腰椎椎间孔外椎体间融合术的三维有限元建模及分析

Establishment of 3D-finite element model for analysis of biomechanical stability of extraforaminal or transforaminal lumbar interbody fusion

关键词:  腰椎椎间融合  微创  三维有限元分析

Key words:  lumbar interbody fusion  minimal invasive  three dimensional finite element analyses

摘要:

目的 采用三维有限元方法比较椎间孔外腰椎椎体间融合术(extraforaminal lumbar interbody fusion, ELIF)与传统经椎间孔腰椎椎体间融合术(transforaminal lumbar interbody fusion, TLIF)，在不同固定方式下的生物力学稳定性。方法 将健康成年男性志愿者腰椎CT片读入Simpleware 2.0，建立L3～L5的三维几何模型。利用Hypermesh，对模型进行有限元网格划分，建立完整L3～L5节段有限元模型。对完整模型进行不同处理，分为正常标本对照组（C组），单边固定ELIF（E1组），单边固定TLIF（T1组），双边固定ELIF（E2组），双边固定TLIF（T2组），单边固定ELIF+对侧经椎板关节突螺钉内固定（E3组），单边固定TLIF+对侧经 椎板关节突螺钉内固定（T3组）。利用Abaqus 6.10，对处理组模型施加相应的载荷及运动附加力，计算腰椎前屈、后伸、左右侧屈及左右旋转6种工况下的L4～L5节段角位移及其他生物力学指标。结果E1与T1组L4～L5活动度均较C组明显减小(P<0.01)。E1组各工况下的活动度小于T1组，尤以左侧屈及右旋时明显(P<0.05)；E1组在各工况下的活动度明显高于T2组(P<0.05)；E3组活动度明显低于E1组(P<0.05)。在400N的载荷下，E2组与T2组、E3组与T3组活动度差异均无统计学意义(P>0.05)。结论 ELIF联合使用对侧经椎板关节突螺钉固定后稳定性得以提高，与TLIF双侧椎弓根螺钉固定在限定载荷下相当，是一种安全有效，更加微创的腰椎椎体间融合术式。

Abstract:

Objective To establish a 3D-finite element model for evaluation of biomechanical stability of extraforaminal lumbar interbody fusion (ELIF) and traditional transforaminal lumbar interbody fusion（TLIF）under different internal fixation. Methods The CT images of health adult males were applied to establish the L3-L5 level 3D geometric model with Simpleware 2.0 software. Hypermesh was used to divide the finite element mesh for establishment of L3-L5 level intact finite element model. The biomechanical stability was analyzed by the established model with the following treatment： E1 (unilateral fixation ELIF), T1 (unilateral fixation TLIF), E2 (bilateral fixation ELIF), T2 (bilateral fixation TLIF), E3 (unilateral fixation ELIF + contralateral translaminar facet screw), T3 (unilateral fixation TLIF + contralateral translaminar facet screw). The corresponding load and additional movement force were exerted in all treatment groups. The angular displacement of L4-L5 and other biomechanics index were calculated in anteflexion，extension，lateral flexion and rotation movement using Abaqus 6.10 software. Results The range of motion (ROM) of E1and T1 was significantly lower than that of C in the intact model (P<0.01). Compared with T1, the ROM of E1 was lower, especially in left lateral flexion and right rotation (P<0.05). Compared with T2，the ROM of E1 was significantly higher (P<0.05). The ROM of E3 was significantly decreased compared with E1(P<0.05). Moreover, the ROM of E3 was not significantly different with that of T2. Under the load of 400N，there were no significant differences between T2 and T3, and between T3 and E3 (P>0.05). Conclusion The established 3D-finite element model shows that the stability of single pedicle screws fixation ELIF will be improved by use of contralateral translaminar facet screw，and it is a safe, more efficient and less invasive operation approach.