Nonsurgical treatment is almost always recommended for management of incomplete (Rockwood type I and II) injuries. Although there has been much controversy regarding the treatment of type III separations, we recommend initial nonsurgical management in the majority of acute cases due to a lack of definitive high-level evidence supporting acute reconstruction [60–63].

Historically, multiple external methods for attempted clavicle reduction and immobilization were described [64–68]. These straps, harnesses, compressive dressings, splints, and casts have been abandoned due to patient discomfort and lack of efficacy.

Today, a generally accepted protocol begins with a period of immobilization in a sling for pain control with adjuntive oral analgesics and ice. This typically lasts for 5–7 days for type I and II injuries, but can be necessary for several weeks with complete separations. As discomfort subsides, early self directed range of motion is initiated with participation in activities of daily living. Formal physical therapy, particularly aquatherapy, can be helpful in achieving full motion and can guide strengthening and training for sports-specific activities. Return to play is variable depending on the severity of injury, ranging from 1 to 2 weeks for low grade sprains to 3–4 months for complete separations. Pregame anesthetic injection can be considered for earlier return to play in elite collegiate and professional contact athletes.

Results after the nonoperative treatment of incomplete (type I and II) injuries are generally described as excellent. Both recreational and high-level athletes commonly return to their desired activities in a timely fashion. In a large cohort of NFL players, a mean of only 9.8 days of participation were lost due to AC injuries. Surgical intervention occurred in only 1.7% over a 12 year period [3]. Similarly, a mean of 11.6 days were lost in NCAA football players [4].

While outcomes of low-grade AC sprains are anecdotally excellent, a number of series do acknowledge residual symptoms from these seemingly benign injuries. Shaw et al. reported significant pain in 40% of patients 6 months post-injury, although this decreased to 14% at final follow-up [69]. In another series of 37 consecutive patients treated nonoperatively for type I and II injuries, 27% required surgical intervention at a mean of 26 months after injury for residual symptoms of pain and instability [70]. At 10-year follow-up of AC sprains, Mikek reported a 52% incidence of at least occasional persistent symptoms [71].

Likewise, excellent results are generally reported with nonoperative treatment of type III complete injuries with good maintenance of shoulder strength and function [72, 73]. While there have been several movements over the last half century advocating for acute surgical management of type III separations, definitive data to support improved clinical results with operative treatment are lacking. Direct comparison studies consistently fail to show a benefit to surgical intervention [74–84]. In 2011, the Cochrane Collaboration published a detailed review examining the surgical vs. nonsurgical controversy surrounding complete separations [60]. Only three randomized trials met their inclusion criteria [74, 83, 77, 85]. Collectively, surgical treatment failed to result in significant gains in comparative shoulder function, and had higher complication rates and longer return to work times. While authors reported insufficient high-level evidence to advocate surgical treatment, they acknowledge small sample sizes and lack of validated outcomes measures in the studies included in their analysis. More recently, Beitzel et al. conducted a systematic review of studies comparing operative with nonoperative management. When data from 14 studies were pooled, a favorable clinical outcome was reported in 88% and 85.5% of surgically and nonsurgically managed patients, respectively [61] (Table 8.1).

Recently, it has been proposed that unreduced, complete AC separations may impair the normally coupled scapuloclavicular mechanics due to the loss of a stable shoulder fulcrum, resulting in scapular dyskinesis and pain. Gumina et al. analyzed scapular motion in 34 patients with chronic type III separations and found abnormal scapulothoracic motion in over 70%, with associated decreases in Constant scores [50]. Associated scapular dyskinesis has subsequently been shown to be responsive to a focused physiotherapy program [86].

Consensus for acute surgical management of Rockwood type IV, V, and VI separations exists despite limited high-level evidence supporting these recommendations [83]. It is generally felt that a large degree of displacement and extensive soft tissue disruption will lead to long-term pain and disruption if left unreduced. Treatment of type III separations have long been considered controversial despite a lack of clear evidence supporting acute surgical management [60–63]. Many surgeons consider operative intervention for cases that are symptomatic after 4–6 weeks of physiotherapy, although there are no clearly defined protocols. Many techniques to obtain and maintain anatomic reduction have been described, with a recent review citing 151 techniques for operative reduction of the AC joint [61]. This number demonstrates the lack of agreement for the superiority of a single method.

Primary AC fixation is generally reserved for acute cases (<3 weeks) in which the injured ligamentous structures are believed to have healing potential. Screws and pins have largely been replaced with plating techniques.

Historically, primary fixation was achieved with Kirschner wires, Steinman pins, or screws. Percutaneous and open techniques have been described [87–92]. This practice has essentially been abandoned in modern practice due to hardware problems, including breakage and migration to organs and vessels in the chest cavity [93, 94].

The hook plate is an alternative method for AC fixation commonly used in Europe [95–97]. A lateral projection off the plate is inserted deep to the acromion with bicortical screw fixation in the clavicle, producing stiff construct to allow for ligament healing [98]. Staged plate removal is often required due to concerns for subacromial impingement and restricted motion [99]. Excellent results have been reported in case series with regard to maintenance of reduction and clinical results [100–103]. However, selected reports of high complication rates are concerning [104, 105].

Similar to AC fixation, primary CC fixation is generally recommended for acute cases (<3 weeks) to promote healing of the torn AC and CC ligaments in an anatomic position. Samuel Cooper is credited with performing the first AC stabilization surgery in 1861 using a wire loop between the coracoid and clavicle, a practice that continued until the late twentieth century [106]. In 1917, Delbet described the first procedure in which a suture looped around the coracoid and was fixed through clavicular bone tunnels.

Many variations have subsequently been described using absorbable and non-absorbable materials. These sutures may be looped around bone, pulled through tunnels, or fixed with anchors. Over the years, methods involving polydioxanonsulfate (PDS), nylon, mersilene, and modern high strength synthetic braided suture have been described [107–113]. Failure of the suture or cutout through bone are well documented complications [114]. Over the last 5 years, novel methods involving the use of suture pulley systems combined with cortical button fixation have been commercially available and gained popularity [115–117]. While these devices theoretically allow for smaller tunnels to be drilled through the coracoid and clavicle with a lesser risk of iatrogenic fracture, intraoperative and postoperative implant failures have been reported [115].

A movement for CC fixation with synthetic ligament grafts occurred but never gained widespread use. Literature focused on the use of polyethylene grafts surfaced in the early 1990s and has reemerged of late [118–124]. Lack of efficacy over other surgical options and the potential for aseptic foreign body reaction have led some surgeons to question their use [125–127].

Primary screw fixation between the clavicle and coracoid was popularized by Bosworth [128]. Coracoclavicular lag screws can be used in isolation or combined with ligament reconstruction and have been made technically easier with the routine use of intraoperative fluoroscopy [129, 130]. While biomechanical studies have shown this to be the most rigid construct when compared to native CC ligament complex, surgeons have expressed concern over hardware complications, iatrogenic fractures, and staged hardware removal [131, 132] (Fig. 8.5).

Biologic CC ligament reconstructions are generally recommended in chronic (>3 weeks) cases in which the native AC and CC ligaments are unlikely to heal effectively, but are utilized by some surgeons for all reconstructions. Free tendon grafts have largely replaced the once common native coracoacromial ligament transfers in order to anatomically reconstruct the conoid and trapezoid.

Weaver and Dunn are credited with describing the use of coracoacromial (CA) ligament to reconstruct the CC ligaments, a technique later modified to include a distal clavicle resection to prevent late symptomatic degenerative changes [133]. The ligament is detached from its acromial insertion through a tenotomy or small osteotomy and transferred to the clavicle [134–136]. The Weaver–Dunn procedure is considered a non-anatomic reconstruction with poor biomechanical properties compared to the native CC ligament complex, particularly with regard to horizontal stability [137, 138]. As a result, supplementary CC fixation is often advocated [139–141]. Nonetheless, excellent clinical and radiographic results have been achieved by multiple authors [142, 136].

A more sophisticated understanding of the complex anatomy and biomechanics of the AC joint have led to a push for more anatomic techniques. As a result, free tendon graft reconstructions have gain popularity over the last decade. Jones et al. originally described using a looped semitendinosus graft around the coracoid and clavicle [143]. Various autografts (gracilis, palmaris) and allografts (tibialis anterior, peroneus brevis) have also been utilized [144, 145].

Several modifications to the technique have been described, and techniques continue to evolve. Bone tunnels or sockets in the clavicle and coracoid have been employed to more anatomically reconstruct the trapezoid and conoid individually [146, 147]. Grafts are generally fixed on the clavicular side with interference screws and a suture button device may be added for supplementary fixation while the graft incorporates [148, 117]. Recently, a novel technique in which the excess lateral trapezoid graft limb has been used to reconstruct the AC ligaments and capsule, as this may provide additional horizontal stability [149, 150] (Fig. 8.6).

Free tendon graft CC reconstruction has been biomechanically shown to best reproduce the horizontal and vertical stability provided by the native CC ligaments [146, 151]. In a prospective direct clinical comparison, Tauber showed more favorable American Shoulder and Elbow Surgeons (ASES) and Constant scores with a semitendinosus reconstruction over a CA ligament transfer [152]. Concern exists for long-term osteolysis and tunnel widening with subsequent coracoid and clavicle fractures [153, 154].

Graft placement at the anatomic footprint of the CC ligaments appears to be critical to maximize fixation, maintain reduction, and achieve optimal biomechanical and clinical results [155, 156]. Cook et al. performed a retrospective review of 28 consecutive reconstruction in an active military population [155]. A mean radiographic failure rate of 28.6% was reported at a mean 7.4 weeks postoperatively, with a medialized graft position predictive of early failure. Authors recommended preoperative templating to ensure optimal clavicular tunnel positions (Fig. 8.7).

Arthroscopic-assisted techniques for AC stabilization have developed with the widespread use and evolution of shoulder arthroscopy. In addition to the potential benefits of a less invasive approach, arthroscopic techniques also allow the surgeon to assess and treat associated glenohumeral pathology. Originally described by Wolf and Pennington, many subsequent variations using both tendon grafts and suture systems have been described [157–167]. While many authors report excellent results with these techniques, no high-level studies comparing arthroscopic and open techniques exist [168]. In isolated series, unacceptably high complication rates have been reported ranging from 22 to 44%, presumably due to the difficulty associated with these techniques [169, 170].

Distal clavicle resection has long been routinely combined with CA ligament transfer and CC reconstruction in an attempt to prevent late symptomatic arthritis. Recently, there has been concern that concomitant resection of the distal clavicle may further exacerbate horizontal instability. A cadaveric biomechanical study by Beaver et al. has questioned the validity of this concern in association with AC stabilization techniques [171]. Similarly, a recent large, multicenter level II study by Barth et al. showed no difference in clinical results with or without distal clavicle resection combined with CC ligament reconstruction for chronic separations [172].

Surgeons have debated the potential benefits of acute surgical intervention in complete separations. Beitzel et al. conducted a systematic review examining the surgical timing of reconstruction [61]. While the definition of delayed reconstruction was not uniform, it was generally considered to be greater than 3–4 weeks after injury. In the four retrospective studies included, favorable outcomes were achieved in 91% of the early treatment group compared with 72% in the delayed cohort, suggesting a possible benefit to expedited intervention when appropriate. However, no prospective study has similarly directly demonstrated this advantage [173–176].

The rehabilitation after AC joint reconstruction remains highly variable among surgeons. Cote et al. provided an excellent review detailing all aspects of the rehabilitation of surgically and nonsurgically treated injuries. The extremity is placed in a platform brace for 6–8 weeks to allow for graft incorporation, although many surgeons advocate a simple sling with early passive motion. After discontinuation of the brace, formal therapy focusing on active assisted range of motion and stretching is initiated. Strengthening begins at approximately 12 weeks.

Acromioclavicular injuries are likely the most common injury to the shoulder girdle in contact athletes. A seemly inconsequential joint, the AC articulation has complex biomechanics that we are continuing to investigate and understand. Disruption of its normal anatomy and stability can lead to abnormal shoulder function and chronic pain. Making definitive statements to guide treatment is difficult given the paucity of high quality research. Since no single method is clearly superior in replicating the anatomy and biomechanics of the native AC joint, surgical techniques continue to evolve.