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

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HardSoft Tissue InjuryFirst-time lateral patellar dislocation with osteochondral fractureMSRA

A 22-year-old woman attends a GP-led urgent treatment centre 2 hours after pivoting while playing netball. She felt her right patella move laterally, then return into position as she fell. She has no previous patellar instability. The knee is moderately swollen. There is tenderness along the medial patellar border and medial retinaculum. The patella is now centred clinically, and she can perform an active straight-leg raise. Distal neurovascular examination is normal. Anteroposterior, lateral and skyline radiographs show a 7 mm osteochondral fracture fragment arising from the medial patellar facet; there is no persistent dislocation. What is the most appropriate management now?

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

Reveal the answer and explanation

Correct answer: E — Arrange urgent assessment by the knee orthopaedic service for the osteochondral fracture

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

This is a first-time lateral patellar dislocation that has spontaneously reduced: the mechanism, transient lateral displacement, medial patellar/retinacular tenderness and current normal patellar position are characteristic. Preserved straight-leg raise makes extensor mechanism rupture unlikely, but does not reduce the significance of the radiographic osteochondral injury. For all first-time patellar dislocations, radiographs are required to identify an osteochondral fracture. An osteochondral fracture is an indication for urgent knee-service referral, because a displaced fragment may represent a repairable intra-articular injury and requires specialist assessment. Therefore, urgent orthopaedic knee review is the appropriate next step. A and D fail because this is not an uncomplicated soft-tissue dislocation suitable for routine conservative follow-up. C would be appropriate after exclusion of osteochondral fracture in an uncomplicated first episode, but physiotherapy alone risks delaying assessment of the fragment. B is attractive because MRI may further define chondral and ligamentous injury, but arranging it routinely from primary care before referral delays the indicated urgent specialist pathway; the demonstrated osteochondral fracture already determines the priority of management.

Reference: Patello-Femoral Joint Dysfunction (Anterior Knee Pain) | NHS Tayside RefGuide (accessed 15 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/?organization=nhs-tayside Dislocated kneecap | NHS (last reviewed 10 March 2026) — https://www.nhs.uk/conditions/dislocated-kneecap/