History
An acromioclavicular joint injury should be considered in any patient complaining of pain over the superior part of the shoulder, [24] particularly after a fall either onto the apex of the shoulder or onto an outstretched hand. Patients may also notice restricted shoulder motion.
In the immediate setting, the patient may initially experience generalized shoulder tenderness and swelling; however, as the diffuse pain resolves, specific point tenderness over the acromioclavicular joint is usually noted.
The athlete may note a significant abrasion or prominence of the distal clavicle. Athletes involved in weight training typically experience pain with specific exercises such as with use of the bench press and dips.
Many individuals experience nocturnal pain and awakening when rolling onto the involved shoulder, which puts pressure on the acromioclavicular joint. Rarely, the patient may report popping or catching in the region of the acromioclavicular joint.
Physical Examination
Patients have pain over the acromioclavicular joint. Swelling, bruising, and a prominent clavicle may be evident, depending on the type of sprain that the patient has sustained. In types I and II sprains, deformity is usually minimal.
In type III injuries, the distal clavicle is abnormally prominent. A prominent clavicle with loss of the normal contour of the shoulder caused by sagging of the acromion is highly suggestive of a ligamentous disruption of the acromioclavicular joint. Of note, clavicle fractures, without acromioclavicular joint sprains, can also cause the clavicle to be prominent.
With an acute injury, the patient has poor shoulder range of motion and moderate pain when trying to raise the arm. These patients can often be seen carrying the affected arm close to the side of their bodies. Alternatively, patients use the unaffected arm to splint the injured extremity. These findings may be clearer when the patient is asked to hold a 10- to 15-lb weight in the hand of the affected arm.
In the acute situation, the examiner may have difficulty ruling out a concomitant rotator cuff tear, as active and passive shoulder abduction maneuvers are difficult to perform in the face of an acromioclavicular joint separation.
The most reliable physical examination test for acromioclavicular joint pathology is the cross-body adduction test. This test assesses the stability of the affected shoulder and should be performed by manipulating the midshaft of the clavicle rather than the acromioclavicular joint itself. The patient elevates the arm on the affected side 90°, while the examiner grasps the elbow and adducts the involved arm across the body.
Although reproduction of pain with this maneuver may occur in patients with posterior capsule tightness or subacromial impingement, pain is suggestive of acromioclavicular joint pathology. Restriction of range of motion, which is rarely associated with acromioclavicular joint pathology, more likely suggests adhesive capsulitis or glenohumeral arthritis.
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Acromioclavicular joint anatomy.
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Classification of acromioclavicular joint injuries.
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Allman/Rockwood classification of acromioclavicular injuries.
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Anteroposterior (AP) radiograph of right shoulder showing step-off of the acromioclavicular (AC) joint.
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Type III acromioclavicular joint separation.
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Type III acromioclavicular joint separation.
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Postoperative coracoclavicular ligament reconstruction. The clavicle is back to its normal position. The anchor in the clavicle keeps the allograft tendon from coming off of the clavicle. Also note the distal clavicle has been excised, because it had traumatic arthritis from the injury.
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Type V separation, characterized by wide displacement of the clavicle in a superior direction relative to the acromion. The radiographic findings denote disruption of the acromioclavicular AC ligaments and coracoclavicular (CC) ligament, as well as the deltoid attachment to the distal clavicle.
