UMEM Educational Pearls

Category: Orthopedics

Title: Posterior Shoulder Dislocations

Keywords: Radiology, orthopedics, shoulder (PubMed Search)

Posted: 5/9/2015 by Brian Corwell, MD
Click here to contact Brian Corwell, MD

Posterior Shoulder Dislocations are uncommon (strong supporting structures vs. anterior)

But commonly missed by physicians

Mechanism: Direct blow anterior shoulder/FOOSH with shoulder internally rotated and ADDucted)

May also see with seizure/electric shock (tetanic contraction)

Clinical findings subtle

Shoulder held in ADDuction and internal rotation. Patient unable to externally rotate arm from this position. If habitus allows, anterior shoulder depression/posterior fullness.

Radiology: Decreased overlap between humeral head and glenoid fossa. Proximal humerus fixed in internal rotation looks like a light bulb on a stick.

Y view will show subtle posterior displacement of humeral head (not as dramatic as is in anterior dislocations!)