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Acute lateral ankle sprain — MSRA MCQ

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ModerateSoft Tissue InjuryAcute lateral ankle sprainMSRA

A 34-year-old woman attends a GP-led urgent treatment centre 90 minutes after inverting her right ankle while stepping off a kerb. She was initially unable to continue walking because of pain, but can now take four weight-bearing steps with a limp. There is mild swelling and bruising over the anterolateral ankle. Maximal tenderness is over the anterior talofibular ligament, just anterior and inferior to the lateral malleolus. There is no tenderness of the posterior edge or tip of either malleolus, the navicular, or the base of the fifth metatarsal. There is no deformity. Active plantarflexion is preserved, calf-squeeze testing produces normal plantarflexion, and distal neurovascular examination is normal. What is the most appropriate management today?

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Correct answer: B — Provide conservative treatment for an ankle sprain without radiographs, including analgesia, compression and early mobilisation as tolerated

Explanation lettering: E = shown as C · C = shown as D · D = shown as E

This is an uncomplicated lateral ankle sprain. Her maximal tenderness is over the anterior talofibular ligament rather than the posterior edge or tip of the malleoli, and there is no midfoot bony tenderness. Although she could not initially continue walking, she can now take four weight-bearing steps. She therefore does not meet the Ottawa ankle-rule threshold for radiography: inability to bear weight must be present both immediately after injury and during assessment, unless there is relevant bony malleolar tenderness. Conservative management is appropriate: give analgesia, compression and elevation advice, and encourage mobilisation/loading as symptoms permit. Safety-net for worsening pain, inability to bear weight, neurovascular symptoms or failure to improve. A is attractive because immediate inability to bear weight is a recognised Ottawa-rule component, but it is insufficient in isolation when current four-step weight bearing is possible. C confuses ligament-region swelling with bony tenderness at the specified malleolar landmarks. D is not indicated in an acute uncomplicated sprain without features suggesting a major tendon injury, occult fracture or persistent diagnostic uncertainty. E would be appropriate for suspected Achilles rupture, neurovascular compromise, dislocation, open injury, or another significant structural injury requiring urgent specialist assessment; none is present here.

Reference: NICE NG38: Fractures (non-complex): assessment and management — Recommendations (2016) — https://www.nice.org.uk/guidance/ng38/chapter/recommendations Evaluation of the Ottawa clinical decision rules for the use of radiography in acute ankle and midfoot injuries in the emergency department (1994) — https://pubmed.ncbi.nlm.nih.gov/7912053/ NHS Tayside RefGuide: Ligament Sprains (Reviewed 2025) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/foot-and-ankle-service/ligament-sprains/?organization=nhs-tayside&useNavigation=true