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Acute grade 3 medial collateral ligament tear — MSRA MCQ

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HardKnee InjuriesAcute grade 3 medial collateral ligament tearMSRA

A 34-year-old recreational skier presents to general practice the morning after a valgus injury to his right knee. His ski did not release during a fall and the knee was forced inwards. He had immediate medial pain but no pop, and was able to leave the slope with assistance. Swelling developed gradually overnight. He has focal tenderness along the medial collateral ligament. Valgus stress testing at 30° of knee flexion produces marked medial joint opening with no firm endpoint; at full extension there is no abnormal opening. Lachman testing has a firm endpoint, posterior sag and posterior drawer testing are negative, and there is no rotational instability. He can straight-leg raise and actively extend the knee fully. Plain radiographs are normal. Distal pulses, sensation and ankle dorsiflexion are normal. What is the most appropriate management today?

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Correct answer: C — Arrange prompt referral to the knee service for assessment of an acute grade 3 medial collateral ligament injury

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

The absent endpoint and marked valgus laxity at 30° indicate a complete (grade 3) medial collateral ligament (MCL) injury. Preservation of stability in full extension is important: it makes major concomitant injury to the posteromedial capsule/cruciate structures less likely. The firm Lachman test, negative posterior-drawer findings, gradual rather than immediate large effusion, and normal neurovascular examination further reduce concern for a cruciate-associated multiligament injury or occult knee dislocation requiring emergency assessment. However, an acute grade 3 MCL tear should not simply be managed as an uncomplicated minor sprain. UK NHS specialty referral guidance recommends knee-service assessment, with further clinical assessment and possible MRI to identify associated internal derangement. Therefore prompt referral is appropriate. A is inappropriate because there is no history of deformity, multiligament instability or neurovascular abnormality. C risks delaying specialist assessment; imaging may be arranged after specialist review. D would be appropriate for a lower-grade isolated MCL sprain with a firm endpoint and clinical improvement. E underestimates the severity of a complete MCL tear and risks missing associated injury.

Reference: NHS Tayside RefGuide: Ligament Tears/Sprains (Current online guidance; accessed 15 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/ligament-tearssprains/