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Suspected uncomplicated anterior cruciate ligament rupture — MSRA MCQ

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ModerateSoft Tissue InjurySuspected uncomplicated anterior cruciate ligament ruptureMSRA

A 26-year-old semi-professional footballer sees his GP 9 days after twisting his right knee while changing direction. He felt a pop and developed a large effusion within 1 hour. He was able to leave the pitch with assistance. Emergency department radiographs were normal. The swelling has reduced and he can now weight bear with a mild limp. He reports one episode of giving way when turning quickly but no locking or catching. He can fully extend the knee. There is no joint-line tenderness. Varus and valgus stress testing is stable at 0 and 30 degrees. Posterior drawer testing is negative. Lachman testing shows increased anterior translation with a soft end point compared with the left knee. Distal neurovascular examination is normal. What is the most appropriate management today?

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Correct answer: E — Refer for structured MSK physiotherapy rehabilitation with analgesia, activity modification and review for persistent rotatory instability

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

This presentation is most consistent with an uncomplicated isolated anterior cruciate ligament (ACL) rupture: a non-contact pivoting mechanism, audible pop, rapid effusion and a positive Lachman test support ACL injury. Crucially, he has regained full extension, has no true mechanical locking, no collateral instability and no features of a multi-ligament injury. These findings make urgent imaging or acute operative assessment inappropriate. UK referral guidance recommends initial contemporary rehabilitation for uncomplicated ACL rupture, with reconstruction considered for people who continue to have functionally significant rotatory instability despite adherence to rehabilitation and functional-strength targets. Therefore, structured MSK physiotherapy, symptom control and avoidance of pivoting sport are appropriate now. A is inappropriate because urgent MRI and specialist assessment are reserved for more concerning patterns, such as a locked knee, multi-ligament injury or major instability. B is unsuitable because prolonged rigid immobilisation and non-weight-bearing are not indicated in a stable, weight-bearing isolated ACL injury and risk stiffness and quadriceps inhibition. C is plausible because MRI can confirm associated injury, but routine MRI should not delay initial rehabilitation in an uncomplicated presentation. D is premature: acute reconstruction is not routinely the first management step for an isolated ACL rupture.

Reference: Ligament Tears/Sprains | NHS Tayside RefGuide (Not stated; current page accessed August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/ligament-tearssprains/ Ligament Tears/Sprains | NHS Tayside RefGuide (Not stated; current page accessed August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/ligament-tearssprains/