Qin L, et al. - Researchers investigated the diagnostic value of the neutrophil CD64 index in synovial and blood vs the standard clinical tests for discrimination prosthetic joint infection (PJI) and aseptic implant failure. They evaluated 50 patients undergoing revision hip and knee arthroplasty in this prospective study. Among these patients, 25 were classified as infected and 25 as not infected. Preoperative measurement of neutrophil CD64 index and percentage of polymorphonuclear neutrophils (PMN%) in synovial fluid, serum CRP, ESR, and serum CD64 index levels was done in all patients. Synovial fluid CD64 index and PMN% discriminated good differentiation between groups of PJI and aseptic failure with AUC of 0.946 and 0.938, respectively. Outcomes support CD64 index in synovial fluid as a promising laboratory marker for screening PJI. Synovial CD64 index with the cut-off values of 0.85 has the potential to differentiate aseptic failure from PJI.