Rotator cuff tear helps to confirm that the pain arises from the shoulder primarily rather than referred from the neck, heart, or gut. If pain is relieved, the test is considered positive for rotator-cuff impingement, of which tendinitis and bursitis are major causes. However, partial rotator-cuff tears may also demonstrate good pain relief, so a positive response cannot rule out a partial rotator-cuff tear. However, with demonstration of good, pain-free function, treatment will not change, so the test is useful in helping to avoid overtesting or unnecessary surgery. Long-term overuse/abuse of the shoulder joint is generally thought to limit range of motion and
Rotator cuff arm, moving it outward and away from the trunk, the rotator cuff compresses the glenohumeral joint, an action known as concavity compression, in order to allow the large deltoid muscle to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle. The anterior and posterior directions of the glenoid fossa are more susceptible to shear force perturbations as the glenoid fossa is not as deep relative to the superior and inferior directions. The rotator cuff's contributions to concavity compression and