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Acute patellar tendon rupture — MSRA MCQ

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HardSoft Tissue InjuryAcute patellar tendon ruptureMSRA

A 49-year-old man attends a GP-led urgent treatment centre 3 hours after missing the final step while descending stairs. His right knee flexed abruptly as he tried to prevent a fall. He felt a snap at the front of the knee and was unable to continue walking without support. He has a tense knee effusion and focal tenderness with a palpable gap immediately inferior to the patella. The patella appears higher than on the left. He cannot perform a straight-leg raise or actively extend the knee from 30 degrees of flexion, although passive extension is full. Distal neurovascular examination is normal. Anteroposterior and lateral radiographs show patella alta but no fracture, avulsion fragment or dislocation. What is the most appropriate management now?

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Correct answer: C — Contact the on-call orthopaedic service now for admission and urgent surgical assessment

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

This is an acute patellar tendon rupture causing extensor mechanism failure. The key linked findings are an eccentric quadriceps load during sudden knee flexion, an infrapatellar palpable gap with patella alta, and inability to perform a straight-leg raise or actively extend the knee. Normal radiographs for fracture do not exclude this diagnosis; indeed, patella alta supports patellar tendon disruption. In UK referral guidance, a suspected quadriceps or patellar tendon rupture with inability to straight-leg raise and a palpable gap requires referral to the orthopaedic on-call service for admission and urgent surgical repair. Imaging may be useful when the diagnosis is genuinely uncertain, but it must not delay escalation when the clinical diagnosis is clear. A is inappropriate because rehabilitation is not first-line for a complete acute extensor mechanism rupture. B delays time-sensitive specialist assessment. C may suit less urgent acute knee injuries without extensor mechanism failure, but this presentation requires on-call orthopaedic involvement. D is initially attractive because ultrasound can demonstrate tendon discontinuity; however, the examination and radiographs already establish a high-probability rupture requiring urgent referral.

Reference: NHS Tayside RefGuide: Knee (Current page; checked 16 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452 NHS Tayside RefGuide: Knee (Current page; checked 16 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452