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Acute quadriceps tendon rupture — MSRA MCQ

Instant feedback + full explanation. One question, done properly.

HardSoft Tissue InjuryAcute quadriceps tendon ruptureMSRA

A 64-year-old man presents to a GP-led urgent treatment centre 6 hours after missing a step and landing with his left knee flexed. He felt sudden anterior thigh pain and fell. He has type 2 diabetes and takes prednisolone 7.5 mg daily for polymyalgia rheumatica. Knee radiographs show no fracture or dislocation. There is moderate suprapatellar swelling and bruising. He has a palpable defect approximately 3 cm proximal to the superior pole of the patella. He cannot perform or maintain an active straight-leg raise and cannot actively extend the knee from 30 degrees of flexion, although passive extension is full. Distal pulses, sensation and ankle movement are normal. He is afebrile and systemically well. 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: A — Immobilise the knee in extension and contact the on-call orthopaedic service for urgent admission and surgical assessment

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

This is an acute quadriceps tendon rupture causing extensor mechanism failure. The decisive features are the flexed-knee mechanism, a palpable suprapatellar gap and inability to perform a straight-leg raise or actively extend the knee. A normal plain radiograph does not exclude this soft-tissue injury. Diabetes and systemic corticosteroid exposure further increase the pre-test probability of tendon rupture, but the management decision is driven by the functional deficit and palpable defect. Urgent orthopaedic assessment is required because a complete quadriceps or patellar tendon rupture with inability to straight-leg raise and a palpable gap requires urgent surgical repair to restore knee extension. The knee should be immobilised in extension while transfer or admission is arranged. A is plausible because ultrasound can identify an extensor mechanism injury, but imaging must not delay urgent orthopaedic referral when the diagnosis is clinically clear. B is similarly inappropriate: MRI may be useful if the diagnosis is uncertain, not as a prerequisite to referral here. D would be appropriate for many stable soft-tissue knee injuries, but not extensor mechanism failure. E is unsuitable because physiotherapy cannot restore continuity of a completely ruptured tendon.

Reference: NHS Tayside RefGuide: Knee (2026 (accessed 15 August 2026)) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452