Advanced imaging of glenohumeral instability: the role of MRI and MDCT in providing what clinicians need to know.

The inherently unstable anatomy of glenohumeral (GH) joint predisposes it to shoulder dislocation. Shoulder dislocation can occur either due to acute trauma or due to chronic microtraumas in the setting of underlying morphological abnormality. A plain radiograph is the initial imaging modality for diagnosis and management of shoulder dislocation and its associated osseous abnormalities such as Hill-Sachs deformity or osseous Bankart lesion. However, advanced imaging techniques such as multidetector CT (MDCT) with three-dimensional (3D) volume rendering and MRI can be helpful in further characterization of osseous abnormalities and detection of associated soft tissue injuries, respectively. These additional findings may be useful for optimal surgical repair for GH joint stabilization. In this pictorial essay, we present the clinically relevant osseous and soft tissue pathologies in various types of shoulder dislocation, with emphasis on pathologies that can be demonstrated using advanced imaging examinations. Discussed pathologies include glenoid fractures, labral tears, Bankart lesion, Hill-Sachs defect, Perthes lesion, anterior labral posterior sleeve avulsion (ALPSA), glenolabral articular disruption (GLAD), humeral avulsion of the glenohumeral ligament (HAGL), Kim lesion, and other associated soft tissue and nerve injuries.