Pathology of failure of the rotator cuff tendon.

In failure of the rotator cuff tendon, interference with its function prevents the rotator cuff from fulfilling its physiologic role. Trauma in younger individuals, calcifying tendinitis, degenerative changes of cuff tendon, and partial- or full-thickness tears cause cuff failure intrinsically. Degenerative changes constitute the most frequent cause of cuff failures and correlate with tendon tearing. An acromial spur, long coracoid process, subacromial bursitis, and thickening of the corocoaromial ligament causes cuff failure extrinsically.