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First-time reduced lateral patellar dislocation without osteochondral fracture — MSRA MCQ

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ModerateKnee InjuriesFirst-time reduced lateral patellar dislocation without osteochondral fractureMSRA

A 22-year-old woman attends a GP-led urgent treatment centre 3 hours after twisting on a planted left foot while playing netball. She saw her patella displace laterally and it reduced spontaneously when she straightened the knee. She can now mobilise with a limp. Examination shows a small effusion, tenderness along the medial patellar border and a positive patellar apprehension test. She can perform a straight-leg raise and has full passive extension. There is no fixed deformity, joint-line tenderness, ligamentous laxity or neurovascular deficit. Anteroposterior, lateral and skyline radiographs show a located patella with no fracture or osteochondral fragment. What is the most appropriate management today?

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

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Correct answer: E — Provide analgesia, encourage weight-bearing as tolerated and arrange early physiotherapy rehabilitation

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

This is a first-time lateral patellar dislocation that has reduced spontaneously. The medial patellar tenderness, apprehension and mechanism support patellofemoral instability. Crucially, she has an intact extensor mechanism (straight-leg raise), no persistent dislocation, no neurovascular abnormality and no osteochondral fracture or loose fragment on appropriate radiographs. In this setting, UK NHS pathways support early rehabilitation and advise against routine immobilisation after a patellar dislocation without fracture. Management should include analgesia, mobilisation as tolerated and early physiotherapy, typically directed at quadriceps control and patellofemoral rehabilitation. A is attractive because immobilisation was historically common, but it is not indicated for an uncomplicated reduced dislocation and may delay recovery. B is inappropriate because there is no fracture, unreduced dislocation or extensor mechanism failure. C is unnecessary before initial conservative management when radiographs exclude an osteochondral fragment and there is no true locking. D would be appropriate if imaging showed an osteochondral fracture/loose body, or if there were recurrent instability or failure to progress with rehabilitation, but not for this uncomplicated first episode.

Reference: ED/MIU Adult (>16 yrs) Orthopaedic Referral Pathway (2025) — https://rightdecisions.scot.nhs.uk/media/t1uki5fm/orthopaedic-referral-pathway.pdf Patellofemoral instability (2026) — https://www.rightdecisions.scot.nhs.uk/ggc-msk-index/knee/patellofemoral-instability/