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:
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.
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.
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.