25dkou464 10.3205/25dkou464 urn:nbn:de:0183-25dkou4641 Meeting Abstract Die Analyse der Synovialflüssigkeit in der Infektionsdiagnostik nach unikompartimenteller Knieendoprothetik: Eine multizentrische retrospektive Studie Donner Donner Stefanie S

Centrum für Muskuloskeletale Chirurgie, Charité Universitätsmedizin Berlin, Berlin, Deutschland

author Meißner Meißner Nils N

Klinik für Orthopädie, Sana Kliniken Berlin-Brandenburg, Kremmen, Deutschland

author Matziolis Matziolis Georg G

Deutsches Zentrum für Orthopädie, Waldkliniken Eisenberg, Universitätsklinik Jena, Eisenberg, Deutschland

author Gramlich Gramlich Yves Y

Agaplesion Markus Krankenhaus Frankfurt, Frankfurt, Deutschland

author Lazic Lazic Igor I

Klinik für Orthopädie und Sportorthopädie, 5. Technische Universität München, Klinikum rechts der Isar, München, Deutschland

author Schrednitzki Schrednitzki Daniel D

Klinik für Orthopädie und Unfallchirurgie, Sana Klinikum Berlin-Lichtenberg, Berlin, Deutschland

author Renz Renz Nora N

Centrum für Muskuloskeletale Chirurgie, Charité Universitätsmedizin Berlin, Berlin, Deutschland

author German Medical Science GMS Publishing House

Düsseldorf

610 20251031 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0634 464 Deutsche Gesellschaft für Orthopädie und Unfallchirurgie Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie Deutsche Gesellschaft für Unfallchirurgie Berufsverband für Orthopädie und Unfallchirurgie Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2025) Abstracts | Gelenkersatz – perioperativ Berlin 20251028 20251031 AB73-3229 TextAim of the study, research question: There are no validated criteria for the diagnosis of periprosthetic joint infection (PJI) in unicompartmental knee arthroplasty (UKA). Particularly, the threshold of synovial fluid leukocyte count for detecting PJI is unknown. This study aims to evaluate appropriate diagnostic thresholds for synovial fluid leukocyte count and polymorphonuclear cells (PMN) percentage for the diagnosis of PJI in patients with failed UKAs.Material and methods: We conducted a multicentre, retrospective cohort study including 5 university-affiliated medical centers and identified 239 patients who underwent septic or aseptic revision of an UKA. Of these, 30 (13%) had a revision for PJI and 209 (87%) had an non-PJI revision. PJI was diagnosed according to EBJIS criteria. Preoperative synovial fluid leukocyte count, synovial polymorphonuclear cell percentage (PMN), serum C-reactive protein (CRP), and white blood cell (WBC) count were evaluated. Receiver operating characteristic curves and Youden’s index were used to assess diagnostic performance and the optimal cut-off for the parameters. Results: Comparing the values of patients with PJI and no PJI, the median synovial leukocyte count (11399/L vs 429/L, p<0.001) and synovial PMN percentage (82% vs 28%, p<0.001) were significantly higher in the PJI group. The optimal cut-offs for diagnosing PJI were 2318/L for synovial fluid leukocyte count (AUC 0.93; sensitivity 83%, specificity 95%) and 64% for PMN percentage (AUC 0.90; sensitivity 76%, specificity 95%). CRP (cut-off 9mg/L; AUC 0.85) and WBC count (cut-off 8G/L; AUC 0.71), showed lower diagnostic accuracy.Discussion and conclusion: This study establishes diagnostic thresholds for PJI specific to UKA, which align with the EBJIS PJI criteria for TKA. Synovial biomarkers, particularly synovial fluid leukocyte count and PMN percentage, demonstrated superior diagnostic performance compared to serum CRP and WBC. These findings underscore the need for tailored diagnostic criteria to improve the accuracy of PJI diagnosis and optimize patient outcomes in UKA revision. 0 0 0 0