Acromioclavicular (AC) joint dislocation constitutes approximately 12% of all shoulder-related injuries and most commonly results from either direct impact or indirect force. This injury can affect individuals across all age groups and is frequently associated with road traffic accidents, sporting incidents—particularly falls during skiing and contact sports, where the incidence may reach up to 41% among football players—military training activities, and accidental falls.

The Rockwood classification system, which ranges from grades I to VI, is the most widely adopted framework for evaluating AC joint injuries, categorizing them according to the severity of ligamentous disruption. Injuries of grades I and II are typically managed through conservative, non-operative measures. Conversely, surgical intervention is often considered necessary for grade III injuries, particularly in individuals engaged in physically demanding occupations or overhead athletic activities. Surgical management is generally indicated for grades IV to VI, given the significant horizontal and vertical instability commonly observed in such cases, which arises from the combined disruption of the acromioclavicular and coracoclavicular ligaments.

Numerous surgical techniques have been proposed for the management of acromioclavicular (AC) joint dislocation. Broadly, these approaches are categorized according to two principal objectives: the promotion of ligament healing and the reconstruction of ligamentous structures.

Ligament healing techniques aim to minimize the distance between the clavicle and the coracoid process, thereby facilitating primary healing of the coracoclavicular (CC) ligament. However, such methods are generally unsuitable for chronic dislocations. In contrast, the second category of surgical intervention involves the reconstruction of the CC ligament and is typically indicated in cases of chronic AC joint dislocation.

Despite various approaches, a definitive gold standard for the surgical management of this injury has yet to be established. Existing studies have reported several limitations associated with current fixation techniques, including non-anatomical restoration, intraoperative trauma, and a range of postoperative complications.

Although non-operative management is commonly recommended for Rockwood type III AC joint dislocations, emerging evidence from recent studies suggests that surgical intervention may yield superior functional outcomes in such cases.

In the present study, the anatomical reconstruction of the acromioclavicular (AC) joint using a double-button fixation system was evaluated in cases of acute AC joint dislocation.

Patients and Inclusion Criteria

A cross-sectional study was conducted in Department of Orthopedics, RDJM Medical College, Muzaffarpur Turki, Bihar between February 2022 and June 2024. Patients who had undergone surgical treatment for acute acromioclavicular (AC) joint dislocation using the double-button fixation system were included. A total of twenty-eight patients were enrolled in the study, comprising twenty-four men and four women, with an age range of 26 to 48 years.

To determine the type of injury, three radiographic views were utilised: the anteroposterior (AP) view (with a 10-degree cranial tilt of the beam, also known as the Zanca view), a true axillary view in the supine position, and a stress view of both sides of the acromioclavicular (AC) joint and coracoclavicular (CC) ligament.

The inclusion criteria were as follows: 1) all cases of acute AC joint dislocation classified as type III, IV, or V according to the Rockwood classification (20); 2) no history of previous shoulder injuries or related surgeries; 3) a follow-up period of at least 10 months. Type III cases were included if radiographs showed that the distal end of the clavicle was displaced by 75 to 100% of its articular surface width and if clinical examination revealed painful palpation and a protuberant clavicular shape during anterior shoulder raising.

All surgeries were performed by a senior surgeon, and all participants underwent the same surgical procedure, using the double endobutton technique.

Surgical Technique

The stability of the shoulder and the reduction of the acromioclavicular (AC) joint were assessed with the patient positioned in the beach chair position. All procedures were performed under either local or general anaesthesia. To prevent infection, three doses of second-generation cephalosporin were administered to all patients.

Initially, the injured upper limb was prepared and draped under standard sterile conditions. Anatomical landmarks, including the anterior portion of the acromion, the distal clavicle, and the coracoid process, were used to determine the skin incision site. A 4–6 cm incision was made after palpating the tip of the coracoid process, and the incision was extended from the base of the coracoid process to 2.5 cm posterior to the AC joint. The incision was then deepened through the subcutaneous tissue.

Next, the anterior deltoid muscle was split 2.5 cm from the AC joint to facilitate exposure of the coracoid process base. Dissection continued between the coracoid process and the distal end of the clavicle. A curved soft tissue elevator was used to carefully dissect the tissue medially and laterally. The lateral flap was extended to fully expose the AC joint.

A 2.4 mm guide pin was placed at the central point of the coracoid process base. This was overdrilled with a 4.5 mm drill. The distance between the anterior and posterior borders on the superior surface of the clavicle was then drilled in the same manner, after which the guide pin and drill were removed.

The Tight Rope device (Arthrex, Naples, FL) was initially inserted into the hole on the clavicle, then passed through the coracoid hole using a button inserter. The first button was flipped and secured under the base of the coracoid process by pulling one of the traction sutures. At this point, anatomical reduction of the AC joint was performed under fluoroscopic guidance, applying pressure to ensure proper alignment.

Once the reduction was achieved, the second button was placed and fixed on the superior surface of the clavicle. Finally, while an assistant maintained the reduction, the button was secured with approximately five knots. Post-operatively, shoulder mobilisation was carefully monitored according to the established protocol.

Follow-up

For all cases, data such as age, sex, mechanism of injury, dominant hand, side of injury, duration of follow-up, and time to surgery were recorded. Functional evaluations were conducted using the Shoulder and Hand Disability (DASH) scale (21), and the Visual Analogue Scale (VAS) both preoperatively and postoperatively. These scores were used to assess outcomes during the follow-up period. Additionally, the vertical distance between the superior border of the coracoid process and the anterior-inferior border of the clavicle was measured on standard anteroposterior radiographs (CC view) for both sides at the final follow-up.

 Statistical Analysis

Data were entered and analyzed using SPSS version 16. For categorical variables, frequency, percentage, mean, and standard deviation (SD) were calculated. To compare pre- and postoperative quantitative data, the paired t-test was employed. A p-value of ≤0.05 was considered statistically significant.

A total of 28 patients with acromioclavicular (AC) dislocation were enrolled in this study. The mean age of the participants was 39.23±6.7 years (range: 26 to 48 years). Of the patients, 24 (82.14%) were male and 4 (17.85%) were female. The injury occurred on the right side in 20 patients (71.4%) and on the left side in 8 patients (28.5%). The mechanism of injury was classified as an accident in 20 cases (71.42%) and a fall in 8 cases (28.57%). According to the Rockwood classification, 16 cases (57.14%) were grade III, 3 cases (10.71%) were grade IV, and 9 cases (32.14%) were grade V.

The mean duration of hospitalization before surgery was 1.7±1.4 days (range: 1 to 4 days), and the mean follow-up time was 19.17±4.38 months (range: 10 to 24 months). Table 1 presents the mean and standard deviation (SD) for the pre- and post-operative VAS, DASH and coracoclavicular (CC) distance for both sides.

The mean pre-operative VAS score was 7.1±1.66 while the mean post-operative VAS score was 1.04±0.84. A significant difference was observed between the pre- and post-operative VAS scores (P<0.05, Table 1). The mean pre-operative DASH score was 20.33±5.3, while the mean post-operative DASH score was 2.4±0.93, showing a significant improvement (P<0.001, Table 1).

However, no significant differences were found between the right and left CC distances (P=0.238, Table 1). The pre- and post-operative radiographic results for a patient who underwent the double-button fixation system are illustrated in Figure 1.

Various methods have been proposed for the management of acute acromioclavicular (AC) joint dislocation, with more than 70 techniques suggested for the treatment of complete AC joint separation (23). However, as the literature suggests, the complication rates associated with these methods are notably high. Other techniques, including the use of Kirschner wires, pins, screws, or hook plates, have also been employed in the management of AC joint dislocation (24–27).

The primary objective across all treatment methods is to restore the normal physiology of the AC joint by reducing the dislocation, stabilising the distal clavicle, and creating an optimal environment for tissue reconstruction. However, many of these methods have shown limited effectiveness. The use of pins or cerclage as temporary fixations, for example, has been associated with a high incidence of degenerative changes, pin breakage, and the migration of instruments into the thoracic cavity, along with bony lesions. Consequently, these methods are not recommended for long-term management (28–30).

Older techniques, such as coracoid process transfer with conjoined tendon attachment or Bosworth coracoclavicular (CC) screw fixation, have become increasingly rare. Studies have shown that coracoid process transfer fails to provide adequate stability to the AC joint and is associated with risks such as musculocutaneous nerve injury, screw failure, loss of fixation, and nonunion of the coracoid. The Bosworth technique, which involves repairing the CC ligament for the management of acute AC joint dislocation, was popularised by Rockwood et al. In this technique, screw removal was suggested 8 to 10 weeks post-surgery for CC ligament healing. However, complications, including ossification, osteolysis, and screw loosening or breakage, have been reported during follow-up (31).

The CC ligament plays a pivotal role in restraining vertical translation forces, while horizontal limitation is mediated by the joint capsule and AC ligament. The biomechanics of the CC ligament complex have been extensively studied, and these studies have highlighted the complex role of this ligament in preventing anterior and superior displacement of the clavicle (32, 33). In some techniques, sutures were employed to reduce the distance between AC joint dislocations. However, these sutures can have sawing effects, leading to the failure of these methods (23, 34).

For AC joint reconstruction, Ponce et al. (2004) utilised nine No. 1 absorbable sutures, wrapped in a tension-cable cord fashion, along with tendon autografts for athletic and revision cases to augment fixation (35).

In the present study, 28 patients with AC joint dislocation who underwent surgical treatment with the double endo-button technique were evaluated. This technique uses two titanium buttons, with sutures applied on both the superior and inferior sides, thereby evenly distributing the load on the joint and preventing the sawing effects that are common with sutures alone.

The results, as reflected in the DASH, VAS, and Constant shoulder scores, indicate that the double endo-button technique yields favourable outcomes for patients with AC joint dislocation. Postoperative DASH and VAS scores were significantly lower, and Constant shoulder scores were considerably higher than preoperative values, suggesting that the patients were satisfied with the results of the surgery. During the follow-up, two cases of heterotrophic ossification were recorded

In a comparable study, Beris et al. (2013) employed a double-button fixation system to manage acute acromioclavicular joint dislocation. They assessed 12 patients, utilising the DASH, Constant, and VAS scores, as well as the coracoclavicular (CC) distance for evaluation. Notably, no instances of AC joint osteoarthrosis, CC calcification, or osteolysis of the distal clavicle or coracoid process were observed. The mean Constant score was significantly higher than the preoperative value of 34.4, while the mean DASH score exhibited a reduction at the final follow-up. Furthermore, the mean VAS score decreased, and the mean CC distance of the operated shoulder was found to be comparable to that of the contralateral side (36). These findings align with the results of the current study.

In another study, Shin et al. (2015) investigated postoperative complications following arthroscopic coracoclavicular (CC) reconstruction using a single adjustable-loop length suspensory fixation device in 18 patients with acute AC joint dislocation. Their results demonstrated satisfactory clinical outcomes post-surgery. However, radiological examinations revealed that in 33% of cases, CC fixation failure exceeding 50% compared to the unaffected side occurred within three months following surgery. Moreover, technical complications related to the adjustable-loop-length suspensory fixation device were reported in eight patients (44%) (37).

The findings of the present study suggest that the double-button fixation system induces minimal disruption to the soft tissues surrounding the CC ligaments, positioning it as a reliable and effective technique for the management of acute acromioclavicular joint dislocation.

Figure 1. Anteroposterior view of the shoulder. A: pre-operation radiograph B: post-operation radiography in a patient with the double-button fixation system.

The double-button fixation system provides favourable clinical and radiological outcomes for the surgical management of acute AC joint dislocation. This technique allows for stable anatomical reduction with minimal soft tissue disruption and a low complication rate, supporting its utility as a reliable treatment option for Rockwood type III–V injuries.

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