The Characterization Of Porous Titanium-Niobium Alloy And The Experimental Study Of Its Biocompatibility

Objective:aseptic loosening is one of the main reason for the failure of artificial joint replacement, while the stability of bone-implant interface is the key factor to prevent aseptic loosening. And the stability of bone-implant interface depends on the combination strength between of bone and biomaterial, that is, osseointegration effect, which is closely related to mechanical feature and surface characteristics of implants. Titanium has good physical properties and good biocompatibility, and Niobium can improve the machinability of titanium alloy, increase the strength of titanium as well as reduce the elastic modulus(Young's modulus). Porous scaffolds are favor of bone tissue ingrowth, and by the tissue ingrowth in the porous structure of the metal implants, the implants are connected to bone, thus it provides a good biological fixation. Therefore, we apply powder metallurgy technology(PM) to develope high porous titanium-niobium alloy (porosity>60%), which has the similar mechanical strength with cancellous bone. We also evaluate its biomechanics, pore size and porosity, biocompatibility and the ability of osseointegration in vivo in order to understand the performance of porous Titanium-Niobium alloys and provide the basis of experimental evidence for the clinical application of porous Titanium-Niobium alloy. Methods:1.allpy powder metallurgy technology(PM) to develop oporous Titanium-Niobium alloy and assess its biomechanics, pore size and porosity;.2.Biocompatibility evaluation, including cytotoxicity test (MTT), cell adhesion and proliferation assay (acridine staining and scanning electron microscopy), inflammation factor detection (IL-6);3.a osseointegration testing in vivo, tailor-made Titanium-Niobium alloy samples were implanted into the proximal femoral medullary cavity of New Zealand white rabbit, and conduct X-ray, scanning electron microscopy, energy dispersive analysis and pull out experiment at2,4and8weeks respectively.Results:1. the mechanical strength (compressive strength and elastic modulus) of porous Titanium-Niobium alloy was closed to cancellous bone;2. pore size and porosity;3.MTT testing showed the Titanium-Niobium alloy had no adverse reaction to rabbit bone marrow mesenchymal stem cells, the toxicity level of material was of0-1level;4. cell adhesion and proliferation experiments showed the titanium-niobium alloy had no significant effect on rabbit bone marrow mesenchymal stem cells, and scanning electron microscope illustrate cells grew well on the surface of the porous Titanium-Niobium alloy, and be ingrowth into the pores of porous material;5.inflammatory factor (IL-6) detection showed porous titanium-niobium alloy did not cause obvious inflammatory response;6. When the porous Titanium-Niobium alloy implanted in femoral proximal medullary cavity of New Zealand rabbits the inflammatory reaction and loosening did not display,;7.X-ray show that the implant and the femoral cortex were bond together;8. scanning electron microscopy and EDS analysis showed that the surface of implants had much calcium deposition, the implanted materials and bone were closely connection and the similar bone tissue grew into the material pore at8th week, which means osseointegration is satisfied. Compared with40%porosity group, the osseointegration of70%porosity group is better;9. mechanical pull out testing showed that the biggest pull-out power of70%porosity group and40%porosity group had no significant difference (P>0.05), but the biggest pull-out power is bigger than the dense group (P<0.05).Conclusion:1. the compressive strength and modulus of elasticity(Young's modulus) of porous Titanium-Niobium alloy is similar to cancellous bone;2. The Titanium-Niobium alloys has good biocompatibility;3. high porosity Titanium-Niobium alloy has good osseointegration effect.