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Complete patellar tendon rupture — MSRA MCQ

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HardKnee InjuriesComplete patellar tendon ruptureMSRA

A 54-year-old man presents to general practice 3 hours after missing a step and landing with his left knee forcibly flexed while attempting to prevent a fall. He felt an immediate pop anteriorly and cannot actively straighten the knee. He can weight-bear only if he keeps the knee extended. Examination shows a large anterior effusion, a palpable gap immediately inferior to the patella, and inability to perform a straight-leg raise. Passive knee extension is full. Distal pulses, sensation and capillary refill are normal. Lateral knee radiography shows no fracture but a high-riding patella. What is the most appropriate management today?

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

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Correct answer: E — Immobilise the knee in extension and arrange same-day orthopaedic on-call assessment for urgent operative repair

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

This is a complete patellar tendon rupture: forced knee flexion against an actively contracting quadriceps, an infrapatellar gap, patella alta and failure of the straight-leg raise together demonstrate extensor-mechanism disruption. A normal radiograph excludes an obvious fracture but does not make this a minor soft-tissue injury. The immediate priority is immobilisation in extension and same-day orthopaedic assessment because restoration of the extensor mechanism requires urgent surgical repair. A is attractive where a partial tendon injury is suspected, particularly if active straight-leg raise is preserved; it is inappropriate when there is clear complete disruption. C may temporarily reduce pain from a tense haemarthrosis but neither establishes nor treats the functional emergency. D is reasonable for diagnostically uncertain internal derangement, but imaging must not delay referral when clinical findings establish extensor-mechanism failure. E is appropriate for uncomplicated sprain or stable patellofemoral injury, not loss of active knee extension. NHS Tayside guidance states that quadriceps or patellar tendon rupture with inability to straight-leg raise and a palpable gap mandates referral to the orthopaedic on-call service for urgent surgical repair. ([rightdecisions.scot.nhs.uk](https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452&utm_source=openai))

Reference: Knee | NHS Tayside RefGuide (Accessed 15 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/?UNLID=678850159202611919452 ED/MIU Adult (>16 yrs): Orthopaedic Referral Pathway (2025) — https://rightdecisions.scot.nhs.uk/media/t1uki5fm/orthopaedic-referral-pathway.pdf