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Posterior shoulder dislocation — MRCEM SBA MCQ

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HardShoulder InjuriesPosterior shoulder dislocationMRCEM SBA

A 43-year-old has severe shoulder pain after an electric shock. The arm is held adducted and internally rotated. An anteroposterior radiograph is reported as showing no fracture and no obvious dislocation, but examination remains markedly restricted. Which additional radiographic view is most useful now?

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

Reveal the answer and explanation

Correct answer: E — Obtain an axillary or modified axillary shoulder radiograph

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

E is correct. Posterior dislocation can be subtle on an anteroposterior image; a second orthogonal view, ideally axillary and otherwise modified axillary or scapular-Y, confirms direction. A comparison AP view repeats the limitation. B evaluates the sternoclavicular joint. C may show the humerus but does not reliably define glenohumeral alignment. D addresses acromioclavicular injury rather than suspected posterior glenohumeral dislocation.

Reference: BESS and BOA, Traumatic anterior instability patient care pathway: https://bess.ac.uk/download/1419/patient-care-pathways/6228/traumatic-anterior-instability-2015.pdf