Subacromial impingement and degenerative changes of the acromioclavicular joint are common causes of shoulder pain. Repetitive overhead use can lead to a painful inflammatory process, termed impingement, of the subacromial bursa and the supraspinatus as they traverse a bony outlet under the acromion. These patients often report pain with overhead activities, lateral shoulder pain, night pain, and pain with abduction and internal rotation. Likewise, hypertrophic changes from a degenerative acromioclavicular joint can lead to localized pain as well as impingement of the underlying rotator cuff. In these patients, anterosuperior pain that worsens with cross-body adduction or reaching behind the back may be more typical.