Presentation
Posterior shoulder dislocation followed by pain and limited movement. The patient is a basketball player.
Patient Data
The patient had traumatic posterior shoulder dislocation with the development of the following:
- Reverse Hill Sachs lesion and Trough line sign as evident by depression of the anteromedial aspect of humeral head.
- Posterior labral tear with avulsion of the posteroinferior labrum which appears hypertrophied. It remains attached to the capsule and periosteum (periosteal sleeve avulsion).
- Posterior de-centering of the humeral head relative to the glenoid consistent with posterior instability.
- Marrow edema of the glenoid.
- Os acriomiale as an incidental finding.
Diagnosis: Posterior labroligamentous periosteal sleeve avulsion (POLPSA) and posterior shoulder instability secondary to posterior shoulder dislocation.
Case Discussion
When posterior shoulder dislocation occurs, the anteromedial aspect of humeral head hits the posterior glenoid resulting in compression fracture of anteromedial humeral head (Reverse Hill Sachs lesion and trough line sign) as well as posterior labral tear, glenoid avulsion fracture and reverse Bankart lesion.
In this patient the avulsed posterior labrum remains attached to a sleeve of periosteum known as Posterior labroligamentous periosteal sleeve avulsion (POLPSA), a recognized reverse Bankart variant. This lesion is associated with posterior shoulder instability and requires surgical intervention.
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