Faculty of Materials Science and Engineering, Hubei University, Wuhan, PR China.
Biomaterials. 2011 Jan;32(2):330-8. doi: 10.1016/j.biomaterials.2010.08.102.
The superelastic nature of bones requires matching biomechanical properties from the ideal artificial biomedical implants in order to provide smooth load transfer and foster the growth of new bone tissues. In this work, we determine the biomechanical characteristics of porous NiTi implants and investigate bone ingrowth under actual load-bearing conditions in vivo. In this systematic and comparative study, porous NiTi, porous Ti, dense NiTi, and dense Ti are implanted into 5 mm diameter holes in the distal part of the femur/tibia of rabbits for 15 weeks. The bone ingrowth and interfacial bonding strength are evaluated by histological analysis and push-out test. The porous NiTi materials bond very well to newly formed bone tissues and the highest average strength of 357 N and best ductility are achieved from the porous NiTi materials. The bonding curve obtained from the NiTi scaffold shows similar superelasticity as natural bones with a deflection of 0.30-0.85 mm thus shielding new bone tissues from large load stress. This is believed to be the reason why new bone tissues can penetrate deeply into the porous NiTi scaffold compared to the one made of porous Ti. Histological analysis reveals that new bone tissues adhere and grow well on the external surfaces as well as exposed areas on the inner pores of the NiTi scaffold. The in vitro study indicates that the surface chemical composition and topography of the porous structure leads to good cytocompatibility. Consequently, osteoblasts proliferate smoothly on the entire implant including the flat surface, embossed region, exposed area of the pores, and interconnected channels. In conjunction with the good cytocompatibility, the superelastic biomechanical properties of the porous NiTi scaffold bodes well for fast formation and ingrowth of new bones, and porous NiTi scaffolds are thus suitable for clinical applications under load-bearing conditions.
骨骼的超弹性性质要求理想的人工生物医学植入物具有匹配的生物力学特性，以实现平稳的负载传递并促进新骨组织的生长。在这项工作中，我们确定了多孔 NiTi 植入物的生物力学特性，并研究了体内实际承载条件下的骨内生长。在这项系统和比较研究中，将多孔 NiTi、多孔 Ti、致密 NiTi 和致密 Ti 植入到兔子股骨/胫骨远端的 5mm 直径孔中 15 周。通过组织学分析和推出试验评估骨内生长和界面结合强度。多孔 NiTi 材料与新形成的骨组织结合得非常好，多孔 NiTi 材料的平均强度最高可达 357N，且具有最佳的延展性。从 NiTi 支架获得的结合曲线显示出与天然骨骼相似的超弹性，挠度为 0.30-0.85mm，从而使新骨组织免受大负载应力的影响。这被认为是新骨组织可以比多孔 Ti 制成的支架更深地渗透到多孔 NiTi 支架中的原因。组织学分析表明，新骨组织很好地附着并在 NiTi 支架的外表面以及内孔的暴露区域上生长。体外研究表明，多孔结构的表面化学成分和形貌导致良好的细胞相容性。因此，成骨细胞在整个植入物上（包括平坦表面、压花区域、孔的暴露区域和互连通道）都能顺利增殖。结合良好的细胞相容性，多孔 NiTi 支架的超弹性生物力学特性有利于新骨的快速形成和内生长，因此多孔 NiTi 支架适合在承重条件下的临床应用。
