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Acute quadriceps tendon rupture — MSRA MCQ

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HardKnee InjuriesAcute quadriceps tendon ruptureMSRA

A 63-year-old man presents to general practice 2 hours after his right knee buckled while he was descending stairs. He did not fall to the ground, but the knee flexed forcibly and he felt a sudden pop above the patella. He has type 2 diabetes and stage 3 chronic kidney disease. He is unable to actively extend the knee or perform a straight-leg raise. Passive extension is full. There is a palpable gap immediately superior to the patella and a moderate haemarthrosis. Lateral knee radiography shows no fracture but a low-riding patella. Distal pulses, sensation and capillary refill are normal. He is afebrile and the knee is not erythematous. 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: B — Refer immediately to the emergency department for same-day orthopaedic assessment

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

This presentation indicates an acute quadriceps tendon rupture causing extensor mechanism failure. The forced knee-flexion mechanism, sudden suprapatellar pop, palpable suprapatellar gap and inability to perform a straight-leg raise are strongly concordant. Patella baja on the lateral radiograph supports quadriceps tendon rupture; in contrast, patellar tendon rupture typically produces patella alta. A normal radiograph excludes an obvious bony fracture but does not exclude this major soft-tissue injury. Suspected extensor mechanism failure requires emergency-department/same-day orthopaedic assessment. Delaying referral for community imaging or routine follow-up risks delaying definitive assessment and repair. MRI or ultrasound may help secondary care define the injury, but neither should precede urgent referral when the clinical diagnosis is clear. A is inappropriate because active extension is absent, not merely painful. B is tempting because MRI characterises tendon injury, but it delays the required acute orthopaedic pathway. C may be appropriate for selected stable injuries after specialist assessment, but not as an alternative to urgent assessment of extensor mechanism failure. E does not address the mechanical discontinuity; the haemarthrosis is a consequence of the injury, not the priority diagnosis.

Reference: Acute knee pain — NHS Dumfries & Galloway DGRefHelp (Last reviewed 11 December 2024) — https://www.rightdecisions.scot.nhs.uk/dgrefhelp-nhs-dumfries-galloway/musculoskeletal-system/knee/acute-knee-pain/ Fractures (non-complex): assessment and management (NG38) — recommendations (17 February 2016) — https://www.nice.org.uk/guidance/NG38/chapter/recommendations