斜外侧椎间融合联合单侧椎弓根钉棒固定术的三维有限元分析（基础研究）

殷  飞1，马  荣2，蔡则成1，于  洋1，杨树龙1，张彦龙1，陈  振2，戈朝晖2

（1 宁夏医科大学 750004 银川市；2 宁夏医科大学总医院骨科 50004 银川市）

基金项目：国家自然科学基金（81460335）；宁夏自然科学基金（2018AAC03138）

第一作者简介：男（1991-），硕士研究生，研究方向：脊柱外科

电话：（0951）6746129  E-mail：2533266437@qq.com

并列第一作者：马荣　　Ｅ－ｍａｉｌ：marongtx228@163.com

通讯作者：戈朝晖  E-mail：myovid@126.com

【摘要】 目的：运用三维有限元分析法验证斜外侧椎间融合术（oblique lateralinterbody fusion，OLIF）辅助单侧椎弓根钉棒固定能否为相应单一融合固定节段提供足够的椎间稳定性。方法：在健康人L3～S1节段CT扫描数据的基础上，利用Mimics、Geomagic、3-Matic软件建立L3～S1三维有限元模型，设定为正常对照组（M0），以此为基础联合使用Freeform等软件分别建立L4/5节段OLIF单纯融合固定（Stand alone）模型（M1）、OLIF辅助单侧椎弓根钉棒固定（Wiltse入路）模型（M2）、OLIF辅助双侧椎弓根钉棒固定（Wiltse入路）模型（M3）。设定500N预载荷作用于L3顶端，再施加10N·m的力矩模拟脊椎直立、前屈、后伸、侧屈及旋转等生理活动，按上述加载条件作用于M0，对模型有效性性进行验证，同时按相同加载条件作用于各有限元模型，观察各有限元模型不同工况下L4/5节段相对活动度（ROM）、椎间融合器和椎弓根钉棒应力分布状况，记录最大应力值。结果：通过与文献数据比较，本有限元模型L4/5节段ROM在不同运动状态下与前人研究结果相近，证明本模型具备有效性。4组有限元模型前屈、后伸、左右侧弯、左右旋转运动状态下ROM值由小到大排序为M3、M2、M1、M0。M2相比M0、M1能较好地控制前屈和后伸，M2的ROM相比M0前屈后伸时变化幅度分别为75.43%、85.20%，相比M1变化幅度分别为58.88%、70.39%。M3相比M2前屈和后伸时稳定性亦较好，M3的ROM相比M2前屈后伸时变化幅度分别为25.55%、25.33%。除外变化幅度差异较小的右侧弯和右旋转状态，M2较M0的ROM变化幅度远大于M2与M3之间ROM的变化幅度。M2相较M0各工况下ROM变化幅度为14.08%~85.20%，M2相较M3各工况下ROM变化幅度为16.44%~25.55%。椎间融合器应力值方面，除直立时M2应力峰值略高于M1，其余运动状态下OLIF各手术组融合器应力峰值随着附加椎弓根钉棒数量的增加而表现出一定的下降趋势，这种趋势以后伸时表现最明显，幅度变化为109.14%。钉棒应力峰值方面，M2钉棒应力峰值除右侧弯时明显低于M3，左侧弯时略低于M3，其余运动状态下其钉棒应力峰值均高于M3，二者应力差异以右侧弯和后伸时较大，M2较M3分别变化-33.09%和76.79%。三组模型钉棒及椎间融合器应力峰值均远未达到其屈服强度。结论：OLIF联合单侧椎弓根钉棒固定模型可以为相应融合固定节段提供足够的椎间稳定性。

【关键词】 有限元分析；腰椎融合术；斜外侧椎间融合术；单侧椎弓根钉棒内固定

doi：10.3969/j.issn.1004-406X.2019.08.09

中图分类号：R687.3，R318.01    文献标识码：A   文章编号：1004-406X（2019）-08-0732-09

Three-dimensional finite element analysisof oblique lateral lumbar interbody fusion combined with unilateral pediclescrew fixation/YIN Fei, MA Rong, CAI Zecheng, et al//Chinese Journal of Spineand Spinal Cord, 2019, 29(8): 732-740

【Abstract】 Objectives: To validate whether oblique lateral interbodyfusion(OLIF) combined with unilateral pedicle screw-rod fixation can providesufficient interbody stability for corresponding fusion and fixation segmentthrough three-dimensional finite element analysis. Methods: To establish athree-dimensional finite element model of L3-S1 segments by Mimics, Geomagic,and 3-Matic software based on CT scan data of L3-S1 of healthy people, and itwas set as normal control group(M0). On such basis, combined with Freeform andother software, OLIF stand alone model(M1) of L4/5, OLIF with unilateralpedicle screw-rod fixation (Wiltse approach) model(M2), and OLIF with bilateralpedicle screw-rod fixation(Wiltse approach) model(M3) were set up. 500N preloadwas applied on the upper surface of L3 and 10N·m moment was applied to simulatethe physiological activities of lumbar spine in standing position, flexion,extension, lateral flexion and rotation. The above loading conditions wereapplied on both the M0, to validate the effectiveness of the model, and allfinite element models, to observe the L4/5 segment range of motion(ROM), stressdistribution of cage and pedicle screw-rod under different working conditions.The maximum stress of cage and pedicle screw-rod should be recorded. Results:It was validated that the finite element model was effective compared with theliterature data. The ROM values of 4 groups in each movement state(flexion,extension, left and right lateral flexion, left and right rotation) were rankedfrom small to large: M3, M2, M1, and M0. M2 showed better stability in flexionand extension than M0 and M1. To be specific, the variation ranges underflexion and extension condition of M2 ROM were 75.43% and 85.20% respectivelycomparing to M0, and 58.88% and 70.39% respectively comparing to M1. M3 showedbetter stability in flexion and extension than M2, and the variation ranges ofM3 ROM were 25.55% and 25.33% under flexion and extension respectivelycomparing to M2. Except smaller difference of variation range under rightbending and right rotation conditions, the variation range of ROM of M2comparing with M0 was much larger than that comparing with M3. Under allworking conditions, the variation ranges of ROM of M2 when compared with M0were 14.08%-85.20%, and that were 16.44%-25.55% when compared with M3. In termsof the peak stress of the cage, except that it was slightly higher in M2 thanin M1 under condition of standing, in other motion states, it showed adecreasing trend with the increase of the number of additional pediclescrew-rod, which was most obvious in extension with a decreasing range of109.14%. In terms of the peak stress of the screw-rod system, it was higher inM2 than in M3 under other states, except that peak stress value of M2significantly lower than that of M3 in right lateral flexion and slightly lowerthan that of the M3 in left lateral bending. The differences of peak stress ofscrew-rod system between M2 and M3 were larger in right lateral bending andretroextension which were -33.09% and 76.79%. The peak stress of the screw-rodand cage in each of the three surgery groups was far from their yield strengthrespectively. Conclusions: The model of OLIF with unilateral pedicle screw-rodfixation can provide sufficient intervertebral stability for the correspondingfusion fixation segment.

【Key words】 Finite element analysis; Lumbar fusion; Oblique lateral interbodyfusion; Unilateral pedicle screw-rod fixation

【Author′s address】 Ningxia Medical University, 750004, Yinchuan, China

图1  人正常L3～S1有限元模型（M0，正侧面观） 图2 OLIF Stand alone模型（M1，正侧面观） 图3 OLIF辅助单侧椎弓根钉棒固定模型（M2，正侧面观）  图4 OLIF辅助双侧椎弓根钉棒固定模型（M3，正侧面观）

Figure 1 L3-S1 finite element model of normal human(M0, the frontal and lateralposition)  Figure 2  Model of OLIF Stand alone(M1, the frontal andlateral position)  Figure 3  Model of OLIF with unilateral pedicle screwfixation(M2, the frontal and lateral position) Figure 4  Model of OLIF withbilateral pedicle screw fixation(M3, the frontal and lateral position)

图5  图中A、B、C、D、E、F、G分别为M2组（OLIF辅助单侧椎弓根钉棒固定）在直立、前屈、后伸、左右侧屈、左右旋转状态下椎间融合器应力云图

Figure 5 The mises stress cloud of cgae of M2(OLIF with unilateral pedicle screwfixation) under 7 motion states, as indicated as A, standing; B, flexion; C,extension; D, left lateral flexion; E, right lateral flexion; F, left rotation;G, right rotation

图6  图中A、B、C、D、E、F、G分别为M2组（OLIF辅助单侧椎弓根钉棒固定）在直立、前屈、后伸、左右侧屈、左右旋转状态下椎弓根钉棒应力云图

Figure6  The mises stress cloud of pediclescrew-rod of M2(OLIF with unilateral pedicle screw fixation) under 7 motionstates, as indicated as A, standing; B, flexion; C, extension; D, left lateralflexion; E, right lateral flexion; F, left rotation; G, right rotation

本文为删节版，原文见《中国脊柱脊髓杂志》2019年8月刊