Introduction
A variety of acromioclavicular joint (ACJ) pathologies can result in pain and reduced function, including arthritis, distal clavicle osteolysis, and instability. Acromioclavicular (AC) pathologies can be broadly categorized into those that are ligament stable (causing ACJ pain) and those that are ligament unstable (AC and coracoclavicular ligament disruption), resulting in high-grade ACJ instability. Nonoperative management is favored as the initial treatment for the ligament-stable group of ACJ pathologies. , In contrast, the management of ACJ instability is controversial, with nonoperative and operative treatments each demonstrating independent risk and complication profiles. This chapter reviews both common and potentially catastrophic complications associated with (1) management of the painful ACJ, (2) nonoperative and operative treatment of ACJ instability, and (3) open versus arthroscopic techniques.
Ligament-stable acromioclavicular joint pathology
Nonoperative
The most common complication with nonoperative treatment of ligament-stable ACJ pathology is that of misdiagnosis or missed concomitant pathology resulting in ineffective or unnecessary interventions. Shoulder pain is the third most common reason for musculoskeletal consultation, and a careful history and physical examination are crucial to differentiate ACJ pathology from that originating from the glenohumeral joint chondral surface(s) or labrum, rotator cuff, or long head biceps tendon. Patients with a symptomatic ACJ present with a history of pain that is aggravated by activities that place increased load on the ACJ, such as push-ups and bench presses. Physical examination is characterized by discrete tenderness over the ACJ and a positive cross-body adduction test. While imaging is needed to confirm the diagnosis, it is important to recognize that ACJ pathology is evident in 50% of asymptomatic patients on plain radiographs and in 82% of asymptomatic patients on MRI. ,
Nonoperative treatment of the painful ACJ focuses on physical therapy, activity modification, nonsteroidal antiinflammatory medications, and intra-articular corticosteroid injections. In select cases where the diagnosis remains unclear, a steroid injection can be both diagnostic and therapeutic. The risks of injections, although small, can include short-term pain, infection, subcutaneous fat atrophy, and depigmentation. Furthermore, the benefits of ACJ injections are often short term (i.e., mean improvement of 20 days) with more than 80% of patients experiencing recurrence of pain.
Operative
Distal clavicle excision (DCE) is the most commonly performed procedure for ACJ pathologies including ACJ arthritis, osteolysis of distal clavicle, and low-grade instability causing pain. DCE was first described in 1941 by Mumford and Gurd and has become the gold standard treatment for the painful ACJ. Predictably good to excellent results are achieved, , with the rate of complications ranging from 2.4% to 64%. The complications can be categorized as inadequate resection, overresection (joint instability), miscellaneous factors, and diagnostic error.
Optimal distal clavicle resection: Anatomy and biomechanics
The AC ligament complex has an important role in maintaining anterior-to-posterior stability, with transection resulting in 100% displacement in either direction. , Thus the aim of excision is to prevent bony contact between the acromion and the clavicle while preserving the AC ligament and capsule. , This is achieved by performing a symmetric (i.e., rectangular) resection involving a minimum of 5 mm of distal clavicle to prevent bone-to-bone contact. However, a resection of greater than 11 mm can compromise the trapezoid ligament in addition to the AC ligament complex. With the goal of preserving the ACJ capsule, optimal resection is either unipolar, with 7 mm of bone removed from the distal clavicle, or bipolar, with smaller resection of both the distal clavicle and medial acromion. When bipolar resections of 5 mm were compared to a 10 mm resection of the distal clavicle, bipolar resections demonstrated improved stability with significantly greater load to failure.
Inadequate resection.
Inadequate resection of the distal clavicle causing persistent pain is the most common complication of ACJ resection. Underresection is more commonly reported following arthroscopic resection, with the posterosuperior quadrant being the most common site for a retained cortical ridge. , DCE requires systematic visualization, anteriorly and posteriorly as well as superiorly and inferiorly, to adequately decompress the joint. Multiple portals should be utilized during arthroscopic resection to ensure that adequate visualization and decompression have been performed.
Overresection.
Overresection can result in iatrogenic ACJ instability. Increased postoperative pain scores are associated with resections exceeding 10 mm. However, resections as low as 8 to 10 mm can result in subtle instability, with patients presenting with unexplained pain and normal radiographs. In this circumstance, stress radiographs will reveal increased anteroposterior translation. If iatrogenic instability is identified, surgical stabilization is often required.
Concomitant pathology.
Concomitant pathology commonly associated with ACJ pathology includes superior labrum anterior posterior (SLAP) lesions, biceps tendinopathy, subacromial impingement, or rotator cuff tendinopathy. When ACJ resection is performed open, concomitant pathology is often missed. Berg and Ciullo found that 15 of 20 patients (75%) with a failed DCE also had a SLAP lesion; 9 of those 15 patients (60%) who underwent further arthroscopic surgery to address this pathology experienced good to excellent results. If an open DCE is the technique of choice, arthroscopic evaluation of the glenohumeral joint can reduce the incidence of missed concomitant pathology. ,
Miscellaneous complications.
Stiffness has been reported in up to 29% of the patients, , resulting in either loss of external rotation or forward elevation. Stiffness is often secondary to infection or heterotopic ossification. Infection is an uncommon complication following open DCE (2%), which is reduced when performed arthroscopically (0.5%). Other rare but reported complications include heterotropic ossification requiring a secondary operation, suprascapular neuropathy, keloid scar formation and skin numbness, and fracture.
Open versus arthroscopic distal clavicle excision
While open and arthroscopic DCE can both provide good to excellent outcomes, the arthroscopic technique provides several distinct advantages ( Table 24.1 ). These include a faster return to activities, lower rates of infection and fracture, the ability to easily identify concomitant pathology, and significantly lower VAS pain scores 1 year postoperatively. While arthroscopic DCE has increased in popularity, underresection leading to unresolved pain remains a known complication. , Open resection remains a viable option in difficult or resistant cases and allows direct visualization of the resection and an opportunity for soft tissue interposition of the trapezius and deltoid fascia during closure, which may contribute to ACJ stability.
| OPEN DISTAL CLAVICLE EXCISION | ARTHROSCOPIC DISTAL CLAVICLE EXCISION | |||||
|---|---|---|---|---|---|---|
| Surgical Complications | N | Complication Rate (%) | % of All Complications | N | Complication Rate (%) | % of All Complications |
| Surgical unspecified | 78 | 2.4 | 30.8 | 247 | 1.9 | 37.4 |
| Infection | 63 | 2.0 | 24.9 | 64 | 0.5 | 9.7 |
| Stiffness/arthrofibrosis | 12 | 0.4 | 4.7 | 77 | 0.6 | 11.6 |
| Pain | 4 | 0.1 | 1.6 | 62 | 0.5 | 9.4 |
| Implant failure | 17 | 0.5 | 6.7 | 42 | 0.3 | 6.4 |
| Nerve palsy/injury | 11 | 0.3 | 4.3 | 35 | 0.3 | 5.3 |
| Wound problems | 21 | 0.7 | 8.3 | 22 | 0.2 | 3.3 |
| Surgical procedure intervention | 9 | 0.3 | 3.6 | 30 | 0.2 | 4.5 |
| Pulmonary embolism | 7 | 0.2 | 2.8 | 21 | 0.2 | 3.2 |
| Fracture | 6 | 0.2 | 2.4 | 5 | 0.0 | 0.8 |
Authors’ preferred acromioclavicular joint resection technique
An arthroscopic bipolar resection involving 5 mm of the distal clavicle and 3 to 5 mm of medial acromion is performed. A 70-degree arthroscope is utilized to ensure that a symmetric rectangular resection is achieved. This is confirmed through multiple portals.
Ligament-unstable acromioclavicular joint pathology
The treatment of ACJ separations varies considerably depending on the grade of instability, most commonly measured using the Rockwood Classification. There is general consensus that Rockwood types I and II are treated nonoperatively with satisfactory outcomes; types IV to VI are best treated surgically , ; and the management of type III injuries remains controversial. The treatment of low-grade instability (types I and II) has minimal complications with the exception of posttraumatic arthritis and osteolysis, which can occur in up to 50% of patients. When nonoperative management fails, these patients are reliably treated with DCE as discussed previously. The management of high-grade ACJ instability (Rockwood III to VI) is much more challenging, with both nonoperative and operative treatments having an array of potential complications. The remainder of the chapter focuses on the management of acute high-grade ACJ instability. While the reported outcomes of acute surgical intervention include patients up to 3 weeks post injury, we aim to intervene within 5 to 7 days for optimal outcomes.
Nonoperative
Approximately 17% to 28% of patients treated nonoperatively for high-grade ACJ instability will develop a complication. The most common complications include soft tissue problems, deformity, pain, and arthritis.
Soft tissue
The use of slings, casting materials, or tape can result in skin breakdown in as many as 20% of patients. , Skin necrosis is most common in Rockwood type V injuries where the clavicle has pierced through the fascia, resulting in increased pressure on the skin and surrounding soft tissues. In a randomized controlled trial from the Canadian Orthopaedic Trauma Society, 4.7% of patients (i.e., 2 of 43 patients) in the nonoperative cohort developed clavicle protrusion, resulting in soft tissue complications necessitating surgical intervention with ACJ stabilization.
Deformity
While residual deformity has not been described as a true complication of nonoperative treatment, this cosmetic deformity is present in all patients managed nonoperatively. , This cosmetic issue should be disclosed to patients during their initial evaluation with acknowledgment that ACJ deformity will become more obvious as the swelling subsides.
Pain
Ongoing pain and weakness are late complications of type III injuries managed nonoperatively, with a reported rate of 25%. The severity of pain is related to the patient’s activity level and can affect between 9% and 23% of high-demand patients. Other causes of pain include scapular dyskinesis or posttraumatic arthritis. , The rate of symptomatic arthritis is 43% for type III separations, while the incidence of posttraumatic osteolysis is 6%.
Miscellaneous
Although rare, neurovascular injuries have been reported, including an acute brachial plexus palsy following a type III ACJ injury which resolved following surgical stabilization. Heterotopic ossification of the coracoclavicular (CC) ligaments and CC interval have been observed with no detrimental effect on range of motion or recovery from the injury.
Operative
More than 150 surgical techniques have been described for the treatment of symptomatic ACJ instability. This large variability is indicative that no single technique has emerged as the gold standard treatment. This has resulted in large variability in the reported complications, with many being technique specific ( Table 24.2 ). Common complications include fracture, infection, and loss of reduction, while less common but potentially life- or limb-threatening complications have been reported, including neurovascular injury.
| Complication Type | Complication | Mode of Stabilization |
|---|---|---|
| Bony erosion | Acromial | Hook plate/K-wires |
| Clavicular | Suspensory devices | |
| Pain | Adhesive capsulitis | Free graft reconstruction |
| ACJ stiffness | Hook plate/K-wires | |
| ACJ arthrosis | Suspensory devices | |
| Persistent shoulder pain with activity | CAL transfer | |
| Implant failure | Loosening of the lateral screw | LARS, hook plate |
| Plate loosening | Hook plate/K-wires | |
| Broken K-wire | Hook plate/K-wires | |
| Failure of the coracoid button | Suspensory devices | |
| Failure of the clavicular button | Suspensory devices | |
| Suture break leading to recurrence of deformity | Suspensory devices | |
| Fracture | Clavicular fracture | Suspensory devices, LARS, hook plate/K-wires |
| Coracoid fracture | Suspensory devices, LARS | |
| Wound related | Superficial infectionDeep infection | Free graft reconstruction, suspensory devices, CAL transfer, hook plate/K-wires |
| Skin irritation secondary to suture knots | Hook plate/K-wires | |
| Draining fistula over the clavicle | Suspensory devices, CAL transfer | |
| Scar related | Hyperesthesia of the donor leg | Free graft reconstruction |
| Mild hypoesthesia of the donor leg | Free graft reconstruction, suspensory devices | |
| Local hypoesthesia in the infraclavicular region | Free graft reconstruction | |
| Tenderness above the cranial implant buttons while carrying a backpack | Suspensory devices | |
| Peri-incisional numbness | Hook plate/K-wires | |
| Graft related | Graft rupture/attenuation | Free graft reconstruction |
| Incomplete rupture of the synthetic ligament | LARS | |
| Loss of reduction | Complete loss of reduction without revision surgery | Free graft reconstruction, suspensory devices, suspensory devices |
| Loss of reduction due to loosening of clavicular button | Suspensory devices | |
| Loss of reduction after coracoid button migration into coracoid drill hole | Suspensory devices | |
| Loss of reduction treated with revision | CAL transfer | |
| Loss of optimal position | Hook plate/K-wires | |
| Recurrent dislocation | Recurrent dislocation without revision surgery | LARS |
| Recurrent dislocation after 3 weeks | CAL transfer | |
| Miscellaneous | Transitory postoperative plexus lesion | Suspensory devices |
| Mild shoulder internal rotation and forward elevation limitations | CAL transfer |
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