Acromioclavicular Separations

Scope and Mini-Open Technique

Elizabeth M. Watson and Stephen J. Snyder

Rockwood classified acromioclavicular injuries into types I to VI. It is commonly agreed that types I and II injuries, which are assumed to have intact coracoclavicular ligaments, can be managed nonoperatively. There is controversy regarding the treatment of grade III acromioclavicular (AC) separations. These injuries are assumed to have disruption of both the AC and the coracoclavicular (CC) ligaments. The current literature demonstrates satisfactory outcomes with both nonoperative and operative management. More recently there has been a trend toward nonoperative management of type III injuries though some authors still favor surgical management in patients who are heavy manual laborers or athletes performing high-demand upper extremity activities. Most authors agree that grades IV, V, and VI injuries should be treated with surgical reconstruction. These injuries have disruption of the AC and CC ligaments, have significant clavicle displacement, and often violate the deltotrapezial fascia.


1.    Rockwood types IV, V, and VI AC dislocations.

2.    Occasionally Rockwood type III AC separations. Surgical treatment is usually reserved for patients who place high demands on the upper extremity, such as heavy laborers and competitive athletes who perform repetitive overhead activities. Surgery is also indicated in rare situations for cosmetic considerations.


1.    Local skin lesions (abrasion, cellulitis)

2.    Associated clavicle shaft fracture

3.    Fracture of the coracoid

Mechanism of Injury

A direct blow to the lateral shoulder, which drives the acromion and the rest of the scapula downward and away from the clavicle, usually produces the injury. This causes a “separation” of the acromion from the clavicle. Sequentially, the AC capsule is disrupted first followed by the CC ligaments. Less commonly, a fall onto the elbow can cause an AC disruption by driving the humerus and scapula superiorly.

Physical Examination

1.    Prominence of the distal clavicle relative to the acromion producing the appearance of a “bump” at the distal clavicle. This prominence often can be both visualized and palpated. Comparison is made to the contralateral side.

2.    Tenderness, bruising, and/or swelling over the AC joint.

3.    Tenting of the skin at the distal clavicle in more severe injuries.

4.    Pain at the AC joint with cross-arm adduction, internal rotation of the arm behind the back, or arm extension.

5.    Supporting the ipsilateral arm and gently displacing the humerus superiorly can demonstrate a “ballotable” AC joint. This drives the scapula and acromion superiorly and thus reduces the position of the acromion relative to the clavicle. At the same time the clavicle is manually “balloted” downward to complete the reduction maneuver. This may be too painful to conduct in the acute setting.

6.    Rarely, paresthesias and vascular compromise can occur from compression to the brachial plexus and subclavian vasculature, especially with a type VI infracoracoid dislocation.

Diagnostic Tests

1.    Standard radiographic anteroposterior (AP) shoulder views may demonstrate the high-riding distal clavicle.

2.    Cephalic tilt view (15 degrees) provides a better AP of the AC joint than the standard shoulder AP view.

3.    Axillary view is useful to demonstrate anterior and posterior displacement of the distal clavicle relative to the acromion, which cannot be appreciated on AP views. This view is also useful to diagnose associated coracoid fractures.

4.    AP “stress” views of both shoulders with the patient holding 10 pounds of weight in each hand can exacerbate the relative downward displacement of the acromion. This test is usually reserved for diagnosing an occult AC separation when the diagnosis is uncertain, though this is seldom necessary.

Special Considerations

The surgeon and patient must understand that this surgical procedure is a major ligament reconstruction, and it should be treated by both with the care and respect needed to afford ample time for healing both the transferred coracoacromial (CA) ligament and the soft tissue envelope.

Preoperative Planning and Timing of Surgery

1.    Immediate surgical intervention is indicated if there is neurovascular compromise or significant tenting of the skin that threatens penetration and conversion to an open injury.

2.    For most types IV, V, and VI injuries, early intervention is preferred although surgery can be delayed for several days or weeks if necessary until local swelling and soft tissue injury has improved.

3.    Most type III injuries can be treated conservatively for a period of time. Surgical intervention is offered when pain, decreased function, or unacceptable cosmetic deformity persists after a trial of conservative therapy. Earlier intervention can be considered for manual laborers or high-level athletes performing repetitive overhead activities.

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