CP and juvenile polyposis syndrome: Meta-analysis confirmed high pooled diagnostic performance for WBC (0.88/0.97) and PMN% (0.84/0.97).<h4>Conclusions</h4>Traditional serum biomarkers remain useful first-line diagnostic tools, whereas synovial biomarkers-particularly α-defensin, D-lactate, CP, and WBC indices-demonstrate superior diagnostic accuracy and may be especially valuable in culture-negative PJI.