General symptoms include fever, sweats, malaise, anorexia, weight loss and apathy. Tachycardia and elevated temperature are consistent with a patient who is toxaemic. Local features are pain relieved by rest, swelling of the affected limb, immobility of associated joints, paralysis in the chronic situation and tenderness in the region of the epiphyseal region of the long bones.
There is a spectrum of presentation depending on the stage of the disease. In the early stages, symptoms may be absent, whereas in the delayed situation, the patient may be septicaemic and any palpation of the affected part may cause excruciating pain. Presentation may also be complicated if the patient has already received a course of oral antibiotics as this may suppress but not cure the infection and therefore mask the signs so that the diagnosis is missed. The differential diagnosis is:
• septic arthritis,
• transient arthritis,
• subperiosteal haemotoma secondary to trauma,
• inflammatory arthropathy (e.g. rheumatoid arthritis),
• chronic subcutaneous infection. Investigations
Haematological tests may find a raised white cell count with neutrophilia. There may also be a raised ESR and CRP Blood cultures may help to identify the causative organism.
In the early stages, plain radiographs may be normal. In later stages, when there has been periosteal stripping with new bone formation and bone necrosis, evidence of subperiosteal new bone formation, bone necrosis with sequestral formation, cavitation with the metaphyseal region and areas of lacunae may be seen. It usually takes approximately 10 days for radiological changes to become apparent and the first change is usually rarefaction of the bone.
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