Objective:To compare the clinical efficacy between the pressing tendon suture with a lateral anchor and the knotted suture with a lateral anchor in the treatment of severe rotator cuff tear under shoulder arthroscopy.Methods:A retrospective study was conducted of the 42 patients who had been treated at Department of Orthopedic Sports Medicine, Affiliated Hospital to Qingdao University from December 2018 to December 2019 for severe rotator cuff tear. They were 13 males and 29 females, with an age of (58.3±10.1) years (from 32 to 74 years). The injury was on the right side in 26 cases and on the left side in 16 cases. Of them, 22 received pressing tendon suture with a lateral anchor under shoulder arthroscopy and 20 knotted suture with a lateral anchor under shoulder arthroscopy. The flexion, abduction and external rotation of the shoulder, Visual Analog Scale (VAS) pain score, University of California-Los Angeles (UCLA) score, Constant-Murley shoulder score, American Shoulder and Elbow Surgeons (ASES) score and imaging MRI Sugaya grading were compared between the 2 groups 12 months after operation.Results:There was no significant difference in the preoperative general data between the 2 groups, showing comparability between them ( P>0.05). At 12 months after operation, the pressing tendon suture group had better abduction and flexion of the shoulder, a lower VAS pain score and a higher ASES score than the knotted suture group, but the differences were insignificant ( P>0.05). At 12 months after operation, the pressing tendon suture group achieved significantly better external rotation (39.2°±11.7°) and significantly higher UCLA score (28.1±4.7) and Constant-Murley shoulder score (77.0±9.3) than the knotted suture group (29.8°±14.6°, 22.1±5.7 and 66.4±11.0) ( P<0.05). At 12 months after operation, the imaging MRI Sugaya grading was significantly lower for the pressing tendon suture group than that for the knotted suture group ( P<0.05). Conclusion:In the treatment of patients with severe rotator cuff tear under shoulder arthroscopy, the pressing tendon suture with a lateral anchor may lead to better clinical prognosis than the knotted suture with a lateral anchor.