Objective: To examine the incidence, etiology, and clinical features of septic arthritis in patients younger than 24 months.
Design: Retrospective, 1988 through 1993 period, chart review-based survey.
Patients: All children with bacteriologically proved septic arthritis that was diagnosed at a medical center serving southern Israel (population 320,000). Septic arthritis was defined by clinical evidence of joint inflammation and a positive synovial fluid or blood culture, antigen detection test, or a standard tube agglutination titer of 160 or greater for Brucella species.
Results: During the 6-year period, 40 children had septic arthritis diagnosed. Twenty-six (65%) were male. The annual incidence of septic arthritis was 37.1 per 100,000. The two most common organisms isolated were Kingella kingae in 19 (48%) and Haemophilus influenzae type b in eight (20%). The clinical presentation was frequently mild: a body temperature of less than 38.3 degrees C was recorded in 14 (35%) of 40 children, leukocyte count of less than 15 x 10(9)/L in 13 (34%) of 38, and erythrocyte sedimentation rate of less than 30 mm per hour in four (11%) of 35. In eight (36%) of 22 patients, less than 50 x 10(9)/L leukocytes were counted in the synovial fluid.
Conclusions: The diagnosis of septic arthritis in young children requires a high index of suspicion, and the disease cannot be excluded on the basis of lack of fever or normal results of laboratory tests. Kingella kingae appears to be the most common cause of septic arthritis in patients younger than 24 months, although confirmatory studies from other geographic areas are still needed.