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Acute quadriceps tendon rupture — MSRA MCQ

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ModerateSoft Tissue InjuryAcute quadriceps tendon ruptureMSRA

A 58-year-old man attends a GP-led urgent treatment centre 2 hours after missing a step while descending stairs. His right knee flexed forcibly as he tried to prevent a fall. He felt a sudden snap immediately above the patella and was unable to continue walking normally. He has marked anterior knee swelling and tenderness, with a palpable defect in the quadriceps tendon approximately 3 cm proximal to the superior pole of the patella. Passive knee flexion and extension are possible but painful. He cannot actively extend the knee from 30 degrees of flexion and cannot perform a straight-leg raise. Distal neurovascular examination is normal. Anteroposterior and lateral knee radiographs show no fracture or dislocation. What is the most appropriate management now?

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

Reveal the answer and explanation

Correct answer: C — Refer immediately to on-call orthopaedics for admission and urgent operative repair

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

This presentation is an acute quadriceps tendon rupture causing extensor mechanism failure. The decisive features are the forced knee flexion mechanism, palpable suprapatellar tendon defect, and inability both to actively extend the knee and to perform a straight-leg raise. Normal radiographs do not exclude tendon rupture. This requires immediate referral to the on-call orthopaedic service for admission and urgent surgical repair. A is inappropriate because delayed routine review risks postponing repair of a functionally complete extensor mechanism disruption. B may be reasonable where the diagnosis is uncertain because ultrasound can help assess suspected extensor mechanism injury, but imaging must not delay referral when the clinical findings are diagnostic. D similarly introduces unnecessary delay; MRI is not required before urgent orthopaedic assessment in this clear presentation. E would be appropriate for a stable soft-tissue knee injury without extensor mechanism failure, but not where active knee extension and straight-leg raise are absent.

Reference: NHS Tayside RefGuide: Knee — Extensor mechanism failure (Date not stated; checked 15 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452