Diagnostic Utility of Synovial Fluid Cell Counts and CRP in Pediatric Knee Arthritis: A 10-Year Monocentric, Retrospective Study.

Background: Orthopedic surgeons often use the intra-articular white blood counts (WBCs) and the percentage of polymorphonuclear cells (PMN) in the diagnosis of an acute swollen and painful knee joint in children. Today, there is no established threshold for the synovial WBC, and their differentiation, as indicative of native joint knee bacterial arthritis. We determine the sensitivity and specificity of synovial WBCs and PMN percentages in the prediction of a community-acquired, acute bacterial native joint septic arthritis (SA) in the pediatric population.