What are rotator cuff disorders?

The rotator cuff is a group of tough, flexible fibers (tendons) and muscles in the shoulder . Rotator cuff disorders occur when tissues in the shoulder get irritated or damaged. Rotator cuff disorders include:

• Inflammation of the tendons (tendinitis) or of a bursa (bursitis). In the shoulder, a bursa is a small, fluid-filled sac that serves as a cushion between the tendons and the bones.
• Impingement, in which a tendon is squeezed and rubs against bone.
• Calcium buildup in the tendons, which causes a painful condition called calcific tendinitis.
• Partial or complete tears of the rotator cuff tendons. See a picture of a torn rotator cuff tendon .

How does the shoulder work, and what does the rotator cuff do?

The shoulder is a joint with three main bones: the upper arm bone (humerus), the collarbone (clavicle), and the shoulder blade (scapula). The bones are held together by muscles, tendons, and ligaments. The rotator cuff keeps the upper arm bone in the shoulder socket and lets you raise and twist your arm.

The shoulder is a ball-and-socket joint. The ball at the top of the upper arm bone fits into the socket of the shoulder blade. This socket is shallow, which lets you move your arm in a wide range of motion. But it also means that the muscles and tendons of the rotator cuff have to work hard to hold the bones in place. As a result, they are easy to injure and are prone to wear and tear.

What causes rotator cuff disorders?

Most rotator cuff disorders are caused by a combination of:

• Normal wear and tear. Using your shoulder for many years slowly damages the rotator cuff. As you age, everyday activities can lead to changes in the rotator cuff, such as thinning and fraying of the tendons and reduced blood supply.
• Overuse. Activities in which you use your arms above your head a lot-such as tennis, swimming, or house painting-can lead to rotator cuff problems. Even normal motions made often over a long period can stress or injure the rotator cuff.

Both normal wear and tear and overuse can lead to impingement, when a tendon rubs against bone. This damages and irritates the tendon, which causes bleeding and inflammation. Over time, damage to the tendon may build up, so the tendon is more easily injured.

It takes great force to tear a healthy rotator cuff tendon. This can happen during sports, an accident, or a severe fall. But even a simple movement like lifting a suitcase can cause a rotator cuff tear in an older adult or someone whose shoulder is already damaged.

What are the symptoms?

Symptoms of a rotator cuff disorder include pain and weakness in the shoulder. Most often, the pain is on the side and front of the upper arm and shoulder. It may hurt or be impossible to do everyday things, such as comb your hair, tuck in your shirt, or reach for something. You may have pain during the night and trouble sleeping.