Managing children with acute non-traumatic limp: the utility of clinical findings, laboratory inflammatory markers and X-rays.

OBJECTIVES: To examine the utility of clinical findings, laboratory markers and X-ray radiographs (X-ray) in the assessment of children presenting with an acute non-traumatic limp.

METHODS: A retrospective review of all children who received hip X-rays over a 2 year period in the Children's Emergency Department, Starship Children's Hospital, Auckland, New Zealand. Children were identified from the radiology database and clinical notes reviewed. Children aged 0-12 years old were included if the limp was acute (less than 2 weeks of duration) with no history of trauma. X-rays were reported by a consultant paediatric radiologist. Univariate and multivariate analysis was performed to determine predictors of osteomyelitis and septic arthritis. Receiver operator curves were used to assess the optimum cut-off points for C reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white cell count (WCC).

RESULTS: A total of 350 patients were enrolled. There were 21 (6%) abnormal X-rays . Fever, non-weight bearing, raised white cell count, raised erythrocyte sedimentation rate and raised CRP were all associated with increased risk of septic hip or osteomyelitis. The optimum inflammatory marker cut-off was a CRP of 12 with a sensitivity of 87% and specificity of 91%.

CONCLUSION: In acute non-traumatic limp, X-rays of the hips diagnose slipped upper femoral epiphysis, as such they should be routinely used from the age of 9 years upwards. Below this age they are of little value. Inflammatory markers have utility in risk-stratifying children and selecting a group in whom to proceed with definitive tests to exclude osteomyelitis or septic hip. Children with a short history and minimal symptoms can be managed with appropriate follow up and no investigations.