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Suspected acute posterior glenohumeral dislocation — MSRA MCQ

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HardShoulder InjuriesSuspected acute posterior glenohumeral dislocationMSRA

A 31-year-old man attends your GP surgery the morning after a witnessed tonic–clonic seizure. Since recovering, he has had severe left shoulder pain. At an urgent treatment centre, an anteroposterior shoulder radiograph was reported as showing no fracture or dislocation, and he was discharged with a sling. He holds the left arm adducted and internally rotated. Passive and active external rotation are both mechanically restricted. There is diffuse posterior shoulder tenderness but no clavicular tenderness. Radial pulse, capillary refill, hand power and sensation are normal. What is the most appropriate management now?

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

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Correct answer: D — Arrange same-day emergency-department assessment for orthogonal shoulder radiographs and hospital-led reduction, without attempting reduction in primary care

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

This presentation is highly suspicious for an unreduced posterior glenohumeral dislocation. The linked discriminators are a seizure mechanism, a shoulder held in adduction and internal rotation, and a mechanical block to external rotation. Posterior dislocations are readily missed on an anteroposterior radiograph; an axillary view, or an alternative orthogonal view such as a scapular-Y or Velpeau view when abduction is not possible, is needed to establish alignment. The normal distal neurovascular examination does not make this suitable for outpatient investigation or fracture-clinic review. This remains an unreduced acute dislocation requiring same-day emergency assessment, appropriate imaging and reduction in a setting able to provide analgesia, sedation and post-reduction reassessment. Reduction should not be attempted in primary care. A is unsafe because repeating the same anteroposterior projection may again miss posterior displacement. B is inappropriate because ultrasound assesses soft tissues but does not exclude dislocation. C delays diagnosis and reduction of a potentially locked dislocation. D recognises the value of cross-sectional imaging but incorrectly creates an outpatient imaging delay; emergency assessment is required first, with CT determined by the emergency and orthopaedic team if fracture-dislocation or humeral-head impaction is suspected.

Reference: NHS Tayside RefGuide: Shoulder and Elbow (Current page; accessed August 2026) — https://www.rightdecisions.scot.nhs.uk/nhs-tayside-refguide/surgery-and-orthopaedics/orthopaedic-and-trauma-surgery/shoulder-and-elbow/?organization=nhs-tayside&useNavigation=true Dislocated shoulder (Last reviewed 17 May 2023) — https://www.nhs.uk/conditions/dislocated-shoulder/ Posterior shoulder dislocations (2015) — https://www.bmj.com/content/350/bmj.h75