Application Of Combined BMP 3-D Interconnected Porous Titanium In Surface Modification Of Implant

The interface between implant and host bone plays key role in maintaining primary and long term stability of the implant. Surface modification of implant can enhance bone ingrowth and increase bone formation to create firm osseointegration between implant and host bone, which might satisfied early and late fixation and reduce the risk of implant loosening. This research mainly focused on development of three dimensions interconnected porous titanium which could be processed to the surface of the implant shaft, while BMP was integrated. Bone formation was observed on the implant interface. Methods: 1. porous titanium was sintered with titanium powder;2. porous titanium combined with BMP was implanted into the muscle of mice to observe its difference from control group;3. implant shaft with surface modification of porous titanium was implanted into the femoral medullary cavity of dogs after combining with BMP. Results: 1. 3-D interconnected porous titanium with pore diameter of 300 - 600n and interval porosity of 50% - 60% was developed, which had its elastic modulus of 0.6~0.7GPa. 2. porous titanium combined with BMP was found to have large amount of fibrous tissue with fibroblastic cells. Bone formation was significantly greater in 6 weeks postoperatively than 3 weeks postoperatively. Three weeks after operation, bone ingrowth was found to reach half of the integrated material layer. Implant-bone surface bone formation was significantly greater in the group of porous titanium combined with BMP than the group of porous titanium combined with BMP- fibrin mixture. Conclusion: 1. 3-D interconnected porous titanium had a similar structure with cancellous bone, while its elastic moduluswas between cancellous bone and cortical bone. 2. Porous titanium combined with BMP could induce tissue formation and stimulate MSCs to transform into bone tissue. 3. After combining with BMP, implant shaft with surface modification of porous titanium had bone formation in the interface layer early after operation. Implant-bone surface bone formation was found to increase with time. Six weeks after operation, bone ingrowth had reached the whole integrated material layer. Two fixation mechanism of mechanical interlock and chemical bond in the implant-bone interface may meet the demand of early fixation.