The “rotator cuff” is a group of 4 muscles and their tendons that are responsible for keeping the shoulder joint stable. These muscles connect the upper-arm bone, or humerus, to the shoulder blade. Unfortunately, injuries to the rotator cuff are very common, either from injury or with repeated overuse of the shoulder. Sometimes, the rotator cuff becomes inflamed or irritated due to heavy lifting, repetitive arm movements, or a fall. A rotator cuff tear occurs when injuries to the muscles or tendons cause tissue damage or disruption. When left untreated, this injury can cause severe pain and a decrease in the ability to use the arm. Rotator cuff tears are called either “full-thickness” or partial-thickness” depending on how severe they are. Full-thickness tears extend from the top to the bottom of a rotator cuff muscle/ tendon. Partial-thickness tears affect at least some portion of a rotator cuff muscle/ tendon, but do not extend all the way through. Rotator cuff tears can cause pain over the top of the shoulder or down the outside of the arm, shoulder weakness, and loss of range of motion in the shoulder. In severe cases, tears may keep you from doing your daily activities or even raising your arm.