What Causes a Rotator Cuff to Tear?
A rotator cuff tear is often the end stage of impingement by a subacromial bone spur. The supraspinatus tendon is especially prone to this. The impingement can damage the bursa (a common cause of shoulder bursitis) and eventually erode the rotator cuff tendons. A torn rotator cuff can also be caused by degeneration or traumatic injury. The rotator cuff tendons have areas of very low blood supply. The more blood supply a tissue has, the better and faster it can repair and maintain itself. The areas of poor blood supply in the rotator cuff make these tendons especially vulnerable to degeneration. The degeneration caused by repetitive shoulder motions helps explain why the rotator cuff tear is such a common sports injury. Rotator cuff tears usually occur in areas of the tendon that had low blood supply to begin with and then were further weakened by degeneration. Excessive force can tear weak rotator cuff tendons. This force can come from trying to catch a heavy falling object or lifting