Novel Biomarkers for Diagnosing Periprosthetic Joint Infection from Synovial Fluid and Serum

Abstract

Background: Synovial fluid bacterial culture is the cornerstone of confirmation or exclusion of periprosthetic joint infection (PJI). The aim of this study was to assess synovial fluid and serum biomarker patterns of patients with total joint arthroplasty (TJA), and the association of these patterns with PJI. Methods: Synovial fluid and serum samples were collected from 35 patients who were admitted to the Arthroplasty Unit of the Department of Orthopaedics and Traumatology at Turku University Hospital. Of the 25 patients who were included in the study, 10 healthy patients with an elective TJA for osteoarthritis served as the control group, and 15 patients who were admitted due to clinical suspicion of PJI with local redness, swelling, wound drainage, pain, and/or fever and who had a positive synovial fluid bacterial culture served as the study group. Logistic regression was used to assess the ability of 37 biomarkers (including cytokines, chemokines, and growth factors) with commercially available tests to detect PJIs. Results: In synovial fluid, the concentrations of sTNF-R1 and sTNF-R2 (soluble tumor necrosis factor receptors 1 and 2) and BAFF (B-cell activating factor, also known as TNFSF13B) were significantly higher in the PJI group (p < 0.002). In serum, the sTNF-R1 concentration was significantly higher in the PJI group, whereas the TWEAK (tumor necrosis factor-like weak inducer of apoptosis) and osteocalcin concentrations were significantly lower (p < 0.002). The sensitivity for detecting PJI using synovial fluid was 1.00 for sTNF-R2, 0.93 for sTNF-R1, and 0.87 for BAFF/TNFSF13B. The specificity of all 3 synovial markers was 1.00. The sensitivity using serum was 0.80 for TWEAK, 0.73 for sTNF-R1, and 0.80 for osteocalcin. The specificity of all 3 serum markers was 1.00. Conclusions: Synovial sTNF-R2 is a promising new biomarker for detecting PJI. We are not aware of any previous reports of the use of sTNF-R2 in PJI diagnosis. More research is needed to assess the clinical importance of our findings. Level of Evidence: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.