CRP and juvenile polyposis syndrome: The aim of the present study was to validate the diagnostic characteristics of synovial fluid IL-1β for preoperative diagnosis of chronic PJI as either a single test or in combination with serum C-reactive protein (CRP), synovial fluid percentage of polymorphonuclear neutrophils (PMN%), or serum erythrocyte sedimentation rate (ESR) and to compare these results with the currently available diagnostic standards.