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Acute traumatic meniscal tear with true knee locking — MSRA MCQ

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HardSoft Tissue InjuryAcute traumatic meniscal tear with true knee lockingMSRA

A 27-year-old man attends a GP-led urgent treatment centre 36 hours after pivoting on his right knee while playing squash. He felt medial knee pain immediately but was able to walk off court. Swelling developed over the following evening. He now reports that the knee has become stuck and he cannot straighten it. Plain knee radiographs are normal. There is a moderate effusion and focal medial joint-line tenderness. The knee cannot be actively or passively extended beyond 25 degrees of flexion, despite analgesia and repeated gentle examination; flexion is limited to 80 degrees. Distal neurovascular examination is normal. There is no erythema, marked warmth, fever, or systemic upset. What is the most appropriate next management step?

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Correct answer: C — Arrange same-day urgent orthopaedic assessment for a suspected locked knee

This is a true locked knee requiring same-day urgent orthopaedic assessment. The important combination is an acute twisting mechanism, delayed effusion and medial joint-line tenderness, followed by a persistent mechanical block to both active and passive extension. The inability to extend beyond 25 degrees, together with flexion limited to 80 degrees, supports a displaced intra-articular lesion, particularly a bucket-handle meniscal tear, rather than pain-related inhibition or transient pseudolocking. Normal radiographs exclude no soft-tissue internal derangement. Urgent orthopaedic assessment is appropriate because a locked knee may reflect a displaced meniscal tear for which timely reduction and possible repair may be required. MRI can help define pathology, but arranging it before specialist assessment risks delaying the relevant pathway. Conservative rehabilitation is appropriate for many non-locked traumatic meniscal injuries, but not where there is a fixed loss of passive movement. Aspiration and corticosteroid injection do not address a mechanical block and are inappropriate without an inflammatory indication. A prolonged conservative trial is appropriate for many degenerative tears or non-urgent mechanical symptoms, not an acutely locked knee.

Reference: Meniscal Problems — NHS Tayside RefGuide (Next review date: 02/07/2027) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/meniscal-problems/?organization=nhs-tayside&useNavigation=true MRI Criteria — NHS Tayside RefGuide (Crawled 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/mri-criteria/?topic=nursing-midwifery Acute knee pain — NHS Dumfries and Galloway RefHelp (Reviewed 11/12/2024) — https://www.rightdecisions.scot.nhs.uk/dgrefhelp-nhs-dumfries-galloway/musculoskeletal-system/knee/acute-knee-pain/