脊柱动态固定的剪切特性与载荷分享的生物力学研究

发布时间：2018-03-18 00:38

本文选题：脊柱动态固定　切入点：剪切　出处：《南方医科大学》2017年博士论文　论文类型：学位论文

【摘要】：目的:1.探讨多节段退行性滑脱生物力学模型的建立,比较L4-L5及L5-S1节段的剪切特性。2.评价腰骶椎后路PEEK棒、滑动棒、转动钉三种动态固定的剪切稳定性。3.评价胸腰椎前路PEEK棒、滑动棒、转动钉三种动态固定的稳定性与载荷分享。方法:1.对8例人体标本的L4-L5及L5-S1节段在300N轴向压缩力下分别于两间隙施加-50N～250N前后方向剪切力。测试完整、小关节损伤及椎间盘损伤三种状态下节段向前的剪切位移,计算剪切刚度。2.采用8例L4-L5节段退行性滑脱模型,在有或无椎间融合器(Cage)植入两种情形下分别测量后路刚性钉棒及PEEK棒、滑动棒、转动钉固定下向前的剪切位移。剪切加载方式同上。3.对8例人体T11-L3节段标本分别在屈伸、侧弯及旋转方向施加5Nm的纯力偶矩,进一步在300N跟随力加载下在屈伸方向施加5Nm纯力偶矩。完整状态测试后行前路L1椎体次全切除,采用椎间模拟钛网(含微力传感器)及T12-L2节段前路钉棒进行内固定重建。分别在椎间钛网全长及短缩2mm(模拟植骨沉降)两种情形下对前路刚性及PEEK棒、滑动棒、转动钉固定的节段运动范围(range of motion,ROM)及椎间载荷等进行测量。结果:1.L4-L5及L5-S1节段椎间盘损伤状态的前剪切位移分别为1.4mm及1.2mm,均较完整状态位移显著增加(P0.05)。2.完整L5-S1节段的前剪切刚度较L4-L5节段显著增加(P0.05),在小关节及椎间盘损伤状态下两节段的前剪切刚度相当。3.后路PEEK棒及转动钉固定的前剪切位移较刚性固定显著增加(P0.05),后路滑动棒固定的位移与之相当。4.椎间Cage植入后所有内固定下的前剪切位移均较Cage植入前减少,动态固定位移减少更明显。5.无论椎间钛网全长或短缩,与前路刚性固定比较,PEEK棒及转动钉固定在各个方向上的ROM均不同程度增加,滑动棒固定的ROM在钛网短缩的前屈方向(有跟随力)减少,在其余方向上与之相当或略增加。6.无论椎间钛网全长或短缩,300N跟随力下三种前路动态固定的椎间载荷值在中立位及屈伸位均大于刚性固定。结论:1.L4-L5及L5-S1节段可同时建立I°退行性滑脱模型。2.完整L5-S1节段比L4-L5节段能更好的抵抗剪切滑脱,但两节段在损伤状态抵抗剪切滑脱的能力相当。3.腰骶椎后路PEEK棒、转动钉固定的剪切稳定性弱于刚性固定,滑动棒固定的剪切稳定性与之相当。4.椎间Cage植入能增强所有后路固定的剪切稳定性,但Cage植入对动态固定的影响要大于刚性固定。5.胸腰椎前路PEEK棒及转动钉固定的稳定性整体上弱于刚性固定,滑动棒固定稳定性与刚性固定相当。6.胸腰椎前路PEEK棒、滑动棒及转动钉固定较刚性固定有更好的椎间植骨载荷分享。
[Abstract]:Objective 1. To establish a biomechanical model of multilevel degenerative spondylolisthesis and compare the shear characteristics of L4-L5 and L5-S1 segments. Stability and load sharing of three kinds of dynamic fixation of sliding rod and rotating nail. Methods: 1. The shear forces of L4-L5 and L5-S1 segments in 8 human specimens were applied to two clearances before and after -50N 250N respectively under 300N axial compression force. The forward shear displacement of small joint injury and intervertebral disc injury was calculated. 2. 8 cases of L4-L5 degenerative slippage model were used. The shear displacement of posterior rigid screw rod and PEEK rod, sliding rod and rotating screw fixation were measured in two cases with or without CageCage. The shear loading mode was as follows: 3. For 8 cases of human T11-L3 segment specimens, they were flexion and extension, respectively. The pure force couple moment of 5Nm was applied in the lateral bend and rotation direction, and the 5Nm pure force moment was applied in the flexion and extension direction under 300N following force. After the complete state test, the anterior L1 vertebra was subtotal excised. The intervertebral titanium mesh (including micro-force sensor) and T12-L2 segment anterior screw rod were used for internal fixation reconstruction. The anterior rigid and PEEK rod, sliding rod, were obtained under the condition of full length of intervertebral titanium mesh and short reduction of 2mm (simulated bone graft subsidence), respectively. The range of motion and the intervertebral load were measured. Results the anterior shear displacement of 1. 1. L4-L5 and L5-S1 segments were 1.4 mm and 1. 2 mm, respectively, which increased P0. 05%. 2. The intact L5-S1 segment. The anterior shear stiffness of L4-L5 segment was significantly higher than that of L4-L5 segment, and the anterior shear stiffness of the two segments was about the same as that of L4-L5 segment under the condition of facet joint and disc injury. The anterior shear displacement of posterior PEEK rod and rotation screw fixation was significantly higher than that of rigid fixation, and the posterior sliding was significantly higher than that of L4-L5 segment. The displacement of rod fixation was the same. 4. After intervertebral Cage implantation, the anterior shear displacement of all internal fixation was less than that of Cage. The reduction of dynamic fixation displacement was more obvious. Regardless of the total length or short contraction of the intervertebral titanium mesh, the ROM of peek rod and rotating nail were increased in different degrees compared with the anterior rigid fixation. The ROM fixed by the sliding rod is reduced in the short flexion direction (with following force) of the titanium mesh. In other directions, the intervertebral load of the three kinds of dynamic anterior fixation is larger than that of rigid fixation in neutral position and flexion and extension position, regardless of the total length of the intervertebral titanium mesh or the short contraction 300N following force. Conclusion: 1. The segments of L4-L5 and L5-S1 can be the same as those of rigid fixation. The complete L5-S1 segment was more resistant to shearing slippage than L4-L5 segment. However, the ability of two segments to resist shear slippage in the injured state is equal. 3. The shear stability of rotation nail fixation is weaker than that of rigid fixation in lumbosacral posterior approach PEEK rod. The shear stability of sliding rod fixation is equivalent to that of slide-rod fixation. 4. Intervertebral Cage implantation enhances the shear stability of all posterior fixations. But the effect of Cage implantation on dynamic fixation was greater than that on rigid fixation. The stability of thoracolumbar anterior PEEK rod and rotation screw fixation was weaker than that of rigid fixation, and the stability of sliding rod fixation was equal to that of rigid fixation. Sliding rod and screw fixation are better than rigid fixation in load sharing of intervertebral bone graft.
【学位授予单位】：南方医科大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R681.5

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