Lower Back Issues

Shoulder Instability

Causes
Shoulder instability often follows an injury that caused the shoulder to dislocate. This initial injury is usually fairly significant, and the shoulder must be reduced. To reduce a shoulder means it must be manually put back into the socket. The shoulder may seem to return to normal, but the joint often remains unstable. The ligaments that hold the shoulder in the socket, along with the labrum (the cartilage rim around the glenoid), may have become stretched or torn. This makes them too loose to keep the shoulder in the socket when it moves in certain positions. An unstable shoulder can result in repeated episodes of dislocation, even during normal activities. Instability can also follow less severe shoulder injuries.

In some cases, shoulder instability can happen without a previous dislocation. People who do repeated shoulder motions may gradually stretch out the joint capsule. This is especially common in athletes such as baseball pitchers, volleyball players, and swimmers. If the joint capsule gets stretched out and the shoulder muscles become weak, the ball of the humerus begins to slip around too much within the shoulder. Eventually this can cause irritation and pain in the shoulder.

A genetic problem with the connective tissues of the body can lead to ligaments that are too elastic. When ligaments stretch too easily, they may not be able to hold the joints in place. All the joints of the body may be too loose. Some joints, such as the shoulder, may be easily dislocated. People with this condition are sometimes referred to as double-jointed.

Symptoms
Chronic instability causes several symptoms. Frequent subluxation is one. In subluxation, the shoulder may slip (sublux) in certain positions, and the shoulder may actually feel loose. This commonly happens when the hand is raised above the head, for example while throwing. Subluxation of the shoulder usually causes a quick feeling of pain, like something is slipping or pinching in the shoulder. Over time, you may stop using the shoulder in ways that cause subluxation.

The shoulder may become so loose that it starts to dislocate frequently. This can be a real problem, especially if you can’t get it back in the socket and must go to the emergency room every time. A shoulder dislocation is usually very obvious. The injury is very painful, and the shoulder looks abnormal. Any attempted shoulder movements cause extreme pain. A dislocated shoulder can damage the nerves around the shoulder joint.

If the nerves have been stretched, a numb spot may develop on the outside of the arm, just below the top point of the shoulder. Several of the shoulder muscles may become slightly weak until the nerve recovers. But the weakness is usually temporary.