Arthroscopic Treatment of Acromioclavicular Joint Dislocation: A Preliminary Study of the Triple FengChao Button Technique

Introduction

Acromioclavicular joint dislocation (ACJD): ACJD is a separation between the distal clavicle and the acromion, typically resulting from shoulder trauma, and accounts for approximately 12% of all shoulder injuries [1]. It is particularly prevalent among athletes and individuals engaged in manual labor [2]. A multitude of surgical interventions are available for the treatment of ACJD. These include external joint fixation methods, which may utilize steel cables, autogenous ligaments, artificial ligaments, or suture buttons, as well as internal joint fixation with Kirschner wires and clavicular hook plates [3,4].

Numerous systematic reviews have confirmed the arthroscopic suture button technique as an accepted and effective treatment for ACJD, with patients often experiencing good to excellent functional outcomes and a rapid return to activity [5,6]. For instance, Fahmy et al [7] documented excellent functional results in a series of 24 patients treated with the arthroscopic TightRope device, with a mean follow-up period of 23.2 months. Similarly, Issa et al [8] reported favorable outcomes in 25 patients who underwent endoscopically-assisted treatment for acute ACJD, with a mean follow-up duration of 76.9 months.

The Endobutton and TightRope systems are frequently cited in the literature as the most popular suture button systems for ACJD repair [9–11]. These systems, which combine buttons with high-strength sutures (or loops), can make the arthroscopic procedure more complex due to their assembly requirements.

Considering the above, we undertook this study with the aim of developing the FengChao button system. Our hypothesis was that the arthroscopic triple FengChao button technique would yield favorable functional outcomes for patients with ACJD.

Material and Methods

INCLUSION AND EXCLUSION CRITERIA:

This study was conducted retrospectively and received approval from the Ethics Committee of Wujin Hospital of Traditional Chinese Medicine (Approval No. WZY2018001), in accordance with the principles of the Declaration of Helsinki. Informed consent was obtained from all patients prior to their inclusion in the study.

The criteria for patient inclusion were as follows: 1)Acute injury of the acromioclavicular joint (ACJ) with the injury occurring within the preceding 3 weeks. 2) Radiologic imaging confirmed a Rockwood grade III or higher, indicating a more severe dislocation. 3) Treatment involved the use of the arthroscopic triple FengChao button technique for joint stabilization.

Exclusion Criteria: Patients were excluded from the study if they underwent fixation using alternative surgical methods.

CHARACTERISTICS OF PATIENTS:

A total of 25 patients who underwent arthroscopic coracoclavicular (CC) ligament reconstruction using the triple FengChao button technique were included in the study. The cohort comprised 16 males and 9 females, with an age range from 21 to 58 years and an average age of 38.2 years. Ten patients presented with a left shoulder injury, while 15 had a right shoulder injury. In accordance with the Rockwood classification system, the injuries were categorized as follows: 14 cases were classified as grade III and 11 cases as grade V. The etiology of the injuries was predominantly sports-related, accounting for 17 cases, while motor vehicle injury was responsible for the remaining 8 cases. The average time from injury to surgical intervention was 6.65±3.21 days (Table 1).

DESIGN OF TRIPLE FENGCHAO BUTTON:

Yuchen Wang conducted a comprehensive comparison and analysis of commercially available coracoclavicular (CC) ligament reconstruction materials. Taking into account the specific characteristics of arthroscopic surgery, Wang designed the current Triple FengChao button system. The FengChao button system is manufactured by WASTON Corp, China, and was developed with a design that emulates the 2 primary components of the CC ligament.

The core component of the system is the titanium button, which resembles a shirt button. To prevent the “cutting effect” on the surrounding tissues, the inner walls of each button hole have been meticulously smoothed. The diameter of the Triple FengChao button ranges from 7.8 to 14.8 mm, and its thickness ranges from 2.5 to 4.5 mm. Additionally, the design allows for easy insertion of multiple strands of high-strength sutures, enhancing the versatility and effectiveness of the system in arthroscopic CC ligament reconstruction procedures (Figure 1).

SURGICAL TECHNIQUE:

All operations were conducted by a single, experienced surgeon, Yuchen Wang, following a standardized protocol. Patients were positioned in a beach chair position following brachial plexus or general anesthesia. Landmarks, including the coracoid process, acromion, and dislocated clavicle, were marked on the skin.

An anterolateral portal was created 2 cm lateral to the coracoid process, and a cavity was formed by palpating the coracoid process with forceps and dilating the surrounding tissue. With the arthroscope in place, an anterosuperior portal was established 1.5 cm above the anterolateral portal.

Soft-tissue debridement on the coracoid process was performed using a radiofrequency device, and the midpoint of the coracoid base was identified. A drill guide was introduced through the anterolateral portal, with the tip positioned beneath the coracoid base. A 2.4-mm guide pin was used to create a tunnel through the midpoint, followed by drilling with a 3.5-mm cannulated drill over the pin. The pin was then removed, leaving the drill in place.

A PDS-2 suture was threaded through the cannulated drill and retrieved through the anterosuperior portal using an arthroscopic grasper. A FengChao button and 3 strands of Ultrabraid suture (Smith & Nephew, USA) were prepared. The PDS-2 suture was used to pass the tails of the Ultrabraid sutures, which were externalized through the anterosuperior portal, with the button positioned beneath the coracoid.

After debridement of the muscle attachment on the lower clavicle surface, a drill guide was inserted through the anterosuperior portal, and 2 tunnels were drilled into the clavicle, 20 mm and 45 mm medial to the ACJ, using a 2.4-mm guide pin. The tails of the Ultrabraid sutures were then externalized through the PDS-2 suture. These suture tails were threaded into the holes of 2 additional FengChao buttons.

Manual reduction of the ACJ was performed by a surgical assistant. A sliding knot was used to achieve further reduction of the ACJ, followed by the application of 3 overhand knots to secure the position (Figure 2).

POSTOPERATIVE REHABILITATION:

Following surgery, all patients were immobilized using a sling for a minimum of 2 weeks to promote initial healing and comfort. On the first postoperative day, a regimen of passive shoulder joint exercises was initiated under the guidance of a physiotherapist to maintain joint mobility and prevent stiffness.

Transitioning to a more active phase of rehabilitation, active shoulder joint exercises were introduced starting 4 weeks after the operation. These exercises aimed to gradually increase the range of motion and strengthen the muscles surrounding the shoulder joint.

To prevent reinjury and allow for optimal healing, patients were advised to refrain from engaging in competitive sports and heavy weight lifting for a period of 12 weeks after surgery. This precautionary measure was taken to ensure that the repaired ligament and joint had sufficient time to consolidate and regain strength.

CLINICAL EVALUATION:

To evaluate the functional outcomes of the surgeries, we used 2 well-established scoring systems: the University of California, Los Angeles (UCLA) Shoulder Score System and the Constant-Murley Scale (CMS). The UCLA Shoulder Score System, which ranges from 0 to 35, classifies the shoulder function from ‘no function’ to ‘normal function’ [12]. The CMS scores range from 0 to 100, with higher scores denoting superior shoulder function [13]. We closely monitored patients for any postoperative complications, including wound infection, loss of reduction, implant migration, or breakage. Additionally, the operative time was documented as a critical parameter of the surgical procedure.

RADIOLOGIC EVALUATION:

Standard anteroposterior (AP) radiographs of the affected shoulder were obtained at 3 critical junctures: preoperatively, 2 days postoperatively, and at the 6-month follow-up. These imaging studies were utilized to measure the coracoclavicular distance (CCD) [14]. For the purposes of this study, a postoperative increase in CCD ranging from 20% to 50% was categorized as a loss of reduction. An increase exceeding 50% was considered a radiological failure, signaling a significant deviation from the intended postoperative anatomical restoration.

STATISTICAL ANALYSIS:

Statistical analysis was conducted utilizing the SPSS software package, version 21.0 (IBM Corporation). To determine whether there were significant differences in the UCLA Shoulder Score, Constant-Murley Scale (CMS), and coracoclavicular distance (CCD) measurements between the preoperative state and the final follow-up, we used either the Wilcoxon signed-rank test or the paired t test. The choice of test was contingent upon the normality of the data distribution, as assessed by standard statistical methods. The threshold for statistical significance was set at a 95% confidence level. Results were considered statistically significant when the P value was less than 0.05.

Results

CLINICAL OUTCOMES:

A total of 25 patients were followed up for a period ranging from 6 to 19 months, with an average follow-up duration of 13.3 months. In terms of functional outcomes, the patients achieved an average score of 92.73±2.96 on the Constant-Murley Scale (CMS) and 31.67±2.38 on the University of California, Los Angeles (UCLA) Shoulder Score, indicating a high level of functional recovery. Almost all patients (96%) expressed ‘high satisfaction’ with their surgical outcomes. In contrast, only 1 patient (4%) reported moderate satisfaction, primarily due to the need for revision surgery. The postoperative UCLA scores, which encompass pain, function, anterior flexion range of motion, anterior flexion strength, and total scores, showed marked improvement over preoperative scores. This improvement was statistically significant (P<0.05). Similarly, the CMS scores at the final follow-up, which include assessments of pain, activities of daily living, range of active motion, and muscle strength, also demonstrated significant enhancement compared to preoperative scores (P<0.05). For a comprehensive overview of the clinical outcome scores, refer to Tables 2 and 3.

The average operative time for the arthroscopic triple FengChao button technique was 52.34±13.76 minutes. All patients (100%) achieved primary wound healing without any incidence of incision infection, clavicle fracture, or coracoid process fracture. Loss of reduction was observed in 2 out of 25 patients. One patient experienced cutting of the coracoid process due to osteoporosis, which led to the loss of reduction. In another case, a patient experienced an accidental fall onto the shoulder 3 days postoperatively. Radiographs revealed a 100% increase in the coracoclavicular distance (CCD) and re-dislocation of the ACJ. Consequently, open revision surgery was performed. Intraoperative findings during the revision surgery included rupture of the Ultrabraid sutures superior to the clavicle. Since the original tunnels were still intact, they were reused, and the sutures were replaced. Postoperatively, the patient was instructed to wear a sling and restrict activities for 6 weeks. At the final follow-up, the patient who underwent revision surgery reported moderate satisfaction. Despite the complications and subsequent surgery, the shoulder joint function was assessed as good.

RADIOLOGICAL OUTCOMES:

The coracoclavicular distance (CCD) was measured at 3 distinct time points: preoperatively, 2 days postoperatively, and 6 months postoperatively. Preoperatively, the CCD measured (21.34±1.32) mm, which significantly decreased to (9.23±1.13) mm 2 days after surgery, and further stabilized at (11.93±1.03) mm by 6 months postoperatively. The reduction in CCD from the preoperative measurement to both the 2-day and 6-month postoperative measurements was statistically significant (P<0.05), indicating a successful surgical intervention in terms of joint stabilization. Notably, there was no significant difference in CCD between the 2-day and 6-month postoperative measurements (P>0.05), suggesting that the surgical repair had achieved a stable reduction over the medium-term follow-up period. We presents a classic case, including pre- and post-operative imaging data, of a 35-year-old male patient,diagnosed of ACJD, Rockwood III. The patient showed no evidence of significant dislocation at the 6-month postoperative follow-up (Figure 3).

Discussion

The present study’s pivotal discovery was the favorable functional outcomes observed with the arthroscopic triple FengChao button technique, with a mean follow-up duration of 13.3 months. These results align with those reported by other researchers who have documented satisfactory outcomes utilizing comparable arthroscopic techniques. For instance, Wang et al [15] reported that 204 patients treated with the suture button technique achieved a higher Constant score (91.59) than those treated with the hook plate method. Similarly, Slullitel et al [16] analyzed a cohort of 41 patients with ACJD who underwent arthroscopic suture button repair. At the final follow-up, these patients demonstrated Constant scores averaging 92.3 points and UCLA scores averaging 31.4 points. In light of these previous studies, the arthroscopic suture button technique has emerged as a favored approach for the treatment of ACJD, yielding robust functional outcomes and rapid recovery times.

Biomechanical research has demonstrated that the FengChao button system, when used to maintain the longitudinal stability of the AC joint, can withstand a higher failure load than the native coracoclavicular (CC) ligament of the human body [17]. This finding underscores the potential of the system in providing enhanced joint stability. However, the repair or reconstruction of the AC joint to address the horizontal instability associated with AC dislocation is a procedure that is increasingly used in clinical practice [18–20]. In the present study, none of the patients underwent AC repair or reconstruction. The decision was influenced by the complexity of the procedure when performed arthroscopically, which necessitates more extensive dissection and is associated with a longer operative time. Furthermore, the incremental stability provided by AC repair or reconstruction is a subject of debate. Weiser et al [21] conducted a cadaver study and observed that direct AC repair did not confer significantly increased stability compared to reconstructions that did not include direct AC repair. This finding suggests that the clinical benefit of adding direct AC repair to reconstruction procedures may be limited.

The Endobutton system and the TightRope system assessed for arthroscopic reconstruction of the CC ligament [22–26]. The Endobutton system was originally used in the suspension fixation of the anterior cruciate ligament reconstruction. It is composed of a polymer loop and a miniature rectangular titanium plate. The elastic fixation’s main structure is a polymer loop, and the suture is used as a strengthening fixation. The polymer loops of the Endobutton are fixed sizes with different lengths. Clinical experience shows that over-reduction or loss of reduction is often caused by an inaccurate loop length selection. The TightRope system is a fixation material specifically designed for reconstruction of the CC ligament. There is a titanium plate under the coracoid and 2 titanium plates on the clavicle. Two high-polymer sutures connect the whole system. The TightRope system cannot be disassembled, so the operation under arthroscopy is cumbersome.

The FengChao button is crafted to resemble a shirt button, with each button hole subjected to a special treatment process that smoothens the inner wall. This innovation is designed to prevent the “cutting effect” on surrounding tissues while allowing for the easy insertion of multiple strands of high-polymer sutures. The FengChao button system consists of 3 titanium plates and 3 high-polymer sutures, meticulously crafted to mimic the double-bundle structure of the CC ligament. This design adheres to the principles of anatomical reconstruction, ensuring a secure and stable repair. The titanium plates are uniquely shaped as buttons to increase the contact area, enhancing the system’s effectiveness. All 25 patients who underwent arthroscopic reconstruction of the CC ligament using the triple FengChao button technique had satisfactory postoperative shoulder joint function and a low rate of complications.

The technical execution of this technique presents several challenges, including: 1) The necessity for the surgeon to possess a solid foundation in arthroscopic surgery, with specialized expertise in shoulder arthroscopy. 2) The accurate determination of the coracoid base’s position through arthroscopic visualization. 3) The careful protection of nerves and blood vessels during the drilling of tunnels to prevent iatrogenic injury. 4) The precise execution of suture passing techniques under arthroscopic guidance, which requires a high level of skill and experience.

Loss of reduction is a frequently encountered complication following ACJ reconstruction. In our study, 2 out of 25 patients exhibited a postoperative increase in the coracoclavicular distance (CCD) by 20% to 50% compared to the unaffected side. This may be due to several factors, including the obliquity of bone tunnel establishment, improper execution of functional exercises postoperatively, and other patient-specific variables. Especially in cases of osteoporosis, there is a notable tendency for bone tunnel enlargement postoperatively, which can lead to loss of reduction. Furthermore, the enlarged bone tunnel can cause the FengChao button to protrude from the coracoidal bone tunnel, leading to an unstable reduction. Gan et al [27] clinically compared these factors in detail through comparative studies. Our study utilized a triple FengChao button technique, which emulates the dual components of the coracoclavicular ligament. This approach demonstrated a lower incidence of loss of reduction when compared to the double button flip technique. Civan et al [28] conducted a comparative analysis of double- versus triple-button reconstruction techniques in patients with ACJ dislocation (ACJD), showing that the triple-button configuration provided greater stability during shoulder flexion and abduction as opposed to the double button technique. Interestingly, despite instances of loss of reduction, good or excellent clinical outcomes are still achievable. Murena et al [29] reported that 21% of patients treated with a suture button technique experienced loss of reduction postoperatively; however, these patients maintained an average Constant score of 97 points, indicative of high functional status.

The present study has several limitations that warrant discussion. Firstly, the study’s retrospective design and the average follow-up period of 13.3 months impose constraints on the comprehensive evaluation of mid-term and long-term outcomes, as well as the identification of potential late complications associated with the arthroscopic triple FengChao button technique. Secondly, the study did not include postoperative computed tomography (CT), magnetic resonance imaging (MRI), or second-look arthroscopy to assess the status of the ACJ. These imaging modalities could have provided a more detailed understanding of the joint’s postoperative condition and healing process. Despite these limitations, to the best of our knowledge, this study is the first analysis of the arthroscopic triple FengChao button technique, offering valuable preliminary insights into its application and efficacy.

Conclusions

In the context of ACJ dislocation treatment, the arthroscopic triple FengChao button technique demonstrated satisfactory short-term functional outcomes. The preliminary success of this approach warrants further investigation to solidify its role in the clinical management of such dislocations. Comparative studies are needed to evaluate the FengChao button technique against other reconstruction methods. Such comparative analyses will be instrumental in determining the relative advantages, potential drawbacks, and optimal applications of the FengChao button technique within the spectrum of AC joint reconstruction surgeries.