How accurate are orthopedic surgeons in diagnosing periprosthetic joint infection after total knee arthroplasty?: A multicenter study

•Only two-third of PJI cases met the new definition for PJI proposed by MSIS.•One-third of PJI cases were diagnosed based on clinical suspicion.•Joint aspiration or histological analysis was not performed in a large number of patients.•Surgeons should perform joint fluid and histologic analysis to assure the accuracy of PJI diagnosis.

BackgroundThe lack of standardized diagnostic criteria for periprosthetic joint infection (PJI) poses a challenge to accurate diagnosis of PJI. Recently, the Musculoskeletal Infection Society (MSIS) proposed diagnostic criteria for PJI. However, it is not known how well these proposed criteria accommodate real clinical scenarios. We determined what proportion of patients satisfied the MSIS criteria, and if MSIS criteria were not met, what other rationales were used to diagnose PJI.MethodsWe retrospectively reviewed the records of 303 patients who underwent two-stage exchange arthroplasty for treatment of PJI of the knee at 17 institutions. The rationale for making the diagnosis of PJI was also recorded, if the case did not meet the MSIS criteria. In addition, detailed information about isolated microorganisms were gathered.ResultsAmong the 303 patients, 198 met the diagnostic criteria proposed by MSIS. Among the 105 patients who did not meet the MSIS criteria, 88% met two or three minor criteria; however joint fluid analysis or histologic analysis was not performed in 85% of these 105 patients. The most common rationale for the diagnosis of PJI was the presence of abnormal physical findings. Microorganisms were identified in only 52% of all patients; the most common organism was coagulase-negative Staphylococcus.ConclusionsThe diagnosis of PJI was based on clinical suspicion in approximately one-third of cases. In this series, joint aspiration or histological analysis was not performed in a large number of patients. Thus, surgeons should perform joint fluid and histologic analysis to assure the accuracy of PJI diagnosis.