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Suspected acute posterior glenohumeral dislocation after seizure — MSRA MCQ

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ModerateShoulder InjuriesSuspected acute posterior glenohumeral dislocation after seizureMSRA

A 34-year-old woman with epilepsy is reviewed in general practice 2 hours after a witnessed generalised tonic-clonic seizure. Since recovering, she has had severe left shoulder pain. An urgent treatment centre obtained a single anteroposterior shoulder radiograph, reported as showing no fracture or dislocation, and provided a sling. Her left arm is held adducted and internally rotated. External rotation is markedly restricted by a firm mechanical block. There is no obvious contour deformity. Distal pulses, capillary refill and sensation over the lateral shoulder are normal. What is the most appropriate management now?

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Correct answer: A — Arrange immediate transfer to the emergency department for orthogonal shoulder imaging and controlled reduction if posterior dislocation is confirmed

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

This is a suspected posterior glenohumeral dislocation. A seizure is a classic mechanism because powerful internal rotator contraction can dislocate the humeral head posteriorly. The fixed internally rotated posture and mechanical block to external rotation are important discriminators. Posterior dislocations may have little visible deformity and can be missed on a single anteroposterior radiograph. She needs immediate emergency-department assessment, including orthogonal imaging: an axillary view is preferred, with a Velpeau or scapular-Y view if an axillary view cannot be obtained. If dislocation is confirmed, reduction should occur in a controlled hospital setting after assessment for associated fracture and neurovascular injury. A normal distal neurovascular examination does not exclude dislocation. A is appropriate for a minor soft-tissue injury only after dislocation has been excluded. B may assess rotator cuff pathology but does not establish glenohumeral alignment in this acute presentation. C repeats the inadequate imaging modality and risks further delay. E is appropriate after confirmed reduction and exclusion of associated injury, not while a locked posterior dislocation remains possible.

Reference: NHS: Dislocated shoulder (accessed 15 August 2026) — https://www.nhs.uk/conditions/dislocated-shoulder/?src=conditionswidget Posterior shoulder dislocations (2015) — https://www.bmj.com/content/350/bmj.h75 Missed posterior shoulder fracture dislocations: a new protocol from a London major trauma centre (2020) — https://bmjopenquality.bmj.com/content/9/1/e000550