Shoulder instability is a problem that occurs when the structures that surround the shoulder joint do not work to keep the ball tightly within its socket. If the joint is too loose, is may slide partially out of place, a condition called shoulder subluxation. If the joint comes completely out of place, this is called a shoulder dislocation. Patients with shoulder instability often complain of an uncomfortable sensation that their shoulder may be about to shift out of place–this is what physicians call “apprehension.”
Causes of Shoulder Instability
Shoulder instability tends to occur in three groups of people:
• Prior Shoulder Dislocators
Patients who have sustained a prior shoulder dislocation often develop chronic instability. In these patients, the ligaments that support the shoulder are torn when the dislocation occurs. If these ligaments heal too loosely, then the shoulder will be prone to repeat dislocation and episodes of instability. When younger patients (less than about 35 years old) sustain a traumatic dislocation, shoulder instability will follow in about 80% of patients.
• Young Athletes
Athletes who compete in sports that involve overhead activities may have a loose shoulder ormultidirectional instability (MDI). These athletes, such as volleyball players, swimmers, and baseball pitchers, stretch out the shoulder capsule and ligaments, and may develop chronic shoulder instability. While they may not completely dislocate the joint, the apprehension, or feeling of being about to dislocate, may prevent their ability to play these sports.
• “Double-Jointed” Patients
Patients with some connective tissue disorders may have loose shoulder joints. In patients who have a condition that causes joint laxity, or double-jointedness, their joints may be too loose throughout their body. This can lead to shoulder instability and even dislocations.
Initial treatment focuses on strengthening the muscles of the shoulder girdle. Having stronger muscles in both the front and back of the shoulder will increase the shoulder’s stability.
Surgical management may be implemented if rehabilitation fails to enhance stabilization. By tightening the shoulder capsule and/or repairing damaged tissue, shoulder stability can be enhanced. This is often performed through an open incision, but an arthroscopic procedure may be recommended in some cases. The prognosis for stability after shoulder surgery is generally good.