Erythrocyte sedimentation rate and C reactive protein in the assessment of suspected bone infection--are they reliable indices?

The child who presents limping or with pain in a limb in the absence of a clear cause is a common problem, yet one which must be taken seriously. In the absence of trauma, infection involving the bone or joint must be carefully excluded clinically and often with the aid of further investigations. Preliminary investigations usually involve measurement of the while cell count (WCC), Erythrocyte Sedimentation Rate (ESR), and C Reactive Protein (CRP) as these are regarded as sensitive indicators for the presence of infection. Radiographs of the appropriate areas may be taken to assess for soft tissue swelling, chronic bone changes or evidence of trauma. The following case report demonstrates that normality of these parameters cannot be used to confidently exclude suppurative osteomyelitis and highlights the value of follow-up in apparently self-limiting conditions.