IL1B and juvenile polyposis syndrome: In the present study on chronic PJI, synovial fluid IL-1β had sensitivity of 97.3% (95% CI, 85.8%–99.9%), specificity of 94.64% (95% CI, 85.1%–98.9%), and AUC of 0.991 (95% CI, 0.945–1.000) when a cutoff value of 312.7 pg/mL was used.