncemented/hybrid uncons-trained, fixed

4,5390.53

(0.35-0.79)1.43

(1.11-1.84)2.08

(1.68-2.57)2.42

(1.98-2.96)2.76

(2.27-3.35)2.88

(2.37-3.50)2.96

(2.43-3.61)2.96

(2.43-3.61)3.27

(2.53-4.22)


1,4840.21

(0.07-0.66)1.02

(0.59-1.75)1.58

(1.01-2.47)1.84

(1.19-2.83)2.32

(1.53-3.50)2.32

(1.53-3.50)3.01

(1.92-4.71)3.86

(2.22-6.66)3.86

(2.22-6.66)

Opetrak


1,4940.69

(0.37-1.28)2.27

(1.59-3.23)2.66

(1.90-3.71)3.40

(2.48-4.64)4.07

(2.99-5.52)4.58

(3.35-6.25)4.58

(3.35-6.25)4.58

(3.35-6.25)4.58

(3.35-6.25)

PFC Sigma Bicondylar Knee

Cemented unconstrained, fixed

115,4730.33

(0.30-0.37)0.79

(0.74-0.85)1.14

(1.07-1.21)1.39

(1.31-1.48)1.61

(1.52-1.70)1.77

(1.67-1.87)1.93

(1.81-2.05)2.12

(1.98-2.27)2.18

(2.03-2.35)

unconstrained, mobile

6,5040.61

(0.45-0.84)1.26

(1.01-1.58)1.89

(1.56-2.29)2.18

(1.82-2.62)2.47

(2.06-2.96)2.59

(2.15-3.11)2.79

(2.29-3.40)2.79

(2.29-3.40)2.79

(2.29-3.40)posterior stabilised, fixed

51,7060.37

(0.32-0.43)0.91

(0.83-1.01)1.39

(1.28-1.51)1.67

(1.54-1.81)1.96

(1.81-2.12)2.10

(1.94-2.27)2.31

(2.12-2.51)2.44

(2.22-2.67)2.79

(2.43-3.21)

posterior stabilised, mobile

5,3460.70

(0.50-0.98)1.62

(1.29-2.04)2.31

(1.89-2.81)2.90

(2.41-3.50)3.27

(2.72-3.94)3.67

(3.03-4.44)4.00

(3.25-4.92)4.00

(3.25-4.92)7.10

(3.00-16.28)


4,1480.33

(0.18-0.60)0.59

(0.35-0.98)1.31

(0.85-2.00)1.43

(0.94-2.19)2.59

(1.64-4.08)2.59

(1.64-4.08)2.59

(1.64-4.08)2.59

(1.64-4.08)2.59

(1.64-4.08)

Constraint unknown

1,6180.26

(0.10-0.68)0.88

(0.51-1.51)1.61

(1.06-2.44)1.89

(1.28-2.80)2.31

(1.58-3.37)2.31

(1.58-3.37)2.57

(1.73-3.79)2.57

(1.73-3.79)2.57

(1.73-3.79)Uncemented/hybrid uncons-trained, fixed

1,6180.31

(0.13-0.75)0.57

(0.30-1.10)1.07

(0.65-1.74)1.30

(0.83-2.04)1.58

(1.04-2.40)1.58

(1.04-2.40)1.58

(1.04-2.40)1.58

(1.04-2.40)1.58

(1.04-2.40)

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Continued >





Profix

Uncemented/hybrid uncons-trained, fixed

2,2730.23

(0.09-0.54)0.80

(0.50-1.28)1.02

(0.66-1.55)1.20

(0.81-1.80)1.29

(0.87-1.91)1.29

(0.87-1.91)1.29

(0.87-1.91)1.29

(0.87-1.91)2.11

(0.95-4.67)

Rotaglide


1,0180.11

(0.01-0.75)0.50

(0.19-1.32)1.58

(0.87-2.85)1.99

(1.15-3.45)2.59

(1.53-4.38)3.12

(1.80-5.37)3.89

(2.17-6.92)3.89

(2.17-6.92)3.89

(2.17-6.92)

Rotaglide +

cemented uncons-trained, mobile

1,6880.42

(0.20-0.84)1.65

(1.13-2.39)2.63

(1.95-3.54)3.19

(2.43-4.19)3.35

(2.56-4.38)3.74

(2.88-4.85)4.00

(3.09-5.18)4.16

(3.21-5.39)4.52

(3.40-6.01)

Scorpio


15,7400.39

(0.31-0.51)1.13

(0.97-1.32)1.72

(1.51-1.96)2.14

(1.90-2.41)2.44

(2.17-2.74)2.73

(2.43-3.07)3.16

(2.79-3.57)3.34

(2.93-3.82)3.52

(3.00-4.13)

unconstrained, mobile

1,1620.26

(0.08-0.80)1.59

(1.00-2.51)2.40

(1.65-3.48)3.13

(2.24-4.36)3.60

(2.60-4.97)3.97

(2.81-5.59)3.97

(2.81-5.59)3.97

(2.81-5.59)3.97

(2.81-5.59)posterior stabilised, fixed

9,9480.29

(0.20-0.42)1.07

(0.87-1.30)1.62

(1.37-1.91)1.94

(1.66-2.27)2.36

(2.03-2.73)2.63

(2.27-3.06)2.85

(2.43-3.33)2.95

(2.50-3.48)2.95

(2.50-3.48)

posterior stabilised, mobile

1,3720.37

(0.15-0.89)0.99

(0.57-1.70)1.48

(0.95-2.31)1.91

(1.28-2.84)2.12

(1.44-3.10)2.25

(1.54-3.28)2.44

(1.67-3.56)2.44

(1.67-3.56)4.71

(1.80-12.02)

Uncemented/hybrid uncons-trained, fixed

4,7120.59

(0.40-0.86)1.34

(1.04-1.73)1.64

(1.30-2.07)1.78

(1.42-2.23)2.13

(1.71-2.66)2.26

(1.81-2.83)3.29

(2.52-4.29)3.45

(2.64-4.52)3.97

(2.81-5.60)

Triathlon


22,3530.38

(0.30-0.48)0.94

(0.79-1.11)1.48

(1.27-1.72)1.76

(1.50-2.05)1.83

(1.56-2.15)2.03

(1.67-2.47)2.91

(1.81-4.66)2.91

(1.81-4.66)-


6,4830.51

(0.35-0.73)1.24

(0.96-1.60)1.47

(1.15-1.89)1.95

(1.45-2.61)2.10

(1.54-2.87)2.10

(1.54-2.87)- - -

Vanguard


14,1850.33

(0.24-0.46)0.91

(0.72-1.14)1.52

(1.23-1.88)2.04

(1.63-2.55)2.48

(1.94-3.18)2.81

(2.05-3.84)3.82

(2.17-6.69)3.82

(2.17-6.69)-


1,9320.53

(0.26-1.06)1.08

(0.63-1.84)1.89

(1.17-3.06)2.49

(1.52-4.07)2.49

(1.52-4.07)2.49

(1.52-4.07)- - -

20 Estimates in blue indicate that fewer than 100 cases remain at risk at the time shown. 21 Brands shown have been used in at least 1,000 primary knee replacement operations for that type of fixation and bearing type.

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Table 3.24 Age and gender distribution of patients undergoing all types of primary knee replacement operations for the period 2003 to 2012.

Gender Number of patients PercentageFemale

Under 55 23,576 4.1

55-59 29,001 5.0

60-64 47,426 8.2

65-69 57,169 9.8

70-74 63,898 11.0

75-79 59,293 10.2

80 and above 50,660 8.7

Male

Under 55 16,887 2.9

55-59 22,126 3.8

60-64 41,468 7.1

65-69 48,537 8.4

70-74 49,842 8.6

75-79 41,114 7.1

80 and above 30,256 5.2

Total 581,253 100.0

Table 3.25 shows the Kaplan-Meier estimated cumulative percentage probability of a patient dying at the indicated number of years after surgery stratified by age group and gender. Males, particularly in the

older age groups, had a higher cumulative percentage probability of dying in the short or longer term after their primary knee replacement operation.

3.3.5 Mortality after primary knee surgery

This section gives the cumulative likelihood of a patient dying at different lengths of time after their primary operation date by age and gender. Cumulative probabilities of a knee replacement patient dying in the short term (by 30 days or 90 days after the primary operation) and in the longer term, up to nine years after their primary operation, are shown. For simplicity here, we do not take into account whether the patient had further operations (i.e. revision of any primary joint) after the primary operation in calculating the cumulative probability of death.

Of the 589,028 records of a primary operation to replace a knee joint over the period 1 April 2003 to 31 December 2012, 181 not did have an NHS number therefore the death details could not be traced. A further 22 had missing age (19) or gender (3). Amongst the remainder, 7,572 were bilateral operations, having

both knees replaced on the same day. Patients identified as having a bilateral operation have had the second recorded joint excluded from the sample used for mortality analysis.

This identified a sample of 581,253 distinct patients who had had a primary operation to replace one or both knees within the NJR data collection and follow up period. Analysis of the cumulative likelihood of a patient dying in the short or medium term after the primary knee surgery are based on this sample of patients. In total, 43,155 deaths were linked to this set of patients over the time period.

Table 3.24 shows, by gender, the age distribution of patients who underwent primary TKR or UKR surgery over the data collection period. Fewer men than women, overall, have had a primary knee replacement and, proportionally, more women than men undergo surgery above the age of 75.

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Tab

le 3

.25

Kap

lan-

Mei

er e

stim

ated

cum

ulat

ive

perc

enta

ge p

roba

bilit

y (9

5% C

I) of

a p

atie

nt d

ying

at t

he in

dica

ted

num

ber

of y

ears

afte

r a

prim

ary

knee

join

t rep

lace

men

t ope

ratio

n (i)

by

age

grou

p an

d ge

nder

and

(ii)

for

all p

atie

nts.

By

gen

der

an

d a

ge

gro

upN

o. o

f p

atie

nts

Cum

ulat

ive

per

cent

age

pro

bab

ility

of

pat

ient

dea

th (9

5% C

I) at

tim

e sh

ow

n if

time

elap

sed

sin

ce p

rim

ary

knee

art

hro

pla

sty

is:

30 d

ays

90 d

ays

1 ye

ar2

year

s3

year

s4

year

s5

year

s6

year

s7

year

s8

year

s9

year

s

Mal

es

<55

yea

rs16

,887

0.04

(0

.02-

0.08

)0.

07

(0.0

4-0.

13)

0.28

(0

.21-

0.38

)0.

70

(0.5

8-0.

86)

1.03

(0

.87-

1.22

)1.

36

(1.1

6-1.

59)

1.89

(1

.62-

2.19

)2.

35

(2.0

3-2.

73)

3.08

(2

.63-

3.60

)4.

03

(3.3

9-4.

79)

4.63

(3

.80-

5.63

)

55-5

9 ye

ars

22,1

260.

07

(0.0

4-0.

11)

0.13

(0

.09-

0.19

)0.

41

(0.3

4-0.

51)

0.96

(0

.83-

1.11

)1.

56

(1.3

9-1.

76)

2.27

(2

.04-

2.53

)3.

05

(2.7

7-3.

37)

3.99

(3

.63-

4.40

)5.

20

(4.7

2-5.

73)

5.95

(5

.37-

6.60

)6.

68

(5.9

0-7.

56)

60-6

4 ye

ars

41,4

680.

08

(0.0

6-0.

11)

0.14

(0

.11-

0.18

)0.

53

(0.4

6-0.

61)

1.33

(1

.22-

1.46

)2.

12

(1.9

7-2.

29)

3.05

(2

.86-

3.26

)4.

23

(3.9

7-4.

50)

5.48

(5

.16-

5.83

)6.

69

(6.2

8-7.

13)

8.51

(7

.93-

9.13

)9.

78

(8.9

9-10

.63)

65-6

9 ye

ars

48,5

370.

12

(0.0

9-0.

16)

0.21

(0

.17-

0.25

)0.

75

(0.6

7-0.

83)

1.70

(1

.58-

1.83

)3.

03

(2.8

6-3.

21)

4.63

(4

.40-

4.87

)6.

26

(5.9

7-6.

56)

8.31

(7

.94-

8.69

)10

.33

(9.8

7-10

.82)

12.5

5 (1

1.94

-13.

19)

14.5

8 (1

3.74

-15.

46)

70-7

4 ye

ars

49,8

420.

18

(0.1

4-0.

22)

0.34

(0

.29-

0.39

)1.

21

(1.1

1-1.

31)

2.84

(2

.69-

3.01

)4.

96

(4.7

5-5.

19)

7.48

(7

.20-

7.77

)10

.22

(9.8

7-10

.59)

13.7

4 (1

3.29

-14.

21)

17.2

6 (1

6.69

-17.

84)

20.8

2 (2

0.08

-21.

5824

.97

(23.

87-2

6.11

)

75-7

9 ye

ars

41,1

140.

38

(0.3

2-0.

44)

0.63

(0

.56-

0.71

)2.

12

(1.9

8-2.

27)

4.63

(4

.42-

4.86

)7.

75

(7.4

6-8.

05)

11.5

9 (1

1.22

-11.

98)

16.0

5 (1

5.58

-16.

54)

21.0

0 (2

0.42

-21.

60)

25.9

7 (2

5.25

-26.

71)

32.0

2 (3

1.07

-32.

99)

38.2

6 (3

6.90

-39.

66)

80+

yea

rs30

,256

0.95

(0

.85-

1.07

)1.

60

(1.4

7-1.

75)

4.40

(4

.17-

4.65

)9.

30

(8.9

5-9.

66)

14.9

9 (1

4.53

-15.

46)

21.8

4 (2

1.27

-22.

43)

29.3

5 (2

8.65

-30.

06)

38.1

6 (3

7.29

-39.

03)

45.7

8 (4

4.75

-46.

83)

53.3

0 (5

2.01

-54.

61)

61.1

0 (5

9.24

-62.

96)

Fem

ales

<55

yea

rs23

,576

0.03

(0

.01-

0.06

)0.

05

(0.0

3-0.

08)

0.15

(0

.11-

0.21

)0.

39

(0.3

1-0.

49)

0.71

(0

.60-

0.85

)1.

02

(0.8

7-1.

19)

1.41

(1

.22-

1.64

)1.

87

(1.6

1-2.

18)

2.22

(1

.90-

2.59

)2.

79

(2.3

6-3.

31)

3.55

(2

.88-

4.37

)

55-5

9 ye

ars

29,0

010.

04

(0.0

2-0.

07)

0.06

(0

.03-

0.09

)0.

25

(0.1

9-0.

31)

0.60

(0

.51-

0.71

)0.

96

(0.8

4-1.

09)

1.44

(1

.28-

1.61

)2.

00

(1.8

0-2.

23)

2.73

(2

.46-

3.03

)3.

64

(3.2

7-4.

05)

4.53

(4

.02-

5.10

)5.

29

(4.6

0-6.

08)

60-6

4 ye

ars

47,4

260.

06

(0.0

4-0.

09)

0.10

(0

.08-

0.13

)0.

35

(0.3

0-0.

41)

0.76

(0

.68-

0.85

)1.

40

(1.2

8-1.

53)

2.00

(1

.85-

2.16

)2.

71

(2.5

2-2.

92)

3.61

(3

.35-

3.88

)4.

66

(4.3

2-5.

02)

5.92

(5

.45-

6.44

)7.

50

(6.7

3-8.

35)

65-6

9 ye

ars

57,1

690.

08

(0.0

6-0.

11)

0.14

(0

.11-

0.18

)0.

46

(0.4

1-0.

52)

1.14

(1

.05-

1.24

)2.

01

(1.8

8-2.

15)

3.02

(2

.85-

3.20

)4.

18

(3.9

6-4.

41)

5.46

(5

.18-

5.75

)6.

69

(6.3

5-7.

05)

8.56

(8

.07-

9.06

)10

.31

(9.6

1-11

.06)

70-7

4 ye

ars

63,8

980.

11

(0.0

8-0.

14)

0.20

(0

.17-

0.24

)0.

74

(0.6

7-0.

81)

1.76

(1

.65-

1.87

)2.

98

(2.8

4-3.

14)

4.48

(4

.29-

4.68

)6.

49

(6.2

4-6.

75)

8.67

(8

.35-

9.01

)11

.18

(10.

76-1

1.62

)13

.82

(13.

27-1

4.40

)17

.15

(16.

30-1

8.03

)

75-7

9 ye

ars

59,2

930.

20

(0.1

7-0.

24)

0.37

(0

.33-

0.43

)1.

31

(1.2

2-1.

41)

2.99

(2

.85-

3.14

)5.

08

(4.8

8-5.

29)

7.69

(7

.44-

7.96

)10

.86

(10.

53-1

1.20

)14

.50

(14.

09-1

4.93

)18

.60

(18.

07-1

9.15

)23

.98

(23.

24-2

4.73

)29

.08

(28.

03-3

0.16

)

80+

yea

rs50

,660

0.48

(0

.42-

0.54

)0.

92

(0.8

4-1.

00)

2.64

(2

.50-

2.79

)5.

74

(5.5

2-5.

96)

9.99

(9

.69-

10.2

9)15

.10

(14.

71-1

5.49

)20

.86

(20.

39-2

1.35

)27

.55

(26.

96-2

8.15

)34

.40

(33.

67-3

5.15

)41

.82

(40.

87-4

2.78

)51

.00

(49.

55-5

2.46

)

All

case

s58

1,25

30.

20

(0.1

9-0.

21)

0.36

(0

.34-

0.37

)1.

15

(1.1

2-1.

17)

2.58

(2

.53-

2.62

)4.

37

(4.3

1-4.

44)

6.54

(6

.46-

6.62

)9.

06

(8.9

6-9.

16)

12.0

0 (1

1.87

-12.

13)

15.0

3 (1

4.87

-15.

19)

18.5

1 (1

8.29

-18.

73)

22.2

7 (2

1.95

-22.

59)




3.3.6 Conclusions

The data shows some strong trends that merit further discussion. We hope that this will provoke debate and encourage surgeons and manufacturers to re-evaluate their practice in light of the evidence provided. We accept that the data are open to other interpretations and we welcome this. Once again, we must stress very strongly that the NJR provides only part of the picture, that of survivorship, and only survivorship of a short- to medium-term duration; and now for the first time some Patient Related Outcome Measures (PROMs). We do not know whether these trends will continue in the longer term. Indeed, one of the lessons that we have learnt is that survivorship is not linear. Moreover, the data are imperfect and we are reliant on surgeons completing the data accurately and recording every procedure without exception. Some data fields continue to be poorly completed making meaningful analysis difficult.

Unlike hip arthroplasty, the practice of knee arthroplasty has not changed significantly over the past eight years. This year’s analysis shows a continuation of the trends shown previously with total knee replacements surviving markedly better than partial knee replacements.

Overall, the data show that short to medium-term survivorship is excellent after almost all common types of total knee replacement regardless of fixation, constraint and bearing type. For the first time we report on PROMs data. This shows that all types of total knee replacement give significant improvement in the majority of patients (see section 3.5).

For bicondylar knee replacements, unconstrained implants tended to have slightly lower revision rates than posterior cruciate-stabilised implants while mobile bearing prostheses tended to have a slightly higher failure rate than fixed bearing prostheses. Thus, the lowest revision rates were associated with a cemented, unconstrained, fixed bearing prosthesis. However, these differences are small and the results in all these groups are acceptable. This also holds true for analysis within brands. This year the brand analysis has been extended to more brands as more have reached the threshold number of cases needed to do this.

Patello-femoral joint replacements have a very high failure rate and were typically revised for pain. However, it should be remembered that patello-femoral joint replacements are undertaken for different reasons than total knee replacements and so a direct comparison of revision rates would be erroneous. Patello-femoral joint replacements may be revised to a total knee replacement because of problems with a different part of the knee and so the reason for revision may be unrelated to the original procedure. In addition, there may be reasons related to the aetiology of patello-femoral arthritis that could explain why replacing the joint, without significantly correcting the underlying biomechanical cause, may not always be a successful strategy. Patello-femoral joints lead to a significant improvement in PROMs, but the improvement is not as marked as with unicondylar and total knee replacements.

Unicondylar knee replacements also have a higher failure rate than total knee replacements. They were commonly revised for pain and loosening. Again, unicondylar knee replacements may be undertaken for different reasons than total knee replacements and they may be revised to a total knee replacement because of disease progression in a non-operated compartment which is unrelated to the original procedure. Therefore, comparing revision rates with total knee replacements is not straightforward. The improvement in PROMs after unicondylar knee replacement is very similar to that achieved by total knee replacement.

We report mortality after knee replacement using slightly different methodology to last year. Once again we show that knee replacement is associated with a slightly lower risk of death compared to hip replacement. We are currently conducting an in-depth study of post-operative mortality.

3.4 Outcomes after primary ankle replacement

Part 3



3.4.1 Overview of primary ankle surgery

This section looks at revision and mortality for all primary ankle operations performed up to 31 December 2012.

There were 1,417 primary operations (see Tables 3.1 and 3.2), including two bilateral operations performed at the same time.

Table 3.26 summarizes the procedures by year of primary operation;

Table 3.26 Number of primary ankle operations by year.

Year of primary Number of procedures2008 3

2009 5

2010 388

2011 505

2012 516

Total 1,417

Table 3.27 Number of primary ankles by ankle brand.

Brand Number (%) Mobility 800 (56.5)

Zenith 280 (19.8)

Box 91 (6.4)

Salto 86 (6.1)

Star 69 (4.9)

Hintegra 56 (4.0)

Rebalance 17 (1.2)

Inbone 2 (0.1)

Taric 1 (0.1)

Not known 15 (1.1)

Total 1,417 (100)

The median age at primary surgery was 67 years (IQR 61 to 74 years) and, overall, the ages of those having a first replacement of an ankle joint ranged between 24 and 91 years. Men made up 57.2% of all who underwent primary ankle replacement surgery.

All procedures were uncemented apart from two in which both cemented talar and tibial components were recorded and a further four for which there was either no component data, or the data were inconsistent.

The procedures were carried out by 165 consultants; 44 (27%) of them performed 10 or more procedures.

The maximum number of procedures carried out by any consultant was 102.

Similarly the total number of units involved was 175; 37 (21%) of them carried out 10 or more procedures. The maximum number of procedures carried out by any unit was 94.

Table 3.27 below shows the distribution of ankle brands. Mobility was the main brand used (56.5% of procedures) followed by Zenith (19.6%).

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3.4.2 Revisions after primary ankle surgery

The maximum follow up time available was 4.63 years and, up to the end of December 2012, only nine revisions of the primary ankle implant had been recorded in the NJR. Estimated cumulative percentage

probabilities of revision (based on Kaplan-Meier estimates) at 30 days, 90 days, 1 year and 2 years, respectively, were: 0.07% (95% CI: 0.01%-0.50%), 0.14% (95% CI: 0.04%-0.58%), 0.24% (95% CI: 0.08%-0.74%) and 1.40% (95% CI: 0.69%-2.83%).

Table 3.28 below lists the stated reasons for the nine revisions.

Table 3.28 Reasons for ankle revision (not mutually exclusive).

Reason Number Infection

High suspicion (e.g. pus or confined micro) 0

Low suspicion (awaiting micro/histology) 4

Aseptic loosening

Tibial component 2

Talar component 0

Lysis

Tibia 1*

Talus 1*

Malalignment 2

Implant fracture

Tibial component 0

Talar component 1

Meniscal component 0

Wear of polyethylene component 0

Meniscal insert dislocation 0

Component migration/Dissociation 1

Pain (undiagnosed) 1

Stiffness 0

Soft tissue impingement 1

Other indication for revision 2

*Same patient had both of these reasons.

3.4.3 Mortality after primary ankle surgery

There were 17 deaths in total. The estimated cumulative percentage probability of death (using

Kaplan-Meier) at 30 days, 90 days, 1 year and 2 years were, respectively: 0.0%, 0.15% (95% CI: 0.04%-0.59%), 1.05% (95% CI: 0.59%-1.85%) and 1.49% (95% CI: 0.88%-2.51%) There were too few deaths for further breakdown by age and gender.

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Annexe to survival analysis

In a departure from our previous reports, in the tables above, we have used Kaplan-Meier estimates for the cumulative probability of failure (i.e. where failure is either a revision or death) at given times t, F(t). Previously we had reported Nelson-Aalen estimates of the ‘cumulative hazard’ (also called ‘integrated hazard’).

This change in reported values brings us more in line with the form of reporting undertaken by other National Registries and, therefore, makes for easier comparison with published work from these and other research bodies.

The cumulative hazard at time t after primary operation, say H(t), is not the same as the cumulative probability of failure, F(t). To understand H(t), first start with the concept of the ‘hazard rate’ (analogous to the ‘force of mortality’ used in actuarial science). In the case of revision, the hazard rate at time t is the (instantaneous) rate at which revisions are performed amongst those cases that have not been revised previously. For discrete observations over time, the cumulative hazard at time t is the cumulative sum of the hazard rates; in continuous time it is the area under (i.e. the integral of) the hazard rate curve. The cumulative hazard here is estimated from the data using Nelson-Aalen estimates to account for the discrete time nature of observations.

Although the ‘cumulative hazard’ (H(t)) and ‘cumulative probability of failure’ (F(t)) are estimated using different approaches, they are mathematically related through the expression F(t)=(1 - e (-H(t))) and so it is possible to estimate one using an estimate of the other. Where

failure rates are less than 10%, the numerical value of e (-H(t)) is numerically close to the value of 1-H(t) and therefore F(t) is close to H(t). The values of F(t) and H(t) do not remain numerically similar once failure rates exceed 10% and then, in general, H(t) will be greater than F(t). This has become particularly noticeable in the NJR data set for mortality where, after nine years, the estimate of H(t) for 80+ year old men now has exceeded 100 (expressed as number of deaths per 100), whereas, because F(t) is a probability, its value cannot exceed 100%.

It is useful to use cumulative hazards for plotting, e.g. to compare revision rates for various sub-groups. As with the cumulative probability of failure, groups with greater cumulative hazards will have the highest revision rates. The shape of each cumulative hazard curve, however, carries useful information about how the revisions occur because the gradient of the curve at any time t estimates the hazard rate. If the plot of the cumulative hazard against time is a straight line, then revisions will have occurred at a constant rate throughout, i.e. the revision rate is independent from time of operation. If the graph increases exhibiting a concave shape, then the risk of revision will be lower initially, increasing with time after operation. The converse is true; if the shape is convex, revision rate would be higher initially.

For the above reasons we give Kaplan-Meier estimates in the tables but have retained estimates of ‘cumulative hazards’ for plotting.

3.5 PROMs outcomes

Part 3



3.5.1 Background to Patient Reported Outcome Measures (PROMs)

PROMs assess the patient’s experience and perspective of the quality of care and treatment they receive when they undergo a NHS-funded hip and/or knee replacement. PROMs are collected via pre- and post-operative questionnaires; the items allow the patient to self report on their state of health and general lifestyle before and after their joint replacement surgery. These outcomes provide a means of determining the impact the procedure has subsequently had on their quality of life. PROMs have been routinely collected by all providers of NHS-funded care in England since April 2009. The initial questionnaire, Q1, is normally administered just prior to the operation and questionnaire Q2 approximately six months following the operation. Additional information is available from: http://www.hscic.gov.uk/PROMs

In this section we have concentrated on the variables that described health benefits following primary hip or knee replacement.

3.5.2 Data linkage from PROMs to HES to NJR

Our base PROMs data file had 445,134 entries (207,436 hips and 230,429 knees).

Q1 and Q2 had already been linked together when received by the NJR.

Linkage between PROMs and the NJR data set could only be made via Hospital Episode Statistics (HES) data spanning the same time period as the PROMs data set.

PROMs to HES matching:

A total of 3% of the PROMs entries had no HES patient identifier (HESID) and a further 24% of the remainder could not be matched to a particular episode in HES (via EPIKEY). Of the remaining 326,876 PROMs entries, there were 2,653 duplicate matches and 16 triplicate matches to HES, meaning that multiple PROMs entries existed for the same HES patient episode. For these multiple matches, we chose the ‘best match’, i.e. the PROMs entry that had the best episode matched rank. In 234 cases there were two equal best matches; we gave priority then to the 144 PROMs entries that were

complete but it was not possible to choose the ‘higher quality’ record from the remaining 90 multiple entries and so these were omitted. This left 324,101 PROMs entries, some of which related to primary and some to revision procedures.

HES to NJR matching:

Within the HES data set, seven rankings were available resulting from linkage methods designed to determine the most likely NJR operation identifier for a given patient/episode in HES. The linkage method utilises and ranks the availability of various combinations of patient information associated with a particular HES episode. Relevant patient related information included patient NHS number, date of episode/entry, provider code, local patient ID, date or year of birth and patient gender. In addition, an episode in HES must have an ‘orthopaedically relevant’ OPCS procedure code associated with the particular episode i.e. OPCS codes must identify an orthopaedic type of event. The linkage rankings were used to assign the most probable NJR operation number to the HES person ID (HESID) and episode (EPIKEY).

Not all of such ‘orthopaedically relevant’ HES episodes had entries in the NJR. However, of the 517, 220 HES entries between 2003 and 2012 we were able to assign 391,240 (75.6%) to an NJR procedure.

PROMs/HES to NJR/HES matching:

Finally, we were able to link 274,729 of the above 324,101 PROMs entries to HES patient episodes with an assigned NJR operation identifier. There were some duplications i.e. instances where more than one PROMs entry could be ascribed to the same NJR operation. At this juncture we linked the PROMs data separately to our linked data files for primary hips and knees, after first removing bilateral operations from the latter. Any remaining duplications were removed pragmatically, by checking gender match, NJR patient identifiers and finally by choosing the PROMs entry where the date of completion of Q1 was closest to the date of the operation.

The remainder of this section provides some simple summary statistics for the PROMs entries that could be matched to our unilateral linked primary hip and knee files.


3.5.3 PROMs outcomes for primary hip replacements

A total of 124,136 of the linked primary hip operations in NJR had an associated PROMs entry; Q1 was complete in 99.7% of these and both Q1 and Q2 were complete in 75.6%. The median (IQR) interval of time from completion of Q1 to the primary operation was 0.59 months (IQR 0.23-1.22; n=84,078) and from primary operation to completion of Q2 was 6.47 months (IQR 6.31 to 6.87; n=83,808).

Table 3.29 opposite shows the overall outcomes after primary hip surgery.

Methodological note

The three health measures in PROMs are the EQ-5D Index, the EQ-5D Health Scale and the Oxford Hip/Knee Scores.

The EQ-5D Index22 is derived from a profile of responses to five questions about health ‘today’, covering activity, anxiety/depression, discomfort, mobility and self care. Weights had been applied to the responses to these questions to calculate the ‘index’. All five questions had to be answered in order to do this. The higher the index the better the patient, with one being the best possible score. The distribution of the EQ-5D Index is such that parametric statistical methods are not suitable for statistical comparison. Non-parametric unpaired and paired comparisons (two-tailed Mann-Whitney and Wilcoxon matched-pairs signed-ranks) have been used here but, because of the ‘ceiling effect’ (scores cannot improve beyond 1), paired comparisons were double-checked with simple sign tests.

The EQ-5D Health Scale is a visual analogue scale (VAS), asking about how the patients rate themselves ‘on the day’ (0=worst, 100=best).

The Oxford Hip/Knee Scores are based on responses to 12 hip or knee specific questions about health ‘in the last four weeks’. Each question is scored from 0 to 4 and the scores are summed to give a score from 0 (worst) to 48 (best). If fewer than three responses to individual questions are missing, they can be replaced by the mean of the remaining questions.

The VAS was not normally distributed, neither were the Oxford Hip and Knee scores at Q2; non-parametric methods of comparison, therefore, were used for both these variables.

Summary statistics used throughout this section are the median and Inter-Quartile Ranges (IQRs). The latter is less sensitive to outliers than a simple range. (Note however that, for paired data, the median difference may not be equal to the difference in medians.)

22 As the index is bounded between 0 and 1, we present results in this section with respect to the EQ-5D Index to three decimal places for greater precision.



Table 3.29 Overall outcomes after primary hip surgery.

Variable Frequency (%)Q2 Satisfaction: Satisfaction after the operation (Describe the results of the operation)

1 Excellent 35,313 (38.5%)

2 Very good 32,147 (35.0%)

3 Good 16,826 (18.3%)

4 Fair 5,739 (6.3%)

5 Poor 1,735 (1.9%)

Q2 Success: Problems now compared to before operation

1 Much better 78,617 (85.6%)

2 A little better 8,715 (9.5%)

3 About the same 2,298 (2.5%)

4 A little worse 1,332 (1.5%)

5 Much worse 908 (1.0%)

Q2 Wound: Wound problems since operation

1 Yes 8,498 (10.0%)

2 No 76,070 (90.0%)

Q2 Bleeding: Bleeding since operation

1 Yes 4,797 (5.8%)

2 No 78,165 (94.2%)

Q2 Urine: Urinary problems after the operation

1 Yes 11,260 (13.3%)

2 No 73,302 (86.7%)

Q2 Allergy: Experienced allergy with respect to drugs after the operation

1 Yes 10,022 (11.7%)

2 No 75,813 (88.3%)

Q2 Re-admitted: Re-admitted to hospital since operation

1 Yes 6,726 (7.3%)

2 No 85,120 (92.7%)

Q2 Further Surgery: Has had another operation on affected site

1 Yes 1,924 (2.1%)

2 No 89,998 (97.9%)

Bias in completion of PROMs is difficult to assess because we do not have details of how many PROMs questionnaires were sent out and how many were returned.

Amongst those NJR cases for whom we had PROMs entries, we checked whether those who had available/

complete measures at Q2 tended to have higher or lower scores at Q1; we found that the Q2 completers tended to have had better scores at Q1, as seen in Table 3.30. It may be that some of the initially less healthy group had died in the interim; this will be explored later.

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Table 3.30 Bias in Q2 completion of EQ-5D Index, EQ-5D Health Scale (VAS), Oxford Hip Score.

Measure Was measure available and complete at Q2?Median (IQR)

of the score at Q1EQ-5D Index

Yes 83,202 0.516 (0.055 to 0.656)

No 33,607 0.159 (-0.016 to 0.620)

P<0.001*

EQ-5D Health Scale (VAS)

Yes 80,394 70 (50-80)

No 31,513 65 (50-80)

P<0.001*

Oxford Hip Score

Yes 92,133 18 (12-24)

No 30,872 15 (10-22)

P<0.001*

*Mann-Whitney U-test

Completion rates for both EQ-5D Index and EQ-5D Health Scale (VAS) tended to be slightly higher in men than in women at both Q1 and Q2. The differences, although ‘statistically significant’, were in fact very small (e.g. for VAS at Q1: completion rates were 91.5% versus 89.3%, respectively, for men and women).

Significant improvements from Q1 to Q2 were seen in all three health measures overall (see Tables 3.31 to 3.33).

Histograms showing comparative distributions of EQ-5D Scale (VAS) and Oxford Hip Scores at Q1 and Q2 for complete pairs are shown in Figures 3.8 and 3.9 respectively.

All hip sub-groups showed significant improvement in EQ-5D Index (Table 3.31).

All the main sub-groups showed improvements in the VAS (Table 3.32) and in the Oxford Hip Score (Table 3.33).

Table 3.31 Changes in EQ-5D Index for hip primaries with index scores at both time points.

EQ-5D Index Number of pairs

Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)

Change (Q2 minus Q1)

Median (IQR) P-value*

All cases 83,2020.516

(0.055-0.656)0.796

(0.691-1)0.380

(0.175-0.694)P<0.001

All cemented 27,3290.364

(0.030-0.620)0.796

(0.639-1)0.413

(0.162-0.694)P<0.001


MoP 23,4820.293

(0.030-0.620)0.779

(0.623-1)0.413

(0.159-0.694)P<0.001

MoM 740.516

(0.055-0.620)0.805

(0.639-1)0.309

(0.159-0.633)P<0.001

CoP 2,8840.516

(0.055-0.656)0.796

(0.691-1)0.380

(0.177-0.697)P<0.001

Others/unsure 8890.516

(0.055-0.691)0.848

(0.691-1)0.380

(0.192-0.684)P<0.001

*Wilcoxon matched-pairs signed-ranks test and checked with sign test. **Sign test.

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Continued >



*Wilcoxon matched-pairs signed-ranks test and checked with sign test. **Sign test.


Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All uncemented 38,6930.516

(0.055-0.691)0.814

(0.691-1)0.380

(0.176-0.691)P<0.001


MoP 15,0540.516

(0.055-0.691)0.814

(0.691-1)0.380

(0.176-0.694)P<0.001

MoM 2,0490.516

(0.055-0.691)0.815

(0.691-1)0.344

(0.165-0.661)P<0.001

CoP 5,3280.516

(0.055-0.689)0.796

(0.689-1)0.380

(0.181-0.694)P<0.001

CoC 15,1750.516

(0.055-0.691)0.848

(0.691-1)0.380

(0.192-0.672)P<0.001

CoM 5140.587

(0.088-0.691)0.796

(0.691-1)0.309

(0.123-0.535)P<0.001


(0.055-0.620)0.796

(0.620-1)0.377

(0.105-0.694)P<0.001

All hybrid 13,0140.516

(0.055-0.656)0.814

(0.691-1)0.413

(0.192-0.697)P<0.001


MoP 8,8290.516

(0.055-0.620)0.812

(0.691-1)0.413

(0.192-0.705)P<0.001

MoM 880.516

(0.025-0.620)0.850

(0.701-1)0.413

(0.235-0.649)P<0.001

CoP 1,6020.516

(0.055-0.656)0.848

(0.691-1)0.396

(0.204-0.695)P<0.001

CoC 2,2910.516

(0.055-0.689)0.850

(0.691-1)0.380

(0.192-0.697)P<0.001


(0.055-0.673)0.796

(0.691-1)0.388

(0.198-0.667)P<0.001

All reverse hybrid 2,4790.260

(-0.003 to 0.620)0.779

(0.620-1)0.413

(0.159-0.707)P<0.001


MoP 1,6360.260

(-0.003 to 0.620)0.779

(0.620-1)0.413

(0.140-0.708)P<0.001

CoP 8310.260

(-0.003 to 0.620)0.796

(0.620-1)0.413

(0.173-0.703)P<0.001


(0.026-0.568)0.760

(0.587-0.908)0.404

(0.202-0.613)P=0.003

(P=0.002**)All resurfacing

MoM 1,6870.587

(0.189-0.691)1 (0.743-1)

0.309 (0.165-0.484)

P<0.001

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Table 3.32 Changes in EQ-5D Health Scale Score (VAS) for hip primaries with scores at both time points.

EQ-5D Health Scale Score (VAS) Number of pairs

Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All cases* 80,394 70 (50-80)

80 (69-90)

9 (-2 to 20) P<0.001

All cemented 26,339 70 (50-80)

80 (65-90)

6 (-5 to 20) P<0.001


MoP 22,556 70 (50-80)

80 (65-90)

6 (-5 to 20) P<0.001

MoM 74 72.5 (50-80)

85 (60-90)

0.5 (-4 to 19) P=0.009

CoP 2,823 70 (50-80)

80 (70-90)

10 (0 to 25) P<0.001

Others/unsure 886 72.5 (59-85)

80 (70-90)

5 (-3 to 20) P<0.001

All uncemented 37,451 70 (50-80)

80 (70-90)

10 (-1 to 22) P<0.001


MoP 14,385 70 (50-80)

80 (70-90)

6 (-4 to 20) P<0.001

MoM 1,958 70 (51-80)

80 (70-90)

9 (-2 to 20) P<0.001

CoP 5,170 70 (50-80)

80 (70-90)

10 (-1 to 25) P<0.001

CoC 14,879 70 (50-80)

80 (70-90)

10 (0 to 25) P<0.001

CoM 505 70 (50-83)

80 (70-90)

10 (-2 to 20) P<0.001

Others/unsure 554 70 (50-80)

80 (65-90)

10 (-1 to 21) P<0.001

All hybrid 12,564 70 (50-80)

80 (70-90)

10 (-1 to 22) P<0.001


MoP 8,450 70 (50-80)

80 (68-90)

8 (-3 to 20) P<0.001

MoM 83 70 (50-80)

80 (70-90)

10 (0 to 25) P<0.001

CoP 1,567 70 (50-80)

80 (70-90)

10 (0 to 25) P<0.001

CoC 2,254 70 (50-80)

80 (70-90)

10 (0 to 25) P<0.001


80 (65-90)

5 (0 to 20) P<0.001

All reverse hybrid 2,378 70 (50-80)

80 (64-90)

9 (-3 to 21) P<0.001


MoP 1,561 70 (50-80)

80 (65-90)

8 (-5 to 20) P<0.001

CoP 806 70 (50-80)

80 (60-90)

10 (0 to 25) P<0.001


55 (40-90)

0 (-18 to 20) P=0.65

All resurfacing

MoM 1,662 70 (57-85)

85 (75-90)

10 (0-20) P<0.001

*Wilcoxon matched-pairs signed-ranks test.

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Table 3.33 Changes in Oxford Hip Score for hip primaries with scores at both time points.

Oxford Hip Score Number of pairs

Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All cases 92,133 18 (12-24)

41 (34-46)

21 (14-28) P<0.001

All cemented 30,551 17 (11-23)

40 (32-45)

21 (14-27) P<0.001


MoP 26,294 17 (11-23)

39 (32-44)

21 (14-27) P<0.001

MoM 83 18 (11-22)

41 (30-46)

21 (12-28) P<0.001

CoP 3,189 17 (12-24)

42 (34-46)

21 (14-28) P<0.001


42 (36-46)

21 (15-27) P<0.001


42 (35-46)

21 (14-28) P<0.001


MoP 16,704 18 (12-24)

42 (34-46)

21 (14-28) P<0.001

MoM 2,240 19 (13-25)

43 (35-46)

21 (14-27) P<0.001

CoP 5,805 18 (12-23)

42 (34-46)

21 (14-28) P<0.001

CoC 16,547 18 (13-24)

43 (36-47)

22 (15-28) P<0.001

CoM 565 20 (14-26)

43 (35-46)

20 (13-27) P<0.001


42 (33-46)

21 (14-28) P<0.001

All hybrid 14,493 18 (12-24)

42 (35-46)

22 (15-28) P<0.001


MoP 9,875 17 (12-24)

41 (34-46)

21 (14-28) P<0.001

MoM 97 18 (13-23)

43 (37-46)

21 (16-27) P<0.001

CoP 1,770 18 (12-24)

43 (36-46)

22 (15-28) P<0.001

CoC 2,516 18 (12-24)

43 (37-47)

23 (15-29) P<0.001


41 (34-46)

21 (14-28) P<0.001

All reverse hybrid 2,755 16 (11-23)

40 (32-45)

20 (13-28) P<0.001


MoP 1,825 16 (11-23)

40 (32-45)

21 (13-27) P<0.001

CoP 918 16 (11-23)

40 (32-45)

20 (14-28) P<0.001

Others/unsure 12 11.5 (10-16.5)

38 (21.5-44)

16.5 (10-28.5) P=0.002

All resurfacing

MoM 1,837 22 (16-28)

44 (38-47)

19 (12-25) P<0.001

*Wilcoxon matched-pairs signed-ranks test.

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Figure 3.8 Histogram to compare the distributions of the EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=80,394). (i) At Q1

(ii) At Q2

5,000

10,000

15,000

Freq

uenc

y

0 20 40 60 80 100

Q1 EQ-5D HEALTH SCALE

5,000

0

10,000

15,000

Freq

uenc

y

0 20 40 60 80 100


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Figure 3.8 Histogram to compare the distributions of the EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=80,394).



Figure 3.9 Histogram to compare the distributions of the Oxford Hip Score between Q1 and Q2 in cases with scores at both time points (n=92,133). (i) At Q1

(ii) At Q2

5,000

0

15,000

10,000

20,000

Freq

uenc

y

Q1 Oxford Hip Score

0 10 20 30 40 50

5,000

0

15,000

10,000

20,000

Freq

uenc

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Q2 Oxford Hip Score

0 10 20 30 40 50

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Figure 3.9 Histogram to compare the distributions of the Oxford Hip Score between Q1 and Q2 in cases with scores at both time points (n=92,133).


3.5.4 PROMs outcomes for primary knee replacements

132,019 of the linked primary knee operations in NJR had an associated PROMs entry; Q1 was complete in 99.7% of these and both Q1 and Q2 were complete in 74.6%. The median (IQR) interval of time from

completion of Q1 to the primary operation was 0.56 months (IQR 0.20-1.22; n=86,908) and from primary operation to completion of Q2 was 6.47 months (IQR 6.31 to 6.90; n=87,171).

Table 3.34 below shows the overall outcomes after primary hip surgery.

Table 3.34 Overall outcomes after primary knee surgery.

Variable Frequency (%)Q2 Satisfaction: Satisfaction after the operation (Describe the results of the operation)

1 Excellent 21,962 (22.7%)

2 Very good 33,626 (34.8%)

3 Good 25,185 (26.1%)

4 Fair 12,186 (12.6%)

5 Poor 3,668 (3.8%)

Q2 Success: Problems now compared to before operation

1 Much better 68,540 (70.8%)

2 A little better 17,127 (17.7%)

3 About the same 4,901 (5.1%)

4 A little worse 3,727 (3.8%)

5 Much worse 2,577 (2.7%)

Q2 Wound: Wound problems since operation

1 Yes 11,825 (13.4%)

2 No 76,265 (86.6%)

Q2 Bleeding: Bleeding since operation

1 Yes 6,768 (7.9%)

2 No 78,915 (92.1%)

Q2 Urine: Urinary problems after the operation

1 Yes 10,635 (12.2%)

2 No 76,231 (87.8%)

Q2 Allergy: Experienced allergy with respect to drugs after the operation

1 Yes 12,244 (13.7%)

2 No 76,938 (86.3%)

Q2 Re-admitted: Re-admitted to hospital since operation

1 Yes 9,295 (9.6%)

2 No 87,467 (90.4%)

Q2 Further Surgery: Has had another operation on affected site

1 Yes 3,236 (3.3%)

2 No 93,646 (96.7%)

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Amongst these NJR cases for whom we have PROMs entries, those who had available completed measures at Q2 tended to have had better scores at Q1, see

Table 3.35 below. As for hips, it may be that some of those with poorer scores at Q1 had died before the Q2 assessment.

*Mann-Whitney U-test

Table 3.35 Bias in Q2 completion of EQ-5D Index, EQ-5D Health Scale (VAS), Oxford Knee Score.

Measure Was measure available and complete at Q2?Median (IQR)

of the score at Q1EQ-5D Index

Yes 87,306 0.587 (0.088-0.691)

No 36,451 0.264 (0.055-0.691)

P<0.001*

EQ-5D Health Scale (VAS)

Yes 84,031 70 (55-80)

No 33,999 70 (50-80)

P<0.001*

Oxford Knee Score

Yes 95,353 19 (13-24)

No 35,311 16 (11-22)

P<0.001*

Completion rates for all three health measures, at both Q1 and Q2, tended to be slightly higher in men than women; the differences, although ‘statistically significant’ ,were very small (e.g. 99.0% vs 98.9% respectively at Q1 and 73.5% vs 72.2% at Q2 for the Oxford Knee Score).

Significant improvements from Q1 to Q2 were seen in all three health measures (see Tables 3.36 to 3.38).

The distributions of EQ-5D Scale (VAS) and Oxford Knee Scores at Q1 and Q2 for complete pairs are shown in Figures 3.10 and 3.11.

All knee sub-groups showed significant improvement in EQ-5D Index (Table 3.36).

All sub-groups except patello-femoral showed small improvements in VAS (Table 3.37).

All sub-groups showed improvements in the Oxford Knee score (Table 3.38).

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Table 3.36 Changes in EQ-5D Index for knee primaries with index scores at both time points.


Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All cases 87,306 0.587 (0.088-0.691)

0.727 (0.620-0.883)

0.275 (0.069-0.568) P<0.001

All cemented 81,358 0.587 (0.088-0.691)

0.727 (0.620-0.883)

0.280 (0.069-0.568) P<0.001

All uncemented 3,782 0.587 (0.101-0.691)

0.727 (0.620-0.848)

0.240 (0.036-0.532) P<0.001

All hybrid 636 0.587 (0.101-0.691)

0.725 (0.587-0.849)

0.240 (0.036-0.532) P<0.001

All patello-femoral 257 0.620 (0.124-0.691)

0.691 (0.516-0.796)

0.105 (0.000-0.311) P<0.001

All unicondylar 1,273 0.620 (0.159-0.691)

0.760 (0.620-1.000)

0.240 (0.036-0.532) P<0.001

Table 3.37 Changes in EQ-5D Health Scale score (VAS) for knee primaries with scores at both time points.

EQ-5D Health Scale Score (VAS) Number of pairs

Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All cases 84,031 70 (55-80)

75 (60-85)

3 (-7 to 15) P<0.001

All cemented 78,239 70 (55-80)

75 (60-85)

3 (-7 to 15) P<0.001


76 (60-86)

4 (-5 to 15) P<0.001

All hybrid 609 70 (60-85)

75 (60-85)

2 (-10 to 15) P<0.001

All patello-femoral 259 70 (50-80)

70 (50-85)

0 (-10 to 15) P=0.16

All unicondylar 1,243 75 (60-85)

80 (65-89)

3 (-9 to 15) P<0.001

Table 3.38 Changes in Oxford Knee Score for knee primaries with scores at both time points.

Oxford Knee Score Number of pairs

Q1 Before operation

Median (IQR)

Q2 After operation

Median (IQR)



All cases 93,353 19 (13-24)

36 (28-42)

16 (9-22) P<0.001

All cemented 88,921 19 (13-24)

36 (28-42)

16 (9-22) P<0.001


35 (27-42)

14 (7-21) P<0.001

All hybrid 678 19 (13-24)

35 (26-42)

15 (7-21) P<0.001

All patello-femoral 282 20 (14-25)

32 (22-40)

10 (4-18) P<0.001

All unicondylar 1,405 21 (15-26)

38 (29-44)

15 (8-21) P<0.001

*Wilcoxon matched-pairs signed-ranks test and checked with sign test.



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Figure 3.10 Histogram to compare the distributions of EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=84,031). (i) At Q1

(ii) At Q2

5,000

0

15,000

10,000

Freq

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0 20 40 60 80 100

5,000

0

15,000

10,000

Freq

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0 20 40 60 80 100

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Figure 3.10 Histogram to compare the distributions of EQ-5D Health Scale Score (VAS) between Q1 and Q2 in cases with scores at both time points (n=84,031).


Figure 3.11 Histogram to compare the distributions of the Oxford Knee Score between Q1 and Q2 in cases with scores at both time points (n=93,353). (i) At Q1

(ii) At Q2

4,000

3,000

2,000

1,000

0

6,000

5,000

Freq

uenc

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Q1 Oxford Knee Score

0 10 20 30 40 50

4,000

3,000

2,000

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0

6,000

5,000

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Q2 Oxford Knee Score

0 10 20 30 40 50

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Figure 3.11 Histogram to compare the distributions of the Oxford Knee Score between Q1 and Q2 in cases with scores at both time points (n=93,353).



3.5.5 Conclusions

Data linkage via HES allowed a match of PROMs data to the subset of NJR records associated with English patients who had had NHS funded primary hip or knee replacement procedures (from the start of the collection of PROMs in April 2009 until the end of the current NJR annual report review period of 31 December 2012). Over a quarter of the identified orthopaedic HES episodes were lost initially due to the absence of a traceable NHS number. Of the remaining PROMs records, between a quarter and 29% of this group of English NHS funded primary hip/knee replacement patients had only completed the pre-operation survey and so we are unable to report on how this patient group evaluated their quality of life post-operation. In addition, based on the median responses (and IQR) to Q1 for this sub-group compared to those who did complete both surveys, these patients tended to be in a poorer state of health prior to surgery. Therefore, in interpreting the PROMs results for those patients who completed both Q1 and Q2, it should be remembered that these are patients who generally were healthier prior to operation and would have a better prospect of surviving to six months after the primary surgery. Thus, pre- to post-operative changes in PROMs health scores are likely to be less improved with the inclusion of the less healthy pre-operative subset of patients lost to follow up.

The vast majority of the 93,846 hip replacement patients who had responded to both Q1 and Q2 indicated at least a ‘fair’ amount of satisfaction post surgery (98.1%) and over 85% of these reported that the problems they had had living with their hip condition before surgery were ‘much better’ after receiving a hip implant.

It is clear that the hip patient group who completed both Q2 and Q1 tended to be in a better state of health before surgery than those who had only completed Q1 (as indicated by higher scores on all three health measures prior to operation for these; most notably on the EQ-5D Index). Therefore, these patients are more likely to have greater resilience to undergoing surgery and are less likely to be susceptible to complications post surgery. This group reported a significant overall improvement in their

quality of life post surgery. The median improvements in score on the three health scales were 0.38 on the EQ-5D Index, 10 points on the VAS score and 21 points on the Oxford Hip Score respectively.

In general, of the knee surgery patient group who completed both questionnaires, most reported enhanced lifestyle and health benefits post operation. Operation outcomes were rated as a success overall, although the proportion of those who were at least satisfied with the outcomes were lower than the ratings for hip surgery on the same items. That is, more than 96% of knee patients with responses to both Q1 and Q2 said they were at least fairly satisfied with the results of their surgery. In addition, just over 70% of these patients intimated that the problems they were faced with at circa six months post surgery as a result of their knee condition were ‘much better’ having had knee surgery.

As noted already for the hip patient group, the knee patient surgical group who had completed both surveys tended to have higher scores at Q1 and thus were in better health overall compared to the group of Q1 only respondees.

Across all knee surgery cases, for the three knee PROMs measures of interest here, there was marked improvement in patient self-reported well-being and health post operation. This was seen as a general increase in median scores and IQR values after surgery i.e. responses to Q2 only and in the median change in Q1 and Q2 knee health scores of 0.275 on the EQ-5D Index, 3 points on the VAS score and 16 points on the Oxford Knee Score respectively. However, the VAS score increase overall was more moderate than for the other two measures.

The median score change was fairly consistent across the main fixation and knee replacement type sub-groups apart from for those undergoing a patello-femoral type knee surgery. Here, the change in health score ratings compared to the other types of main knee replacement types suggested that post-surgery benefits to health and lifestyle were slightly less improved than for other types of knee replacements.

4.1 Introduction

Part 4Trust-, Local Health Board- and unit-level activity and outcomes 2012



Part Four shows indicators for hip and knee joint replacement procedures by unit and Trust. This section was first included last year and has been updated as part of the Government’s transparency agenda. It is based on procedures carried out during the 2012 calendar year and submitted to the NJR by 28 February 2013.

Part Four information is based on the actual operation date (1 January to 31 December 2012) whereas data in Part One is based on the date the procedure was submitted (1 April 2012 to 31 March 2013). It is therefore possible for a hospital to have zero submissions in Part Four but not be listed as a nil returner in Part One.

4.2 Unit outlier analysis methodology

Part 4



Unit outlier analysis covers the period from 1 April 2003 to 31 December 2012.

The outlier analyses made use of funnel plots from statistical process control methodology. These aim to distinguish normal variation between units (which is to be expected) from unusual differences (termed ‘special cause’ variation), which may indicate the need for further investigation. Funnel plots enable units of different sizes to be compared; performance indicators based on smaller numbers of patients will have greater variability and this in turn is reflected by wider control limits.

Summary of the methodology for unit revision rates:

•The standardised revision ratio (SRR) is plotted against the number of expected revisions. The SRR is the total number of revisions divided by the number of expected revisions for that unit’s caseload in respect of the age group, gender, and the diagnosis of the patients. If the SRR is 1, the number of revisions is compatible with the number expected for that unit.

•Control limits for funnel plots are normally set at 95% and 99.8% (roughly equivalent to 2 or 3 standard deviations). Our normal six-monthly review process focuses on those above the upper limit of the latter; one might expect, however, that one in 500 would be outside the 99.8% limits (above or below) just by chance. In the table below we have highlighted in light red (1) units above the upper limit of the 99.8% control limits but also indicate in dark red (2) those that are

much more extreme, i.e. above the upper limit of the 99.99% control limits.

Previous annual reports have discussed in detail how metal-on-metal bearing surfaces are associated with higher revision rates than other bearing surfaces. Many of the outlying hip units identified from this analysis have more commonly used stemmed metal-on-metal and resurfacing procedures, and although use of these implants has now almost ceased in the UK, the higher revision rates for these implants are likely to be reflected in the returns made by these units for some years to come. This may explain their higher revision rates.

Summary of the methodology for unit 90-day mortality rates:

•The standardised mortality ratio (SMR) is plotted against number of expected deaths. The SMR is the number of actual deaths within 90 days of primary joint replacement divided by the number of expected deaths in this period. The number of expected deaths has been calculated after adjustment for patient characteristics (age, gender, and ASA grade of patients). In addition, for hip units, adjustment is made for whether the operation was undertaken for trauma.

•Control limits are as for revisions above.

Any units identified as potential outliers in Part Four have been notified. All units are provided with an Annual Clinical Report and additionally have access to an online NJR Management Feedback system (See section 1.4.6).

Compliance, Consent and Linkability are:

Red if lower than 80%

Amber if equal to or greater than 80% and lower than 95%

Green if 95% or more

• Compliance figures may be low due to delayed data entry• Linkability for some hospitals will be lower than expected if they have private patients from outside England and Wales• Part Four data covers procedures carried out between 1 January 2012 and 31 December 2012

Outlier analyses are:

Light red if units are outside 99.8% control limits (approx 3 standard deviations (SDs))

Dark red if units are outside 99.99% control limits

Please note for the data in following table:

The table uses the following footnotes: 23. Compliance (NHS Trust/Local Health Board Only) - the percentage of cases submitted to the NJR compared to HES/PEDW. 24. Consent Rate - percentage of cases submitted to the NJR with patient consent confirmed. 25. Linkability - the proportion of records which include a valid patient’s NHS number compared with the number of procedures recorded on the NJR. 26. Outliers with respect to 90-day mortality following primary operations performed from 2003 onwards. Units outside 99.8% control limits (approx 3 SDs) are flagged in light red (1); those outside 99.99% control limits are flagged in dark red (2). 27. Outliers with respect to revisions (at any time) following primary operations performed from 2003 onwards. Units outside 99.8% control limits (approx 3 SDs) are flagged in light red (1); those outside 99.99% control limits are flagged in dark red (2).

1

2


www.njrcentre.org.uk

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242

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si C

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ity L

ocal

H

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%

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68

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n C

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oyal

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97

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ombe

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© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

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Boa

rd/C

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ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

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ate

(%) 2

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abili

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(%) 2

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Per

cent

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HS

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and

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1

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Hos

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ches

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oyal

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88%

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79

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47%

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and

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plia

nce

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/Loc

al

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nly)

23

Ho

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No

. of

Pro

ced

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20

12

No

. of

Co

nsul

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s 20

12

Co

nsen

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ate

(%) 2

01224

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abili

ty

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2012

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cent

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23 C

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HS

Tru

st/L

ocal

Hea

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oard

Onl

y) -

the

per

cent

age

of c

ases

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mitt

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JR c

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ared

to

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S/P

ED

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24 C

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- p

erce

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the

NJR

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pat

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sent

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firm

ed25

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- t

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rop

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the

num

ber

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.26

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liers

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resp

ect t

o 90

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3 on

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nits

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); th

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99.9

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27 O

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ith re

spec

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); th

ose

outs

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99.9

9% c

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ark

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(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Cou

nty

Durh

am a

nd D

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S Fo

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S Tr

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ity H

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224

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173

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143

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mar

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115

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HS

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HS

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en E

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338

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© N

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nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

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Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

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abili

ty

(%) 2

01225

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rag

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SA

Gra

de

2012

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cent

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e P

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rag

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ion

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10A

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ated

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H

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2

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am H

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ord)

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%

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Lan

cash

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S Tr

ust

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eral

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pita

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73%

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2.1

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69.7

15%

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al B

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mar

y70

1554

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633

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%41

%

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sex

Hos

pita

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HS

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t Hos

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19

99%

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bour

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Elio

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pita

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57

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2.1

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HS

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n Tr

ust

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al H

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139

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ters

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al H

ospi

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044

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%


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cal H

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rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

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e P

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2012

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rag

e A

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Op

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ion

2012

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cent

age

of

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ated

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ceta

bul

ar

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20

12

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cent

age

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20

12

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-

90 D

ay

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rtal

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-

90 D

ay

Mo

rtal

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-

Hip

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e27

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-

Kne

e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

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ns p

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rmed

from

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3 on

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ds. U

nits

out

side

99.

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ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Gre

at W

este

rn H

ospi

tals

NH

S Fo

unda

tion

Trus

t93

%

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Gre

at W

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1,11

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%

Guy

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S Fo

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tion

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hom

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224

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Ham

pshi

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chin

gbro

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pita

l62

47

97%

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0%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

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rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

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2012

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rag

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Op

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ion

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Per

cent

age

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10A

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ceta

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ced

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1

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HS

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tle H

ill H

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741

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144

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2

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ity H

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n Tr

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n Tr

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t77

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l (D

enm

ark

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372

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gsto

n H

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ospi

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%


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t/Lo

cal H

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rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

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rag

e A

ge

At

Op

erat

ion

2012

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cent

age

of

10A

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ated

A

ceta

bul

ar

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lant

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ced

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20

12

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cent

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ary

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ced

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20

12

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liers

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90 D

ay

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rtal

ity

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s26

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liers

-

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ay

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rtal

ity

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es26

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liers

-

Hip

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e27

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liers

-

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e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

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kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

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ared

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the

num

ber

of p

roce

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ecor

ded

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liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Lanc

ashi

re T

each

ing

Hos

pita

ls N

HS

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datio

n Tr

ust

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S Tr

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pel A

llerto

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ospi

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1,13

320

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99%

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68.9

0%99

%

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isha

m H

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care

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S Tr

ust

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de T

reat

men

t Cen

tre26

96

88%

96%

2.2

36%

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16%

93%

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n an

d D

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able

Hos

pita

l NH

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tion

Trus

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%

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n &

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628

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239

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HS

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way

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S Fo

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tion

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way

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687

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241

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2

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Che

shire

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pita

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HS

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n Tr

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99

97%

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18%

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ospi

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S Tr

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833

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%

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erfie

lds

Gen

eral

Hos

pita

l64

212

85%

89%

2.2

45%

67.5

6%99

%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

Ave

rag

e A

ge

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Op

erat

ion

2012

Per

cent

age

of

10A

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ated

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ceta

bul

ar

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lant

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rim

ary

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ced

ures

20

12

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cent

age

of

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ated

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90 D

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ay

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rtal

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es26

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liers

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on K

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s H

ospi

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HS

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datio

n Tr

ust

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on K

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s H

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389

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New

ham

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ity H

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HS

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eway

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tre18

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ham

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eral

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0%10

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folk

and

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wic

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nive

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tion

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t99

%

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folk

& N

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ich

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pita

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369

2099

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243

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tham

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eral

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pita

l NH

S Tr

ust

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tham

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eral

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pita

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cute

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312

85%

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%

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th B

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2.2

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2

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th C

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firm

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769

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ther

n D

evon

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lthca

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HS

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th D

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trict

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ther

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t77

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na P

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le T

reat

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t Cen

tre32

24

97%

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46%

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thor

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%58

%


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t/Lo

cal H

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rd/C

ompa

ny

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plia

nce

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S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

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rag

e A

ge

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Op

erat

ion

2012

Per

cent

age

of

10A

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ated

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ceta

bul

ar

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lant

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rim

ary

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ced

ures

20

12

Per

cent

age

of

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ated

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ary

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ced

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20

12

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90 D

ay

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-

90 D

ay

Mo

rtal

ity

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es26

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liers

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Hip

R

evis

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e27

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liers

-

Kne

e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Nor

th M

iddl

esex

Uni

vers

ity H

ospi

tal

NH

S Tr

ust

75%

Nor

th M

iddl

esex

Hos

pita

l22

16

100%

100%

2.3

27%

68.6

0%99

%

Nor

th T

ees

and

Har

tlepo

ol N

HS

Foun

datio

n Tr

ust

93%

Uni

vers

ity H

ospi

tal o

f Har

tlepo

ol84

48

92%

100%

2.1

44%

67.5

19%

80%

2

Uni

vers

ity H

ospi

tal o

f Nor

th T

ees

94

78%

89%

2.1

38%

75.4

0%10

0%2

Nor

thum

bria

Hea

lthca

re N

HS

Foun

datio

n Tr

ust

94%

Hex

ham

Gen

eral

Hos

pita

l55

613

98%

99%

1.8

41%

68.5

41%

100%

Nor

th T

ynes

ide

Gen

eral

Hos

pita

l74

115

100%

99%

2.1

44%

69.4

16%

100%

2

Wan

sbec

k H

ospi

tal

785

1310

0%99

%2.

145

%69

.229

%10

0%

Nor

th W

est L

ondo

n H

ospi

tals

NH

S Tr

ust

77%

Cen

tral M

iddl

esex

Hos

pita

l35

715

89%

96%

2.0

38%

69.0

0%81

%

Nor

thw

ick

Park

Hos

pita

l10

16

72%

96%

2.2

48%

73.1

0%56

%

Not

tingh

am U

nive

rsity

Hos

pita

ls

NH

S Tr

ust

102%

Not

tingh

am C

ity H

ospi

tal

1,17

217

98%

100%

2.2

45%

69.2

7%64

%

Que

ens

Med

ical

Cen

tre N

ottin

gham

U

nive

rsity

Hos

pita

l31

314

99%

100%

2.1

41%

69.4

9%77

%

Oxf

ord

Uni

vers

ity H

ospi

tals

NH

S Tr

ust

99%

John

Rad

cliff

e H

ospi

tal

252

100%

100%

1.9

24%

74.4

0%10

0%

Nuf

field

Orth

opae

dic

Cen

tre1,

791

1894

%96

%2.

143

%68

.60%

82%

Penn

ine

Acut

e H

ospi

tals

NH

S Tr

ust

73%

Fairf

ield

Gen

eral

Hos

pita

l61

617

77%

97%

2.2

39%

69.5

19%

66%

Nor

th M

anch

este

r Gen

eral

Hos

pita

l36

610

84%

91%

2.2

42%

68.4

16%

26%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

Ave

rag

e A

ge

At

Op

erat

ion

2012

Per

cent

age

of

10A

R

ated

A

ceta

bul

ar

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Per

cent

age

of

10A

R

ated

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emo

ral

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lant

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rim

ary

Pro

ced

ures

20

12

Out

liers

-

90 D

ay

Mo

rtal

ity

Hip

s26

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liers

-

90 D

ay

Mo

rtal

ity

Kne

es26

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liers

-

Hip

R

evis

ion

Rat

e27

Out

liers

-

Kne

e R

evis

ion

Rat

e27

Roy

al O

ldha

m H

ospi

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202

1264

%95

%2.

238

%69

.338

%6%

Pete

rbor

ough

and

Sta

mfo

rd

Hos

pita

ls N

HS

Foun

datio

n Tr

ust

87%

Pete

rbor

ough

City

Hos

pita

l81

616

86%

96%

2.2

40%

69.8

68%

70%

Plym

outh

Hos

pita

ls N

HS

Trus

t92

%

Derri

ford

Hos

pita

l86

015

97%

99%

2.2

44%

68.1

1%54

%

Pool

e H

ospi

tal N

HS

Foun

datio

n Tr

ust

47%

Pool

e H

ospi

tal

106

1083

%87

%2.

534

%74

.90%

82%

Ports

mou

th H

ospi

tals

NH

S Tr

ust

84%

Que

en A

lexa

ndra

Hos

pita

l1,

162

2210

0%99

%2.

040

%69

.315

%99

%

Rob

ert J

ones

and

Agn

es H

unt

Orth

opae

dic

And

Dis

trict

Hos

pita

l N

HS

Trus

t10

1%

Rob

ert J

ones

& A

gnes

Hun

t O

rthop

aedi

c H

ospi

tal

2,94

435

98%

99%

2.0

43%

68.8

24%

92%

Roy

al B

erks

hire

NH

S Fo

unda

tion

Trus

t89

%

Roy

al B

erks

hire

Hos

pita

l92

517

99%

100%

2.1

40%

69.1

4%97

%1

Roy

al B

olto

n H

ospi

tal N

HS

Foun

datio

n Tr

ust

96%

Roy

al B

olto

n H

ospi

tal

424

1186

%86

%2.

443

%67

.80%

98%

Roy

al C

ornw

all H

ospi

tals

NH

S Tr

ust

89%

Roy

al C

ornw

all H

ospi

tal (

Trel

iske

)56

519

84%

94%

2.2

48%

70.4

13%

56%

St M

icha

el's

Hos

pita

l39

017

84%

92%

1.8

40%

68.0

14%

42%

Roy

al D

evon

and

Exe

ter N

HS

Foun

datio

n Tr

ust

93%

Roy

al D

evon

& E

xete

r Hos

pita

l (W

onfo

rd)

1,44

712

92%

97%

2.1

43%

70.5

0%99

%

Roy

al F

ree

Lond

on N

HS

Foun

datio

n Tr

ust

76%

The

Roy

al F

ree

Hos

pita

l28

18

77%

100%

2.2

34%

71.1

79%

99%


Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

Ave

rag

e A

ge

At

Op

erat

ion

2012

Per

cent

age

of

10A

R

ated

A

ceta

bul

ar

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Per

cent

age

of

10A

R

ated

F

emo

ral

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Out

liers

-

90 D

ay

Mo

rtal

ity

Hip

s26

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liers

-

90 D

ay

Mo

rtal

ity

Kne

es26

Out

liers

-

Hip

R

evis

ion

Rat

e27

Out

liers

-

Kne

e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Roy

al L

iver

pool

and

Bro

adgr

een

Uni

vers

ity H

ospi

tals

NH

S Tr

ust

87%

Bro

adgr

een

Hos

pita

l67

817

64%

80%

2.1

45%

67.2

3%51

%

The

Roy

al L

iver

pool

Uni

vers

ity

Hos

pita

l63

932

%10

0%2.

641

%72

.10%

73%

Roy

al N

atio

nal O

rthop

aedi

c H

ospi

tal

NH

S Tr

ust

88%

The

Roy

al N

atio

nal O

rthop

aedi

c H

ospi

tal (

Stan

mor

e)1,

189

1888

%99

%2.

038

%62

.925

%99

%

Roy

al S

urre

y C

ount

y H

ospi

tal N

HS

Foun

datio

n Tr

ust

89%

Roy

al S

urre

y C

ount

y H

ospi

tal

670

999

%99

%2.

040

%70

.27%

17%

Roy

al U

nite

d H

ospi

tal B

ath

NH

S Tr

ust

103%

Roy

al U

nite

d H

ospi

tal

687

1778

%97

%2.

239

%69

.54%

70%

Salfo

rd R

oyal

NH

S Fo

unda

tion

Trus

t70

%

Salfo

rd R

oyal

340

1236

%84

%2.

347

%67

.20%

66%

Salis

bury

NH

S Fo

unda

tion

Trus

t96

%

Salis

bury

Dis

trict

Hos

pita

l68

010

99%

99%

2.1

41%

71.0

0%49

%

Sand

wel

l and

Wes

t Birm

ingh

am

Hos

pita

ls N

HS

Trus

t91

%

City

Hos

pita

l50

211

98%

98%

2.2

37%

68.2

0%35

%

Sand

wel

l Gen

eral

Hos

pita

l23

910

92%

97%

2.2

43%

68.6

0%46

%

Scar

boro

ugh

and

Nor

th E

ast

York

shire

Hea

lth C

are

NH

S Tr

ust

106%

Scar

boro

ugh

Gen

eral

Hos

pita

l58

88

84%

100%

2.1

49%

69.8

0%89

%

Shef

field

Tea

chin

g H

ospi

tals

NH

S Fo

unda

tion

Trus

t69

%

Nor

ther

n G

ener

al H

ospi

tal

539

2692

%96

%2.

243

%70

.365

%96

%

Roy

al H

alla

msh

ire H

ospi

tal

824

1197

%98

%2.

344

%69

.472

%96

%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

Ave

rag

e A

ge

At

Op

erat

ion

2012

Per

cent

age

of

10A

R

ated

A

ceta

bul

ar

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Per

cent

age

of

10A

R

ated

F

emo

ral

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lant

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P

rim

ary

Pro

ced

ures

20

12

Out

liers

-

90 D

ay

Mo

rtal

ity

Hip

s26

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liers

-

90 D

ay

Mo

rtal

ity

Kne

es26

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liers

-

Hip

R

evis

ion

Rat

e27

Out

liers

-

Kne

e R

evis

ion

Rat

e27

Sher

woo

d Fo

rest

Hos

pita

ls N

HS

Foun

datio

n Tr

ust

97%

Kin

gs M

ill H

ospi

tal

659

1591

%93

%2.

143

%68

.17%

99%

New

ark

Hos

pita

l14

25

60%

99%

1.8

40%

70.5

0%10

0%

Shre

wsb

ury

and

Telfo

rd H

ospi

tal

NH

S Tr

ust

85%

Roy

al S

hrew

sbur

y H

ospi

tal

93

89%

89%

2.1

25%

76.6

13%

75%

The

Prin

cess

Roy

al H

ospi

tal

512

693

%98

%2.

238

%69

.40%

78%

Sout

ham

pton

Uni

vers

ity H

ospi

tals

N

HS

Trus

t62

%

Sout

ham

pton

Gen

eral

Hos

pita

l57

218

80%

85%

2.1

40%

67.1

11%

83%

Sout

h D

evon

Hea

lthca

re N

HS

Foun

datio

n Tr

ust

93%

Torb

ay H

ospi

tal

802

1793

%99

%2.

240

%70

.933

%95

%

Sout

hend

Uni

vers

ity H

ospi

tal N

HS

Foun

datio

n Tr

ust

89%

Sout

hend

Hos

pita

l91

910

100%

100%

2.1

41%

70.5

23%

34%

Sout

h Lo

ndon

Hea

lthca

re N

HS

Trus

t74

%

Prin

cess

Roy

al U

nive

rsity

Hos

pita

l15

09

97%

95%

2.4

39%

74.7

0%84

%

Que

en E

lizab

eth

Hos

pita

l Woo

lwic

h12

510

98%

98%

2.5

46%

70.8

0%43

%

Que

en M

ary'

s H

ospi

tal S

idcu

p70

720

97%

99%

2.0

39%

70.5

0%94

%

Sout

hpor

t and

Orm

skirk

Hos

pita

l N

HS

Trus

t96

%

Orm

skirk

& D

istri

ct G

ener

al H

ospi

tal

524

810

0%99

%2.

041

%70

.58%

99%

Sout

h Te

es H

ospi

tals

NH

S Fo

unda

tion

Trus

t93

%

Fria

rage

Hos

pita

l69

314

83%

100%

2.0

44%

68.2

1%98

%

The

Jam

es C

ook

Uni

vers

ity H

ospi

tal

649

1399

%99

%2.

245

%67

.816

%84

%

Sout

h Ty

nesi

de N

HS

Foun

datio

n Tr

ust

100%

Sout

h Ty

nesi

de D

istri

ct H

ospi

tal

290

610

0%10

0%2.

239

%69

.310

0%93

%1


Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

nts

2012

Ave

rag

e A

ge

At

Op

erat

ion

2012

Per

cent

age

of

10A

R

ated

A

ceta

bul

ar

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Per

cent

age

of

10A

R

ated

F

emo

ral

Imp

lant

Hip

P

rim

ary

Pro

ced

ures

20

12

Out

liers

-

90 D

ay

Mo

rtal

ity

Hip

s26

Out

liers

-

90 D

ay

Mo

rtal

ity

Kne

es26

Out

liers

-

Hip

R

evis

ion

Rat

e27

Out

liers

-

Kne

e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

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(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Sout

h W

arw

icks

hire

NH

S Fo

unda

tion

Trus

t89

%

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k H

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810

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%2.

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.50%

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lthca

re N

HS

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t85

%

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l (To

otin

g)15

78

96%

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2.4

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%

St H

elen

s an

d K

now

sley

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NH

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ust

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ston

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pita

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111

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1

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kpor

t NH

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tion

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t92

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Step

ping

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pita

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ostic

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HS

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n Tr

ust

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1

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HS

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n Tr

ust

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sells

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l Hos

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%

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HS

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n Tr

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n H

ospi

tal

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440

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nt V

erno

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eatm

ent C

entre

512

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041

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© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

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abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

Mal

e P

atie

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2012

Ave

rag

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Op

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ion

2012

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cent

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Prin

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S Tr

ust

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t81

%

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en E

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The

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am N

HS

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datio

n Tr

ust

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2

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al B

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al B

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tion

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t73

%

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al O

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1,36

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87%

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65.8

16%

63%

The

Roy

al W

olve

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S Tr

ust

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ss H

ospi

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243

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83%

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pita

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S Tr

ust

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tting

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67

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2.1

34%

68.5

5%28

%

Uni

ted

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olns

hire

Hos

pita

ls N

HS

Trus

t74

%

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nty

Hos

pita

l Lou

th14

15

99%

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2.0

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30%

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ntha

m a

nd D

istri

ct H

ospi

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272

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0%2.

131

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56%

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oln

Cou

nty

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pita

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712

84%

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2.2

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50%

100%

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rim H

ospi

tal

461

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241

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%


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t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

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cent

age

Mal

e P

atie

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2012

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rag

e A

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At

Op

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ion

2012

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cent

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of

10A

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ated

A

ceta

bul

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ced

ures

20

12

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cent

age

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ary

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ced

ures

20

12

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liers

-

90 D

ay

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rtal

ity

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s26

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liers

-

90 D

ay

Mo

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ity

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es26

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liers

-

Hip

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evis

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e27

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liers

-

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e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

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kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

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ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

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liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Uni

vers

ity C

olle

ge L

ondo

n H

ospi

tals

N

HS

Foun

datio

n Tr

ust

96%

Uni

vers

ity C

olle

ge H

ospi

tal

313

1057

%93

%2.

136

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.74%

29%

Uni

vers

ity H

ospi

tal B

irmin

gham

NH

S Tr

ust

80%

Que

en E

lizab

eth

Hos

pita

l B

irmin

gham

329

13%

78%

2.2

44%

73.9

0%10

0%

Uni

vers

ity H

ospi

tal o

f Nor

th

Staf

ford

shire

NH

S Tr

ust

80%

City

Gen

eral

Hos

pita

l64

112

100%

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2.2

44%

68.6

2%79

%

Uni

vers

ity H

ospi

tal o

f Sou

th

Man

ches

ter N

HS

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datio

n Tr

ust

82%

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hens

haw

e H

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tal

438

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%2.

139

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Uni

vers

ity H

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tol N

HS

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datio

n Tr

ust

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tol R

oyal

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pita

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tol R

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mar

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0%

Uni

vers

ity H

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entry

and

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arw

icks

hire

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S Tr

ust

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pita

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t Cro

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922

97%

97%

1.9

39%

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6%63

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Uni

vers

ity H

ospi

tal (

Cov

entry

)55

725

96%

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2.4

39%

70.6

7%84

%

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vers

ity H

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tals

of L

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ster

N

HS

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t85

%

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ld H

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11

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r Gen

eral

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pita

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798

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140

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%92

%

Uni

vers

ity H

ospi

tals

of M

orec

ambe

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ay N

HS

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datio

n Tr

ust

73%

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ess

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eral

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pita

l38

67

98%

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2.0

45%

69.5

1%99

%

Roy

al L

anca

ster

Infir

mar

y16

411

99%

92%

2.3

42%

70.9

30%

97%

Wes

tmor

land

Gen

eral

Hos

pita

l36

913

84%

99%

1.9

41%

68.0

1%93

%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

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e P

atie

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2012

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rag

e A

ge

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erat

ion

2012

Per

cent

age

of

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ated

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ceta

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ar

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ced

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12

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alto

n H

ospi

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n Tr

ust

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ringt

on H

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tal

525

796

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244

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Wes

tern

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HS

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22

Wat

ford

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pita

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79

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nive

rsity

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pita

l N

HS

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t69

%

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t Mid

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nive

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pita

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07

64%

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52%

98%

Wes

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lth N

HS

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991

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t Suf

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Wes

t Suf

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711

100%

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2.1

42%

71.0

64%

95%

Whi

pps

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ss U

nive

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pita

l N

HS

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t13

2%

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pps

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ss U

nive

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pita

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99

72%

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2.1

31%

70.3

13%

56%

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al U

nive

rsity

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chin

g H

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tal

NH

S Fo

unda

tion

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t92

%

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we

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pita

l44

512

85%

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2.5

41%

72.2

0%99

%

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ridge

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915

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67.3

0%10

0%

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cute

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pita

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HS

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t81

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a H

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ire R

oyal

Hos

pita

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36

87%

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2.1

39%

69.8

13%

94%


Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

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abili

ty

(%) 2

01225

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rag

e A

SA

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de

2012

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cent

age

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e P

atie

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2012

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rag

e A

ge

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Op

erat

ion

2012

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cent

age

of

10A

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ated

A

ceta

bul

ar

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lant

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rim

ary

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ced

ures

20

12

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cent

age

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ated

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rim

ary

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ced

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20

12

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90 D

ay

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rtal

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90 D

ay

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rtal

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liers

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Hip

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e27

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liers

-

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e R

evis

ion

Rat

e27

23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

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kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

oper

atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

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ged

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ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

revi

sion

s (a

t any

tim

e) fo

llow

ing

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ary

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atio

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rmed

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200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

are

flag

ged

in li

ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Wrig

htin

gton

Wig

an a

nd L

eigh

NH

S Fo

unda

tion

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t96

%

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htin

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145

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86%

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ley

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ust

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efor

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Aspe

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BM

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%

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ark

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%



© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

Boa

rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

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ced

ures

20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

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abili

ty

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rag

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SA

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de

2012

Per

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rag

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ge

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erat

ion

2012

Per

cent

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ated

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ced

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ing

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I Har

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BM

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I Hud

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348

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ak H

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119

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I Lan

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85

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%

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%

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17

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%

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192

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Trus

t/Lo

cal H

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rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

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nly)

23

Ho

spita

l

No

. of

Pro

ced

ures

20

12

No

. of

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nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

01224

Link

abili

ty

(%) 2

01225

Ave

rag

e A

SA

Gra

de

2012

Per

cent

age

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e P

atie

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2012

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rag

e A

ge

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erat

ion

2012

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cent

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of

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ated

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23 C

omp

lianc

e (N

HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

ubm

itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

ude

a va

lid p

atie

nt’s

NH

S n

umb

er c

omp

ared

with

the

num

ber

of p

roce

dur

es r

ecor

ded

on

the

NJR

.26

Out

liers

with

resp

ect t

o 90

-day

mor

talit

y fo

llow

ing

prim

ary

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atio

ns p

erfo

rmed

from

200

3 on

war

ds. U

nits

out

side

99.

8% c

ontr

ol li

mits

(app

rox

3 S

Ds)

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ged

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ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

27 O

utlie

rs w

ith re

spec

t to

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sion

s (a

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e) fo

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nits

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side

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ol li

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(app

rox

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Ds)

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ged

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ght r

ed (1

); th

ose

outs

ide

99.9

9% c

ontr

ol li

mits

are

flag

ged

in d

ark

red

(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

BM

I The

Chi

ltern

277

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56

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n N

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ath

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© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

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rd/C

ompa

ny

Com

plia

nce

(NH

S T

rust

/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

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ced

ures

20

12

No

. of

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nsul

tant

s 20

12

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nsen

t R

ate

(%) 2

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abili

ty

(%) 2

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Ave

rag

e A

SA

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de

2012

Per

cent

age

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e P

atie

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rag

e A

ge

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ion

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cent

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ated

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urgi

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re36

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87%

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Cro

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t Med

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100

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ce H

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149

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315

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th

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field

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lth B

rent

woo

d H

ospi

tal

9212

99%

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44%


Trus

t/Lo

cal H

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rd/C

ompa

ny

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plia

nce

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S T

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al

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nly)

23

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. of

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20

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No

. of

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s 20

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ty

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Per

cent

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23 C

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HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

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mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

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24 C

onse

nt R

ate

- p

erce

ntag

e of

cas

es s

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itted

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the

NJR

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pat

ient

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sent

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ed25

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kab

ility

- t

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rop

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ord

s w

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ared

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the

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ect t

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); th

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ide

99.9

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); th

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ide

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ged

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ark

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(2).

© N

atio

nal J

oint

Reg

istr

y 20

13

Nuf

field

Hea

lth B

right

on H

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idge

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he M

anor

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field

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lth T

unbr

idge

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ls

Hos

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83

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49%

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© N

atio

nal J

oint

Reg

istr

y 20

13

Trus

t/Lo

cal H

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Boa

rd/C

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Com

plia

nce

(NH

S T

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al

Hea

lth B

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nly)

23

Ho

spita

l

No

. of

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ced

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20

12

No

. of

Co

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s 20

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Co

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Per

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Trus

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rd/C

ompa

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nce

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23

Ho

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No

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ced

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20

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No

. of

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s 20

12

Co

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ate

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abili

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SA

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e P

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rag

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ion

2012

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cent

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ated

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23 C

omp

lianc

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HS

Tru

st/L

ocal

Hea

lth B

oard

Onl

y) -

the

per

cent

age

of c

ases

sub

mitt

ed t

o th

e N

JR c

omp

ared

to

HE

S/P

ED

W.

24 C

onse

nt R

ate

- p

erce

ntag

e of

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es s

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itted

to

the

NJR

with

pat

ient

con

sent

con

firm

ed25

Lin

kab

ility

- t

he p

rop

ortio

n of

rec

ord

s w

hich

incl

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a va

lid p

atie

nt’s

NH

S n

umb

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ared

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the

num

ber

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Out

liers

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resp

ect t

o 90

-day

mor

talit

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prim

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ns p

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rmed

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nits

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side

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rox

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ged

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ght r

ed (1

); th

ose

outs

ide

99.9

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ontr

ol li

mits

are

flag

ged

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ark

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(2).

27 O

utlie

rs w

ith re

spec

t to

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sion

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ark

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© N

atio

nal J

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Reg

istr

y 20

13©

Nat

iona

l Joi

nt R

egis

try

2012

Pine

hill

Hos

pita

l29

111

100%

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1.9

45%

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Ren

acre

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all H

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179

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55

92%

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49%

96%

Row

ley

Hal

l Hos

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56

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The

Ber

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2

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re G

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k H

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%



© N

atio

nal J

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Reg

istr

y 20

13

Trus

t/Lo

cal H

ealth

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rd/C

ompa

ny

Com

plia

nce

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S T

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/Loc

al

Hea

lth B

oard

O

nly)

23

Ho

spita

l

No

. of

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ced

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20

12

No

. of

Co

nsul

tant

s 20

12

Co

nsen

t R

ate

(%) 2

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Link

abili

ty

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Ave

rag

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de

2012

Per

cent

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atie

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rag

e A

ge

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Op

erat

ion

2012

Per

cent

age

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ated

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ced

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Glossary



A

Acetabular component The portion of a total hip replacement prosthesis that is inserted into the acetabulum - the socket part of a ball and socket joint.

Acetabular cup See Acetabular component.

Acetabular prosthesis See Acetabular component.

Antibiotic-loaded bone cement See cement.

Arthrodesis A procedure where the bones of a natural joint are fused together (stiffened).

Arthroplasty A procedure where a natural joint is reconstructed with an artificial prosthesis.

ABHI Association of British Healthcare Industries - the UK trade association of medical device suppliers.

ASA American Society of Anaesthesiologists scoring system for grading the overall physical condition of the patient, as follows:P1 – fit and healthy; P2 – mild disease, not incapacitating; P3 – incapacitating systemic disease; P4 – life threatening disease; P5 – expected to die within 24 hrs without an operation.

B

Bearing type The two surfaces that articulate together in a joint replacement. Options includemetal-on-polyethylene, metal-on-metal, ceramic-on-polyethylene, ceramic-on-metal and ceramic-on-ceramic.

Bilateral operation Operation performed on both sides, e.g. left and right knee procedures, carried out during a single operation.

BMI Body mass index. A statistical tool used to estimate a healthy body weight based on an individual’s height. The BMI is calculated by dividing a person’s weight (kg) by the square of their height (m2).

BOA British Orthopaedic Association - the professional body representing orthopaedic surgeons.

Bone cement See cement.

Brand (of prosthesis) The brand of a prosthesis (or implant) is the manufacturer's product name, e.g. the Exeter V40 brand for hips, the PFC Sigma brand for knees, the Mobility brand for ankles, the Delta Xtend brand for shoulders and the Coonrad Morrey for elbows.

C

CQC Care Quality Commission. Regulators of care provided by the NHS, local authorities, private companies and voluntary organisations.

Case ascertainment Proportion of all relevant joint replacement procedures performed in England and Wales that are entered into the NJR.

Case mix Term used to describe variation in surgical practice, relating to factors such as indications for surgery, patient age and gender.

Cement The material used to fix cemented joint replacements to bone - polymethyl methacrylate (PMMA). Antibiotic can be added to bone cement to try and reduce the risk of infection.

Cemented Prostheses designed to be fixed into the bone using cement.

Cementless Prostheses designed to be fixed into the bone by bony ingrowth or ongrowth, without using cement.

Compliance The percentage of all total joint procedures that have been entered into the NJR within any given period compared with the expected number of procedures performed. The expected number of procedures can be the number of levies returned, or for the NHS Sector only, the number of procedures submitted to HES and PEDW.

Competing risks survival analysis An alternative to standard survival analysis methods (such as Kaplan-Meier estimation or the Cox proportional hazards model) when there are competing risks. A competing risk can prevent the event of interest from occurring (in this case, death is a competing risk to the risk of revision as patients who die will never experience revision). A competing-risks survival analysis adjusts the results accordingly.

Confidence interval (CI) A confidence interval (CI) gives an estimated range of values which is likely to include the unknown population parameter (e.g. a revision rate) being estimated from the given sample. If independent samples are taken repeatedly from the same population, and a confidence interval calculated for each sample, then a certain percentage (confidence level: e.g. 95%) of the intervals will include the unknown population parameter.


Confounding Systematic variation due to the presence of factors not on the causal pathway, which affect the outcome, which are unequally distributed amongst interventions being compared which leads to inaccurate inferences about the results.

Cox proportional hazards model A semi-parametric survival analysis model commonly used to model time-to-event data as it does not require the underlying hazard function to take a particular shape. As it is a multi-variable model, it can be used to explore the effects of covariates on the outcome of interest and reduce the impact of confounding.

Cross-linked polyethylene See modified polyethylene.

Cumulative hazard An ‘accumulated’ hazard rate over time; the hazard rate at a particular point in time is the rate of occurrence of the event (revision or death) amongst those in whom the event has not yet occurred. Estimated using the Nelson-Aalen estimate.

Cup See Acetabular component.

D

Data collection periods for annual report analysis

The NJR Annual Report Part One reports on data collected between 1 April 2012 and 31 March 2013 – the 2012/13 financial year. The NJR Annual Report Parts Two and Four analyse data on hip, knee, ankle, elbow, and shoulder procedures undertaken between 1 January and 31 December 2012 inclusive – the 2012 calendar year. The NJR Annual Report Part Three reports on hip, knee and ankle joint replacement revision rates for procedures that took place between 1 April 2003 and 31 December 2012.

DDH Developmental dysplasia of the hip. A condition where the hip joint is malformed, usually with a shallow socket (acetabulum), which may cause instability.

DH Department of Health.

DVT Deep vein thrombosis. A blood clot that can form in the veins of the leg, and is recognised as a significant risk after joint replacement surgery.

E

Excision arthroplasty A procedure where the articular ends of the bones are simply excised, so that a gap is created between them, or when a joint replacement is removed and not replaced by another prosthesis.

F

Femoral component (hip) Part of a total hip joint that is inserted into the femur (thigh bone) of the patient. It normally consists of a stem and head (ball).

Femoral component (knee) Portion of a knee prosthesis that is used to replace the articulating surface of the femur (thigh bone).

Femoral head Spherical portion of the femoral component of the artificial hip replacement.

Femoral prosthesis Portion of a total joint replacement used to replace damaged parts of the femur (thigh bone).

Femoral stem The part of a modular femoral component inserted into the femur (thigh bone). Has a femoral head mounted on it to form the complete femoral component.

Flexible parametric proportional hazards model

Developed by Royston and Parmar, this model extends the standard Cox proportional hazards approach by modelling the baseline distribution parametrically using a restricted cubic spline function. This allows more flexibility in modelling the shape of the baseline hazard function than using standard parametric distributions.

Funnel plot A graph of a performance measure for each unit plotted against the unit’s number of cases. Control limits are shown to indicate acceptable performance.

G

Glenoid component The portion of a total shoulder replacement prosthesis that is inserted into the scapula – the socket part of a ball and socket joint in conventional shoulder replacement or the ball part in reverse shoulder replacement.

Glenoid head Domed head portion of the glenoid component of the reverse shoulder replacement attached to the scapula.



H

Head See Femoral head and/or Humeral head.

Healthcare provider NHS or independent sector organisation that provides healthcare; in the case of the NJR, orthopaedic hip, knee, ankle, elbow or shoulder replacement surgery.

HES Hospital Episode Statistics. Data on case mix, procedures, length of stay and other hospital statistics collected routinely by NHS hospitals in England.

HQIP Healthcare Quality Improvement Partnership. Manages the NJR on behalf of the Department of Health. Promotes quality in health and social care services and works to increase the impact that clinical audit has nationally.

Humeral component (elbow) Part of a total elbow joint that is inserted into the humerus (upper arm bone) of the patient to replace the articulating surface of the humerus.

Humeral component (shoulder) Part of a total or partial shoulder joint that is inserted into the humerus (upper arm bone) of the patient. It normally consists of a humeral stem and head (ball) in conventional shoulder replacement or a humeral stem and a humeral cup in a reverse shoulder replacement.

Humeral cup The shallow socket of a reverse shoulder replacement attached to the scapula.

Humeral head Domed head portion of the humeral component of the artificial shoulder replacement attached to the humeral stem.

Humeral prosthesis Portion of a total joint replacement used to replace damaged parts of the humerus (upper arm bone).

Humeral stem The part of a modular humeral component inserted into the humerus (upper arm bone). Has a humeral head or humeral cup mounted on it to form the complete humeral component.

Hybrid procedure Joint replacement procedure in which cement is used to fix one prosthetic component while the other is cementless. For hip procedures, the term hybrid covers both reverse hybrid (cementless stem, cemented socket) and hybrid (cemented stem, cementless socket).

I

Image/computer-guided surgery Surgery performed by the surgeon, using real-time images and data computed from these to assist alignment and positioning of prosthetic components.

Independent hospital A hospital managed by a commercial company that predominantly treats privately-funded patients but does also treat NHS-funded patients.

Index joint The primary joint replacement that is the subject of an NJR entry.

Indication (for surgery) The reason for surgery. The NJR system allows for more than one indication to be recorded.

ISTC Independent sector treatment centre (see Treatment centre).

K

Kaplan-Meier Estimates of the cumulative probability of failure (revision or death) that properly take into account ‘censored’ data. Censorings arise from incomplete follow up; for revision, for example, a patient may have died or reached the end the analysis period (end of 2012) without having been revised. The estimates do not adjust for any confounding factors.

L

Lateral resurfacing (elbow) Partial resurfacing of the elbow with a humeral surface replacement component used with a lateral resurfacing head inserted with or without cement.

Levy Additional payment placed on the sales of specific hip, knee, ankle, elbow, and shoulder implants to cover the costs associated with the ongoing operation and development of the NJR.

Linkable percentage Linkable percentage is the percentage of all relevant procedures that have been entered into the NJR, which may be linked via NHS number to other procedures performed on the same patient.

Linkable procedures Procedures entered into the NJR database that are linkable to a patient's previous or subsequent procedures by the patient's NHS number.

Linked total elbow Where the humeral and ulnar parts of a total elbow replacement are physically connected.


LHMoM Large head metal-on-metal. Where a metal femoral head of 36mm diameter or greater is used in conjunction with a femoral stem, and is articulating with either a metal resurfacing cup or a metal liner in a modular acetabular cup. Resurfacing hip replacements are excluded from this group.

LMWH Low molecular weight Heparin. A blood-thinning drug used in the prevention and treatment of deep vein thrombosis (DVT).

M

MDS Minimum dataset, the set of data fields collected by the NJR. Some of the data fields are mandatory (i.e. they must be filled in). Fields that relate to patients' personal details must only be completed where informed patient consent has been obtained.

MDS 1 (MDSv1) Minimum dataset version one, used to collect data from 1 April 2003. MDS 1 closed to new data entry on 1 April 2005.

MDS 2 (MDSv2) Minimum dataset version two, introduced on 1 April 2004. MDS 2 replaced MDS 1 as the official data set on 1 June 2004.

MDS 3 (MDSv3) Minimum dataset version three, introduced on 1 November 2007 replacing MDS 2 as the new official data set.

MDS 4 (MDSv4) Minimum dataset version four, introduced on 1 April 2010 replacing MDS 3 as the new official dataset. This dataset has the same hip and knee MDS 3 dataset but includes the data collection for total ankle replacement procedures.

MDS 5 (MDSv5) Minimum dataset version five, introduced on 1 April 2012 replacing MDS 4 as the new official dataset. This dataset has the same hip, knee and ankle MDS 4 dataset but includes the data collection for total elbow and total shoulder replacement procedures.

MHRA Medicines and Healthcare products Regulatory Agency – the UK regulatory body for medical devices.

Minimally-invasive surgery Surgery performed using small incisions (usually less than 1Ocm). This may require the use of special instruments.

Mixing and matching Also known as 'cross breeding'. Hip replacement procedure in which a surgeon chooses to implant a femoral component from one manufacturer with an acetabular component from another.

Modified Polyethylene Any component made of polyethylene which has been modified in some way in order to improve its performance characteristics. Some of these processes involve chemical changes, such as increasing the cross-linking of the polymer chains or the addition of vitamin E and/or other antioxidants . Others are physical processes such as heat pressing or irradiation in a vacuum or inert gas.

Modular Component composed of more than one piece, e.g. a modular acetabular cup shell component with a modular cup liner, or femoral stem coupled with a femoral head.

Monobloc Component composed of, or supplied as, one piece, e.g. a monobloc knee tibial component.

N

Nelson-Aalen estimator An estimate of the cumulative hazard rate.

NHS National Health Service.

NICE National Institute for Health and Care Excellence.

NICE benchmark See ODEP ratings.

NJR National Joint Registry for England, Wales and Northern Ireland. The NJR has collected and analysed data on hip and knee replacements since 1 April 2003, on ankle replacements since 1 April 2010 and on elbow replacements and shoulder replacements since April 2012. It covers both the NHS and independent healthcare sectors to ensure complete recording of national activity in England, Wales and Northern Ireland.

NJR Centre National coordinating centre for the NJR.

NJR StatsOnline Web facility for viewing and downloading NJR statistics on www.njrcentre.org.uk

O

ODEP Orthopaedic Data Evaluation Panel of the NHS Supply Chain. www.odep.org.uk



ODEP ratings ODEP ratings are the criteria for product categorisation of prostheses for primary total hip replacement against benchmarks. The letter represents the strength of evidence and the number the length of time in years during which the implant has been studied. The full benchmark is 10A and the entry is at 3 years with progression through 5 and 7 years. Pre-entry submissions are also recorded. “A” represents strong supporting evidence for the use of the prosthesis, “B” less strong but acceptable evidence. All implants that are used without a 10-year benchmark should be followed up closely.

OPCS-4 Office of Population, Censuses and Surveys: Classification of Surgical Operations and Procedures, 4th Revision – a list of surgical procedures and codes.

Outlier Data for a surgeon, unit or implant brand that falls outside of the defined control limits.

P

Pantalar (ankle) Affecting the whole talus, i.e. the ankle (tibio talar) joint, the subtalar (talo calcaneal) joint and the talonavicular joint.

Patella resurfacing Replacement of the surface of the patella (knee cap) with a prosthesis.

Patello-femoral knee Procedure involving replacement of the trochlear and replacement resurfacing of the patella.

Patello-femoral prosthesis Two-piece knee prosthesis that provides a prosthetic (knee) articulation surface between the patella and trochlear.

Patient consent Patient personal details may only be submitted to the NJR where explicit informed patient consent has been given or where patient consent has not been recorded. If a patient declines to give consent, only the anonymous operation and implant data may be submitted.

Patient physical status See ASA.

Patient procedure Type of procedure carried out on a patient, e.g. primary total prosthetic replacement using cement.

Patient-time The summation of time (in years) for a cohort of primary procedures where the time is measured from the primary date to either date of revision, date of patient's death or analysis date (last observation date).

PDS The NHS Personal Demographics Service is the national electronic database of NHS patient demographic details. The NJR uses the PDS Demographic Batch Service (DBS) to source missing NHS numbers and to determine when patients recorded on the NJR have died.

PEDW Patient Episode Database for Wales. The Welsh equivalent to Hospital Episode Statistics (HES) in England.

Poisson distribution This distribution expresses the probability of a number of relatively rare events occurring in a fixed time if these events occur with a known average rate and are independent of the time since the last event. It is a special case of the binomial distribution in that it models discrete events.

Primary hip/knee/ankle/elbow/shoulder replacement

The first time a total joint replacement operation is performed on any individual joint in a patient.

Prosthesis Orthopaedic implant used in joint replacement procedures, e.g. a total hip, a unicondylar knee, a total ankle, a reverse shoulder or a radial head replacement.

PROMs Patient Reported Outcome Measures.

PTIR Patient-Time Incidence Rate. This is the rate of occurrences of an event (i.e. revision) for a given total time at risk.

R

Radial head component (elbow) Part of a partial elbow joint that is inserted into the radius (outer lower arm bone) of the patient to replace the articulating surface of the radial head. May be monobloc or modular.

Resurfacing (hip) Resurfacing of the femoral head with a surface replacement femoral prosthesis and insertion of a monobloc acetabular cup, with or without cement.

Resurfacing (shoulder) Resurfacing of the humeral head with a surface replacement humeral prosthesis inserted, with or without cement.

Reverse shoulder replacement Replacement of the shoulder joint where a glenoid head is attached to the scapula and the humeral cup to the humerus.

Revision burden The proportion of revision procedures carried out as a percentage of the total number of surgeries on that particular joint.

Revision hip/knee/ankle/elbow/shoulder replacement

Operation performed to remove (and usually replace) one or more components of a total joint prosthesis for whatever reason.


S

Shoulder hemiarthroplasty Replacement of the humeral head with a humeral stem and head or shoulder resurfacing component which articulates with the natural glenoid.

Single-stage revision A revision carried out in a single operation.

Subtalar joint (ankle) The joint between the talus and the calcaneum.

Surgical approach Method used by a surgeon to gain access to, and expose, the joint.

Survivorship analysis A statistical method that is used to determine what fraction of a population, such as those who have had a particular hip implant, has survived unrevised past a certain time. See Kaplan-Meier.

T

Talar component Portion of an ankle prosthesis that is used to replace the articulating surface of the talus at the ankle joint.

TAR Total ankle replacement (total ankle arthroplasty). Replacement of both tibial and talar surfaces, with or without cement.

TED stockings Thrombo embolus deterrent (TED) stockings. Elasticised stockings that can be worn by patients following surgery and which may help reduce the risk of deep vein thrombosis (DVT).

THR Total hip replacement (total hip arthroplasty). Replacement of the femoral head with a stemmed femoral prosthesis and insertion of an acetabular cup, with or without cement.

Thromboprophylaxis Drug or other post-operative regime prescribed to patients with the aim of preventing blood clot formation, usually deep vein thrombosis (DVT), in the post-operative period.

Tibial component (knee) Portion of a knee prosthesis that is used to replace the articulating surface of the tibia (shin bone) at the knee joint. May be modular or monobloc (one piece).

Tibial component (ankle) Portion of an ankle prosthesis that is used to replace the articulating surface of the tibia (shin bone) at the ankle joint.

TKR Total knee replacement (total knee arthroplasty). Replacement of both tibial and femoral condyles (with or without resurfacing of the patella), with or without cement.

Total condylar knee Type of knee prosthesis that replaces the complete contact area between the femur and the tibia of a patient’s knee.

Treatment centre Treatment centres are dedicated units that offer elective and short-stay surgery and diagnostic procedures in specialties such as ophthalmology, orthopaedic and other conditions. These include hip, knee, ankle, elbow, and shoulder replacements. Treatment centres may be privately funded (independent sector treatment centre – ISTC). NHS Treatment Centres exist but their data is included in those of the English NHS Trusts and Welsh Local Health Boards to which they are attached.

Trochanter Bony protuberance of the femur, found on its upper outer aspect.

Trochanteric osteotomy Temporary incision of the trochanter, used to aid exposure of hip joint during some types of total hip replacement.

Two-stage revision A revision procedure carried out as two operations, often used in the treatment of deep infection.

Type (of prosthesis) Type of prosthesis is the generic description of a prosthesis, e.g. modular cemented stem (hip), patello-femoral joint (knee), talar component (ankle), reverse shoulder (shoulder) and radial head replacement (elbow).

U

Ulnar component (elbow) Part of a total elbow joint that is inserted into the ulna (inner lower arm bone) of the patient to replace the articulating surface of the ulna. May be linked or unlinked.

Uncemented See cementless.

Unicondylar arthroplasty Replacement of one tibial condyle and one femoral condyle in the knee, with or without resurfacing of the patella.

Unicondylar knee replacement See Unicondylar arthroplasty.

Unilateral operation Operation performed on one side only, e.g. left hip.

Unlinked total elbow Where the humeral and ulnar parts of a total elbow replacement are not physically connected.



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