不同骨密度条件下寰椎后路螺钉生物力学稳定性的有限元分析

发布时间：2018-06-24 03:09

本文选题：有限元分析 + 寰椎椎弓根螺钉　；参考：《第二军医大学》2017年硕士论文

【摘要】：研究目的:1、运用计算机有限元的方法建立正常骨密度、骨质疏松寰椎模型,为进一步研究寰椎后路螺钉生物力学稳定性建立可靠有效的平台。2、在已建立模型上比较两种寰椎后路螺钉技术分别在单皮质和双皮质置钉方式下的稳定性,探讨骨密度变化对寰椎后路螺钉生物力学稳定性的影响。研究方法:以一名成年男性志愿者枕骨至第三颈椎(C0-C3)的CT资料逆向重建出颈椎的三维点云模型,以专业建模软件建立几何实体模型,再将其导入Hypermesh 12中根据相关文献报道参数以及参数换算公式设置材料属性,获得正常骨密度、骨质疏松的寰椎模型,最后与文献报道的有限元模型对比验证。在所建立的寰椎正常骨密度、骨质疏松有限元模型上,按寰椎椎弓根螺钉(C1pedicle screws,C1PS)、寰椎侧块螺钉(C1 lateral mass screws,C1LMS)技术分别在单皮质和双皮质置钉方式下进行装配,然后在Abaqus6.9软件中模拟螺钉的轴向拔出的动态过程,记录“骨-螺钉”界面应力-位移曲线图并分析其力学稳定性。结果:1、建立了具有61101个单元和18900个节点的完整寰椎有限元模型(图1-2和图1-3),通过与文献报道中的有限元模型对比,验证了所建模型的合理性。2、正常骨密度条件下,双皮质C1PS把持力最好,单皮质C1LMS把持力最差,两者相差约83%。骨质疏松条件下,双皮质C1PS把持力最好,单皮质C1LMS把持力最差,两者相差约199%。双皮质和单皮质C1PS在骨质疏松条件下最大拔出力比正常骨密度时降低了约40%和48%。而单皮质和双皮质C1LMS在同种情况下则降低了约63%和64%。结论:骨质疏松时皮质骨、松质骨强度均下降,对于寰椎后路螺钉的稳定性均有所影响,但是寰椎椎弓根螺钉轴向拔出力下降程度低于侧块螺钉;寰椎椎弓根螺钉的抗拔出应力主要集中在后弓至侧块的连接部即“椎弓根”,且此时单皮质置钉或双皮质置钉轴向拔出力相差不大,故对于骨质疏松的患者使用单皮质椎弓根螺钉更为合理。
[Abstract]:Objective to establish a model of atlas vertebra with normal bone density and osteoporosis by computer finite element method. In order to further study the biomechanical stability of posterior atlas screw, a reliable and effective platform. To investigate the effect of bone mineral density on biomechanical stability of posterior atlas screw. Methods: the 3D point cloud model of cervical vertebrae was reconstructed from occipital to third cervical spine (C0-C3) CT data of an adult male volunteer, and the geometric solid model was established by professional modeling software. The atlas model of normal bone density and osteoporosis was obtained by introducing it into HyperMesh 12 according to the reported parameters and the conversion formula of parameters. Finally, it was compared with the finite element model reported in the literature. In the established finite element model of atlas normal bone mineral density and osteoporosis, according to C1pedicle screwsC1PS and C1 lateral mass screwsC1LMS, they were assembled with single cortex and double cortex respectively. Then the dynamic process of axial pull-out of screw was simulated in Abaqus6.9 software, and the stress-displacement curve of "bone-screw" interface was recorded and its mechanical stability was analyzed. Results: 1, a complete finite element model of atlas with 61101 elements and 18900 nodes was established (figure 1-2 and figure 1-3), and the rationality of the model was verified by comparing it with the finite element model reported in the literature. The biocortical C1PS was the best, and the monocortex C1LMS was the worst, the difference was about 83%. Under the condition of osteoporosis, the biocortical C1PS was the best, and the monocortex C1LMS was the worst, the difference between them was about 1999. The maximal pullout force of bicortex and monocortical C1PS was about 40% and 48% lower than that of normal BMD under osteoporosis. The C _ 1 LMS of monocortex and biocortex decreased by 63% and 64% in the same condition. Conclusion: the strength of cortical bone and cancellous bone decreased during osteoporosis, which affected the stability of posterior atlas screw, but the axial pull-out force of atlas pedicle screw was lower than that of lateral mass screw. The anti-pull-out stress of atlas pedicle screw was mainly concentrated in the joint between the posterior arch and lateral mass, that is, "pedicle screw", and the axial pull-out force of single cortical screw or double-cortical screw had little difference at this time. Therefore, it is more reasonable to use single cortical pedicle screw in patients with osteoporosis.
【学位授予单位】：第二军医大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R687.3

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