Diagnosis of Infected total knee arthroplasty

Warakorn Jingjit, MDOrthopaedic Department, Faculty of Medicine

Chiang Mai University

One of the most devastating & challenging complication

Immense financial & psychological burden

Cost of treatment 15,000 - 60,000 $ / TKA

Hebert CK, CORR, 1996Sculco TP, Orthopedics, 1995

Incidence

• 0.39% in primary TKA

• 0.97% in revision TKA

Kurtz S, JBJS, 2008

Projection of the TKA & THA number

Kurtz S, JBJS, 2007

Projection of the TKA & THA infection

Risk factors

1. Patient / host 2. Surgical environment3. Surgical technique4. Postoperative management

Risk factorsPatient / host• Immunocompromise

– RA (4.4%)– Steroid therapy– DM (7%)– Poor nutrition• Albumin <3.5g/dl: 7-fold• Lymphocyte <1,500 cells/mm3: 5-fold– HIV– Organ transplant

• Hypokalemia• Tobacco use• Obesity

• Debilitation– Advanced age– Alcoholism– Renal failure– Cirrhosis– Prolonged pre-op

hospitalization• Hypothyroidism• Previous surgery• Psoriasis• Previous infection• Concurrent infection

Risk factorsSurgical environment• Personnel• Clean air

Laminar air flow, UV light• Surgical attire• Operative site preparation

Ritter MA, CORR,1988Ritter MA, Orthop Clin North Am,1989

Berg M, JBJS (Br), 1991Ritter MA, CORR, 1999

Peersman G, CORR, 2001

Risk factorsSurgical technique

• Operative time > 2.5 hrs

Peersman, CORR, 2001

Surgical time

Risk factorsSurgical technique

Single most effective method of ↓ infection 1st gen. cephalosporin Allergy vancomycin / clindamycin 30-60 min before incision

(peak serum bone conc. within 20 min) Repeat every 4 hrs & bleed >1,000 ml Discontinue 24 hrs after surgery

Prophylactic antibiotic

Risk factorsSurgical technique

• High risk 1o TKA, revision TKA

Prophylactic antibiotic bone cement

Risk factors

• Hinged prosthesis• Infection rate at 10 yrs ~ 15%

• Bengtson S, Acta Orthop Scand, 1991• Hanssen AD, CORR, 1995

• Schoifet SD, JBJS, 1990

ImplantSurgical technique

Post operative management• Bacteremia: oral > GI > GU procedure • Avoid in first 3-6 mo (high incidence)AAOS & ADA 1997• First 2 yrs, specific risk factor for all pts ATB prophylaxis• After 2 yrs consider in high risk ptsRecommended regimens (before procedure 1 hr)• Cephalexin, cephradine, amoxicillin 2 g. oral • Cephalosporin 1 g / ampicillin 2 gm IV / IM • Clindamycin 600 mg oral (allergy to penicillin)• Clindamycin 600 mg IV / IM (allergy to penicillin)

Risk factors

Advisory statement. J Am Dent Assoc, 1997

Potential risks of hematojenous total joint infection

• All patients for the first 2 years after joint replacement• lmmunocompromised / immunosuppressed patients

- Inflammatory arthropathies - Drug-induced immunosuppression- Rheumatoid arthritis - Radiation-induced immunosuppression- Systemic lupus erythematosus

• Patients with comorbidity conditions - Previous prosthetic joint infections - HIV infection- Poor nutrition - Insulin-dependent diabetes- Hemophilia - Malignancy

Advisory statement. J Am Dent Assoc, 1997

Predominant organisms

Microbiology

Goldman RT, CORR, 1996

Microbiology

• Fungal infection = rare

Candida = predominant

• Mycobacterium tuberculosis = rare

Microbiology

• Mucopolysaccharide biofilm• Protect from antibodies, phagocytes, ATB., • ↑ virulence

Microbiology

• Methicillin-resistant organism vancomycin

Ries MD, J Arthroplasty, 2001

• Rifampicin = good biofilm & tissue penetration

improve success when use ĉ other synergistic agent

Zimmerli W, JAMA, 1998

Differential diagnosis

• Periprosthetic fx• PF problem• Aseptic loosening• Soft tissue disruption

A painful knee is infected until proved otherwise

Insall, 1981

• Instability• RSD• HO• Arthrofibrosis

Clinical history Physical examination Radiography Hematologic studies

Radionuclide studies

Aspiration

DiagnosisFundamental of diagnosis

* * * High index of suspicion * * *

Pathology

Diagnosis

History• Pain = most common presenting symptom• Typical = rest / night / persistent / progressive pain• Progressive stiffness• Hx of prolong postop drainage, ATB treatment Physical examination

• Swelling, effusion, warmth, erythema, tenderness• Painful range of motion• Persistent wound drainage

strongly suggestion early aggressive Rx

Diagnosis

• Swab wound not recommend

• Empirical ABO for wound drainage mask symptoms, affect subsequent C/S, predispose for drug resistant

• Diagnosis in early postop period – ESR, CRP limit value – Typically by arthrocentesis

Aspiration• Leucocyte count & differentiation • Gram strain (sens 97%, spec 26%) (• Culture for aerobic & anarobic bacteria

>1,700/ml3, PMN > 65% (sens 94-97%, spec 88-98%)Trampuz A, Am J Med, 2004

• Ongoing ATB stop for several wks before aspiration

Mark Coventry Award Paper

“Synovial WBC count is an excellent test for diagnosing infection within 6 wks after 1oTKA

with an optimal cut-off 27,800 cells/mm3 and 89% PMN”

Sens 84%, spec 99%, PPV 94%, NPV 98%

Craig J. Della VallePresented at the Knee Society Specialty Day Meeting

March 13, 2010, New Orleans

Diagnosis of early post-operative infection following TKA: The utility of synovial fluid cell count and differential

Hematologic studiesESR

– Positive > 30 mm/hr (sens 80%, spec 62.5% )– False positive: infection elsewhere, inflammation,

CNT dis, neoplasm, recent operation (< 3 mo)– False negative: prior antibiotics

CRP– Positive > 10 mg/L (sens & spec 85%)– Return to normal within 3 wks after operation

ESR + CRP: PPV 83%, NPV 100%

For chronic infection

Barrack RL, CORR, 1997Swanson KC, The adult knee, 2003

Guideline for ESR & CRP

1. Normal ESR & CRP reliable for the absence of infection

2. CRP more useful than ESR for monitoring

3. Use with other tests for the diagnosis of infection

Spangehl MJ, JBJS, 1999

PCR

• Molecular genetic diagnosis• Identify 16S RNA gene• Expensive• Time-dependent• False positive

Remain experimental modality !!!

Mariani BD, CORR, 1996

X-ray

Sequential plain radiographs• Progressive radiolucencies• Focal osteopenia / osteolysis of subchondral bone• Periosteal new bone formation

Morrey BF, CORR, 1989

• Bone destruction – infection present > 10-21 days• Lytic lesion – destroy 30-50% of bony matrix

Early infection – no abnormal finding !!!

Radioisotope scan

Occasionally helpful in chronic infection

• Tc-99m MDP• In-111 leukocyte scan• Tc-99m sulfur colloid

Radioisotope scan

Isotope Sensitivity Specificity Accuracy

Tc 99m 95% 20% 54%

Indium 111 77% 75% 90%

Tc 99m + In111 100% 97% 97%

Palestro CJ, Radiology, 1991

Occasionally helpful in chronic infection

Intraoperative tissue frozen section

• Widely use• Result depend onAdequate & representative tissue obtainingAccurate interpretation by skilled pathologist

> 5 PMN/HPF at least 5 fields Sens 100%, spec 96%

>10 PMN/HPF at least 5 fields Sens 25%, spec 98%

Feldman DS, JBJS, 1995Della Valle CJ, JBJS 1999

Reliable predictor for infection

• >10 PMN/HPF: sens 84%, spec 99%, PPV 89%, NPV 98%• 5-10 PMN/HPF: need other test to differentiate• <5 PMN/HPF: infection was highly unlikely

Lonner Jh et al, JBJS,1996

Intraoperative tissue frozen section

Intraoperative gram strain

• Unreliable• Low sensitivity = 0-14.7%

Atkins BL, J Clin Microbiol, 1998Della Valle CJ, J Arthroplasty, 1999

Intraoperative culture

Gold standardSample: fluid & tissue

Joint capsule Synovial lining IM tissue Granulation tissue Bone fragments

• False +ve: contamination• False -ve: prior ATB, transport system, lab

- Duff GP, CORR, 1996 - Bauer TW, JBJS, 2006

Definite diagnosis

At least one of the following

1. Same organism from c/s ≥ 2 specimens by aspiration / deep tissue from surgery

2. Intraarticular tissue histopathology = acute inflammation3. Gross purulence at the time of surgery4. Actively discharging sinus tract

Hansen, CORR, 1994

At least one of the following

1. Open wound / sinus tract communicate ĉ joint2. Systemic signs / symptoms ĉ pain & purulent fluid3. At least 3 of 5 ESR > 30 mm/hr CRP >10 mg/L Frozen section > 5 PMN/HPF Preoperative aspiration c/s ≥ 1 +ve Intraoperative c/s ≥ 1 +ve

Spangehl MJ, JBJS, 1999

Definite diagnosis

Type1 Type2 Type3 Type4

Timing Positive intraop C/S

Early postoperative

infection

Acute hematogenous

infection

Late (chronic)infection

Definition Same organism

≥2 from C/S

Occurring within first month after

surgery

Hematogenousseeding of previously

well-functioning prosthesis

Chronic indolent

clinical course; present >1

month

Segawa &Tsukayama classification

* * * Guide to treatment * * *

“Classify on the basis of clinical presentation”

Basic treatment options

1. Antibiotic suppression2. Debridement ĉ prosthesis retention3. Resection arthroplasty4. Arthrodesis5. Amputation6. Reimplantation - one / two stage

Treatment