The rotator cuff is a group of four muscles and their associated tendons that wrap around the shoulder joint. Together they stabilise the ball within the socket of the shoulder, and allow the arm to be lifted, rotated, and controlled during overhead activities. A rotator cuff tear occurs when one or more of these tendons is partially or fully disrupted.
Tears may be traumatic — caused by a fall, a sudden forceful movement, or a direct impact — or degenerative, developing gradually over time as the tendon tissue ages and weakens. Degenerative tears are more common and typically affect people over the age of 50, though they can occur at any age in people who perform repetitive overhead activities.