Yoshihiro Hirakawa1, Tomoya Manaka2, Kumi Orita1, Yoichi Ito3, Koichi Ichikawa1, Hiroaki Nakamura1. 1. Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan. 2. Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan. Electronic address: manaka@med.osaka-cu.ac.jp. 3. Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan; Osaka Shoulder Center, Ito Clinic, Osaka, Japan.
Abstract
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.
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 humanBMP-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.