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Reconstruction of the coracoclavicular (CC) ligament using a single TightRope (ST) system has some complications. We attempted to use a double TightRope (DT) system to reduce complications and obtain the ideal therapeutic effect.
This investigation aimed to compare the ST and DT systems in terms of efficacy and safety in treating acromioclavicular (AC) joint dislocation.
Sixty-six cases of acute AC joint dislocation between January 2013 and January 2018 were retrospectively reviewed. All patients were divided into 2 groups based on treatment with the ST or DT system. Patients were evaluated radiologically and clinically using the Disability of Arm, Shoulder, and Hand, Constant, and visual analog scale scores as clinical outcome measures at 1 day, 3 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery. The CC distance and displacement ratio were assessed radiologically.
The mean follow-up period was 49 months. Satisfactory clinical outcomes were obtained after CC fixation in both groups. No intergroup difference was found regarding the visual analog scale (P = .80), Disability of Arm, Shoulder, and Hand (P = .42), or Constant score (P = .28) at 2 years. However, there was a significant difference in the displacement ratio at 6 weeks (P < .0001), 3 months (P < .0001), 6 months (P < .0001), 1 year (P < .0001), and 2 years (P < .0001) postoperatively between the 2 groups. There were 3 complications in the ST group, including 1 case of secondary coracoid fracture, 1 case of AC joint arthrosis combined with ossification of the CC ligaments, and 1 case of clavicular erosion. All complications occurred in the ST group.
Both surgical methods are effective in treating AC joint dislocation, but the DT system is more reliable for reduction maintenance.
Dislocation of the acromioclavicular (AC) joint represents a spectrum of soft tissue structure disruptions that can result in acute pain around the joint, chronic pain, and changes in shoulder biomechanics resulting in long-term disability. The AC joint is stabilized by the coracoclavicular (CC) ligaments, joint capsule, and trapezio clavipectoral fascia. The CC ligaments are one of the most important anatomic structures for maintaining stability of the AC joint;
The adjustable-loop-length suspensory fixation device can be used to treat CC ligament disruption, and it lends stability to the AC joint by supplying suspensory fixation between the clavicle and the coracoid process.
CC fixation using an adjustable-loop-length suspensory fixation device has shown promising results in previous studies.
However, some problems associated with the adjustable-loop-length suspensory fixation device, including increases in the CC distance over time, pullout of the clavicular or coracoid buttons at the attachment sites, and fracture of the clavicle, have also been reported.
Native CC ligaments have anatomic attachments distinct from those in this system, which results in altered AC joint stability and functionality. The CC ligament complex is composed of the conoid and trapezoid ligaments, which are primary shoulder suspensory ligaments. Although structurally similar, these ligaments are different with respect to function and orientation, thereby mediating AC joint stability. Ideal reconstruction methods should roughly replicate the trapezoid and the conoid of the CC ligament complex to ensure that a normal CC interval is maintained until the soft tissue around the CC ligaments fully heals. Therefore, in the present study, we used 2 TightRope (an adjustable-loop-length suspensory fixation device) systems to reconstruct the CC ligaments and thereby achieve ideal fixation and avoid complications.
The purpose of this investigation was to evaluate radiological and clinical outcomes of CC fixation using the single TightRope (ST) or double TightRope (DT) system for acute AC dislocation and to report intraoperative and postoperative complications. Our hypothesis was that AC reconstruction using the DT system would provide satisfactory shoulder function restoration and acceptable radiological outcomes with minimal complications.
Materials and methods
This was a retrospective study of clinical cases of acute AC joint dislocation diagnosed between January 2013 and January 2018 at our hospital. AC joint dislocation was diagnosed based on both clinical and radiographic assessments within a 3-day period after the original injury, and surgery was performed within 2 weeks after injury. Injuries were defined as Rockwood classification
grade III when both the AC ligament and the CC ligaments were torn, the attachment point of the deltoid and trapezius muscles was torn, and the distal clavicle was unstable in both the horizontal and vertical planes. The inclusion criteria were as follows: (1) acute AC joint dislocation ranked higher than grade III (grade III not included) in the Rockwood classification system; (2) no prior shoulder injuries or surgeries; (3) no related injuries; (4) treatment with the ST or DT system; and (5) a minimum of 2 years of follow-up. All patients were treated by 1 surgeon in this study. The exclusion criteria were as follows: (1) grade I, II, III, or VI subluxation/dislocation of the AC joint; (2) open AC joint dislocation; (3) combination with vascular or neural injury; (4) dislocation for more than 3 days or chronic AC joint dislocation; (5) ipsilateral shoulder injury; (6) combination with coracoid process fracture or scapulothoracic dissociation of the injured shoulder; (7) history of surgery on the injured shoulder; and (8) limited life expectancy due to significant medical comorbidity or other contraindications to surgery.
We retrospectively analyzed 66 patients meeting these inclusion criteria in this study; 34 patients were treated with the ST system, whereas 32 patients were treated with the DT system. Sixteen shoulders were excluded based on the exclusion criteria during the time period of the study.
In the present study, all patients were treated with the TightRope system. The TightRope system is an adjustable-loop-length suspensory fixation device. Both ends of this device consist of an oblong coracoid button and a round clavicular button, and the 2 metal buttons are connected by a No. 5 FiberWire. The coracoid button engages under the coracoid process through the coracoid tunnel, and the clavicular button lies over the clavicle between the insertion sites of the 2 CC ligaments.
Although the surgical technique has been previously described in detail,
In the DT group, the first conoid clavicular and coracoid tunnels were made in the distal clavicle and coracoid base, respectively, and the second conoid clavicular and coracoid tunnels were made in the distal clavicle and coracoid base, respectively (Fig. 1).
In the ST group, a clavicular tunnel was created approximately 2 cm medial to the lateral edge of the clavicle. The coracoid tunnel was created at the central portion of the coracoid base.
The oblong button of the TightRope was advanced through the tunnels from the coracoid to the clavicle. The TightRope suture tails were pulled to advance the round button under the coracoid until the reduction of the clavicle was noted to be satisfactory under direct visualization. Finally, the TightRope was tightened. The sutures were tied over the top of the TightRope using a surgeon’s knot and 4 additional half-hitches.
Patients were asked to use shoulder immobilizers for 3 weeks, keeping them on except for when bathing or performing exercises to improve elbow extension and flexion. Patients were only allowed movement below shoulder height for the first 6 weeks, after which full movement was permitted. Patients were instructed to avoid any heavy resistance work for 3 months postoperatively.
Before surgery and at the follow-up visits 1 day, 3 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery, images in the Zanca view were acquired. The Disability of Arm, Shoulder, and Hand,
and visual analog scale scores were used as primary assessments by an independent reviewer to gauge shoulder function in these patients. In addition, the CC distance and displacement ratio were assessed radiologically. The CC distance, defined as the distance from the anteroinferior border of the clavicle to the superior border of the coracoid process, was determined based on standard anteroposterior images of the AC arch obtained both preoperatively and at the final follow-up for each shoulder (Fig. 2). The displacement ratio was defined as the value calculated by dividing the difference in the CC distance between the affected and unaffected sides by the CC distance on the unaffected side. All X-ray films were of the Zanca view, which is shot with the X-ray beam placed 10° cephalad to the perpendicular plane.
Quantitative data are presented as the mean ± standard deviation. Furthermore, comparison of continuous variables was performed using the Mann-Whitney U test, whereas categorical data were analyzed using the χ2 test. All statistical analyses were conducted using SPSS 18.0 (IBM Corp., Armonk, NY, USA) software. P < .05 was considered to indicate statistical significance.
Group ST consisted of 22 men and 12 women, with a mean age of 44.7 years (range, 19-67 years) at the time of surgery, and group DT consisted of 20 men and 12 women, with a mean age of 44.8 years (range, 15-62 years) at the time of surgery (Table I). Patients were followed up for 24-82 (mean, 49) months. Clinical and radiologic analyses were performed for 66 patients. Patient demographics are summarized in Table I. No statistically significant differences were found between the 2 groups with regard to age (P = .99), sex (>.99), involved side (P = .09), injury mechanism (P = .27), interval from initial trauma to surgery (P = .23), or Rockwood classification (P = .61) (Table I).
Table IPatient demographics
Sample size (n)
Age (yr), mean ± SD (range)
44.7 ± 14.9 (19-67)
44.8 ± 11.9 (15-62)
Dominant arm, n (%)
Mean time to surgery, days ± SD (range)
1.9 ± 1.1 (1-3)
1.6 ± 0.80 (1-3)
Grade of AC dislocation, n (%)
Causes of injury, n (%)
Fall from a height
SD, standard deviation; AC, acromioclavicular; ST, single TightRope; DT, double TightRope.
Patients resumed their former work with a mean time to the resumption of work of 7.0 ± 0.9 (range, 6-8) weeks in group ST and 6.8 ± 0.8 (range, 6-8) weeks in group DT, and there was no significant difference between the 2 groups (P = .29, 95% confidence interval [CI]: −0.63 to 0.19). At the final follow-up evaluation, there was no significant difference between the 2 groups in the visual analog scale (P = .80, 95% CI: −0.35 to 0.26), Disability of Arm, Shoulder, and Hand (P = .42, 95% CI: −1.10 to 0.46), or Constant (P = .28, 95% CI: −2.31 to 0.67) score at 2 years after surgery (Supplementary Table S1). No severe functional limitations were found in group ST or DT. Thus, both the ST and DT systems demonstrated good therapeutic efficacy in the repair of shoulder function. The functional outcomes were similar between the 2 devices.
We followed all patients in the 2 groups for at least 2 years, and we reviewed the patients at the following timepoints: 1 day, 3 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery. The mean CC vertical distance was classified according to the grade of AC dislocation (Supplementary Table S2). The mean CC distance on the affected side in group ST was 15.7 ± 3.4 (range, 5.5-22.1) mm preoperatively, and it increased by 88.7% ± 31.2% (range, 41.3%-138.2%) on average compared with that on the unaffected side before surgery. The mean CC distance on the affected side in group DT was 15.9 ± 3.3 (range, 9.6-21.8) mm preoperatively, and it increased by 91.3% ± 30.4% (range, 40.8%-135.4%) on average compared with that on the unaffected side before surgery. Radiological assessment revealed the complete reduction of the AC joint postoperatively in both groups, and there was no significant difference in performance between the 2 surgical methods on imaging 1 day after the operation (P = .35) (Table II).
Table IIComparison of displacement
Group ST (mm)
7.4 ± 2.9 (2.1-12.3)
0.1 ± 0.2 (−0.2 to 1.1)
0.3 ± 0.1 (0.1-0.6)
2.4 ± 1.5 (0.3-5.8)∗
2.9 ± 1.4 (0.4-5.7)∗
3.1 ± 1.5 (0.4-6.5)∗
3.1 ± 1.5 (0.4-6.5)∗
3.2 ± 1.5 (0.4-6.4)∗
Group DT (mm)
7.6 ± 2.7 (3.2-12.5)
0.1 ± 0.2 (−0.1 to 0.8)
0.2 ± 0.2 (0-0.8)
0.3 ± 0.2 (0.1-0.9)∗
0.4 ± 0.2 (0.1-1.1)∗
0.4 ± 0.2 (0.2-1.1)∗
0.6 ± 0.2 (0.2-1.0)
0.7 ± 0.2 (0.4-1.2)∗
−1.27 to 1.49
−0.15 to 0.05
−0.14 to 0.00
5.63 to 6.92
−3.03 to −2.00
−3.21 to −2.14
−3.13 to −2.06
−3.10 to −2.03
ST, single TightRope; DT, double TightRope; CI, confidence interval.
Values are mean ± standard deviation (range). P < .05 was considered statistically significant and marked with “∗.”
We calculated the displacement ratio as a percentage by dividing the difference in the CC distance between the affected and unaffected sides by the CC distance on the unaffected side. There was no significant difference in the mean displacement ratio preoperatively between the 2 groups (P = .73) (Table III). However, the mean displacement ratio at 1 day, 3 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively in group ST was 1.7% ± 2.3% (range, −2.1% to 5.4%), 3.1% ± 1.4% (range, 1.1%-6.1%), 28.7% ± 17.8% (range, 8.4%-71.8%), 35.3% ± 17.1% (range, 11.3%-12.4%), 37.7% ± 7.8% (range, 12.9%-74.1%), 38.0% ± 18.0% (range, 10.8%-76.6%), and 38.7% ± 18.0% (range, 11.8%-80.3%), respectively. The mean displacement ratio at 1 day, 3 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively in group DT was 1.2% ± 2.2% (range, −2.0% to 9.4%), 2.35 ± 2.0% (range, 0%-9.6%), 4.2% ± 1.8% (range, 1.1%-10.1%), 5.1% ± 2.1% (range, 1.8%-13.0%), 5.3% ± 2.2% (range, 2.1%-13.5%), 6.7% ± 2.5% (range, 2.6%-11.6%), and 8.0% ± 2.5% (range, 4.4%-14.3%), respectively. There was a significant difference in the displacement ratio at 6 weeks (P < .0001), 3 months (P < .0001), 6 months (P < .0001), 1 year (P < .0001), and 2 years (P < .0001) postoperatively between the 2 groups (Table III). We found that the CC distance was significantly increased after 6 weeks in group ST (P < .0001), whereas the CC distance changed much less in group DT.
Table IIIComparison of displacement ratio
Group ST (%)
88.7 ± 31.2 (41.3-138.2)
1.7 ± 2.3 (−2.1 to 5.4)
3.1 ± 1.4 (1.1-6.1)
28.7 ± 17.8 (8.4-71.8)∗
35.3 ± 17.1 (11.3-12.4)∗
37.7 ± 7.8 (12.9-74.1)∗
38.0 ± 18.0 (10.8-76.6)∗
38.7 ± 18.0 (11.8-80.3)∗
Group DT (%)
91.3 ± 30.4 (40.8-135.4)
1.2 ± 2.2 (−2.0 to 9.4)
2.3 ± 2.0 (0-9.6)
4.2 ± 1.8 (1.1-10.1)∗
5.1 ± 2.1 (1.8-13.0)∗
5.3 ± 2.2 (2.1-13.5)∗
6.7 ± 2.5 (2.6-11.6)∗
8.0 ± 2.5 (4.4-14.3)∗
−12.66 to 18.04
−0.65 to 1.56
−1.63 to 0.08
−30.85 to −18.24
−36.28 to −24.10
−38.66 to −26.01
−37.70 to −24.85
−37.21 to −24.35
ST, single TightRope; DT, double TightRope; CI, confidence interval.
Values are mean ± standard deviation (range). P < .05 was considered statistically significant and marked with “∗.”
There were 3 complications in this study. There was 1 case of secondary coracoid fracture at the coracoid tunnel combined with fixation failure (Fig. 3). This patient was female and had initially been injured by falling from a height, and we had chosen the ST system to fix the AC joint in the first operation. The patient’s postoperative CC distance had recovered well, but when the patient was re-examined after 6 weeks, we found a secondary coracoid fracture and fixation failure. This patient underwent a second operation with the DT system. After the second operation, the patient’s CC distance recovered well. On follow-up, we found no complications, such as fixation failure or an obvious secondary increase in the CC distance. There was 1 case of AC joint arthrosis combined with ossification of the CC ligaments in a 47-year-old male patient 6 months after surgery (Fig. 4). The CC interval on the affected side preoperatively and 1 day, 3 weeks, and 6 weeks postoperatively was 13.5, 8.3, 8.5, and 13.5 mm, respectively. The patient had been treated with the ST system, and although obvious ossification of the CC ligaments was found on X-ray examination, the patient had no shoulder movement limitations. There was 1 case of cortical surface erosion in a 56-year-old male patient 1 year after surgery (Fig. 5). The patient had been treated with the ST system, and radiography showed an increased CC interval (CC interval on the affected side preoperatively at 1 day, 3 weeks, and 6 weeks postoperatively of 15.4, 7.6, 7.7, and 13.4 mm, respectively) caused by superior cortical surface erosion of the clavicle by the clavicular button and part of the plate sunk into the clavicle. The clavicular hole was obviously larger than before. The latter 2 patients strictly followed the rehabilitation plan, without any additional motion or other external forces.
This is the first comparative study on the application of 1 vs. 2 TightRope systems in the treatment of acute AC joint dislocation. In this study, satisfactory clinical outcomes were obtained after CC fixation in both groups. However, radiological outcomes revealed a significant difference in the CC distance 6 weeks postoperatively (P < .0001). The DT system showed much less change in the CC distance. This finding indicates that the DT system was more stable in maintaining the CC distance.
There was a significant difference in the mean displacement ratio at 6 weeks (P < .0001), 3 months (P < .0001), and 6 months (P < .0001) between the 2 groups. We found that the displacement ratio changed most obviously in group ST within 6 weeks postoperatively. Six weeks later, the CC distance was relatively stable in group ST. This may have been related to the time required for ligament repair (6 weeks) and the fact that the CC distance often changes little after 6 weeks. According to the trend of the CC distance data, we believe that the period of greatest instability after AC joint surgery is within 6 weeks postoperatively and that displacement and fixation failure occur mostly within 3-6 weeks.
The 2 components of the native CC ligaments have different anatomic attachments and provide vertical and horizontal stability for the AC joint. However, the ST system provides only single-point vertical fixation and cannot restore the horizontal stability of the AC joint. Compared with the horizontal instability of the ST system, biomechanical experiments have proven that the DT system provides good horizontal stability.
There was 1 patient with a secondary coracoid process fracture in group ST. The main reason for treatment failure in this case was a fall on the right shoulder 6 weeks after the primary surgery. Furthermore, in this case, another reason for the CC interval reduction failure was that the coracoid hole was not at the coracoid base, and its position was obviously forward (Fig. 3, C and D, white arrow). The coracoid base is known to be anatomically larger and wider than the coracoid forepart, and positioning of the coracoid hole in the coracoid forepart is weaker than that in the coracoid base.
There was 1 case of AC joint arthrosis combined with ossification of the CC ligaments, and we suspected that this may also have been related to insufficient fixation of the ST system.
has demonstrated that the synthetic materials used for CC cerclage have a sawing effect due to rotational motion of the clavicle with damage to the lateral clavicle and the coracoid process, and this effect is greater when the ST system is applied. The stress distribution on the clavicle with the use of the DT system prevents such clavicular erosion.
The use of CC guides increased the accuracy of TightRope placement and reduced the incidence of complications, such as fractures of the distal clavicle and the coracoid process, which are frequently reported complications in open and arthroscopic reconstruction methods.
First, the relatively small sample size and the retrospective design of the study may have affected the statistical results. Second, the DT system still could not restore the native CC ligaments anatomically and allow the ligaments to fully recover. However, its mode of reconstruction with 2 sutures does provide greater stability. The high rate of early radiological complications and the obvious change in the CC distance in patients treated with the ST system are sufficient to show the need to modify the ST system.
We conclude that both the ST and DT systems are effective in treating AC joint dislocation but that the DT system is more reliable for reduction maintenance.
Feng Gu and Lei Tan contributed equally to this paper. Tiecheng Yu conceived the experiments, Feng Gu and Lei Tan wrote the main manuscript text, Tiejun Wang prepared the figures, and Tiecheng Yu edited the draft. Qiangqiang Wen, Zilong Su and Zhenjiang Sui analyzed the data. All authors reviewed the manuscript.
The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
This study was carried out in accordance with the guidelines for the care for human subjects adopted by the First Hospital of Jilin University. The study protocol was approved by the Research Ethics Committee of the First Hospital of Jilin University (ref. no. 2020-360), and written informed consent was obtained from all participants.