Effect of Suture Absorbability on Rotator Cuff Healing in a Rabbit Rotator Cuff Repair Model

Background: Various suture materials can be clinically used for rotator cuff repair (RCR). RCR with high-strength nonabsorbable sutures may not be ideal, because it may cause stress shielding, which may hinder enthesis regeneration and maturation in the tendon-bone interface. RCR with strength-decreasing sutures (ie, absorbable sutures) may be a better choice. However, the effects of suture absorbability on enthesis regeneration and maturation have not been investigated. Hypothesis: The use of absorbable sutures in RCR would produce a better tendon-bone connection structure, which provides histological and biomechanical advantages over the use of nonabsorbable sutures. Study Design: Controlled laboratory study. Methods: A supraspinatus tear was created on the right shoulder in 108 of 120 skeletally mature male rabbits. The animals were randomly divided into 3 groups, with 36 rabbits in each group, to undergo RCR individually with total absorbable, partial absorbable, and nonabsorbable sutures (TAS, PAS, and NAS). Twelve animals in each group were sacrificed at 4, 8, and 12 weeks after surgery, with 6 operated shoulders used for histological evaluation to detect enthesis regeneration and maturation and the other 6 for biomechanical testing. The remaining 12 animals without supraspinatus tear were used as control. Results: At 12 weeks, in the tendon-bone interface, enthesis regeneration was detected in the TAS group but not in the NAS group. A mature enthesis appeared in the TAS group but not in the NAS group. In the PAS group, enthesis regeneration was also observed; however, the fibrocartilage was not abundant and the enthesis maturity not good as compared with the TAS group. Biomechanical testing showed that the rotator cuff-greater tuberosity connection structure in the TAS and PAS groups had greater values of ultimate load to failure, stiffness, and stress than the NAS group at all time points. Conclusion: In RCR in an acute rabbit rotator cuff tear model, the use of sutures with absorbability lead to enthesis regeneration, increased maturity of rotator cuff insertion, and enhanced rotator cuff-greater tuberosity connection.