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Why TKR Fails: Revision Total Knee Replacement Basic Principles

Dr.Sandeep Agrawal Agrasen Hospital Gondia Maharashtra India drsandeep123@gmail.com

Why Knees Fail

1. Infection 2. Extensor lag 3. Stiffness 4. Tibio-Femoral Instability (Collateral Lig. Incompetence) 5. Fracture 6. Loose of femur or tibia (or progression of disease in uni knee) 7. Patella instability & Malrotation 8. Breakage 9. Pain- No Diagnosis

Why Knees Fail

Infection !Standard work up including bloods, aspiration, nuclear scans !Two - Stage Revision

Why Knees Fail

Extensor lag !Quads rupture probably best treated with allograft. !If superimposed infection may need an arthrodesis

Why Knees Fail

Stiffness Global Flexion contracture Poor flexion !Need to address Quads scarring and balance Flex & Ext gaps

Why Knees FailTibio-Femoral Instability If ligaments are present, they must be correctly tensioned and balanced by choosing the correct prosthesis size and positioning it correctly. In many cases, constraint will not be necessary. If the ligaments have failed, a constrained implant still needs perfect alignment

Why Knees Fail

Fracture !Commonly of the femur in the supracondylar region. Risk factors include:

i) osteopenic bone, ii) a notch in the anterior femoral cortex, iii) poor flexion.

!Can be successfully reconstructed with refined techniques of internal fixation. !In others, however, the bone quality is so poor that revision knee arthroplasty with distal femoral allograft or prosthetic replacement is essential.

Why Knees Fail

Loose femur or tibia !Radiolucencies Subsidence progression of disease in uni knee

Why Knees Fail

Patella instability & Malrotation

Why Knees Fail

8. Breakage !!9. Pain- No Diagnosis

Principles of Revision

1. Diagnosis 2. Revise… don’t repeat 3. Use Revision Implants 4. Complete Revision 5. Couple tibia to femur 6. Medullary Fixation 7. Control Alignment

3 Step Technique1.Tibial platform !2. Knee in Flexion: Femoral rotation !B. Femoral component size !C. Joint line !3. Knee in extension

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Couple the tibia & femur !

Soft tissues !

Is constraint required?

ExposureAttention to detail !• Synovectomy • Re-establish gutters • Lateral retinacular release • Liberate quads from femur • Gentle manipulation • Quads split

Removal

1. Oscillating saw 2. Reciprocating saw 3. Stacked osteotomes

Implantation

!Tibial with stems. !Knee in Flexion

A. Femoral rotation B. Femoral component size C. Joint line

!Knee in extension (tension ligaments)

Step 1

Re-establish Tibial Platform

Step 2:

Stabilize Knee in Flexion !Rotation: Transepicondylar axis !B. Stability: Femoral component size !C. Joint Line: Inferior pole patella

Femoral Componentsizing

Implant to restore ligaments (LCCK)

Extension Gap position

Flexion Gap Size

Femur controls the soft tissues

Femoral Componentsizing

• Augments to fit bone

Joint Line :Inferior pole patella above Joint Line

Step 3

Stabilize in Extension Distal defect defined

Constraint!!Constraint should only be used in revision total knee arthroplasty after the principles of extension, flexion gap and medial and lateral collateral ligament balancing are performed.

Constraint

!As little constraint as possible should be used. !If stability cannot be obtained progressive levels of constraint should be tested and used in the revision construct.

Constraint

!If there is functional loss of the medial or lateral collateral ligament or if there is an inability to balance the flexion or extension gap, a constraining condylar device that provides varus valgus stability should be used.

Rotating Hinge

!!Rotating hinged implant should be considered when both collateral ligaments are incompetent because of massive femoral bone loss and in the elderly patient with genu recurvatum

95% BW is loaded through the condyles

BW load does not shift posteriorly through full ROM

Shear forces are reduced with rotation platform

Dislocation !“RHK designs with a short,tapered central rotating stem should be used with caution in patients with bone and soft tissue compromise that may allow excessive distraction and implant dislocation.” (JBJS March 2003)

LEARNING MESSAGE

Establish the cause for failure Have revision implants Adequate exposure and removal Build the knee from the Tibia Femur controls tissue tension and joint line Use more constraint if needed Rotating Hinge for gross instabilty and bone loss

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