腰椎管狭窄的动态MRI研究及手术模型的有限元分析

发布时间：2018-09-04 20:40

【摘要】：目的:探讨腰椎椎管狭窄症患者硬膜囊、侧隐窝等随体位变化的规律;并解释其症状与影像学表现的“分离现象”。构建腰椎有限元模型;比较后路全椎板切减压与椎板切除+椎弓根钉内固定的应力分布及对腰椎度的影响,探讨减压手术对腰椎稳定性的影响、以及辅以椎弓根钉内固定的必要性。方法:随机选取2016年7月-2017年1月就诊于天津医院的腰椎管狭窄症患者进行全腰椎动态位MRI检查,采用Mimics17.0进行测量收集椎管横截面积、椎管矢径等参数,分析其变化规律。以CT资料为基础,利用Mimics10.01、Rhino5.0、Abaqus6.12等软件进行建模并验证模型有效性。以L3椎体为主要手术节段,分别构建全椎板切除组、内固定组有限元模型。设定S1椎体下部自由度为0,在L1椎体上部施加400N预载荷模拟人体自身负荷,然后分别施加8N·m,6N·m,4N·m弯矩模拟屈伸、旋转等运动。结果:共记8例患者(5女3男)完成检查。测量分析结果:1)骨性椎管矢径不随体位发生明显变化;硬膜囊矢径、硬膜囊矢径/骨性椎管矢径比值在前屈位最大,后伸位最小。2)骨性椎管横截面积不随体位发生明显变化;硬膜囊横截面积、硬膜囊横截面积/骨性椎管横截面积在前屈位最大,后伸位最小。3)左、右两侧盘黄间隙在前屈位时均显著增加,下腰椎尤其显著;左、右两侧盘黄间隙比值未表现出明显规律,均在1.0左右。有限元研究显示:1)正常组在后伸、扭转时较部分体外实验数据偏大,但无统计学差异,不影响后续分析。2)全椎板切除组各工况下ROM及椎间盘平均应力较术前升高,手术节段较明显,屈伸、旋转运动尤为显著;3)内固定组各工况下ROM及椎间盘平均应力较术前减小,手术节段较明显,在屈伸及侧屈运动时较为显著;4)全椎板切除组各工况下ROM较内固定组均不同程度升高,前屈运动最明显;全椎板切除组各椎间盘平均应力较内固定组增加,手术节段更显著;5)两组的非手术节段在各工况下ROM变化不显著,椎间盘平均应力均增加,尤其L5S1节段显著。结论:1)硬膜囊矢径、横截面积、盘黄间隙等在腰椎前屈时最大,后伸时最小;2)纤维性椎管的体位性变化与椎间盘、硬膜外脂肪等的变化相关;3)骨性椎管的径线不随体位发生显著变化;4)腰椎管狭窄是退变基础上发生的,上位腰椎节段性活动造成的椎间孔动态性狭窄;5)全椎板切除减压可造成腰椎活动度、各椎间盘平均应力增加,可导致腰椎稳定性下降,甚至失稳;6)椎弓根内固定可改善腰椎稳定性,但非手术节段可出现应力集中,可加速退变;7)临床实践中应考虑人体自身的代偿修复能力,严格把握内固定融合指征及节段,避免邻近节段病变。
[Abstract]:Objective: to investigate the changes of dural sac and lateral recess in patients with lumbar spinal stenosis, and to explain the "separation phenomenon" between symptoms and imaging manifestations. The finite element model of lumbar vertebrae was established, the stress distribution of posterior total laminectomy and pedicle screw fixation was compared with that of laminectomy, and the effect of decompression on lumbar stability was discussed. And the necessity of pedicle screw internal fixation. Methods: the lumbar spinal stenosis patients in Tianjin Hospital from July 2016 to January 2017 were randomly selected for the whole lumbar dynamic MRI examination. The cross-sectional area and the sagittal diameter of the spinal canal were measured by Mimics17.0, and the change rules were analyzed. Based on CT data, Mimics10.01,Rhino5.0,Abaqus6.12 and other software are used to model and verify the validity of the model. The finite element models of laminectomy group and internal fixation group were constructed with L3 vertebrae as the main segment. The degree of freedom in the lower part of S1 vertebra is 0, and 400N preload is applied to the upper part of L1 vertebra to simulate the human body's own load, and then the bending moment is applied to simulate the motion of flexion and extension, rotation and so on, respectively. Results: 8 patients (5 women and 3 men) completed the examination. The ratio of sagittal diameter of dural sac to sagittal diameter of bony vertebral canal was the largest in anterior flexion position, and the minimum in extension position was 2. 2) the cross-sectional area of osseous spinal canal did not change significantly with postural position, and the ratio of sagittal diameter of dural sac to sagittal diameter of bony vertebral canal was the largest in anterior flexion position and the smallest in posterior extension position. The cross sectional area of dural sac, the cross sectional area of dural sac / osseous spinal canal was the largest in anterior flexion position and the smallest in posterior extension position. The ratio of the right side of the disc to the yellow space showed no obvious regularity, which was about 1.0. The finite element analysis showed that the ROM and average stress of intervertebral disc in the normal group were higher than those in the pre-operation group, but there was no statistical difference in the extension and torsion of the normal group, but there was no significant difference in the follow-up analysis of the two groups, and the mean stress of the ROM and intervertebral disc in the total laminectomy group was higher than that before the operation. The mean stress of ROM and intervertebral disc in the internal fixation group was significantly lower than that in the preoperative group, and the operative segment was more obvious than that in the operation group, and the mean stress of the intervertebral disc in the internal fixation group was significantly lower than that in the preoperative group. In flexion, extension and lateral flexion movement, the ROM in the laminectomy group was higher than that in the internal fixation group, and the anterior flexion movement was the most obvious, and the average stress of each disc in the total laminectomy group was higher than that in the internal fixation group, and that in the laminectomy group was higher than that in the internal fixation group. There was no significant change in ROM and the mean stress of intervertebral disc increased in both groups, especially in L5S1 segment. Conclusion: the sagittal diameter of dural capsule, cross sectional area, yellow disc space and so on are the largest in anterior flexion of lumbar vertebrae and the smallest in extension of lumbar vertebrae. 2) the changes of position and intervertebral disc in fibrous spinal canal. The change of epidural fat was related to the change of epidural fat (3) the diameter of the bony spinal canal did not change significantly with the position. 4) the stenosis of the lumbar spinal canal occurred on the basis of degeneration. The dynamic stenosis of intervertebral foramen caused by segmental activity of upper lumbar vertebrae 5) total laminectomy and decompression can result in lumbar movement, the average stress of each intervertebral disc increases, and the stability of lumbar vertebrae decreases. Even instability 6) pedicle internal fixation can improve the stability of lumbar vertebrae, but stress concentration may occur in non-operative segment and accelerate degeneration. 7) in clinical practice, the compensatory repair ability of human body itself should be considered, and the indication and segment of internal fixation fusion should be strictly grasped. Avoid adjacent lesions.
【学位授予单位】：天津医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R687.3

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