Posterior instability (Reprinted from Operative Techniques in Sports Medicine, July, 2000)

Posterior shoulder instability is a pathology that is increasingly seen in athletes. Excessive capsular laxity was originally proposed as the key comp onent. Recent cadaveric and arthroscopic work has identified the importance of glenolabral integrity and glenoid depth in maintaining glenohumeral sta bility. Arthroscopic techniques to treat posterior instability are emerging . Until recently, reports of arthroscopic reconstruction focused entirely o n capsular glenohumeral stability by altering two separate mechanisms: deep ening of the glenoid concavity and reducing the capsular joint volume. This is accomplished by shifting the capsule to buttress the glenoid labrum. Th us increasing capsular tension increases the resultant compressive force ve ctor into a deepened glenolabral concavity that, when combined together, en hances glenohumeral stability. In clinical and laboratory settings, we have shown that posteroinferior shoulder instability is associated with both ca psular laxity and well-defined pathological lesions of the glenolabral conc avity. Our results indicate that arthroscopic posterior capsulolabral repai r and augmentation is a useful tool to restore the depth of the glenolabral concavity and to reduce the redundant posteroinferior capsule. This techni que is effective in treating posteroinferior instability.