-Defensin conventional markers of inflammation in periprosthetic joint infection: a retrospective study.

Background: Diagnosing periprosthetic joint infection (PJI) remains a significant challenge for healthcare professionals. Commonly utilized inflammatory markers include erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and white blood cells (WBC). Human -defensin 1 (-defensin) is an antimicrobial peptide elevated in infection, yet its diagnostic value for PJI has not been explored. The purpose of this study was to evaluate the efficacy of synovial -defensin as a diagnostic marker for PJI and to compare its performance with ESR, serum CRP, and WBC.

Methods: We conducted a single-center retrospective study from October 2022 to June 2023. A total of 105 joint fluid samples from revision patients at the Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra were collected intraoperatively (71 hips, 34 knees) and frozen. According to MSIS criteria, 64 patients were defined as positive for PJI and the remaining 41 were negative. Synovial -defensin levels were quantified using ELISA, serum CRP levels by immunoturbidimetry, and blood ESR and WBC were analyzed. Sensitivity and specificity were determined using ROC curves, and diagnostic performance was compared using the area under the curve (AUC). Cut-off values for diagnosing PJI were established.

Results: Levels of synovial -defensin, ESR, serum CRP, and WBC were significantly higher in the PJI group compared to the non-PJI ( < 0.0001). The AUCs were 0.948 for -defensin, 0.884 for ESR, 0.902 for CRP, and 0.767 for WBC, with a combined AUC of 0.994. Sensitivity/specificity for -defensin, ESR, CRP, and WBC were 0.966/0.830, 0.887/0.791, 0.930/0.771, and 0.820/0.682, respectively. Optimal predictive cut-off values were 1105.8 pg/mL for -defensin, 11.5 mm/h for ESR, 5.55 mg/L for CRP, and 7.3 × 10/mm for WBC.

Conclusion: The synovial -defensin assay demonstrated greater sensitivity and specificity for the diagnosis of PJI compared to ESR, serum CRP and WBC. Therefore, -defensin shows promise as a diagnostic marker for PJI. Simultaneous determination of all markers may increase diagnostic confidence.