Title: Diagnosis of Periprosthetic Joint
Liaisons: Benjamin Zmistowski BS
Leaders: Craig Della Valle MD (US), Thomas W Bauer MD (US), Konstantinos N. Malizos MD,PhD (International)
Delegates: Abbas Alavi MD, Hani Bedair MD, Robert E Booth MD, Peter Choong MD, Carl Deirmengian MD, Garth D Ehrlich PhD, Anil Gambir MD, Ronald Huang MD, Yair Kissin MD, Hideo Kobayashi MD, Naomi Kobayashi MD, Veit Krenn MD, Drago Lorenzo MD, SB Marston MD, Geert Meermans MD, Javier Perez MD, JJ Ploegmakers MD, Aaron Rosenberg MD, C Simpfendorfer MD, Peter Thomas MD, Stephan Tohtz MD, Jorge A Villafuerte MD, Peter Wahl MD, Frank-Christiaan Wagenaar MD, Eivind Witzo MD
Vol 1, Num S1, September 2014
Question 1A: What is the definition of periprosthetic joint infection (PJI)?
Consensus: PJI is defined as: * Two positive periprosthetic cultures with phenotypically identical organisms, or * A sinus tract communicating with the joint, or * Having three of the following minor criteria: - Elevated serum C-reactive protein (CRP) AND erythrocyte sedimentation rate (ESR) - Elevated synovial fluid white blood cell (WBC) count OR ++change on leukocyte esterase test strip - Elevated synovial fluid polymorphonuclear neutrophil percentage (PMN%) - Positive histological analysis of periprosthetic tissue - A single positive culture
Delegate Vote: Agree: 85%, Disagree: 13%, Abstain: 2% (Strong Consensus)
Question 1B: What are some considerations for the definition of PJI?
Consensus: Clinically, PJI may be present without meeting these criteria, specifically in the case of less virulent organisms (eg P. acnes). Synovial leukocyte esterase can be performed as a rapid office or intraoperative point of care test using urinalysis strips. In the case of a bloody aspiration, centrifugation has been shown to preserve the accuracy of the colorimetric test for leukocyte esterase.
Delegate Vote: Agree: 76%, Disagree: 14%, Abstain: 10% (Strong Consensus)
Question 2: Do you agree with the American Academy of Orthopaedic Surgeons's (AAOS) algorithm for diagnosis of PJI?
Consensus: The following is an adaptation of the AAOS's algorithm for the diagnosis of PJI. This algorithm should be applied to patients who present with a painful or failed arthroplasty.
Delegate Vote: Agree: 91%, Disagree: 0%, Abstain: 9% (Strong Consensus)
Considerations: Clinical judgment should not be outweighed by use of the diagnostic algorithm or any one individual test. A preoperative aseptic diagnosis using this algorithm should not eliminate suspicion for PJI. Patients should be considered to have a higher probability of infection if they have a history of persistent pain or stiffness and any of the following: Recent bacteremia, Multiple surgeries on the same joint, History of periprosthetic joint infection, Comorbidities predisposing patients to an immunocompromised state, eg diabetes mellitus, inflammatory arthropathy, or malnourishment, Factors that increase risk of skin barrier penetration, eg intravenous drug use, poor wound conditions, psoriasis, chronic venous stasis, or skin ulceration, Superficial surgical site infection related to the joint. Physical exam findings suggestive of PJI: Wound dehiscence, or Joint warmth, redness, or swelling Plain radiographic signs suggestive of PJI: Signs of loosening of previously well-fixed components (particularly loosening seen within the first 5 years postoperatively), Osteolysis or bone resorption around the prosthetic components should not be considered to be related to wear of the bearing surface, particularly if seen at less than 5 years post-operatively, Subperiosteal elevation, or Transcortical sinus tracts. It is important to note that plain radiographs are generally normal in the setting of PJI.
Question 3A: What should the threshold be for ESR, serum CRP, PMN%, and WBC count for ACUTE PJI?
Consensus: The approximate cutoffs listed below apply to tests obtained fewer than 6 weeks from the most recent surgery: No threshold for ESR could be determined as it is not useful in diagnosis of acute PJI. CRP > 100 mg/L (knee and hip), Synovial WBC count>10,000 cells/μL, and Synovial PMN%>90%.
Delegate Vote: Agree: 81%, Disagree: 12%, Abstain: 7% (Strong Consensus)
Question 3B: What should the threshold be for ESR, serum CRP, PMN%, and WBC count for CHRONIC PJI?
Consensus: The approximate cutoffs listed below apply to tests obtained more than 6 weeks from the most recent surgery: ESR > 30 mm/hr, CRP > 10 mg/L, Synovial WBC count > 3,000 cells per μL, and Synovial PMN% > 80%.
Delegate Vote: Agree: 81%, Disagree: 14%, Abstain: 5% (Strong Consensus)
Question 3C: What should the threshold be for ESR, serum CRP, PMN%, and WBC count for PJI in inflammatory arthropathies?
Consensus: Based upon very limited evidence, we recommend no change from the above thresholds for ESR, serum CRP, PMN%, and WBC count for PJI diagnosis in patients who have underlying inflammatory arthopathies. However, further research is needed to confirm this statement.
Delegate Vote: Agree: 87%, Disagree: 9%, Abstain: 4% (Strong Consensus)
Question 4: In analyzing synovial fluid cell count, what are important techniques to minimize variation?
Consensus: To accurately analyze synovial fluid cell count we recommend that (1) synovial fluid WBC count results be transformed using the synovial red blood cell (RBC), serum RBC, and serum WBC concentrations to adjust for traumatic aspirations and (2) in joints with metal-on-metal components a manual WBC analysis should be performed.
Delegate Vote: Agree: 92%, Disagree: 1%, Abstain: 7%.
Question 5: How long should routine cultures be kept?
Consensus: We recommend that routine cultures should be maintained between 5 and 14 days. In cases of suspected PJI with low virulence organisms or if preoperative cultures have failed to show bacterial growth and the clinical picture is consistent with PJI (suspected culture-negative PJI) the cultures should be maintained for 14 days or longer.
Delegate Vote: Agree: 93%, Disagree: 5%, Abstain: 2%.
Question 6A: Is there a role for routine acid-fast bacillus (AFB) and fungal testing in suspected PJI?
Consensus: In proven or suspected PJI, AFB and fungal cultures should be limited to those patients at risk for such infections or when other traditional pathogens have not been identified and clinical suspicion persists.
Delegate Vote: Agree: 92%, Disagree: 6%, Abstain: 1% (Strong Consensus)
Question 6B: Is there a role for routine AFB and fungal testing in suspected aseptic failure?
Consensus: No. AFB and fungal cultures do not play a role in presumed aseptic cases (eg cases where a synovial fluid WBC count and differential performed preoperatively were not suggestive of infection).
Delegate Vote: Agree: 91%, Disagree: 7%, Abstain: 2% (Strong Consensus)
Question 7A: How many intraoperative tissue samples should be sent for culture in suspected PJI cases and cases of suspected aseptic failure?
Consensus: In most revision procedures, more than 3 but not more than 6 distinct intraoperative tissue samples should be sent for aerobic and anaerobic culture.
Delegate Vote: Agree: 88%, Disagree: 10%, Abstain: 2% (Strong Consensus)
Question 7B: How should culture samples be obtained?
Consensus: Tissue or fluid samples from representative area should be taken, preferably from the interface, each sample taken with an unused instrument. We strongly recommend against swab cultures from wound or periarticular tissues.
Delegate Vote: Agree: 97%, Disagree: 2%, Abstain: 1% (Strong Consensus)
Question 7C: Should antibiotic be withheld prior to obtaining samples for culture in all cases?
Consensus: No. Perioperative prophylactic antibiotics should be withheld only in cases with a high suspicion for PJI in which an infecting organism has not been isolated.
Delegate Vote: Agree: 87%, Disagree: 12%, Abstain: 1% (Strong Consensus)
Question 8: Is there a role for routine sonication of the prosthesis? If so, in which group of patients should this be done?
Consensus: No. We do not recommend routine sonication of explants. Its use should be limited to cases of suspected or proven PJI (based upon presentation and other testing) in which preoperative aspiration does not yield positive culture and antibiotics have been administered within the previous 2 weeks.
Delegate Vote: Agree: 84%, Disagree: 9%, Abstain: 7% (Strong Consensus)
Question 9: Is there a role for molecular techniques such as polymerase chain reaction (PCR) for diagnosis of PJI? If so, in which group of patients should this be done?
Consensus: Nucleic acid based testing is not currently a recommended routine diagnostic test for PJI. In cases with high clinical suspicion of infection but negative cultures or other diagnostic tests, molecular techniques with or without sonication may help identify the unknown pathogens or antibiotic sensitivity for targeting antimicrobial therapies.
Delegate Vote: Agree: 96%, Disagree: 3%, Abstain: 1% (Strong Consensus)
Question 10: Is there a role for imaging modalities in the diagnosis of PJI?
Consensus: Plain radiographs should be performed in all cases of suspected PJI. Magnetic resonance imaging (MRI), computed tomography (CT), and nuclear imaging currently DO NOT have a direct role in the diagnosis of PJI but may be helpful in the identification of other causes of joint pain/failure.
Delegate Vote: Agree: 93%, Disagree: 7%, Abstain: 0% (Strong Consensus)