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Post-Stroke Shoulder Subluxation – Mechanism — SCE Neurology MCQ

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EasyNeurorehabilitationPost-Stroke Shoulder Subluxation – MechanismSCE Neurology

A 65-year-old man with a left MCA stroke has developed post-stroke shoulder pain. The shoulder is subluxated inferiorly. He has no CRPS features. His arm is flaccid (MRC 0/5). What is the mechanism of shoulder subluxation after stroke?

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Correct answer: A — Loss of supraspinatus and deltoid muscle tone (flaccidity) allows the weight of the paralysed arm to pull the humeral head inferiorly out of the glenoid fossa — the shoulder joint relies on muscle tone for stability

Post-stroke shoulder subluxation occurs because the glenohumeral joint has minimal bony stability — it relies on rotator cuff muscles (particularly supraspinatus) and deltoid for stability. In the flaccid stage after stroke, loss of tone in these muscles allows gravity to pull the heavy arm inferiorly, causing subluxation. Prevention: proper arm positioning/support from the first day (slings, arm troughs, foam supports, lap trays), careful handling by all staff. Treatment: electrical stimulation to supraspinatus/deltoid, taping, and progressing to active exercises as tone returns. A: Spasticity occurs later; subluxation occurs in the flaccid phase. C: No fracture. D: No ligament rupture. E: Not the mechanism.

Reference: RCP Stroke Guidelines; NICE CG162