The shoulder can lose its normal retaining structures. The shoulder joint is surrounded by a capsule which is reinforced by a thickened area known as a ligament. Stretching or tearing of these reinforcement structures allows for abnormal slippage of the arm bone (humerus) and the shoulder cup (glenoid).
Patients will experience a feeling that the shoulder “is coming out of its joint” with activity. Sometimes, overhead activities such as pitching a baseball or serving in tennis will cause the arm to go numb. This is known as “dead arm syndrome.”
Evaluation usually involves a provocative physical exam and a specialized study such as MRI or CT arthrogram. An arthrogram is a test which involves injecting contrast material (dye) into a joint to better outline the internal structures. This test helps differentiate between normal anatomy and areas of injury.
This condition may respond to an exercise program but recurrent episodes and non-responsive joints may require physical therapy and/or surgical treatment.