腰椎经椎间孔入路椎间融合生物力学特性研究

发布时间：2018-01-23 03:39

本文关键词： 融合器椎弓根螺钉有限元仿真生物力学特性活动度　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：腰椎间融合器(Cage)植入配合椎弓根螺钉-连接棒固定,已发展成为了治疗腰椎退行性病变的主要融合和固定方式。经椎间孔入路腰椎间融合术(TLIF)作为一种相对较新的脊椎融合术式,由于其具有较大程度保留椎体的完整性,减轻神经损伤,融合率高,术后并发症少等优点,目前已经广泛地应用于临床中,然而手术中Cage的植入位置角度仅凭医生的主观经验,缺乏系统性的研究。因此,本文利用有限元仿真和离体实验相结合的研究方法,旨在探究TLIF术后Cage和椎弓根螺钉-连接棒固定系统对于椎体节段的稳定性和生物力学特性影响规律,并确定出相对较好的TLIF术融合方式。考虑到椎间盘纤维环材料的高度非线弹性,基于连续介质力学,建立了纤维环各向异性纤维增强超弹性本构模型,并利用ABAQUS/Standard中用户自定义材料子程序UANISOHYPER_INV,编译实现应用于腰椎TLIF融合数值模拟。基于健康成年志愿者腰椎CT扫描薄层数据,利用医学图像处理软件Mimics重建了腰椎几何模型,再导入有限元软件HyperMesh中建立了正常腰椎L4-L5节段模型以及按不同角度(30,45°,60°)植入Cage的椎弓根螺钉单/双边固定的TLIF融合模型,比较了术后在四种生理活动下融合节段活动度ROM大小,融合器与椎间盘上下终板接触界面、融合器、纤维环和椎弓根螺钉上的von Mises应力峰值和应力分布等生物力学特性。模拟结果表明,在相同的生理活动下,单/双侧固定时L4-L5融合节段术后稳定性大幅提升,而Cage植入角度对节段稳定性有一定影响,表现为与腰椎矢状面夹角越小,前屈、后伸时椎体稳定性越高,而侧弯、轴向旋转时稳定性则越低;融合器、接触界面、椎间盘纤维环、单/双椎弓根螺钉的应力分布随着生理活动和Cage植入角度不同存在差异,双侧固定时容易导致其中一侧椎弓根螺钉-连接棒受力集中,而且Cage对于轴向载荷分担能力也下降,因此最终确定最佳融合方式为Cage斜向45°植入椎间盘并且配合单侧椎弓根螺钉棒-连接棒系统内固定。最后,本文设计了动物生物力学离体实验,以猪腰椎标本作为实验对象,对比分析了TLIF融合对腰椎融合节段和邻近节段稳定性的影响。实验结果表明,单纯固定时融合节段在各生理活动下ROM值大幅降低,而TLIF术前屈/后伸和侧弯时ROM数值进一步降低,但轴向旋转时反而有所升高;TLIF术对于邻近节段稳定性影响表现为上邻近节段的各个方向的ROM值均较大幅度降低,而对下邻近节段的影响较小,仅在侧弯时其ROM值有一定降低。
[Abstract]:Lumbar interbody fusion cage (Cage) was implanted with pedicle screw and connective rod fixation. Transforaminal lumbar interbody fusion (TLIFs) is a relatively new spinal fusion method for the treatment of lumbar degenerative diseases. Because of its advantages of preserving the integrity of vertebral body, reducing nerve injury, high fusion rate and less postoperative complications, it has been widely used in clinical practice. However, the placement of Cage in surgery is only based on the doctor's subjective experience, lack of systematic research. Therefore, this paper uses finite element simulation and in vitro experiments. The purpose of this study was to investigate the effects of Cage and pedicle screw-rod fixation system on the stability and biomechanical characteristics of vertebral segment after TLIF. Considering the high non-linear elasticity of disc annular material, the anisotropic fiber reinforced hyperelastic constitutive model is established based on continuum mechanics. And the use of ABAQUS/Standard user-defined material subprogram UANISOHYPER_INV. Based on the data of lumbar spine CT scanning thin layer of healthy adult volunteers, the geometry model of lumbar vertebrae was reconstructed by medical image processing software Mimics. The L4-L5 segment model of normal lumbar vertebrae was established by introducing the finite element software HyperMesh and 30 掳45 掳according to different angles. 60 掳Cage was implanted into the pedicle screw single / bilateral fixed TLIF fusion model, and the ROM size of fusion segment was compared under four physiological activities after operation. The biomechanical characteristics of von Mises stress peak and stress distribution on the interface between the fusion cage and the upper and lower endplate of the disc, the fusion cage, the fibrous ring and the pedicle screw were obtained. Under the same physiological activity, the stability of L4-L5 fusion segment was significantly improved after unilateral / bilateral fixation, and the Cage implantation angle had a certain effect on the stability of L4-L5 fusion segment. The lower the sagittal angle with the lumbar vertebrae, the higher the stability of the vertebral body when it is extended, but the lower the stability is when the lateral bend and axial rotation. The stress distribution of fusion cage, contact interface, intervertebral disc fiber ring and single / double pedicle screw varied with physiological activity and Cage implantation angle. Bilateral fixation is easy to lead to one side of the pedicle screw-connecting rod force concentration, and Cage for axial load sharing ability also decreased. Therefore, the best fusion method is Cage oblique 45 掳intervertebral disc implantation and internal fixation of unilateral pedicle screw rod system. Finally, animal biomechanical in vitro experiment was designed. The effects of TLIF fusion on the stability of lumbar fusion segment and adjacent segment of lumbar vertebrae were compared and analyzed with porcine lumbar vertebrae specimen as the experimental object. The ROM value of fusion segment decreased significantly under various physiological activities while the ROM value decreased further during flexion / extension and lateral bending of TLIF before operation but increased at axial rotation. The effect of TLIF on the stability of adjacent segments was as follows: the ROM values of all directions of upper adjacent segments were significantly lower than those of lower adjacent segments. Only in the lateral bending, its ROM value has a certain decrease.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R687.3

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