Instability and rotator cuff tear.

Prevalence of rotator cuff tears after traumatic dislocation increases with advancing age, as a consequence of the age-associated deterioration of structures and mechanical properties of the tendons of the rotator cuff. These act as effective stabilizers of the joint, compressing the humeral head in the three-dimensional concavity of the glenoid. It is impossible to establish whether a lesion of the capsulo-labrum complex or of the rotator cuff causes or follows a dislocation, regardless of whether it is anterior or posterior. A peripheral nerve or a brachial plexus injury can be associated with tendon lesion and instability, developing the 'terrible triad' of the shoulder. Both conservative and surgical management are possible, and surgeons must choose the most appropriate management modality according to the biologic age of the patients, functional demands, and type of lesion.