The mechanism underlying most AC joint separations is caused by traffic accidents and downfall, traumatic injury to the AC joint runs up to 9% of all shoulder injuries in human beings . Treatment of AC joint separations is remained controversial, for the high grade AC dislocations, some studies have recommended conservative treatment, however, many studies showed those patients may later report unsatisfactory outcomes, at least 40% of conservative treatment patients associated with significant residual symptoms, these patients may end up seeking a surgical treatment after many weeks or months of persistent shoulder symptoms [11, 12]. Chronic AC joint instability may be associated with persistently painful and weak shoulders, most of the studies recommended surgery for whom nonsurgical treatment has failed after many weeks or months of persistent shoulder symptoms. Long-term stability requires that the initial fixation is strong enough to maintain reduction throughout the biological healing process. Surgical techniques and implants are multifaceted, various methods of fixation like K-wires, clavicular hook plate, Tight-Rope technique, with no gold standard procedure.
Many studies recommend using tendon grafts or suture-button configurations for the treatment of high grade AC dislocations injuries, because it had significant improved clinical results compared with nonsurgical treatment . However, recent studies confirmed the incidence of complication after reconstruction of the AC ligaments was reported to be ranged from 27–52%, and 20% of the patients were identified with clavicle fracture complication.Tendon grafts may fail due to stretch during remodeling, and the failure of suture-button configurations associated with knot slippage or button migration. Cook et al  demonstrated an early failure rates as great as 29% with AC ligament reconstruction. The 2 buttons are now connected with a tape for Tight-Rope system can be self-propelled adjust reconstruction length, which has been shown to resist higher loads . All the patients had outcome scores available at 2 year or greater, the present study showed successful short term clinical outcomes for the patients who treated with arthroscopic assisted fixation using Tight-Rope system, with statistically significant difference between the preoperative and postoperative constant score and VAS scores, the most patients were regained their normal range of motion, and very satisfied with function of their shoulder at last review.
During the past decade, growing interest has focused on the reconstruction techniques for high-grade AC joint dislocations, compared with the open surgical techniques, evidence indicates that all-arthroscopic approach is advantageous for treating these patients because it is minimally invasive procedure allows successful reduced the risk of infection and big scar [17, 18]. Arthroscopic technique using the Tight-Rope system is minimally invasive procedure avoids the need of second procedure for implant extraction, and fixation failure or a loss of reduction after plate removal, this result in faster recovery and better shoulder function results . In line with previous studies, compared with clavicular hook plate group, patients treated with arthroscopic assisted fixation using Tight-Rope system was subject to smaller length of skin incision, estimated blood loss and decreased length of hospital stay. Patients who underwent clavicular hook plate had a higher incidence of partial loss of reduction or fixation failure and infection than those of Tight-Rope system group. Furthermore, our study showed an important advantage of the arthroscopic approach for treating these patients is simultaneously achieving diagnosis and treatment of the frequently (14.3%) associated glenohumeral joint lesions.
Many studies recommend using double Tight-Rope technique for the treatment of high grade AC dislocations [20, 21]. However, Patzer et al  analyzed the clinical and radiological results of arthroscopically assisted Tight-Rope technique for high grade AC dislocations injuries, it was found that there was no significantly different between single and double Tight-Rope technique group. Furthermore, previous study confirmed the constant score of shoulder after Tight-Rope technique was reported to be ranged from 86.4 to 96.3 [23, 24]. Referring to our study, the mean postoperative constant score was 89.3 ± 4.2 in Tight-Rope group, and 83.3 ± 8.8 in clavicular hook plate group, the mean post-operative VAS scale was 1.2 ± 0.6 in Tight-Rope group, and 1.8 ± 1.1 in clavicular hook plate group. In a retrospective data investigated 69 patients, Jensen et al  confirmed that the arthroscopically assisted reduction of acute AC joint separations with the Tight-Rope technique advantages over the clavicular hook plate fixation. In line with previous studies, compared with patients of clavicular hook plate group, those patients of Tight-Rope group demonstrated statistically significant improvement in the constant score and VAS score at the end of follow up respectively.
Several limitations were also detected in this study. First of all, our current study is a single-center study, and a relatively small number of patients were treated with arthroscopic assisted fixation using Tight-Rope system may introduce bias into the results, further prospective study with an increased sample size is required to definitely the answer of question whether the arthroscopically assisted Tight-Rope technique is superior to the open procedure or not. Second, our study is not fully showed what the outcome results would be while performing AC reconstruction alone without performing any other glenohumeral joint lesions surgery, the difference in outcomes could be related to the management of other pathology in 14.3% of patients. Third, we just observed the constant score and VAS score of shoulder within 2 year after injury in patients with AC reconstruction, therefore, a prospective study with long-term follow-up is necessary.
The present study showed successful short term clinical outcomes for the patients who treated with arthroscopic assisted fixation using Tight-Rope technique, the most patients were regained their normal range of motion, and very satisfied with the function of their shoulder at last review. Compared with the clavicular hook plate technique, Tight Rope technique is advantageous for treating these patients because it is minimally invasive procedure with low morbidities and superior clinical outcom