Anatomy and function of the glenohumeral ligaments in anterior shoulder instability.

The anatomy of the glenohumeral ligaments has been shown to be complex and variable and their function is highly dependent on the position of the humerus with respect to the glenoid. The superior glenohumeral ligament with the coracohumeral ligament was shown to be an important stabilizer in the inferior direction, even though the coracohumeral ligament is much more robust than the superior glenohumeral ligament. The middle glenohumeral ligament provides anterior stability at 45 degrees and 60 degrees abduction whereas the inferior glenohumeral ligament complex is the most important stabilizer against anteroinferior shoulder dislocation. Therefore, this component of the capsule is the most frequently injured structure. An appropriate surgical procedure to repair the inferior glenohumeral ligament complex after shoulder dislocation must be considered. In addition, a detached labrum can lead to recurrent anterior instability and a compromised inferior glenohumeral ligament complex. However, additional capsular injury usually is necessary to allow anterior dislocation.