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Purpose To compare the absorbable and nonabsorbable suture knots on the tendon on bone-to-tendon healing during the early phase in a rat rotator cuf tear (RCT) model. Methods Fifty-two male Sprague-Dawley rats (10 weeks old; mean weight, 380 g) were used in this study, and 51 of them were randomly assigned into three groups: absorbable suture group (ASG, n = 22), nonabsorbable suture group (NSG, n = 22), and sham surgery group (SSG, n = 7), and the remaining rat was used to take surgical pictures. Bilateral supraspinatus tendon tears were created and repaired immediately in ASG and NSG. Three rats from ASG and NSG were killed for Western blot and histological evaluation at 3 days, 1 week, and 4 weeks after surgery. At 4 weeks, four rats from each group were killed for biomechanical test, and three rats from SSG were used for histological evaluation. Results Absorbable suture knots on the tendon completely degraded at 4 weeks. However, nonabsorbable suture knots remained intact between the tendon and articular side. ASG showed a stronger inlammatory reaction at 3 days and 1 week, but a weaker reaction at 4 weeks as conirmed by gross observation and Western blot. Besides, ASG showed superior biomechanical properties in terms of maximum load to failure and stifness at 4 weeks. Modiied Bonar score revealed superior maturity for tissue healing in ASG to that in NSG at 4 weeks. Furthermore, inferior bone-to-tendon interface and weakest link formation were observed in NSG on histologic images. Conclusion Absorbable suture knots on the tendon contributed to better mechanical properties compared with the nonabsorbable one after rotator cuf repair.