Evaluation Of Synovial Fluid Neutrophil CD64 Index As A Screening Biomarker Of Periprosthetic Joint Infection

Background: Periprosthetic joint infection(PJI)remains a major clinical challenge.Neutrophil CD64 index,Fc-gamma receptor 1(FcγR1),plays an important role in mediating inflammation of bacterial infections and therefore could be a valuable biomarker for PJI.The aim of this study is to compare the neutrophil CD64 index in synovial and blood diagnostic ability with the main available clinical tests for discrimination PJI and aseptic implant failure.Methods: This prospective study was initiated to enroll patients undergoing hip and knee revision arthroplasty.According to Musculoskeletal Infection Society(MSIS)criteria,25 patients were classified as infected and 25 as not infected.In all patients,neutrophil CD64 index and percentage of polymorphonuclear neutrophils(PMN%)in synovial fluid,serum C-reactive protein(CRP),erythrocyte sedimentation rate(ESR)and blood CD64 index levels were measured preoperatively.The receiver operating characteristic(ROC)curves and the area under the curve(AUC)were analyzed for each biomarker.Results: Samples were collected and analyzed from 50 patients.The blood CD64 index showed no significant difference between the two groups(P =.091).Synovial fluid CD64 index and PMN% discriminated good differentiation between groups of PJI and aseptic failure with AUC of0.946(95% CI 0.842-0.990)and 0.938(95% CI 0.832-0.987)separately.0.85 was determined as the optimal threshold value of synovial CD64 index for the diagnosis of PJI,with a sensitivity of 92.00%,a specificity of96.00% and DOR of 227.11.Conclusion: The present study demonstrates that CD64 index in synovial fluid could be one promising laboratory marker for screening PJI.The cut-off values of 0.85 for synovial CD64 index has the potential to distinguish the septic from aseptic failure of prosthesis.