Posterior Shoulder Dislocation

History & PhysicalA 25yo male complains of shoulder pain after

falling forward on his outstretched hand after leaving a club. On exam, he holds his right arm internally rotated and adducted

Diagnosis: Post. Shoulder Dislocation

Light bulb sign: Humeral head looks rounded on AP view and posterior to the glenoid fossa on axillary view

Empty glenoid sign: Increased distance between the articular surface of humeral head and anterior glenoid

Normal range: 0-6mmThrough defect: Curved dense line, indicating impaction

fracture of the antero-medial surface of the humeral head

Closed reductionOperative repair if closed reduction unsuccessful

ImmobilizationPlace in sling and swath

Obtain post reduction filmPhysical therapy and early mobilization to

prevent frozen shoulderOrtho follow up

Prognosis if often excellent if detected early but very susceptible to reinjury and repeated dislocations if detected late

ED Management

History typically of axial load to the adducted and internally rotated arm (fall on outstretched arm or blow to the front of shoulder

Although the mechanism of fall on outstretched arm is more common, test questions will often use a pt presenting after a seizure or electrical shock

Only 20% abduction needed to obtain axillary view, but if unable to obtain, use a scapular Y view

Associated withDetachment of posterior glenoid labrum (reverse

Bankhart)Defect of the anteromedial aspect of the humeral head

(reverse Hill-Sachs)Fractures of the humeral tuberosities, shaft, and/or

humeral neck.

Pearls

Additional Images

Additional Images

Additional Images

Marx J MD; Hockberger R MD; Walls R MD. Rosen’s emergency medicine. 7th ed.

Simon R; Sherman S; Koenigsknecht S. Emergency orthopedics: the extremities. 5th ed. McGraw Hill Publishing.

Wheeless C R III MD. Wheeless textbook of orthopedics. www.wheelessonline.com.

References