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First-time traumatic lateral patellar dislocation with osteochondral fracture — MSRA MCQ

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HardSoft Tissue InjuryFirst-time traumatic lateral patellar dislocation with osteochondral fractureMSRA

A 22-year-old woman attends a GP-led urgent treatment centre 2 hours after twisting on her planted left leg while changing direction during netball. She felt a pop and fell. A teammate reports that the patella was visibly displaced laterally for several seconds before apparently moving back into place as the knee was straightened. She has a large effusion, marked tenderness along the medial patellar border and a positive patellar apprehension test. Active knee extension is intact and she can perform a straight-leg raise. Distal neurovascular examination is normal. Anteroposterior, lateral and skyline radiographs show the patella reduced, with a small displaced osteochondral fragment in the lateral gutter. What is the most appropriate management now?

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Correct answer: E — Arrange urgent orthopaedic knee assessment, with analgesia and supported immobilisation pending review

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 first-time traumatic lateral patellar dislocation that has spontaneously reduced. The reported transient lateral deformity, medial patellar tenderness and apprehension support disruption of medial stabilising tissues; intact active extension and a straight-leg raise make extensor-mechanism rupture unlikely. The decisive additional finding is a displaced osteochondral fragment on radiography. This requires urgent orthopaedic knee assessment because an osteochondral fracture may require specialist assessment and treatment, rather than routine conservative rehabilitation alone. A is inappropriate because the patella is already reduced radiographically and clinically. C would be reasonable for an uncomplicated reduced patellar dislocation without an osteochondral fracture after appropriate acute assessment, but not in this case. D may occasionally improve pain from a tense haemarthrosis but does not address the osteochondral injury or replace urgent referral. E delays specialist management; MRI may be arranged by orthopaedics if required, but the radiographic fragment already establishes an urgent referral indication.

Reference: Patello-Femoral Joint Dysfunction (Anterior Knee Pain) | Right Decisions, NHS Tayside RefGuide (Page date not stated; checked 16 August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/knee/patello-femoral-joint-dysfunction-anterior-knee-pain/ Dislocated kneecap - NHS (Last reviewed 10 March 2026) — https://www.nhs.uk/conditions/dislocated-kneecap/ Patellofemoral instability | Right Decisions, NHS Greater Glasgow and Clyde (Page date not stated; checked 16 August 2026) — https://www.rightdecisions.scot.nhs.uk/ggc-msk-index/knee/patellofemoral-instability/