Background: Bone morphogenetic protein 2 (BMP-2) plays an important role in the tendon-to-bone repair process. However, there is no previous literature on acceleration of the tendon-to-bone repair process by BMP-2 delivered by β-tricalcium phosphate (β-TCP). The aim of this study was to investigate the accelerated effect of recombinant human BMP-2 (rhBMP-2) delivered by β-TCP on the tendon-to-bone repair process.
Methods: The infraspinatus tendon of elderly female Japanese white rabbits was detached from its insertion site on the humerus. A bone tunnel (4.2 mm) was created at the original insertion site of the tendon, which was repaired using the McLaughlin procedure after filling in β-TCP (porosity 75%) without BMP-2 (control group) or with 10 µg rhBMP-2 (BMP group). The rabbits were sacrificed at the second, fourth, and eighth weeks after surgery for histologic analysis and biomechanical testing. We also evaluated the maturity of the tendon-to-bone junction using the tendon-to-bone maturity score.
Results: Histologic analysis revealed no significant difference between the groups at 2 and 8 weeks but a more abundant organized fibrocartilage at the tendon-to-bone junction in the BMP group at 4 weeks. The tendon-to-bone maturity score improved sequentially. The interface of the BMP group at 4 weeks had significantly improved biomechanical properties than that of the control group.
Conclusion: The tendon-to-bone repair process was facilitated by the use of rhBMP-2 delivered by β-TCP at 4 weeks.
Keywords: Bone morphogenetic protein; histologic analysis; infraspinatus tendon; rotator cuff repair; tendon-to-bone repair; β-tricalcium phosphate.
Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.