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Adult septic arthritis — RCPSC EM MCQ

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ModerateMusculoskeletalAdult septic arthritisRCPSC EM

A 61-year-old man has a swollen painful knee 3 days after intra-articular steroid injection. Temperature is 38.4°C, CRP is 140 mg/L, and radiograph shows no fracture. He can barely flex the knee. What is the most appropriate next step?

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Correct answer: E — Urgent arthrocentesis with synovial fluid culture before antibiotics if feasible

Septic arthritis must be excluded in an acutely hot swollen joint, especially after injection. Synovial fluid analysis and culture are central, followed by empiric antibiotics and orthopaedic involvement.

Reference: Canadian musculoskeletal infection practice; emergency medicine consensus