Drain fluid cultures can rule in but cannot rule out infection persistence after surgical treatment of periprosthetic joint infections

Background: Periprosthetic joint infection (PJI) is one of the most common reason for implant failure in arthroplasty. Surgical therapy is essential but there is no standardized guideline to determine infection eradication in multiple-step revision surgery. To date, clinical and laboratory inflammation markers and preoperative arthrocentesis are controversial to evaluate the infection status before reimplantation and therefore are often combined. Drain fluid cultures enable a microbiological analysis without need for further invasive procedure after revision surgery. This retrospective study evaluates the diagnostic per-formance of drain fluid cultures in diagnosing infection persistence according to the MSIS definition of PJI. Methods: Drain samples have been taken after every revision surgery for microbiological testing. Af-terwards, the results have been assigned to the infection status according to the diagnostic criteria of the MSIS definition of PJI. Results: 1084 revision surgeries in 183 patients have been included, resulting in a total sample size of 1552 drain fluid cultures. Overall sensitivity was 36.0%, specificity was 90.7% and ROC-AUC was 0.63. Conclusion: Due to a high specificity and a low sensitivity drain fluid cultures can rule in but cannot rule out infection persistence in PJI. (c) 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.