Reinforcement of tendon attachment to bioactive porous titanium by BMP-2-induced ectopic bone formation

Achieving a firm attachment between a tendon and a metal remains a major challenge in orthopedic surgery. In this study, we developed a simple model for evaluating the strength of this attachment using bioactive porous titanium, and confirmed whether bone morphogenic protein-2 (BMP-2) can be a help in achieving a firm attachment by ectopic bone formation. Rectangular plate-shaped implants were soak-loaded with BMP-2 (B+ group) and were implanted within the patellar tendon of a rabbit. Implants without BMP-2 (B- group) were used as controls, and they were harvested at 4 and 8 weeks postoperation for mechanical tests and for histological and histomorphometric study. The pull-out failure load of the B+ group was significantly higher than that of the B- group and new bone was more prevalent within the pores and around the implants in the B+ group than in the B- group. The model used in this study was feasible for evaluating the tendon-metal attachment, and a combination of bioactive porous titanium and BMP-2 was found to attach firmly to the tendon.