Synovial fluid IL-1β appears useful for the diagnosis of chronic periprosthetic joint infection

Purpose: The purpose of this study was to investigate the role of synovial fluid interleukin (IL)-1 beta in diagnosing chronic periprosthetic joint infection (PJI) and to identify the optimal threshold of synovial fluid IL-1 beta for differentiating chronic PJI from aseptic failure after knee and hip arthroplasties. Methods: Between January 2019 and December 2019, we prospectively included patients scheduled to have a revision surgery for chronic PJI or aseptic failure after total joint arthroplasty. Then, synovial IL-1 beta was additionally measured along with routine preoperative diagnostic serum and synovial biomarkers. The receiver operating characteristic (ROC) curves and area under the curve (AUC) were analyzed for each biomarker to determine diagnostic efficacy. Results: Of the 93 patients included, their demographic data were not found to be statistically significant. The median synovial IL-1 beta levels were significantly higher in the chronic PJI group than in the aseptic group (894.73 pg/mL vs. 34.49 pg/mL, P<0.01). The AUC for synovial fluid IL-1 beta was 0.991, which was higher than serum ESR (0.627) and CRP (0.712). The optimal threshold value for detecting chronic PJI of synovial IL-1 beta was 312.7 pg/mL, with a sensitivity of 97.3% and a specificity of 94.64%. And the combined measurement of synovial fluid IL-1 beta and synovial fluid PMN% can led to a specificity of 1, and a negative predictive value (NPV) of 1. Conclusions: The present study demonstrated that synovial fluid IL-1 beta is a valuable biomarker for detection of chronic PJI. The combination of synovial fluid IL-1 beta and PMN% led to an improvement in specificity compared with evaluation of each single index.

Automated summary

The study demonstrates the valuable role of synovial fluid IL-1 beta in diagnosing chronic PJI, with the combined measurement of IL-1 beta and PMN% leading to increased specificity.