Importance of suture Endobutton augmentation in type 2B clavicle fracture fixation using a locking plate

Article information

Clin Shoulder Elb. 2025;28(2):163-169

Publication date (electronic) : 2025 May 29

doi : https://doi.org/10.5397/cise.2025.00038

Hilal Yağar^,1, Ceyhun Çağlar², Zeynel Mert Asfuroğlu³, Murat Aydın⁴

¹Department of Orthopedics and Traumatology, Niğde Ömer Halisdemir University Medical School, Niğde, Türkiye

²Department of Orthopedics and Traumatology, Yıldırım Beyazıt University Medical School, Ankara, Türkiye

³Department of Orthopedics and Traumatology, Mersin University Medical School, Mersin, Türkiye

⁴Department of Orthopedics and Traumatology, Darıca Hospital Park, Kocaeli, Türkiye

Corresponding Author: Hilal Yağar Department of Orthopedics and Traumatology, Niğde Ömer Halisdemir University Medical School, Niğde 51200, Türkiye Tel: +90-50-5896-8028 Email: hilalyagar1989@gmail.com

Received 2025 January 3; Revised 2025 March 13; Accepted 2025 March 24.

Abstract

INTRODUCTION

Clavicle fractures are relatively common, comprising approximately 3% of all fractures in adults [1,2]; 16.6%–26% of these are distal end fractures [1,3,4]. These fractures often result from direct trauma, such as a fall on the shoulder, traffic accidents, or sport injuries [1,5].

The distal end of the clavicle is associated with the coracoclavicular (CC) ligament, which consists of the trapezoid ligament on the lateral side and the conoid ligament on the medial side [6]. Neer classified distal 1/3 clavicle fractures based on their relationship with the CC ligament [6]. In 1982, Rockwood further classified Neer type 2 fractures into two subgroups. In type 2a distal clavicle fractures, the fracture occurs medial to the CC ligament. Type 2b distal clavicle fractures have two fracture patterns. In the first pattern, the fracture occurs in the center of the CC ligaments, the conoid ligament is torn, and the trapezoid ligament remains intact. In the second fracture pattern, the fracture occurs lateral to the CC ligament and the conoid and trapezoid ligaments are torn [7]. In these fractures, the trapezius muscle displaces the proximal fragment posteriorly; however, the distal fragment is directed inferiorly with the weight of the arm. Thus, instability develops in both horizontal and vertical directions [6].

Instability in distal clavicle fractures with impaired integrity of the CC ligament poses a serious risk for nonunion, necessitating surgical intervention [8]. Despite a consensus on the need for surgery in cases of unstable distal clavicle fractures, various surgical techniques are available including CC screw applications, locking plate applications, hook plate applications, and arthroscopy-assisted surgical treatments [9-11].

In cases of Neer type 2b fractures with CC disruption, CC augmentation can be performed either independently or in combination with plate applications. Augmentation techniques may involve the use of suture anchors, reinforced sutures, CC screws, suture Endobutton fixation, and tendon and ligament reconstructions [12-15]. However, few limited studies have investigated the efficacy of CC augmentation in these fractures [16-18]. In addition, the biomechanical adequacy of plate fixation alone is an important concern in this multidirectional instability [18].

This study aimed to evaluate the radiological and functional outcomes of CC augmentation using the suture Endobutton technique in conjunction with locking plate application for Neer type 2b clavicle fractures.

METHODS

This study was conducted at the Department of Orthopedics and Traumatology, Niğde Ömer Halisdemir University, between March 1, 2016, and January 1, 2023. The study was conducted following the principles of the Declaration of Helsinki. Written informed consent was waived due to the retrospective nature of the study. The Institutional Review Board of Faculty of Medicine, Niğde Ömer Halisdemir University approved the study protocol (No. 2023/26).

In this retrospective study, two groups of patients were compared: group 1 (locking plate with CC augmentation) and group 2 (locking plate without CC augmentation). Among the patients, 42 of 50 met the following inclusion criteria: (1) acute Neer type 2b fracture, (2) internal fixation with distal clavicle locking plate with or without CC suture Endobutton fixation, (3) normal shoulder function before injury, (4) regular follow-up >6 months postoperatively, and (5) no previous surgery on the same shoulder. Patients with a follow-up <6 months, chronic injuries, open fractures, presence of arthritis in the shoulder joint, clavicle fractures accompanied by coracoid process fractures, systemic diseases that may affect union (e.g., diabetes, hyperthyroidism, hypothyroidism), and pathological fractures were excluded from the study.

Among the patients, distal clavicle locking plate application without CC augmentation was performed for 23 patients (group 2), and a combination of this application with CC augmentation was performed for 19 patients (group 1). This study included the patient cohorts of three orthopedic surgeons. One surgeon exclusively performed surgeries with CC augmentation, and the other two surgeons performed surgeries without CC augmentation. This distribution of surgical techniques allowed a comparative evaluation while minimizing selection bias and ensuring that treatment decisions were based on surgeon preference rather than patient-specific factors. Data including age, sex, union time, range of motion, complications, and implant failures during the follow-up period were recorded. The Constant-Murley score (CMS) [19] of the patients in the 6th postoperative month were recorded and compared. The presence of union was determined based on direct radiographs by two board-certified orthopedists. The surgeons classified clavicle fractures according to the Neer classification using only x-rays. The term "late union" referred to unions that occurred after the 12th week.

Surgical Technique and Postsurgical Care

Distal clavicle locking plate with suture Endobutton fixation (group 1)

A single dose of prophylactic antibiotic was administered preoperatively. The patient was positioned in the beach chair position under general anesthesia. A standard anterior 6- to 8-cm incision was made over the clavicle. The fracture was reduced, and temporary fixation was achieved with one K-wire. The acromioclavicular (AC) joint was identified, and plate positioning was ensured using a syringe. Then, the locking plate was placed with consideration of distal fragment anatomy to allow maximum screw engagement. Under fluoroscopic guidance, a guide wire was inserted from the clavicle (posterior to the locking plate), maintaining the coracoid process centrally by engaging the four cortices (Fig. 1). Following drilling on the guide wire, a suture Endobutton system was placed on the lower part of the coracoid process and superior surface of clavicle (posterior to the locking plate) under fluoroscopic guidance. Postoperative radiographs of the locking plate with suture Endobutton system are shown in Fig. 2.

Fig. 1.

Intraoperative view of locking plate application with coracoclavicular augmentation.

Fig. 2.

Preoperative (A) and postoperative (B) radiographs of the locking plate with suture Endobutton system.

Distal clavicle locking plate without suture Endobutton fixation (group 2)

A single dose of prophylactic antibiotic was administered preoperatively. The patient was positioned in the beach chair position under general anesthesia. A standard anterior 6- to 8-cm incision was made over the clavicle. The fracture was successfully reduced, and temporary fixation was achieved using a single K-wire. The AC joint was identified, and plate positioning was ensured using a syringe. Then, the locking plate was placed in the distal fragment with consideration of the anatomy, allowing maximum screw management. Fluoroscopic imaging was conducted with precautions to ensure the screws did not penetrate the AC joint (Fig. 3).

Fig. 3.

Postoperative radiographs of the clavicle fixated with locking plate.

Postsurgical care

All patients were instructed to use a shoulder sling for 4 weeks. Isometric and passive shoulder exercises were initiated in the early postoperative period. In the 3rd to the 6th weeks, patients started engaging in active and active-assisted range of motion exercises. Strengthening exercises were initiated after the 8th week.

RESULTS

In the study cohort, 13 patients (31.0%) were female and 29 (69.0%) were male. The age ranged from 21 to 61 years with a mean of 40.5 years (±11.5 years) and a median of 42.5 years. Significant difference was not observed between the right and left sides or between sexes across the groups (P>0.05 for each) (Table 1).

Table 1.

Sex and side information of the patients included in the study

The t-test analysis results indicated a significant difference in union time (weeks) (t(40)=–2.11, P=0.04) and 6-month CMS (t(40)=4.19, P=0.01). Based on these results, group 1 exhibited a shorter duration of union and higher 6-month CMS compared with group 2. Significant difference was not found between the groups in variables of anterior flexion (t(40)=0.76, P=0.45), external rotation (t(40)=–0.02, P=0.98), and age (t(40)=–0.24, P=0.81). The demographic data, radiological findings, and clinical results of the patients included in the study are presented in Table 2.

Table 2.

Demographic data, radiological findings, and clinical results of the patients included in this study

Significant difference was not observed in postoperative complications between the two groups (P>0.05). However, postoperative complications developed in six patients without CC augmentation (group 2); implant failure occurred in two patients, leading to implant revision; two patients experienced skin irritation, and one patient exhibited late union in the 14th week. In patients with CC augmentation (group 1), complications occurred in three, with implant failure in one. At 1 month postoperatively, the locking plate failed in this patient, but the suture Endobutton system remained stable, resulting in a 2-mm increase in CC distance. The patient had no comorbidities but had a history of smoking, which may have influenced the healing process. Bone union and good shoulder function were achieved without reoperation (Fig. 4). Late union was observed in one patient, achieved in the 12th week. One patient experienced an early superficial infection and responded to debridement and antibiotic treatment. All patients achieved union and no other serious complications. The complications in the study patients are presented in Table 3.

Fig. 4.

Implant failure of locking plate with coracoclavicular augmentation.

Table 3.

Number of complications in the patients included in this study

DISCUSSION

This study was novel because the short-term results of CC augmentation in type 2b distal clavicle fracture fixation using a distal clavicle locking plate were compared. The biomechanical effectiveness of CC augmentation in unstable distal clavicle fractures has been investigated in only a few studies. In a biomechanical study on cadavers, Madsen et al. [20] evaluated the effectiveness of CC augmentation in addition to locking plate application against cyclic load. CC fixation added stability to type 2b distal clavicle fractures fixed with a plate and screws when loaded to failure. In biomechanical studies, CC augmentation was shown to provide a more stable fixation. This might lead to better short-term functional outcomes by enabling faster rehabilitation and accelerating the union process.

In a cohort study involving 18 patients, Cho et al. [21] performed fixation of Neer type 2b clavicle fractures by applying only a suture Endobutton and obtained a high union rate (94.4%) after 6 months. Vikas et al. [18] used one Endobutton and No. 2 fiber wire for CC augmentation after pre-contoured locking distal clavicle plate application in distal clavicle fractures in 32 patients with CC disruption. The authors reported union in all patients at an average of 11±2.8 weeks. In a retrospective series of 12 patients, Han et al. [22] applied CC augmentation with a suture anchor to the coracoid process in addition to the locking plate. In the 12th week, union was achieved in all patients. In the present study, union was achieved in all fractures in both groups, with faster union observed in patients who underwent CC augmentation.

Esenyel et al. [10] performed CC fixation with percutaneous lag screw application in type 2 distal clavicle fractures in a series of 16 patients. The authors performed hardware removal after union was achieved and found no postoperative limitation of joint motion. In a retrospective study conducted with 24 patients, Perskin et al. [16] performed CC augmentation with a locked distal anatomic plate and suture Endobutton in Neer type 2b clavicle fractures. The authors observed radiological union in 96% of the patients and found a mean shoulder forward elevation of 168° (120°–180°) and a mean external rotation of 57° (20°–90°). In the present study, the range of motion was similar to that reported in the literature, and significant difference was not found in the two groups.

In a study involving 28 patients, Yang et al. [23] achieved reduction by wrapping a Mersilene tape under the coracoid in unstable distal clavicle fractures and securing it on the clavicle. The authors evaluated the patients using the University of California Los Angeles shoulder rating score. The researchers reported excellent results in 20 patients and good results in 8 patients [23]. Seyhan et al. [17] conducted a study with 36 patients, comparing three CC augmentation techniques. In the first group, a tension band was applied to the fracture line with a K-wire, and the Ethibond suture was passed under the coracoid and tied on the clavicle for CC augmentation. In the second group, a CC lag screw was applied over the locked plate for CC augmentation. In the third group, CC augmentation was performed using the suture Endobutton technique over the locked plate. In the group in which augmentation was performed with a suture Endobutton, the CMS was higher at 3, 6, and 12 months [17]. Hohmann et al. [24] applied a distal radius locking plate to unstable distal clavicle fractures and performed CC augmentation with a suture Endobutton posterior to the plate. The authors demonstrated that a sufficient number of screws could be inserted in distal fractures with small fragments with this technique and reported high constant Disabilities of the Arm, Shoulder and Hand (DASH) and Shoulder Pain and Disability Index (SPADI) scores at the 1-year follow-up [24]. In a retrospective study conducted with 23 patients, Salazar et al. [25] comparatively evaluated the efficacy of CC augmentation using an anchor in addition to locking plate application in Neer type 2 and type 5 distal clavicle fractures. The authors obtained similar Quick-DASH scores in the two patient groups in the study. Wang et al. [26] used a titanium cable as a CC augmentation technique in a prospective study with 36 patients. Following the locking plate application, the cable was passed under the coracoid and fixed on the upper surface of the plate. The authors compared the CMSs of patients at 12 months with hook plate application and obtained significant results. Yan et al. [27] compared hook plate application with gracilis tendon and CC ligament reconstruction with a suture anchor in a prospective study performed with 42 patients. The researchers showed higher CMSs in the reconstruction group in the short term. In the present study, higher CMSs were obtained in the CC augmentation group at the 6-month follow-up.

In a retrospective study involving 25 patients, Shin et al. [28] applied a contoured locking plate without CC augmentation in patients with Neer type 2 clavicle fracture. The authors found an average 10% increase in CC distance on the fracture side compared with sides without fractures. However, the authors reported that this radiological difference did not affect functional outcomes. Singh et al. [29] conducted another retrospective study with 74 patients, evaluating complications in Neer type 2 and type 5 clavicle fractures. The authors found that hook plates had a higher risk of complications and reoperation than contoured plates and suture Endobuttons. The authors [29] recommended avoiding routine use of hook plates. The researchers also noted that using transosseous sutures alone led to greater joint stability and fewer complications. A meta-analysis reported a higher frequency of major complications after hook plate fixation than in other treatment modalities but without significant difference in minor complications [11]. The results of the present study indicated that CC augmentation did not influence the development of complications. Furthermore, the surgical technique used in this study allowed successful union without revision surgery, even if implant failure develops. In cases requiring implant removal, such as irritation, safely removing the plate without removing the suture Endobutton was possible, even in the early period.

This study had several limitations including its retrospective nature, a small number of patients from a single center, and lack of randomization. Variation in surgical procedures among surgeons may have introduced selection bias rather than reducing it because differences in surgeon techniques and preferences could have influenced the results. In this study, only short-term results were evaluated although the patients had longer follow-up periods. Long-term functional results after union were not evaluated in this study. Multicenter randomized controlled studies and biomechanical investigations are urgently needed on this subject. Certain patient-related factors, such as smoking status, diabetes, and obesity, may influence fracture healing. However, complete and consistent data on these variables could not be obtained. In addition, although operative time could provide valuable insights into the technical challenges of the procedure, the dataset did not include reliable records for a meaningful comparison. Furthermore, the lack of other functional scores in the dataset due to the retrospective design is an important limitation.

CONCLUSIONS

Results of the present study demonstrated that CC augmentation with a suture Endobutton, in addition to locking plate application for type 2B distal clavicle fractures, resulted in more favorable short-term functional and radiological outcomes. The focus in future studies should be on long-term follow-up and assessment of a wider range of functional outcomes to provide a more comprehensive evaluation of CC augmentation in type 2B distal clavicle fractures.

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