The acromioclavicular (AC) joint is a diarthrodial joint formed by the distal clavicle and medial facet of the acromion. Its principal function is to suspend the scapula from the clavicle, thereby supporting the weight of the upper extremity. The AC joint capsular ligaments are the primary horizontal stabilizers of the AC joint, limiting anterior and posterior translation.¹ The conoid and trapezoid ligaments, which comprise the coracoclavicular (CC) ligaments, provide restraint to superior and inferior displacement. The trapezoid ligament is lateral to the conoid ligament and is a significant restraint to axial compression in line with the longitudinal axis of the clavicle.²

The AC joint is most commonly injured from a direct impact on the tip of the shoulder with the arm adducted. The force is transmitted to the acromion, displacing it inferiorly and medially, while the clavicle maintains its normal position. The AC joint capsular ligaments alone are involved in low-grade injuries (types I and II) (Fig. 14-1). High-grade injuries involve the CC ligaments as well. The standard treatment for type I and II injuries is nonoperative. A sling may be used on an as needed basis. Return to sporting activities and labor can be expected at 2 to 6 weeks. Late, symptomatic arthritic change at the AC joint may develop and can be treated by distal clavicle excision. Currently, the majority of acute type III injuries are treated nonoperatively with an initial period of immobilization.^3,4,5,6,7 Schlegel et al.⁸ demonstrated in a prospective study that 80% of type III injuries did well with nonoperative management. Nonetheless, a 17% deficiency in bench press strength was still present at 2 years. In chronically painful type III injuries, operative treatment is generally recommended. Other authors, however, recommend acute operative treatment of type III injuries in heavy laborers and high-level throwers.⁹ Acute surgical reconstruction of type IV, V, and VI AC separations is widely accepted.¹⁰

The evolution of AC joint reconstruction began in 1861 when Sir Samuel Cooper attempted repair with a loop of silver wire.¹¹ Since that time, more than 100 different reconstructive procedures have been described in the literature.¹² Unfortunately, no single surgical procedure has completely addressed all of the issues of AC joint separations. During the 1970s and 1980s, fixation methods emphasized intra-articular fixation across the AC joint using pins and plates.^13,14,15,16 In 1972, Weaver and Dunn¹⁷ introduced a technique of reconstruction utilizing the coracoacromial (CA) ligament. Numerous modifications of their original technique have been described, using methods to augment the CA ligament during the early healing phase of the reconstruction. Current trends in AC joint reconstruction focus on fixation between the clavicle and coracoid, thus reconstructing the coracoclavicular ligaments. A variety of augmentation devices such as the Bosworth screw,¹⁸ nonabsorbable and absorbable sutures,^19,20 Dacron tape,²¹ and GoreTex grafts,²² have been used and reported in the literature with good results. However, complications of infection, bone erosion, and reoperation for hardware removal continue to make these methods of reconstruction less than ideal^{23,24,25,26,27} (Fig. 14-2).