Compression of the rotator cuff tendon between the arm bone and the shoulder blade results in impingement syndrome (under the acromion, subacromial; under the coracoid process, subcoracoid), causing pain upon movement of the shoulder. The symptoms usually subside after a course ofnon-operative treatment shoulder injections and physiotherapy.  Your surgeon may advise  surgery to smooth the bone (acromioplasty) if the symptoms are not resolving, or if it is associated with rotator cuff tear.