颈椎单节椎体平移错缝对颈椎主要结构应力影响的有限元分析

目的:探讨颈椎单节椎体平移错缝对颈椎主要结构应力的影响。方法:选取1名无颈部病变的健康志愿者,采用GE 64层螺旋CT机对该志愿者进行层厚0.625 mm的螺旋扫描及断层图像处理,扫描范围为颅底至C 7椎体下缘。基于CT扫描数据,应用三维有限元建模处理软件建立正常颈椎三维有限元模型,并对模型进行有效性验证。基于建立的正常颈椎三维有限元模型,通过对各特定节段椎体分别进行平移运动(位移1.5 mm,不超过椎间盘1/4),模拟颈椎单节椎体平移错缝,获得颈椎单节椎体平移错缝三维有限元模型。基于Abaqus6.10有限元分析软件观察颈椎单节椎体平移错缝对椎动脉、脊髓、关节突关节、椎间盘等颈椎主要结构应力的影响。结果:①正常颈椎三维有限元模型验证结果。本研究所建立的正常颈椎三维有限元模型涉及744628个单元、248212个节点;模型外观逼真,包含了颈椎椎体、椎板、棘突、横突、关节突、椎间盘、椎动脉、脊髓、韧带等重要解剖结构。模型具有良好的活动度,其前屈、后伸、侧屈、旋转活动度与经典文献报道的数据基本一致。②颈椎单节椎体平移错缝对颈椎主要结构应力的影响。颈椎单节椎体平移错缝会对椎动脉、脊髓、关节突关节及椎间盘的应力产生影响。C 2平移错缝时椎动脉增加的应力最大(42.81 Pa),C 6次之(30.62 Pa),C 5最小(21.19 Pa)。C 6平移错缝时脊髓增加的应力最大(32.12 Pa),C 5次之(30.46 Pa),C 1最小(5.59 Pa)。颈椎单节椎体平移错缝会对其上、下位关节突关节及椎间盘的应力产生影响,其下位关节突关节和椎间盘的应力大于上位关节突关节和椎间盘的应力。结论:颈椎单节椎体平移错缝后,椎动脉、脊髓、关节突关节及椎间盘等颈椎主要结构的应力均会受到影响。

Influence of translational dislocation of single-segment cervical vertebral body on the stresses of main structures of cervical vertebra:a finite element analysis

Objective:To explore the influence of translational dislocation of single-segment cervical vertebral body on the stresses of main structures of cervical vertebra.Methods:A healthy volunteer without cervical lesions was selected.The spiral scanning was performed on the volunteer by using GE 64-MSCT with 0.625-mm slice thickness from skull base to inferior border of C 7 vertebral body,and the tomographic image processing was carried out.Based on CT scanning data,a three-dimensional(3D)finite element model of normal cervical vertebra was built by using 3D finite element modeling and processing software,and its validity was verified.The translational dislocation of single-segment cervical vertebral body was simulated in the 3D finite element model of normal cervical vertebra,and a 3D finite element model of translational dislocation of single-segment cervical vertebral body was obtained.The influence of translational dislocation of singlesegment cervical vertebral body on stresses of main cervical structures including vertebral artery,spinal cord,zygapophyseal joint and intervertebral disc was observed by using Abaqus6.10 finite element analysis software.Results:The 3D finite element model of normal cervical vertebra involved 744,628 units and 248,212 nodes and included important anatomical structures such as cervical vertebral body,vertebral plate,spinous process,transverse process,articular process,intervertebral disc,vertebral artery,spinal cord and ligament,moreover,the model had very realistic appearance and good range of motion including anteflexion,backward extension,rotation and lateral flexion,which were basically consistent with the literature data.The stresses of vertebral artery,spinal cord,zygapophyseal joint and intervertebral disc can be affected by translational dislocation of single-segment cervical vertebral body.The vertebral artery had high-to-low increased stress when translational dislocation was performed on C 2(42.81 Pa),C 6(30.62 Pa)and C 5(21.19 Pa)in turn.The spinal cord had high-to-low increased stress when translational dislocation was performed on C 6(32.12 Pa),C 5(30.46 Pa)and C 1(5.59 Pa)in turn.The stresses of superior and inferior zygapophyseal joints and intervertebral discs can be affected by translational dislocation of single-segment cervical vertebral body,and the stresses of inferior zygapophyseal joint and intervertebral disc were greater than that of superior zygapophyseal joint and intervertebral disc.Conclusion:The stresses of main structure of cervical vertebra,including vertebral artery,spinal cord,zygapophyseal joint and intervertebral disc,can be affected by translational dislocation of single-segment cervical vertebral body.