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Journal of Shoulder and Elbow Surgery

Comparison of single versus double TightRope system in the treatment of acute acromioclavicular joint dislocation

Open AccessPublished:November 04, 2020DOI:https://doi.org/10.1016/j.jse.2020.10.002

      Background

      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.

      Purpose

      This investigation aimed to compare the ST and DT systems in terms of efficacy and safety in treating acromioclavicular (AC) joint dislocation.

      Methods

      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.

      Results

      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.

      Conclusions

      Both surgical methods are effective in treating AC joint dislocation, but the DT system is more reliable for reduction maintenance.

      Level of evidence

      Keywords

      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;
      • Li H.
      • Wang C.
      • Wang J.
      • Wu K.
      • Hang D.
      Restoration of horizontal stability in complete acromioclavicular joint separations: surgical technique and preliminary results.
      thus, recent surgical treatments for dislocation of the AC joint have focused on CC interval fixation.
      • Cho C.H.
      • Kim B.S.
      • Kwon D.H.
      Importance of additional temporary pin fixation combined coracoclavicular augmentation using a suture button device for acute acromioclavicular joint dislocation.
      ,
      • Wylie J.D.
      • Johnson J.D.
      • DiVenere J.
      • Mazzocca A.D.
      Shoulder acromioclavicular and coracoclavicular ligament injuries: common problems and solutions.
      Recently, reconstruction of the CC ligaments using an adjustable-loop-length suspensory fixation device was introduced as a surgical technique.
      • Beris A.
      • Lykissas M.
      • Kostas-Agnantis I.
      • Vekris M.
      • Mitsionis G.
      • Korompilias A.
      Management of acute acromioclavicular joint dislocation with a double-button fixation system.
      ,
      • El Sallakh S.A.
      Evaluation of arthroscopic stabilization of acute acromioclavicular joint dislocation using the TightRope system.
      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.
      • Basyoni Y.
      • El-Ganainy A.E.
      • Aboul-Saad M.
      Acromioclavicular joint reconstruction using anchor sutures: surgical technique and preliminary results.
      ,
      • Defoort S.
      • Verborgt O.
      Functional and radiological outcome after arthroscopic and open acromioclavicular stabilization using a double-button fixation system.
      ,
      • El Sallakh S.A.
      Evaluation of arthroscopic stabilization of acute acromioclavicular joint dislocation using the TightRope system.
      ,
      • Ladermann A.
      • Gueorguiev B.
      • Stimec B.
      • Fasel J.
      • Rothstock S.
      • Hoffmeyer P.
      Acromioclavicular joint reconstruction: a comparative biomechanical study of three techniques.
      ,
      • Murena L.
      • Vulcano E.
      • Ratti C.
      • Cecconello L.
      • Rolla P.R.
      • Surace M.F.
      Arthroscopic treatment of acute acromioclavicular joint dislocation with double flip button.
      ,
      • Salzmann G.M.
      • Walz L.
      • Schoettle P.B.
      • Imhoff A.B.
      Arthroscopic anatomical reconstruction of the acromioclavicular joint.
      ,
      • Walz L.
      • Salzmann G.M.
      • Fabbro T.
      • Eichhorn S.
      • Imhoff A.B.
      The anatomic reconstruction of acromioclavicular joint dislocations using 2 TightRope devices: a biomechanical study.
      ,
      • Wellmann M.
      • Zantop T.
      • Petersen W.
      Minimally invasive coracoclavicular ligament augmentation with a flip button/polydioxanone repair for treatment of total acromioclavicular joint dislocation.
      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.
      • Martetschlager F.
      • Horan M.P.
      • Warth R.J.
      • Millett P.J.
      Complications after anatomic fixation and reconstruction of the coracoclavicular ligaments.
      ,
      • Milewski M.D.
      • Tompkins M.
      • Giugale J.M.
      • Carson E.W.
      • Miller M.D.
      • Diduch D.R.
      Complications related to anatomic reconstruction of the coracoclavicular ligaments.
      ,
      • Shin S.J.
      • Kim N.K.
      Complications after arthroscopic coracoclavicular reconstruction using a single adjustable-loop-length suspensory fixation device in acute acromioclavicular joint dislocation.
      ,
      • Wang D.
      • Bluth B.E.
      • Ishmael C.R.
      • Cohen J.R.
      • Wang J.C.
      • Petrigliano F.A.
      Early complications of acromioclavicular joint reconstruction requiring reoperation.
      One reason for CC interval reduction failure is that a single fixation system cannot restore the native CC ligament anatomy.
      • Mazzocca A.D.
      • Santangelo S.A.
      • Johnson S.T.
      • Rios C.G.
      • Dumonski M.L.
      • Arciero R.A.
      A biomechanical evaluation of an anatomical coracoclavicular ligament reconstruction.
      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

       Patients

      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
      • Scott J.C.
      • Orr M.M.
      Injuries to the acromioclavicular joint.
      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.

       Surgical technique

      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,
      • Zhao Y.
      • Tan L.
      • Tang W.
      • Yu T.
      A new coracoclavicular guider for minimally invasive anatomic coracoclavicular reconstruction with two TightRope systems in acute acromioclavicular joint dislocation.
      it can be briefly summarized as follows.
      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).
      • Zhao Y.
      • Tan L.
      • Tang W.
      • Yu T.
      A new coracoclavicular guider for minimally invasive anatomic coracoclavicular reconstruction with two TightRope systems in acute acromioclavicular joint dislocation.
      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.
      Figure thumbnail gr1
      Figure 1Placement of the conoid and trapezoid clavicular tunnels in the distal clavicle and coracoid base, respectively. (A) Marking of the distal clavicle for conoid and trapezoid clavicular tunnel placement. The center of this part of the clavicle was marked in red for conoid clavicular tunnel placement on top of the clavicle. The center of the red point to the distal end of the clavicle was marked in yellow for trapezoid clavicular tunnel placement on top of the clavicle. (B) Marking of the coracoid base for conoid and trapezoid coracoid tunnel placement. The conoid coracoid tunnel was placed at the posterior aspect of the coracoid base, 5 mm lateral to the medial border, as indicated by the red point. The trapezoid coracoid tunnel was placed 5 mm medial to the lateral border of the coracoid, as indicated by the yellow point. There was a >10-mm bony bridge between the 2 tips.
      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.

       Postoperative rehabilitation

      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.

       Outcomes

      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,
      • De Smet L.
      The DASH questionnaire and score in the evaluation of hand and wrist disorders.
      Constant,
      • Constant C.R.
      • Murley A.H.
      A clinical method of functional assessment of the shoulder.
      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.
      • Saccomanno M.F.
      • DE Ieso C.
      • Milano G.
      Acromioclavicular joint instability: anatomy, biomechanics and evaluation.
      Figure thumbnail gr2
      Figure 2Representative preoperative and postoperative X-rays from the 2 groups. (A) Preoperative anteroposterior radiograph showing acute acromioclavicular joint dislocation type V according to the Rockwood classification. Coracoclavicular (CC) distance: vertical distance measured between the uppermost border of the coracoid process and the lateral aspect of the conoid tubercle. (B) Postoperative anteroposterior radiograph showing satisfactory CC reconstruction using the double TightRope system. (C) Postoperative anteroposterior radiograph showing satisfactory CC reconstruction using the single TightRope system.

       Statistical analysis

      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.

      Results

      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
      FactorsGroup STGroup DTP value
      Sample size (n)3432
      Age (yr), mean ± SD (range)44.7 ± 14.9 (19-67)44.8 ± 11.9 (15-62).99
      Sex: male/female22/1220/12>.99
      Dominant arm, n (%)16 (47.1)22 (68.8).09
      Mean time to surgery, days ± SD (range)1.9 ± 1.1 (1-3)1.6 ± 0.80 (1-3).23
      Grade of AC dislocation, n (%).61
       IV14 (41.2)11 (34.4)
       V20 (58.8)21 (65.6)
      Causes of injury, n (%).27
       Car accident8 (23.5)6 (18.8)
       Sports activity2 (5.9)6 (18.8)
       Fall from a height24 (70.6)20 (62.5)
      SD, standard deviation; AC, acromioclavicular; ST, single TightRope; DT, double TightRope.

       Functional results

      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.

       Radiographic results

      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
      Time GroupPreoperativelyPostoperatively3 weeks6 weeks3 months6 months1 year2 years
      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)∗
      P value.87.35.05<.0001∗<.0001∗<.0001∗<.0001∗<.0001∗
      t value0.160.951.9719.339.7510.009.639.58
      95% CI−1.27 to 1.49−0.15 to 0.05−0.14 to 0.005.63 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
      Time GroupPreoperativelyPostoperatively3 weeks6 weeks3 mo6 mo1 yr2 yr
      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)∗
      P value.73.42.07<.0001∗<.0001∗<.0001∗<.0001∗<.0001∗
      t value0.350.821.827.789.9110.219.729.56
      95% CI−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 “∗.”

       Complications

      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.
      Figure thumbnail gr3
      Figure 3Preoperative and postoperative X-rays of the patient with fixation failure. (A) Preoperative anteroposterior radiograph showing acute acromioclavicular joint dislocation type V according to the Rockwood classification. (B) Postoperative anteroposterior radiograph showing satisfactory coracoclavicular reconstruction using the single TightRope system. (C, D) Secondary coracoid fracture at the coracoid tunnel (white arrow) combined with fixation failure 6 weeks after the operation.
      Figure thumbnail gr4
      Figure 4Preoperative and postoperative X-rays of the patient with ossification of the coracoclavicular (CC) ligaments. (A) Preoperative anteroposterior radiograph showing acute acromioclavicular joint dislocation type V according to the Rockwood classification. (B) Postoperative anteroposterior radiograph showing satisfactory CC reconstruction using the single TightRope system. (C) The CC distance was increased at 3 months compared with 1 day postoperatively on anteroposterior radiography. (D) The CC distance was increased at 6 months compared with 1 day postoperatively on anteroposterior radiography, and ossification of the CC ligaments was observed (white arrow).
      Figure thumbnail gr5
      Figure 5Preoperative and postoperative X-rays of the patient with clavicular cortical surface erosion. (A) Preoperative anteroposterior radiograph showing acute acromioclavicular joint dislocation type V according to the Rockwood classification. (B) Postoperative anteroposterior radiograph showing satisfactory coracoclavicular (CC) reconstruction using the single TightRope system immediately after the operation. (C) Anteroposterior radiograph showing an increased CC interval caused by superior cortical surface erosion of the clavicle (arrow) by the clavicular button and part of the plate sinking into the clavicle at 2 years compared with 1 day postoperatively on anteroposterior radiography. The clavicular tunnel was obviously larger than before.

      Discussion

      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.
      • Fukuda K.
      • Craig E.V.
      • An K.N.
      • Cofield R.H.
      • Chao E.Y.
      Biomechanical study of the ligamentous system of the acromioclavicular joint.
      ,
      • Walz L.
      • Salzmann G.M.
      • Fabbro T.
      • Eichhorn S.
      • Imhoff A.B.
      The anatomic reconstruction of acromioclavicular joint dislocations using 2 TightRope devices: a biomechanical study.
      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.
      • Lim Y.
      • Sood A.
      • van Riet R.
      • Bain G.
      Acromioclavicular joint reduction, repair and reconstruction using metallic buttons-early results and complications.
      ,
      • Motta P.
      • Maderni A.
      • Bruno L.
      • Mariotti U.
      Suture rupture in acromioclavicular joint dislocations treated with flip buttons.
      Micromovement of joints and stimulation of ligaments may cause ossification of the ligaments.
      • Jari R.
      • Costic R.S.
      • Rodosky M.W.
      • Debski R.E.
      Biomechanical function of surgical procedures for acromioclavicular joint dislocations.
      ,
      • Jobmann S.
      • Buckup J.
      • Colcuc C.
      • Roessler P.P.
      • Zimmermann E.
      • Schuttler K.F.
      • et al.
      Anatomic ligament consolidation of the superior acromioclavicular ligament and the coracoclavicular ligament complex after acute arthroscopically assisted double coracoclavicular bundle stabilization.
      ,
      • Shin S.J.
      • Jeon Y.S.
      • Kim R.G.
      Arthroscopic-assisted coracoclavicular ligament reconstruction for acute acromioclavicular dislocation using 2 clavicular and 1 coracoid cortical fixation buttons with suture tapes.
      The increase in the CC distance in the patient also confirmed this point of view.
      There was also 1 case of clavicular erosion in our study. Previous research
      • Guttmann D.
      • Paksima N.E.
      • Zuckerman J.D.
      Complications of treatment of complete acromioclavicular joint dislocations.
      ,
      • Jerosch J.
      • Filler T.
      • Peuker E.
      • Greig M.
      • Siewering U.
      Which stabilization technique corrects anatomy best in patients with AC-separation? An experimental study.
      ,
      • Metzlaff S.
      • Rosslenbroich S.
      • Forkel P.H.
      • Schliemann B.
      • Arshad H.
      • Raschke M.
      • et al.
      Surgical treatment of acute acromioclavicular joint dislocations: hook plate versus minimally invasive reconstruction.
      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.
      • Clavert P.
      • Meyer A.
      • Boyer P.
      • Gastaud O.
      • Barth J.
      • Duparc F.
      Complication rates and types of failure after arthroscopic acute acromioclavicular dislocation fixation. Prospective multicenter study of 116 cases.
      ,
      • Dyrna F.
      • Berthold D.P.
      • Feucht M.J.
      • Muench L.N.
      • Martetschläger F.
      • Imhoff A.B.
      • et al.
      The importance of biomechanical properties in revision acromioclavicular joint stabilization: a scoping review.
      ,
      • Kennedy B.P.
      • Rosenberg Z.S.
      • Alaia M.J.
      • Samim M.
      • Alaia E.F.
      Radiographic features and complications following coracoclavicular ligament reconstruction.
      ,
      • Pan X.
      • Lv R.Y.
      • Lv M.G.
      • Zhang D.G.
      TightRope vs clavicular hook plate for Rockwood III-V acromioclavicular dislocations: a meta-analysis.
      ,
      • Rush L.N.
      • Lake N.
      • Stiefel E.C.
      • Hobgood E.R.
      • Ramsey J.R.
      • O'Brien M.J.
      • et al.
      Comparison of short-term complications between 2 methods of coracoclavicular ligament reconstruction: a multicenter study.
      ,
      • Shin S.J.
      • Kim N.K.
      Complications after arthroscopic coracoclavicular reconstruction using a single adjustable-loop-length suspensory fixation device in acute acromioclavicular joint dislocation.

       Limitations

      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.

      Conclusion

      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.

      Author contributions

      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.

      Disclaimer

      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.

      Supplementary data

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