fracture may mimic a shoulder dislocation An AP, scapular “Y” view, and an axillary view are preferred to show the position of the dislocation and the presence of any fractures If the patient has a history consistent with dislocation but has more range of motion than expected and the radiograph is normal, the patient may have spontaneously reduced a dislocated shoulder or subluxated the glenohumeral joint and only sprained the ligaments overlying the glenoid fossa An apprehension test may confirm the subluxation diagnosis (see Fig 43.3 ) Actual tears of the rotator cuff are uncommon before 21 years of age However, if the rotator cuff muscles are damaged or weak, the humeral head is displaced upward during overhead motion This may impinge the tendon of the supraspinatus muscle and the subacromial bursa between the humeral head and the acromion or coracoid process Impingement symptoms usually occur with repetitive overhead motions (e.g., throwing a ball) The pain is commonly notable over the deltoid area though it may be poorly localized There are several tests for rotator cuff injuries that rely on fatiguing the secondary muscles and isolate the rotator cuff muscles including Neer, Hawkins, and anterior impingement testing The painful arc test (see Fig 43.4 ) has the best sensitivity and specificity Plain radiographs are usually normal, and magnetic resonance imaging is necessary to diagnosis rotator cuff injuries but does not need to be done emergently