"Posterior shoulder dislocations are far less common than anterior shoulder dislocations and can be difficult to identify if only AP projections are obtained. A high index of suspicion is helpful."
"posterior HAGL lesion"
"posterior labrocapsular periosteal sleeve avulsion (POLPSA lesions)"
"shoulder pseudodislocation: on AP projection, an inferiorly subluxed humeral head can mimic a posterior shoulder dislocation"
Expected headings
"Mechanism"
"Plain film series usually suffices in making the diagnosis, although cross-sectional imaging (CT or MRI) is often used to assess the presence and extent of articular surface injury (reverse Hill-Sachs defect), glenoid injury (reverse Bankart lesion) or ligamentous injury. Ultrasound is uncommonly used; however, it may be useful in the emergency setting."