Management of Shoulder Instability

Abstract

I nstability of the glenohumeral joint falls into two categories, traumatic and atraumatic. Both have a variety of nonoperative and operative treatments. In general, traumatic means that a stabilizing structure is torn or broken. In atraumatic instability, a specific trauma may not be identifiable-rather, the mechanisms that together stabilized the shoulder no longer do so; for example, a weakening of muscles may allow a loose but previously functional joint to become unstable. We discuss below these categories of instability in terms of the evaluation, nonoperative management, and surgical management with its corresponding postoperative rehabilitation. We distinguish instability from laxity. Instability is the inability to maintain the humeral head articular surface centered in the glenoid fossa. Laxity is the amount of joint motion allowed by the joint capsule and the configuration of the joint itself. A relatively large amount of motion may be allowed by a particular joint configuration and capsule, while still maintaining the humeral head articular surface centered in the glenoid fossa: laxity does not necessarily imply instability. 2