摘要
背景:老年骨质疏松患者同时罹患高位腰椎间盘突出的发病人数逐年增加,行常规后入路椎板减压及椎间融合术后腰椎整体力学强度及邻近椎体的生物力学性能改变尚未明确。有限元分析方法以其无创、可重复性高、结果精确等优势在生物力学领域具有重要价值。目的:基于有限元分析方法,针对老年骨质疏松患者的特定人群,建立L_(3/4)椎板减压椎间融合的有限元模型,评估弯腰动作下骨骼内固定复合体的生物力学情况。方法:利用Mimics 21.0提取脊柱CT的DICOM数据建立腰椎(T_(12)-L_(5))三维骨性结构,导入Geomagic wrap 2017,通过重划网格、删除钉状物、剪切模型、填充空洞、探测并编辑轮廓线、构造曲面片及格栅、拟合曲面等操作建立L_(3/4)全椎板减压模型。利用Solidworks 2017构建椎弓根螺钉、连接杆、椎间融合器,将其组装于L_(3/4)全椎板减压模型,通过拉伸、等距曲面、移动与复制实体等操作建立椎间盘、关节突软骨等结构。应用ANSYS Workbench 17.0进行材料赋值、模拟脊柱韧带、网格划分、施加作用力及限定边界条件,建立完整骨质疏松性L_(3/4)椎板减压及椎间融合脊柱有限元模型。观察弯腰工况下L_(3/4)椎板减压及椎间融合全腰椎有限元模型的应力、应变及位移云图。结果与结论:(1)应力云图方面:T_(12)-L_(1)椎体平均应力值最高,L_(2)下降24%,L_(3)下降55%,L_(4-5)下降约80%;L_(4/5)关节突区域应力集中程度最高,L_(2/3)次之,L_(1/2)及T_(12)/L_(1)程度轻;螺钉与连接杆交界处应力集中明显,螺钉在椎弓根进出口处次之;(2)应变与位移云图方面:L_(4/5)及L_(2/3)关节突的应变程度最高,T_(12)/L_(1)及L_(1/2)的应变程度次之,L_(3/4)节段融合器、椎弓根螺钉及连接杆无任何可见变形;各节段椎间盘均出现较大变形;(3)提示多软件协同操作可顺利构建老年骨质疏松性L_(3/4)椎板减压及椎间融合脊柱有限元模型;老年腰椎术后患者可耐受前屈动作,证实L_(3/4)椎板减压及椎间融合能够维持脊柱形态并保证脊柱稳定性,但是需警惕胸腰椎应力性骨折及邻椎病的发生。
BACKGROUND:The incidence of high lumbar disc herniation in elderly patients with osteoporosis is increasing.The changes in lumbar overall mechanical strength and biomechanical properties of adjacent vertebrae after conventional posterior approach decompression and interbody fusion have not been clarified.Finite element analysis has great value in the field of biomechanics because of its advantages of non-invasiveness,high repeatability and accuracy.OBJECTIVE:To explore the establishment of a finite element model of senile osteoporotic L_(3/4) lamina decompression using finite element analysis and intervertebral fusion spine,and to evaluate the biomechanical status of the internal fixation complex of bones under bending motion in elderly patients with osteoporosis.METHODS:Mimics 21.0 was used to extract the DICOM data of the spine CT to establish the 3D bony structure of the lumbar spine(T_(12)-L_(5)),which was imported into Geomagic wrap 2017.The L_(3/4) full lamina decompression model was established after redrawing the mesh,deleting the nails,cutting the model,filling the cavity,detecting and editing the contour line,constructing curved surfaces and grids,fitting curved surfaces and other operations.Solidworks 2017 was used to construct pedicle screws,connecting rods,and intervertebral fusion cages,which were assembled into the L_(3/4) full lamina decompression model.Intervertebral discs and articular process cartilage and other structures were established through operations such as stretching,isometric surfaces,moving and copying entities.ANSYS Workbench 17.0 was utilized for material assignment,simulating spinal ligaments,meshing,applying force and limiting boundary conditions.A complete osteoporotic L_(3/4) laminar decompression and intervertebral fusion spine finite element model was established.The stress,strain and displacement cloud diagram of the L_(3/4) lamina decompression and intervertebral fusion full lumbar spine finite element model were observed under simulated bending conditions.RESULTS AND CONCLUSION:(1)In terms of the stress cloud diagram:The T_(12)-L_(1) vertebra had the highest average stress value;L_(2) dropped by 24%;L_(3) dropped by 55%,and L4-5 dropped by about 80%.The stress concentration in the L4/5 articular process area was the highest,followed by L_(2)/3,and lighter in L_(1)/2 and T_(12)/L_(1).The stress concentration at the junction of the screw and the connecting rod was obvious,followed by the screw at the entrance and exit of the pedicle.(2)In terms of strain and displacement cloud map:The strain degree of L4/5 and L_(2)/3 articular process was the highest;the strain degree of T_(12)/L_(1) and L_(1)/2 was the second,and the L_(3/4) segmental fusion cage,pedicle screw and connecting rod had no any visible deformation.The intervertebral discs of all segments showed great deformation.(3)It is concluded that the cooperative operation of multiple software can successfully construct a finite element model of the spine with L_(3/4) lamina decompression and intervertebral fusion in elderly patients with osteoporosis.Elderly patients after lumbar spine surgery can tolerate forward flexion,confirming that L_(3/4) laminar decompression and intervertebral fusion can maintain the shape of the spine and ensure the stability of the spine,but it is necessary to be alert to the occurrence of thoracolumbar stress fractures and adjacent spondylopathy.
作者
张敏
彭婧
张强
陈德旺
Zhang Min;Peng Jing;Zhang Qiang;Chen Dewang(Nanchang Hongdu Hospital of Traditional Chinese Medicine,Nanchang 330000,Jiangxi Province,China)
出处
《中国组织工程研究》
CAS
北大核心
2024年第6期847-851,共5页
Chinese Journal of Tissue Engineering Research
基金
江西省卫生计生委中医药科研课题(2018A161)
江西省卫生计生委科技计划项目(20184031)
江西省卫生健康委科技计划项目(202140176),项目负责人均为张敏。
关键词
腰椎模型
骨质疏松
椎板减压
椎间融合
有限元模型
生物力学
lumbar spine model
osteoporosis
laminar decompression
intervertebral fusion
finite element model
biomechanics
