Reconstruction of large chronic rotator cuff tear can benefit from the bone–tendon composite autograft to restore the native bone–tendon interface

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 some evidence to use the 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 (simple tendon pullout direct repair to bone) 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 and stiffness. Tissue histology demonstrated an organised extracellular matrix, a clear tidemark, 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. CONCLUSIONS: Bone–tendon autograft for chronic rotator cuff reconstruction is superior to the primary repair regarding biomechanical property and histological structure. Our study may provide some evidence in support of the reconstruction of a chronic rotator cuff tear using bone–tendon composite autografts in clinical practice. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: The current study finds the bone-tendon autograft can restore the normal bone-tendon interface, which can not regenerate after repair and is the key factor affecting re-tear. The bone-tendon autografts from our body can be the candidates for rotator cuff tear reconstruction especially the large to massive rotator cuff tear in the future to reduce the re-tear after rotator cuff tear.