Posterior shoulder dislocation
Key facts
- Posterior glenohumeral dislocations are uncommon (≈2-4% of shoulder dislocations) but are frequently missed-up to half may be undiagnosed at first presentation. Maintain a high index of suspicion with suggestive mechanisms (seizure, electrocution, axial load on an adducted/internally rotated arm) or characteristic clinical signs (see MoD synopsis).
- Common causes: seizures or electrocution (often bilateral), direct trauma with the arm adducted and internally rotated, and high-energy injuries.
- Early recognition and timely reduction reduce morbidity and the need for surgery; delayed diagnosis increases likelihood of operative management and complications (see MoD synopsis).
Clinical features and examination
Typical presentation (acute)
- Severe shoulder pain with reluctance to move the limb.
- Arm held adducted and internally rotated; marked loss of external rotation is a key sign.
- Flattened anterior shoulder contour with posterior prominence or a palpable humeral head behind the glenoid.
- Reduced abduction may be present.
Chronic / missed presentations
- Persistent stiffness or reduced external rotation that can be mistaken for adhesive capsulitis.
- Chronicity makes closed reduction more difficult or impossible.