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Suspected subtle Lisfranc injury — MSRA MCQ

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HardAnkle and FootSuspected subtle Lisfranc injuryMSRA

A 37-year-old man presents to a GP-led minor injuries unit 18 hours after stepping off a kerb while carrying a heavy box. His right foot was plantar-flexed and twisted during the fall. He has marked midfoot pain, cannot take four steps, and cannot tolerate standing for weight-bearing radiographs. There is swelling and focal tenderness over the first and second tarsometatarsal joints, with plantar midfoot bruising. Neurovascular examination is normal. Non-weight-bearing three-view foot radiographs show no fracture or dislocation. What is the most appropriate management now?

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

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Correct answer: B — Immobilise the foot, keep him non-weight-bearing, and arrange urgent same-day orthopaedic or emergency assessment for CT-based stability assessment

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

This is a clinically suspected subtle Lisfranc injury despite normal initial radiographs. The linked discriminators are an indirect twisting load through a plantar-flexed foot, focal first–second tarsometatarsal tenderness, inability to bear weight and plantar midfoot bruising. Plantar bruising is particularly concerning for disruption of the Lisfranc complex. Normal non-weight-bearing radiographs do not exclude a nondisplaced or predominantly ligamentous injury. Weight-bearing radiographs are useful for demonstrating instability, but he cannot tolerate them now. He therefore needs immobilisation and strict non-weight-bearing while urgent orthopaedic or emergency assessment obtains CT to identify occult fracture and assess tarsometatarsal alignment; MRI may subsequently be required if ligamentous instability remains uncertain. A is unsafe because early loading may displace an unstable midfoot injury. B is plausible because the suspected structure is ligamentous, but ultrasound does not adequately assess occult fractures or tarsometatarsal alignment. C would be reasonable only if weight-bearing imaging were feasible promptly and specialist assessment could safely follow; delaying assessment in this high-suspicion presentation is inappropriate. E is suitable for selected suspected occult fractures with low concern for instability, but repeat non-weight-bearing films may remain falsely reassuring in Lisfranc injury.

Reference: Acute Lisfranc injury management (2024) — https://pubmed.ncbi.nlm.nih.gov/39615511/ Fractures (non-complex): assessment and management — recommendations (2016; last reviewed 2025) — https://www.nice.org.uk/guidance/ng38/chapter/recommendations Inconsistent radiographic diagnostic criteria for Lisfranc injuries: a systematic review (2023) — https://pubmed.ncbi.nlm.nih.gov/38012651/