MR imaging of the shoulder: first dislocation versus chronic instability.

Traumatic dislocation of the shoulder is a frequent injury in the young and active population. An acute shoulder dislocation often denotes a onetime traumatic episode, whereas chronic shoulder instability indicates multiple recurrent dislocations. Imaging, in particular MRI, is a useful tool that can accurately demonstrate the typical soft tissue and osseous markers of shoulder dislocation. However, the ability to differentiate between first time versus recurrent dislocation based on imaging remains in question. In this article, we describe the underlying biomechanics of glenohumeral stability as well as the imaging features and treatment options of shoulder dislocation. A review of current literature is presented, aimed to shed light about the potential role of imaging in distinguishing first dislocation versus chronic instability.