Anatomic Acromioclavicular Joint Reconstruction

Albert Lin, MD

Mark William Rodosky, MD

Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Lin and Dr. Rodosky.

PATIENT SELECTION

Acromioclavicular (AC) joint injuries are common injuries that account for as many as half of all athletic shoulder injuries.¹ The most frequent mechanism of AC joint separation is a direct fall onto an adducted shoulder. The forces transmitted often result in inferior and medial displacement of the acromion while the clavicle remains stabilized to the bony thorax through the sternoclavicular joint.² Patients may present with local swelling, apparent deformity with prominence of the distal clavicle, pain over the AC joint, and accentuation of pain with cross-body adduction or abduction. The stability of an AC joint separation on physical examination may also be assessed, with the ability to reduce depending on the acuity of the injury and the severity of soft-tissue injuries. In higher energy injuries, associated injuries to the clavicle, scapula, proximal humerus, and neurovascular structures such as the brachial plexus should be assessed. Separations of the AC joint are often classified by the Rockwood classification scheme (Table 1), which usually dictates the treatment options. Type I injuries, where there is no appreciable deformity of the AC joint, and type II injuries, where there may be disruption of the AC joint capsule but not of the coracoclavicular ligaments and thus no vertical instability, are almost uniformly treated nonsurgically.

TABLE 1 Rockwood Classification of Acromioclavicular Joint Injuries

Type	AC Ligaments	CC Ligaments	Deltopectoral Fascia	Radiographic CC Distance Increase	Radiographic AC Appearance	AC Joint Reducible?
I	Sprained	Intact	Intact	Normal (1.1-1.3 cm)	Normal	N/A
II	Disrupted	Sprained	Intact	<25%	Widened	Yes
III	Disrupted	Disrupted	Disrupted	25%-100%	Widened	Yes
IV	Disrupted	Disrupted	Disrupted	Increased	Posterior clavicle displacement	No
V	Disrupted	Disrupted	Disrupted	100%-300%	N/A	No
VI	Disrupted	Intact	Disrupted	Decreased	N/A	No
AC = acromioclavicular, CC = coracoclavicular, N/A = not applicable. Adapted from Simovitch R, Sanders B, Ozbaydar M, Lavery K, Warner JJ: Acromioclavicular joint injuries: Diagnosis and management. J Am Acad Orthop Surg 2009;17[4]:207-219.

Indications for surgical treatment include type IV, V, and VI AC joint separations; these represent higher energy mechanisms of injury and associated soft-tissue disruption. These injuries are not reducible on physical examination, with type IV AC joint separations representing posterior displacement of the clavicle through the trapezius; type V injuries representing detachment of the deltoid, trapezius, and fascia or the dynamic stabilizers of the AC joint from the clavicle; and type VI injuries representing a rare entity in which the clavicle is inferiorly displaced under the coracoid in the setting of high-energy trauma with associated fractures of the shoulder girdle and brachial plexus.

The decision regarding nonsurgical versus surgical treatment of type III injuries is controversial.³^,⁴^,⁵^,⁶ Type III injuries represent injuries to both the AC joint capsule and the coracoclavicular ligaments, resulting in horizontal and vertical instability, and are manually reducible on physical examination. There is no consensus in the
literature regarding surgical versus nonsurgical treatment.³^,⁴^,⁵^,⁶ Surgical treatment for a type III injury can usually be reserved for patients who have persistent pain and instability after a trial of conservative therapy of at least 3 months. A relative indication for acute stabilization of a type III injury may be a sport or job that places a high demand on the shoulder.¹

Contraindications to AC joint stabilization or reconstruction include type I and II injuries, coracoid fracture, clavicle fracture, glenohumeral arthritis, and patients who lack the ability to comply with postoperative rehabilitation protocols.

Several procedures exist to stabilize the AC joint. The authors’ preferred method is open anatomic AC joint reconstruction using hamstring autograft or allograft because biomechanical testing has demonstrated this to be the strongest construct that most closely approximates the native AC joint.⁷

PREOPERATIVE IMAGING

Radiography

Standard radiographs are crucial for diagnosing and classifying AC joint injuries. Routine shoulder radiographs should include true AP and axillary lateral views. The axillary lateral view can be invaluable in distinguishing a type IV injury¹ (Figure 1, A). To assess the AC joint, a Zanca view (10° to 15° cephalic tilt) with the patient upright and the injured arm unsupported should be obtained¹ (Figure 1, B). The uninjured extremity should be assessed, if possible on the same radiograph, to allow comparison of AC joint asymmetry and coracoclavicular distance. Although not routinely taken, a Stryker notch view can be obtained if a coracoid fracture is suspected and not adequately visualized on the other films.¹

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