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Suspected spontaneously reduced tibiofemoral knee dislocation with multiligament injury and possible popliteal

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HardKnee InjuriesSuspected spontaneously reduced tibiofemoral knee dislocation with multiligament injury and possible popliteal vascular injuryMSRA

A 43-year-old woman presents to a GP-led urgent treatment centre 3 hours after stepping off a low kerb. Her planted right knee twisted and appeared grossly deformed to her partner before it “clunked back” into position. She has a BMI of 43 kg/m² and was unable to weight-bear immediately after the injury. Examination shows a large effusion, extensive medial and lateral bruising, marked anterior and posterior translation on Lachman and posterior drawer testing, and varus and valgus laxity in full extension. Ankle dorsiflexion and eversion are normal. Her feet are warm with brisk capillary refill and palpable, symmetrical dorsalis pedis and posterior tibial pulses. Plain radiographs show no fracture and normal tibiofemoral alignment. What is the most appropriate management today?

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Correct answer: A — Transfer to the emergency department for urgent orthopaedic and vascular assessment, including CT angiography

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

This is a suspected spontaneously reduced tibiofemoral knee dislocation with multiligament knee injury. The witnessed transient deformity is crucial: normal alignment on subsequent radiographs does not exclude a dislocation that has reduced. Marked laxity of both cruciates plus collateral instability in extension indicates disruption across multiple stabilising structures rather than an isolated ligament injury. The immediate priority is exclusion of popliteal vascular injury. Knee dislocation is an indirect sign of vascular trauma in the North of Scotland Major Trauma Guideline. That guideline advises CT angiography as soon as possible when indirect signs are present and specifically cautions against using apparently reassuring perfusion findings to exclude injury. Obesity additionally increases vascular-injury risk after knee dislocation. A is plausible for a stable isolated ligament injury, but bracing and rehabilitation must not delay acute vascular assessment here. B is useful later for characterising ligamentous and meniscal damage, but MRI is not the urgent investigation for possible arterial injury. D incorrectly treats palpable pulses and capillary refill as sufficient exclusion of vascular trauma. E may be appropriate after emergency assessment and stabilisation, but reconstruction planning is not today’s priority.

Reference: NHS Grampian North of Scotland Major Trauma Guidelines: Vascular trauma associated with fractures / dislocations (Undated; checked 16 August 2026) — https://www.rightdecisions.scot.nhs.uk/north-of-scotland-major-trauma-guidelines/generalvascularurology/vascular-trauma-associated-with-fractures-dislocations/ Can Vascular Injury be Appropriately Assessed With Physical Examination After Knee Dislocation? (2016) — https://pubmed.ncbi.nlm.nih.gov/26847454/