Threshold for Synovial Cell Count and Neutrophil Differential in Diagnosis of Periprosthetic Knee Infection: A Multi-Institutional Study

Introduction: Synovial fl­uid analysis is an important tool in the work-up of suspected periprosthetic joint infection (PJI). Yet, there is confl­icting guidance for the analysis of synovial fl­uid aspiration, including a lack of uniform thresholds for white blood cell (WBC) count and neutrophil percentage (PMN%)1-3. Therefore, a multi-institutional study was undertaken to reassess these thresholds, compare preoperative versus intraoperative sample collection, and assess variation in results between institutions