University of Virginia Health System

Shoulder impingement syndrome involves the compression of a shoulder muscle tendon, the shoulder bursa (a lubricating sac that helps with the sliding of tendons), and the long head of the biceps tendon, all of which are located under the top part of the shoulder blade called the acromion arch. Impingement (pinching) most often occurs in repetitive overhead activities such as swimming, skiing, serving a tennis ball, spiking a volleyball, throwing a ball, or jobs involving overhead reaching.

Signs and Symptoms:
The athlete complains of pain around the top of the shoulder over the acromion arch. Touching the area with some pressure usually increases the pain and the discomfort. When the physician puts downward pressure on the acromion while elevating the athlete's arm in a forward-flexed manner the pain can be reproduced to indicate impingement. If the athlete's arm is raised overhead while the shoulder blade is stabilized and pain occurs, this is another positive sign that impingement exists.

Causes:
Shoulder impingement syndrome is closely related to shoulder instability. This instability has been brought about by laxity of the shoulder muscle tendons (called the rotator cuff) that have to position the head of the arm bone (humerus) against the shoulder girdle during overhead activities. Failure of these shoulder muscles to maintain the humeral head properly allows for excessive movement of the head to occur. Eventually this repetitive stress leads to the inflammation of the tendons and bursa located under the acromion arch. The acromion actually impinges (pinches) these structures when the space between them narrows. Prolonged inflammation of these structures can cause additional muscular weakness, a thickened bursa, and the possible rupture of the two tendons.

Treatment:
Initial treatment focuses on pain relief by limiting overhead activity, administering ice to the affected area, and the use of nonsteroidal anti-inflammatory medications. As soon as the pain will allow, an exercise program is begun concentrating on shoulder muscle stretching and strengthening exercises. Most athletes will respond to these treatment measures and return to their sport without further treatment. When the athlete fails to respond to the treatment, the athlete should be re-evaluated for other causes of pain that may actually involve an injury of the rotator cuff muscles and tendons of the shoulder girdle. If the athlete's shoulder fails conservative treatment, surgery may be indicated.

Proper stretching and strengthening of the involved muscles and associated tendons is one of the mainstays of treatment. Stretching involves gently stretching the shoulder in all directions. This is combined with strengthening the muscles of the forearm.

Surgical treatment begins with the arthroscopic evaluation of the shoulder joint and the subacromial space. If there is evidence of pathologic changes, arthroscopic acromioplasty (removal of some of the acromion) is often recommended to relieve the mechanical impingement. Also, arthroscopic surgery can be used to repair partial rotator cuff tears. In advanced stages of the syndrome, open surgical repair is required to repair complete rotator cuff tears, perform an acromioplasty, and remove a compromised bursa.

It must always be remembered that a repaired rotator cuff can be torn again as a result of either overzealous therapy or another traumatic incident. So, having patience during the rehabilitation process is a virtue. Depending on the type of surgical treatment, the athlete can return to full, unrestricted pain-free activity as early as three to six months or it may take more than a year to recover. In severe situations, the athlete will not be able to return to the same level of sports activity.