The rotator cuff is the group of muscles and tendons that connect the upper arm bone (humerus) to the shoulder socket. The cuff provides mobility and support to the shoulder joint. Rotator cuff tears are injuries caused by either acute trauma or degenerative wear and tear.

For example, an acute tear could occur if a person falls on an outstretched arm or lifting an overly heavy item with a jerking motion. A tear can also occur with a broken collarbone or dislocated shoulder. Most degenerative tears occur because the tendon has worn down over time due to aging or overuse. The dominant arm is usually more susceptible to wear and tear. If you have a degenerative tear in one shoulder, likelihood of the second shoulder tearing increases.

Different factors can contribute to degenerative tears such as repeating the same motions over and over again. Sports such as baseball, tennis, rowing, and weightlifting can put a person at risk for overuse tears. Jobs and chores can also cause overuse tears.

As a person ages, the blood supply in the tendons also diminishes. This impairs the body's natural ability to repair it, ultimately leading to a tear.