Glenohumeral Joint Instability: A Review of Anatomy, Clinical Presentation, and Imaging.

The glenohumeral joint is intrinsically predisposed to instability because of the bony anatomy but maintained in alignment by many important structures, including the glenoid labrum, glenohumeral ligaments (GHLs), and muscles and tendons. Trauma and overuse can damage these stabilizers, which may then lead to subluxation or dislocation and eventually recurrent instability. This is most common in the anterior direction, which has several recognizable patterns of injury on advanced imaging, including humeral Hill Sachs deformities, bony Bankart lesion of the anteroinferior glenoid, soft tissue Bankart lesions, Bankart variant lesions (Perthes and ALPSA lesions), and HAGL/GAGL lesions. Similar reverse lesions are seen, as well as unique posterior lesions, such as Bennett and Kim's lesions. When symptoms of apprehension and instability in more than one direction are seen, one should consider multidirectional instability, which often presents with a patulous joint capsule. Finally, owing to significant impacts of daily activities and quality of life, surgical correction of labral tears, bony Bankart defects, Hill Sachs defects, and capsular laxity, may be considered.