Characterization Of Porous Titanium-niobium Alloy,Biocompatibility And Study In Defects Of The Bone Graft

ObjectiveThe loss of osteon caused by congenital or acquired diseases are called bone defects. It is commonly occurs in skull, mandible and tibia, of which the tibia defects have the most frequent occurrence. Due to the lack of osteon, the bone regeneration are handicapped and the wound are difficult to heal with accompany of infection. These reasons make the bone defects repair the most difficult and complex.part in bone surgery. In bone defect repairs, while the bone graft method are still broadly used in the clinic, it also has a serials of problems. So it is urged that the research and development of the ideal alternative synthetic bone graft material (or implant material) has become important in the medical and biological materials science.In nowadays artificial alloy are served as an implant material and have a widely used, but its inappropriate in biocompatibility and mechanical compatibility are one of the major cause of failure after surgery. So searching for alloys with better biocompatibility and mechanical compatibility becomes the key in the repair of bone defects fields. According to the recent research, the Titanium-Niobium alloy is considered to be an excellent implant material with appropriate physical properties and considerable biocompatibility. The Niobium can improve the machinability of titanium alloy, and also improve the strength of Titanium, while reducing the modulus of elasticity, making it more similar to human bone density. In the other way, the porous of implant material surface are found be benefit for the attachment of bone cells and support the bone tissue ingrowth. Meanwhile the scientific researcher has discovered that some key cytokines involved in bone cell differentiation, such as bone morphogenetic protein (BMP), which can induce stem cells to differentiate into bone cells. It plays a key role in bone regeneration. Put it all together, thecomposite materials, the Titanium-niobium alloy with BMP might be a newly implant materials to improve the efficiency on bone defect repair.MethodsThe porosity of titanium-niobium alloy are produced by powder metallurgy technology, and then the alloy are evaluated by its biomechanical strength, pore size and porosity. The second part is the vitro biocompatibility testing based most on the Human umbilical cord mesenchymal stem cells (HuMSC).The experiment includes the cytotoxicity test (MTT), cell adhesion and proliferation assay (acridine orange staining and scanning electron microscopy), The subcutaneous detect inflammation (immunohistochemistry). The third part of the article used the rabbit tibial defect model for bone integration of detection, the composite alloy specimens implanted eight weeks after X-ray, scanning electron microscopy, EDS analysis and mechanical compression experiments. All these results provided the evidence that the material implanted improve the repair of bone defect situation.Results(1)70%porosity of porous titanium-niobium alloy have the elastic modulus of about2.23GPa compressive strength of94.8MPa and close the density of human bone, thus with good mechanical properties.The pore size of the alloy are about200-500μm in the three-dimensional connectivity between the pores, the surface rough;(2) MTT assay results showed that the titanium-niobium alloy materials did not significantly inhibit the proliferation of MCS cells and does not cause apoptosis and necrosis,with0-1grade level of cytotoxicity.(3) Cell adhesion and proliferation test showed that the alloy does not affect cell growth.(4) The specimen subcutaneous implant materials in vivo shows it does no significant degradation and shedding appear and have no obvious ulceration or malignant phenomenon, it support the view that the material have a high biological stability and low toxicity. Immunohistochemical results also confirmed that it did not cause significant inflammatory response;(5) New Zealand white rabbit tibia bone defect model found that the implanted material does not cause tissue ulceration, muscle atrophy, and the inflammation abscess phenomenon, the wound healed well. In the X-ray film, the composite implant materials showed materials and bone tissue are linked closely together, the more bone growth mainly in cancellous bone, compared to other better.(6). Electron microscopy experiments and EDS are also show that calcium deposition in the surface of70%porosity of porous titanium-niobium alloy group and bone closely. Osteoid formation, porosity and pore deep growth are better than other groups.(7). Mechanical compression of the tibia after8weeks show that composite group (with BMP)have better compression results, with better mechanical properties.Conclusion(1). Low modulus of elasticity (70%porosity) of porous Titanium-Niobium alloy have a similar to propriety of cancellous bone in strength and elastic modulus;(2).70%porosity titanium-niobium alloy have a considerable biological capacitive and low cell toxicity;(3). The composite BMP alloy material owned by the effective good mechanical compatibility, promote the repair of bone defects.