Absorbable suture knots on the supraspinatus tendon prevent adverse effects of nonabsorbable suture knots in a rat model.

Abstract

To compare the absorbable and nonabsorbable suture knots on the tendon on bone-to-tendon healing during the early phase in a rat rotator cuff tear (RCT) model. Fifty-two male Sprague-Dawley rats (10weeks old; mean weight, 380g) 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 3days, 1week, and 4weeks after surgery. At 4weeks, four rats from each group were killed for biomechanical test, and three rats from SSG were used for histological evaluation. Absorbable suture knots on the tendon completely degraded at 4weeks. However, nonabsorbable suture knots remained intact between the tendon and articular side. ASG showed a stronger inflammatory reaction at 3days and 1week, but a weaker reaction at 4weeks as confirmed by gross observation and Western blot. Besides, ASG showed superior biomechanical properties in terms of maximum load to failure and stiffness at 4weeks. Modified Bonar score revealed superior maturity for tissue healing in ASG to that in NSG at 4weeks. Furthermore, inferior bone-to-tendon interface and weakest link formation were observed in NSG on histologic images. Absorbable suture knots on the tendon contributed to better mechanical properties compared with the nonabsorbable one after rotator cuff repair.