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Septic arthritis — RACP Adult Medicine MCQ

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EasyRheumatologySeptic arthritisRACP Adult Medicine

A 67-year-old man with diabetes presents with an acutely swollen painful knee and fever. The joint is hot with markedly reduced range of motion. There is no history of trauma. What is the most appropriate investigation?

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Correct answer: B — Urgent synovial fluid aspiration for microscopy, culture and crystal analysis

Suspected septic arthritis requires urgent synovial fluid analysis before or alongside empirical antibiotics. Serum urate does not exclude infection, and radiographs cannot rule out septic arthritis. RF is irrelevant acutely, and fever strengthens rather than removes the need for aspiration.

Reference: Therapeutic Guidelines (eTG) Antibiotic; Australian Rheumatology Association