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Suspected septic arthritis of the ankle — MSRA MCQ

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HardAnkle and FootSuspected septic arthritis of the ankleMSRA

A 63-year-old man presents to general practice with 18 hours of rapidly worsening pain and swelling of his right ankle. He has seropositive rheumatoid arthritis treated with adalimumab and methotrexate, and crystal-proven gout that has previously affected only his first metatarsophalangeal joints. He had an ultrasound-guided intra-articular corticosteroid injection into the right ankle 8 days ago. He is unable to bear weight. His temperature is 38.1°C. The tibiotalar joint is diffusely swollen, hot and erythematous, with severe pain on minimal passive plantarflexion or dorsiflexion. There is no calf swelling, skin ulceration, penetrating injury or recent trauma. What is the most appropriate management today?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Arrange immediate transfer to emergency care for suspected septic arthritis and hospital joint aspiration, cultures and urgent treatment

Explanation lettering: E = shown as A · A = shown as B · B = shown as E

This presentation should be managed as septic arthritis until proved otherwise. The key discriminators are an acutely hot, swollen monoarthritis with fever, inability to bear weight and severe pain on passive joint movement. His rheumatoid arthritis and immunosuppressive treatment further increase the pre-test probability of joint infection. The recent intra-articular procedure is an additional reason not to assume this is a routine gout flare. B is correct because suspected septic arthritis requires immediate emergency assessment, where urgent synovial-fluid aspiration, microbiological sampling, drainage where indicated and intravenous antimicrobial treatment can be coordinated. This must take priority over establishing whether gout is also present. A is tempting because he has crystal-proven gout, but prior gout does not exclude septic arthritis, and systemic corticosteroids could worsen an untreated infection. C does not address a likely intra-articular infection; cellulitis would not usually produce such marked pain on passive tibiotalar movement. D introduces an avoidable delay: imaging does not replace urgent assessment and aspiration. E is inappropriate in primary care because aspiration and antimicrobial decisions need urgent hospital coordination, and intra-articular steroid is contraindicated when septic arthritis is suspected.

Reference: GGC MSK foot and ankle: Red flags (Reviewed 28 November 2025) — https://www.rightdecisions.scot.nhs.uk/ggc-msk-foot-and-ankle/initial-assessment/red-flags/?searchTerm=2024 Septic Arthritis / Osteomyelitis (Native joint, not diabetic ulcer associated) (2026) — https://www.rightdecisions.scot.nhs.uk/antimicrobial-prescribing-nhs-borders/adult-hospital-guidance/musculoskeletal-and-joint/septic-arthritis-osteomyelitis-native-joint-not-diabetic-ulcer-associated/ Septic arthritis (Reviewed 23 March 2023) — https://www.nhs.uk/conditions/septic-arthritis/