Dynesys系统单节段固定腰椎模型的建立与有限元分析

发布时间：2018-08-27 17:30

【摘要】：退变性腰椎疾病是腰腿痛常见的病因，保守治疗效果欠佳的患者，往往需要接受手术进一步治疗。而应用的钉-棒内固定系统的脊柱融合手术，是目前手术治疗腰椎退变性疾病的金标准。这种内固定系统可保证椎骨间的融合，及桥接节段的稳定。然而，脊柱融合手术被发现可造成邻近节段反常的压力。这种高刚度的椎弓根钉-棒系统，可能在脊柱手术邻近节段，起到了加速退行性病变进程的作用。非融合技术随之被提出，现阶段最近最具代表性的内固定装置为Dynesys动态中和系统。其将钉-棒系统连接同侧椎弓根螺钉的钛棒换成了更柔韧的套管及绳索。其设计理念上的先进性，能否带来实际应用中令人满意的效果，且其在国外初步应用的疗效，能否在国内得到复制，一直受到广泛的关注。目的：1.建立腰椎（L2-L5）有限元模型，并对其有效性进行验证；2.建立Dynesys植入腰椎、及传统钉棒系统植入腰椎有限元模型；3.模型间比较：在3种模型上施加相同的前屈、后伸、侧向弯曲、旋转扭矩，通过有限元分析软件计算，比较标准腰椎模型、坚强内固定模型、Dynesys动态内固定模型，三种模型在前屈、后伸、侧向弯曲、旋转状态下，固定节段（L3-L4）及上位邻近节段（L2-L3）的椎间活动度及椎间盘应力；4.方法间比较：将本研究结果与以往病例回顾研究及体外实验研究结果进行初步比较。方法：1.建立并验证L2-L5腰椎有限元模型。对健康男性患者腰椎CT数据，应用Mimics软件进行分割，提取骨骼及椎间盘断层图像，建立几何三维模型。应用HyperMesh软件对三维模型进行网格划分、赋予材料属性等有限元前处理。并通过Abaqus软件进行有限元运算。通过“距离——应力”的应力分布曲线，及“压缩力——位移”曲线，验证有限元模型的有效性。2.Dynesys及钉-棒系统固定腰椎模型的建立及有限元分析。通过Pro/Engineer软件制作内固定装置模型，在mimics软件下，模拟手术于L3-L4植入两种内固定器械。在前屈、后伸侧向弯曲、旋转四种工况下，比较未置钉腰椎模型、Dynesys系统固定腰椎模型及钉棒系统固定腰椎模型的L2-L3、L3-L4椎间活动度，椎间盘应力及小关节应力。结果：1.建立包括椎骨、椎间盘、韧带的L2-L5腰椎有限元模型，并验证了其有效性。2.建立了Dynesys系统及钉棒系统固定腰椎的有限元模型。3.Dynesys系统固定腰椎模型在内固定植入节段，与未置钉模型相比椎间活动度降低67%，头侧邻近节段椎间活动度增加11%；而传统坚强内固定降低手术节段椎间活动度81.6%，增加头侧邻近节段活动度21.3%。动态固定在手术节段卸载了大部分应力，而对上位邻近节段造成的影响较钉-棒系统小。动态固定对于间盘及小关节应力的影响，，介于无固定与坚强固定之间。4.本研究通过有限元分析得到的椎间活动度的结果，与本科室以往病例回顾研究及他人体外测试结果相一致。结论：1.基于腰椎CT断层扫描图像，建立了标准化的、通过验证的、可用于进一步分析的腰椎有限元模型；2.Dynesys系统固定腰椎模型有限元分析，在椎间活动度方面的结果，与以往病例回顾分析的结果相似，即Dynesys系统可为固定节段提供稳定，并对上位邻近节段活动度造成较小的影响；Dynesys系统对腰椎应力方面的影响与坚强固定相比，对上位临近节段椎间盘应力及小关节应力的影响较小。
[Abstract]:Degenerative lumbar spine disease is a common cause of low back and leg pain, and patients with poor conservative treatment often need further surgery. Spinal fusion with a screw-rod system is the gold standard for surgical treatment of lumbar degenerative diseases. This system ensures intervertebral fusion and bridging of segments. Stability. However, spinal fusion has been found to cause abnormal pressures in adjacent segments. This high stiffness pedicle screw-rod system may play a role in accelerating the progression of degenerative lesions in adjacent segments of spinal surgery. Non-fusion techniques have been proposed, with Dynesys being the most recent representative instrumentation at this stage. Neutralization system. It replaces the titanium rod of the screw-rod system with the flexible cannula and rope of the ipsilateral pedicle screw. Whether the advanced design concept can bring satisfactory results in practical application, and whether the curative effect of the preliminary application abroad can be replicated in China, has been widely concerned.
Objective: 1. To establish a finite element model of the lumbar spine (L2-L5) and verify its effectiveness; 2. To establish a finite element model of the lumbar spine with Dynesys implantation and traditional screw-rod system implantation; 3. Comparison between models: the same forward flexion, backward extension, lateral bending and rotational torque were applied to the three models, and the standard lumbar was compared by finite element analysis software. Vertebral model, rigid internal fixation model, Dynesys dynamic internal fixation model, three models in flexion, extension, lateral bending, rotation state, fixed segment (L3-L4) and upper adjacent segment (L2-L3) intervertebral mobility and disc stress; 4. Method comparison: The results of this study and previous case review and in vitro experimental results. Make a preliminary comparison.
Methods: 1. Establish and validate the L2-L5 finite element model of lumbar vertebrae. Segment the CT data of lumbar vertebrae of healthy male patients with Mimics software, extract the tomographic images of bone and intervertebral disc, and establish the geometric three-dimensional model. Finite element calculation is carried out. The validity of the finite element model is verified by the stress distribution curve of "distance-stress" and the curve of "compressive force-displacement". 2. The establishment and finite element analysis of the model of the fixed lumbar vertebrae with Dynesys and the screw-rod system. The model of the internal fixation device is made by Pro/Engineer software, and the operation is simulated by MICs software. The L2-L3, L3-L4 intervertebral mobility, intervertebral disc stress and facet joint stress were compared under four conditions: flexion, lateral flexion and rotation.
The finite element models of L2-L5 lumbar spine including vertebrae, intervertebral disc and ligament were established and validated. 2. The finite element models of Dynesys system and screw-rod system were established. 3. Dynesys system was used to fix the lumbar spine in the implanted segment. Compared with the model without screw fixation, the intervertebral mobility was reduced by 67% and the adjacent segment was reduced. Dynamic fixation unloaded most of the stress in the operative segment, but had little effect on the upper adjacent segment. Dynamic fixation had no effect on the stress in the disc and facet joints. Between fixation and rigid fixation. 4. The results of intervertebral mobility obtained by finite element analysis in this study are consistent with the results of previous retrospective studies of undergraduate cases and other in vitro tests.
Conclusion: 1. A standardized and validated finite element model of the lumbar spine was established based on the CT scan images of the lumbar spine; 2. The results of finite element analysis of the fixed lumbar spine model with Dynesys system were similar to those of the retrospective analysis of the previous cases, that is, Dynesys system could be provided for the fixed segment. Dynesys system has less effect on the stress of lumbar spine than rigid fixation.
【学位授予单位】：大连医科大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R-332;R681.5

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