基于CT图像的人体腰椎反求建模及有限元分析研究

发布时间：2018-05-07 08:05

本文选题：椎弓根螺钉内固定系统 + CT图像　；参考：《广西科技大学》2013年硕士论文

【摘要】：为了解人体正常腰椎、椎间盘的受力情况以及植入椎弓根螺钉内固定系统的腰椎在不同状态下的最易断裂点，利用医学数字影像生成及编辑软件Mimics将腰椎L_4-L_5节段CT图像进行反求生成三维模型、并导入工程设计软件UG NX对模型修复整理，再导入有限元分析软件Ansys Workbench中进行各种不同载荷工况下的分析，得出在不同载荷状态下的椎体、椎间盘应力云图与位移云图，并对结果进行强度校核，为医学提供理论支撑。研究过程中，首先，利用Mimics将CT断层扫描图像重建为人体正常腰椎L_4-L_5节段三维模型，导入UG并建立包含纤维环及髓核的椎间盘，模拟了人体腰椎的真实结构。通过UG与Ansys Workbench的无缝接口导入Ansys Workbench中，对模型赋值并进行有限元分析，得出人体直立、前屈、左右旋转作用时，正常腰椎的椎体、椎间盘的应力云图及位移云图。结果表明，最大位移发生于L_4椎体前部或椎间盘上表面前部，而小关节接触面由冠状面转变为矢状面，容易遭受负载的破坏，所以最大应力均出现L_4下关节突附近，，其中旋转时的28.211MPa为最大。其次，将模型进行简化，利用材料力学的理论公式对直立时的有限元分析进行强度校核，结果表明，有限元分析结果接近理论计算结果，且相对误差较小，计算结果可靠，为临床医学提供理论参考；最后，模拟建立植入椎弓根螺钉的腰椎三维模型并进行有限元分析，得到人体直立、前屈、左右旋转作用时的等效应力云图及位移云图。结果表明：最大应力均出现于螺钉中部，表明植入的椎弓根螺钉可缓解椎体的承载负担，并且可使腰椎变形减小。
[Abstract]:In order to understand the stress of the normal lumbar vertebrae, the intervertebral disc and the most easily broken point of the lumbar vertebrae implanted with the pedicle screw internal fixation system in different states, Using the medical digital image generation and editing software Mimics, the lumbar spine L_4-L_5 segment CT image is inversely generated into the three-dimensional model, and the engineering design software UG NX is introduced to repair the model. Then the finite element analysis software Ansys Workbench was introduced to analyze the vertebral body, intervertebral disc stress cloud and displacement cloud under different load conditions, and the results were checked to provide theoretical support for medicine. In the course of the study, firstly, Mimics was used to reconstruct the CT tomography image into the normal L_4-L_5 segment of human lumbar vertebrae, then introduced into UG and established the disc containing fibrous ring and nucleus pulposus to simulate the real structure of human lumbar vertebrae. Through the seamless interface between UG and Ansys Workbench into Ansys Workbench, the model was assigned and finite element analysis was carried out, and the stress cloud and displacement cloud of normal lumbar vertebra and intervertebral disc were obtained when the body was upright, flexor, and left and right rotated. The results showed that the maximum displacement occurred in the anterior part of the L4 vertebra or the anterior part of the upper surface of the intervertebral disc, while the facet joint contact surface changed from the coronal plane to the sagittal plane, which was liable to be damaged by the load, so the maximum stress appeared near the L4 inferior articular process. The 28.211MPa of rotation is the largest. Secondly, the model is simplified and the strength of the vertical finite element analysis is checked by the theoretical formula of material mechanics. The results show that the finite element analysis results are close to the theoretical calculation results, and the relative error is small, and the calculation results are reliable. Finally, the three-dimensional model of lumbar vertebrae pedicle screw was established and finite element analysis was carried out to obtain the equivalent stress cloud image and displacement cloud image of human body under the action of upright, forward flexion, left and right rotation. The results showed that the maximum stress appeared in the middle of the screw, which indicated that the pedicle screw could relieve the load of the vertebral body and reduce the deformation of the lumbar vertebrae.
【学位授予单位】：广西科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R816.8

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