In an unstable shoulder joint, the ligaments of the shoulder become loose or unstable as a result of injury or trauma causing dislocation. In some people, the shoulder structure is naturally loose, causing multiple dislocations of the shoulder. As it becomes loose, the head of the upper arm bone (humerus) has a tendency to slip out of the socket, causing either partial or full dislocation. The supporting structures in the shoulder (ligaments, tendons and cartilage) can become damaged, and contribute to instability.

Your surgeon will make a diagnosis through imaging, examination and various testing of the shoulder, and you may subsequently require surgical treatment. During your initial consultation, your surgeon will discuss the different kinds of surgery with you, including a Bankart repair and capsular shift.