Instability may be a dislocation or subluxation. A dislocation is when the “ball” comes completely out of the “socket.” It may be out for only seconds or longer. It may become lodged out of the joint and require treatment at an emergency room to reinsert. Subluxation is when the “ball” comes only partially out of the “socket.” It returns spontaneously into the socket. Dislocation is a more serious form of instability than subluxation. The shoulder is the most mobile joint in the body and instability is common. Dislocation is usually caused by trauma. Subluxation may occur without trauma. Subluxation may occur in athletes whose shoulder becomes stretched in their sport, such as baseball pitchers or swimmers.
When shoulders suffer a typical antero-inferior dislocation, the inferior glenohumeral ligament is torn. In most cases it does not heal and shoulders suffer repeated dislocations. The younger the person is at the time of the initial dislocation, the likelier this is to be true. When repeated dislocations occur surgery is usually needed.
Tightening or repair of the shoulder ligaments can be performed either through a traditional open incision or arthroscopically. While it is often successful, the arthroscopic results so far have not been as good as traditional open surgery using an incision. The arthroscopic repair involves the use of three portals. The open repair is performed similarly but with an incision.
Treatment involves repair of the glenoid labrum (a lip of rubbery tissue attaching to the shoulder socket). The capsule may also be sutured to tighten it or it may be pulled upward to take up slack. Bio-absorbable suture anchors are embedded into the bone to anchor the repair.
Thermal capsular shrinkage may also be employed to tighten the shoulder ligaments. This process uses energy in the form of heat imparted by a variety of instruments to shrink the capsule and tighten the shoulder. This generally is used to “fine tune” a minor amount of shoulder looseness. Permanent damage to the shoulder ligaments has been reported from using thermal capsular shrinkage.
Success rates are high but patients must protect the shoulder for six months to allow healing.