Rotator Cuff Injury

What is a Rotator Cuff Tear?
The "rotator cuff" is a group of 4 muscles and their tendons (which attach them to the bone). These muscles connect the upper-arm bone, or humerus, to the shoulder blade. The important job of the rotator cuff is to keep the shoulder joint stable. 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.
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.
Tears often develop as a result of either a traumatic event or long-term overuse of the shoulder. These conditions are commonly called acute or chronic:

• An acute rotator cuff tear is one that just recently occurred, often due to a trauma such as a fall or lifting a heavy object.
• Chronic rotator cuff tears are much slower to develop. These tears are often the result of repeated actions with the arms working above shoulder level—such as with ball-throwing sports or certain work activities.

People with chronic rotator cuff injuries often have a history of rotator cuff tendon irritation that causes shoulder pain with movement. This condition is known as shoulder impingement syndrome (SIS).
Rotator cuff tears also may occur in combination with injuries or irritation of the biceps tendon at the shoulder, or with labral tears (to the ring of cartilage at the shoulder joint).