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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
Recommended