Paired comparison study of bone-tendon composite autograft with bone-tendon direct repair for the treatment of chronic large rotator cuff tear in a rat model.

Abstract

Purpose: We designed a paired controlled study to investigate the advantages of using bone-tendon composite autograft to reconstruct chronic rotator cuff tear compared with primary repair and provide sound evidences for the reconstruction of chronic rotator cuff tear using bone-tendon composite autograft. Method: Thirty-eight Sprague-Dawley rats were used. The native bone-tendon junctions of supraspinatus and Achilles tendon insertion from two rats were harvested for gross and histological observation. Another thirty-six rats had bilateral supraspinatus tenotomy from the great tuberosity. Three weeks later, primary repair was performed on one side and the other side was reconstructed using an Achilles-calcaneus composite autograft from the ipsilateral leg. Nine rats were sacrificed for biomechanical testing and another three were sacrificed for histological evaluation at 3, 6, and 9 weeks after surgery respectively. Results: The Achilles-calcaneus composite autograft group showed significantly better biomechanical characteristics at 3 and 6 weeks in terms of maximum load, maximum stress, stiffness, and Young’s modulus. However, there was no significant difference between the two treatment groups at 9 weeks after repair. Tissue histology demonstrated an organized extracellular matrix, a clear tide mark, and distinct fibrocartilage layers in the composite graft group, similar to those of the native bone-tendon interface. Additionally, clear bone to bone healing and tendon to tendon healing were observed. By contrast, the conventional primary repair could not regenerate the structure of the native bone-tendon interface, although bone-tendon interface healing progressed. Conclusions: Bone-tendon autograft for chronic rotator cuff reconstruction is superior to the primary repair regarding biomechanical property and histological structure. Our study provides sound evidence for the reconstruction of chronic rotator cuff tear using bone-tendon composite autograft in the future clinical practice.