Subacromial (subdeltoid) bursitis:
The subacromial bursa lies between the acromion and the rotator cuff. It cushions the coracoacromial ligament from the supraspinatus muscle. When the arm is resting at the side, the bursa protrudes laterally from beneath the acromion. When the arm is abducted, it rolls medially beneath the bone. Subacromial bursitis is frequently associated with supraspinatus tendonitis because inflammation extends from one structure to the next. Repetitive activities with an elevated arm most frequently cause inflammation of the bursae. Examples of this include frequent pitching of a baseball or lifting luggage overhead. Less commonly, a primary process, such as rheumatoid arthritis, gout, or tuberculosis, may lead to bursitis. Patients often exhibit tenderness over the greater trochanter. Difficulty in abduction may occur, specifically from 70-100 degrees.