The shoulder is the most mobile joint in the body, with a flat socket and a round head. There is little intrinsic stability in the shoulder joint, and the stability is maintained by ligaments. There are two types of shoulder instability. There is a traumatic unidirectional instability, when the shoulder is pulled out of socket by trauma. This is particularly common in younger athletes, and usually results in tearing away of the ligaments from the bone. This is called a Bankart lesion. Patients who are under 25 and sustain a shoulder dislocation with a Bankart lesion, are at a higher risk of recurrence. If they remain active, most of these patients will require shoulder stabilization. There is controversy as to whether the patient should be treated with stabilization after an initial dislocation. Although this has the advantage of decreasing further damage to the shoulder with repeat dislocations, there is a small group of patients who will be able to do well after the dislocation. For a patient who needs to be ready for athletic season or who does not want to experience another shoulder dislocation, a primary shoulder repair is a reasonable option. Otherwise, a trial of conservative treatment can be attempted with a short period of immobilization for comfort, followed by a good strengthening program. If the shoulder remains in place, then no further treatment is required. If a second shoulder dislocation occurs, then I would recommend proceeding with stabilization. Patients who have had multiple dislocations should consider surgery to prevent further damage to the shoulder joint which may ultimately result in arthritis in the shoulder.
The second type of shoulder instability is due to multidirectional laxity. These are patients who have loose ligaments, and the shoulder gradually stretches out over time. In contrast to patients with unidirectional instability, these patients have instability both anteriorly and posteriorly and inferiorly. There is often no good history of trauma, and the ligament attachments are usually intact, with the ligament simply being stretched. Also in contrast to a traumatic instability, these are generally treated with conservative measures. The mainstay of treatment is a good strengthening program and proprioceptive training program for the muscles about the scapula and the rotator cuff. Most patients can be successfully treated with these measures.
In a small group of patients who are unsuccessfully treated with conservative measures, surgical intervention is undertaken. This generally will consist of an arthroscopic anterior-posterior and inferior capsulorrhaphy. This is an outpatient surgery. The recovery time after surgery is prolonged, and the patient should understand that although they may have a more stable shoulder, the shoulder will be stiff and they will lose some motion. Some patients with multidirectional instability will be unhappy with this.