高强度医用不锈钢植入器件的轻量化设计和生物力学适配性

High nitrogen nickel free stainless steel (HNNFSS) has begun to be used in clinic, which possesses excellent mechanical properties, corrosion resistance and biocompatibility. Especially its strength is two times more than that of the conventional 316L stainless steel, but this advantage is not fully used in optimization of both the structure and the size of the implant devices. In this project, the effects of the changes of hollow structure, including distribution, size, quantity and shape of hole, etc., and the dimensional of HNNFSS bone plate on the biomechanical behavior of bone plates will be studied by means of finite element analysis, and the biomechanical behavior of bone plate will be also in vitro studied through use of bone specimens. Based on the above studies, the hollow structure and dimension of HNNFSS bone plate will be optimized in order to realize a preliminary lightweight design for the bone plate. Finally the effects of the hollow structure and dimension changes of HNNFSS bone plate on its biomechanical behavior and implantation performance will be studied and veriefied through animal tests. The compatibility rule between the lightweight design and the biomechanics of HNNFSS bone plate will be established, which will provide fundamental support and materials data for design and development of new type of high strength stainless steel implant devices.

已临床应用的高氮无镍不锈钢具有优良的力学性能、腐蚀性能和生物相容性，特别是其强度接近医用316L不锈钢强度2倍左右，但是临床用植入器件并没有充分利用其高强度的优势而进行结构尺寸的优化设计。本项目采用有限元方法，模拟研究高氮无镍不锈钢接骨板的尺寸和空心结构变化（包括孔的数量、形状、尺寸及分布等）对其力学行为的影响规律，通过离体骨骼标本模拟研究接骨板的生物力学行为。在此基础上，优化接骨板的尺寸和结构，进行高强度高氮无镍不锈钢接骨板的轻量化设计。最后通过动物试验验证接骨板的空心结构和尺寸变化对其生物力学行为和植入功效的影响规律，建立高氮无镍不锈钢接骨板的轻量化设计和生物力学的适配性准则，为新型高强度不锈钢植入器件的轻量化设计和开发提供理论依据和基础数据。

高氮无镍不锈钢具有优良的力学性能、疲劳性能、耐腐蚀性能和生物相容性，在20%冷变形时具有最佳的力学性能组合。为了充分发挥医用高氮无镍不锈钢的高强度性能优势，通过有限元模拟研究了无镍不锈钢骨板尺寸减薄对接骨板力学适配性的影响规律，并通过动物实验进行了验证。研究结果建议高强度高氮无镍不锈钢接骨板的厚度可以较临床不锈钢接骨板减薄15%左右，不影响其服役过程中的应力分布和功能。通过12周动物骨折模型研究了轻量化高氮无镍不锈钢骨板对骨折愈合后的生物力学的影响。结果表明，厚度减薄约14%的高氮无镍不锈钢接骨板固定兔子骨折股骨更有利于骨折的愈合和恢复。.同时模拟研究空心结构高氮无镍不锈钢接骨板内孔的数量及孔径变化对弯曲抗力和应力分布的影响规律，结果表明随着孔数的量和孔径的增加，接骨板的轻量化率呈线性提高，同时三点弯曲时的弯曲抗力也明显降低，均成线性关系，应力分布随着孔的加入逐渐均匀。对于高强度的高氮无镍不锈钢而言，采用三孔结构及孔径为接骨板厚50%的设计，可以实现约15%的轻量化，而且保持较高的抗弯曲性能。同时根据研究结果，建议临床用316L不锈钢接骨板和钛合金接骨板可以采用双孔结构，孔径控制在接骨板厚度的50%以内，能够实现10%左右的轻量化，同时弯曲抗力不明显下降。