Description

Instability refers to laxity in the “ball and socket” or scheduler joint. Instability can occur for several reasons. The severity and the direction of instability depends on the causal pathology. The shoulder joint may be unstable with the humeral head, or “ball” of the “ball and socket joint” having too much motion toward the front, back, top or bottom of the glenoid, or socket. If the humeral head is loose in more than one direction, it is referred to as multidirectional instability.

What are the causes?

Glenohumeral instability may result from an acute or chronic injury, causing damage to the ligaments, labrum, rotator cuff or capsule surrounding the joint. Once the ligaments, tendons, and muscles around the shoulder become loose or torn, dislocations can occur repeatedly. It may also be inherited and result from a genetic disease known to cause loose joints like Ehlers Danlos Syndrome or Marfan Syndrome.

What are the symptoms?

Patients with glenohumeral instability have pain and inflammation associated with excessive motion of the “ball” on the “socket”. Patients complain of “looseness” or anxiety because their shoulder feels like it’s about to “pop out” of place. Clicking and grinding may occur, as well as weakness depending on the underlying cause of the instability. Some patients may be able to voluntarily dislocate their shoulders, which is an indicator that surgical repair may not restore proper shoulder function.

How is it diagnosed?

Your surgeon will perform a thorough history and physical exam with X-rays. During the exam, your surgeon will move the shoulder through a range of motion to test for instability in all planes, as well as attempt to keep the shoulder in place to see if symptoms resolve. X-rays may or may not show evidence of instability. MRI (with a special dye) is helpful in viewing damage to the labrum and rotator cuff that surround the shoulder joint.