Significant differences in the rate of periprosthetic joint infections in revision hip and knee arthroplasty depending on the applied definition

Background

Differentiating periprosthetic joint infections (PJI) from aseptic failure is challenging in total joint arthroplasty. To date, there is no consensus about the most accurate criteria to diagnose PJI. The current study compares common diagnostic PJI criteria.

Methods

256 total hip and knee arthroplasties that underwent revision surgery between 2017 and 2022 were retrospectively classified as PJI or non PJI according to the following definitions: 2011 Musculoskeletal Infections Society (MSIS), 2013 Infectious Disease Society of America (IDSA), 2018 updated MSIS-criteria (MSIS-18), 2018 International Consensus Meeting on Periprosthetic Joint Infections (ICM), 2021 European Bone and Joint Infections Society (EBJIS), Pro-Implant Foundation, and the surgeons’ assessment at the time of surgery. Accuracy, sensitivity, specificity, and predictive values were calculated with reference to (1) microbiological culture results, (2) MSIS-criteria, and (3) the surgeons’ diagnosis. Results were compared between hip- and knee arthroplasties using Fisher’s Exact- or Chi-square test, outcomes were compared between two criteria using Pearson correlation.

Results

PJI was diagnosed in 47.7% of cases applying MSIS-criteria, 49.2% for IDSA-criteria, 52.3% for MSIS-18 criteria, 55.5% for ICM-criteria, 62.1% for EBJIS-criteria, 67.2% for Pro-Implant-criteria, and 55.1% according to the surgeons’ judgment. Pro-Implant-criteria showed the lowest concordance with microbiological cultures and a rate of 35.5% culture negative infections. ICM- and MSIS-18-criteria showed best concordance with the surgeons’ diagnosis.

Conclusion

The current study showed that the diagnosis of PJI is highly dependent on the applied diagnostic criteria. EBJIS- and Pro-Implant-criteria classified more cases as PJI compared to other diagnostic criteria. Care should be taken to avoid overdiagnosis and overtreatment, especially if low synovial white blood cell thresholds are applied as definite criteria to diagnose PJI.