Preoperative Synovial Fluid Cultures, and Biopsy Cultures After Dry Tap Aspiration, Are Valuable in Diagnosing a Periprosthetic Joint Infection: A Retrospective Study.

Periprosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty. Synovial fluid aspiration and preoperative tissue biopsy cultures can be helpful diagnostic tools for PJI. The aim of this study is to evaluate the diagnostic value of synovial fluid aspirations in general, and preoperative biopsies after inconclusive or dry tap aspiration in patients undergoing revision hip arthroplasty in particular. Patients who underwent diagnostic aspiration and subsequent preoperative biopsy and/or revision surgery between January 2015 and January 2024 were included in the study. Synovial fluid aspirations and tissue samples obtained from biopsy and revision surgery were interpreted using the European Bone and Joint Infection Society criteria for PJI. In total, 207 patients were included with 231 synovial fluid aspirations. The sensitivity and specificity of synovial fluid aspiration cultures were 76% and 98%. In 62 cases, tissue biopsies were performed, of which 23 were after dry tap aspiration. Tissue biopsies after dry tap aspiration had a sensitivity of 44% and a specificity of 93%. Tissue biopsies after dry tap aspiration led to the confirmation of PJI in 7/23 cases. Synovial fluid aspiration yields reliable results when evaluating a patient for suspicion of PJI. Diagnosing PJI can, however, be troublesome if the synovial fluid aspiration provides a dry tap or inconclusive result. Tissue biopsy cultures after dry tap aspiration are a feasible way to confirm PJI.