Abstract:[Objective] To compare the clinical efficacy of modified Endobutton plate combined with anchor under shoulder arthroscopy and hook plate in the treatment of acute unstable acromioclavicular joint dislocation.[Method] 63 patients with acute unstable acromioclavicular joint dislocation admitted to our hospital from August 2014 to June 2018 were retrospectively analyzed.They were divided into different groups according to the operation methods.Among them,29 cases were treated with modified Endobutton plate combined with anchor fixation under shoulder arthroscopy (the shoulder arthroscopy group),and 34 cases were treated with hook plate fixation (the hook plate group).[Result] Both groups were operated smoothly,the wound healed in one stage,and there was no injury of blood vessel and nerve.There was no significant difference in operation time and bleeding volume between the shoulder arthroscopy group and the hook plate group (P >0.05).63 cases were followed up for 12 to 24 months,with an average of (15.39±3.26) months.The coracoclavicular and acromioclavicular spacing on the first day after operation in both groups were significantly reduced compared with those before operation (P<0.05),and there was no significant difference in coracoclavicular and acromioclavicular spacing between the two groups on the first day and 12 months after operation (P >0.05).In the shoulder arthroscopy group,there were no complications such as loop rupture,coracoid process fracture,fracture around clavicular tunnel and dissolution of bone tunnel.There were 6 cases of subacromial dissolution,3 cases of subacromial impingement and 1 case of dislocation after removal of hook plate in the hook plate group.The incidence of complications between the two groups was significantly different (P<0.05).Constant shoulder function score was significantly better in the shoulder arthroscopy group than in the hook plate group at 1,3,6 and 12 months follow up (P<0.05).[Conclusion] Modified Endobutton plate combined with anchor fixation under shoulder arthroscope for acute unstable acromioclavicular joint dislocation has the advantages of minimally invasive surgery,safety,anatomical fixation,less complications,simultaneous treatment of shoulder joint injury,good recovery of shoulder joint function and no need of secondary internal fixation.Compared with hook plate,the clinical effect is more satisfactory.