人工椎间盘的研制及其有限元模型的应力分析

自行研制“框架”人工椎间盘（ALDFS）,并建立腰椎运动节段ALDFS置换的有限元模型,研究ALDFS的应力分布.方法：1.从骨组织工程学、脊柱生物力学、材料学和临床循证医学角度设计,采用无磁性的医用钛合金加工制成ALDFS.2.选取一名健康男性志愿者行薄层CT扫描图像,应用逆向工程技术重建腰椎模型.结合ALDFS的三维模型,建立腰椎运动节段ALDFS置换的腰椎模型,然后通过ANSYS12.0转换成有限元模型,最后模拟腰椎节段的运动,研究ALDFS的应力分布.结果：1.ALDFS由三枚自攻自锁螺钉、两端托板和立柱组成ALDFS两端的藕根形仿生学托板由主板和侧板组成.主板是撑起上下椎体的两端带翼的马蹄印形藕根状结构的截面.侧板是在椎体侧面,安装两枚平行自锁固定螺钉,与主板的一枚纵行螺钉在椎体内相互交锁固定假体.2.成功建立腰椎运动节段ALDFS置换的有限元模型,包括77268个单元.ALDFS的分布特点为：1）所有运动状态下,杵臼关节正中部周围区域应力最大；2）立柱和上托板承受的应力为下托板的6～7倍；3）所有运动状态中,正压状态下立柱和上托板正中部周围区域承受的应力最大；4）所有运动状态中,立柱均承受三个方向的力,其中侧弯时Z轴方向承受的力最大.结论：1.AL-DFS的上托板与立柱之间永久性±5～10°的微动,可一定程度上保留椎间盘的功能.2.建立ALDFS三维有限元模型并进行其应力分析是可行的,结果是可信的.

Designment of artificial disc and its stress analysis

Purpose：to design the model of the artificial lumbar disc of frame style （ALDFS） and to establish the finite element model of the ALDFS replacement of the lumbar motion segment.At last,the stress distribution of the ALDFS model is received.Method：1.According to the bone tissue engineering,spine biomechanics,materials science and clinical evidence -based medicine,ALDFS was constructed by Tc 4.2.Applying the reverse engineering technology with the selected L2 ～ L3 thin-section CT images of a healthy male volunteer,we rebuild the lumbar spine model.Relying on the model of the ALDFS and Anstys12.0,the finite element model of the ALDFS replacement was generated.With the load of 500 N and 10 N · m moment in compression,lateral bending and axial rotation was applied on the clinical model,the stress of the ALDFS model was calculated.Results：1.The model of the ALDFS was made up of three self-lock screwes,amph-palettes and the column.Amph-palettes are composed of a cardinal plate of structure of lotus root with two wings and a lateralia with two selflock screws.Two self-lock screws of lateralia are inter-locked with a longitudinal screw on amph-palette in the vertebral body.2.The finite element model of the ALDFS replacement of the lumbar motion segment were successfully established.The finite element model of ALDFS replacement contained 77 268 elements.The stress distribution of the ALDFS showed some characteristics as follows：1） The stress exerted around the center of the joint is biggest in all motion states.2） The column and the upper plate bear 6 ～ 7 times stress as much as the lower plate 3） The biggest stress exists around the center of the upper plate and the column during compression in all motion states.4）The column bear forces in three directions and forces in Z-axis is biggest during lateral bending in all motion states.Conclusion：1.To some extent,ALDFS can retain the function of the disc,by keeping permanent activity about ± 5 ～ 10 °between the upper plate and the column.2.Establishment of three-dimesional finite element model of ALDFS and analysis of its stress are feasible.