Our objectives were to assess the clinical and microbiological aspects of septic osteoarthritis in children admitted to our center from 1987 until July 1997 and to determine the sensitivity of ultrasound in this age group.
The medical records of 36 children diagnosed as having septic osteoarthritis of the hip were reviewed retrospectively. The diagnosis had been based on clinical criteria, along with synovectomy and drainage of purulent material from the affected joint. An X-ray and/or ultrasound had been performed when the diagnosis was suspected.
Nineteen children were diagnosed during the neonatal period, 8 between the ages of 1 and 12 months and 9 older than one year of age. Mean age at diagnosis was 16.8 +/- 6.2 months (median 29 days, range 6 days to 13 years). The hip was involved in 32 children, the ankle in 3 and the elbow in 1. A microbiological diagnosis was achieved in 22 cases (61%) by culture from blood, CSF, and/or synovial fluid. The most common isolates were Gram positive cocci (S. aureus in 9 cases and coagulase negative Staphylococcus in 3). The diagnostic value of the X-rays was very low (18%). The ultrasound was initially considered abnormal in 64.5% of the patients, with a lower sensitivity in the neonatal period. After a mean follow-up period of 36 months, the outcome was good in 86% of the cases, although three children continue with sequelae. Two preterm infants died due to sepsis associated with the osteoarthritis.
At the time of diagnosis of septic arthritis of the hip, the ultrasound is frequently normal. Due to the poor outcome when there is a delay in surgery, we suggest immediate synovectomy and drainage when there is clinical suspicion of septic arthritis despite an apparently normal ultrasound.