上颈椎三维六面体网格有限元模型的建立及有效性验证

Development and validation of a three-dimensional hexahedral finite element model of the upper cervical spine

目的 改善目前国内上颈椎有限元模型质量,建立具有详细解剖结构的上颈椎三维非线性六面体网格有限元模型并验证其有效性,以期应用于临床相关生物力学研究.方法 对一名健康成年男性志愿者,采用16排螺旋CT机进行0.5 mm薄层扫描,获得枕骨底C0到C3的体层图像数据并以Dicom格式保存.将数据导入Mimics 10.01软件,进行上颈椎三维几何模型重建,利用ICEM软件对C0～ C3三维重建模型进行六面体网格划分,关节软骨面间隙为0.5 mm,终板厚0.2 mm,关节软骨面定义为滑动接触,摩擦系数设为0.1.再运用Hypermesh V10.0调整网格质量,加载韧带,初步建立上颈椎（C0～ C3）三维六面体单元有限元模型.随后进行材料赋值、边界约束,模拟模型产生前屈、后伸、旋转、侧屈运动,将数据导入有限元软件ABAQUS 6.11进行各椎体三维运动的计算分析.最后将模型的三维活动度（ROM）及各工况下的应力云图与体外实验及其他模型文献数据进行有效性对比验证.结果 建立了具有详细解剖结构的上颈椎三维非线性六面体有限元模型,整个模型共30 550个节点和41 909个单元,模型运动范围及应力分布与文献数据相符合.结论 建立的上颈椎有限元模型具有较高的真实性,可应用于临床相关生物力学研究.

Objective To improve the current quality of the upper cervical spine finite element models in China by developing and validating an anatomically detailed three-dimensional hexahedral finite element model of the upper cervical spine for use in clinically relevant biomechanical research.Methods The finite element model was developed with detailed anatomy from 16-slice computed tomographic images of the occiput to the C3 with 0.5 mm thickness from a healthy male subject.The image data were saved in Dicom format,and then imported into the Mimics 10.01 software for reconstructing three-dimensional geometric model of the upper cervical spine.By using the ICEM software,the C0-C3 three-dimensional hexahedral finite element model was reconstructed,with the thickness of the endplates set to 0.2 mm,the gap of facet joints set to 0.5 mm and defined as sliding contact with the friction coefficient being 0.1.Then,the Hypermesh V10.0 software was employed to adjust the mesh quality,load the ligament,and preliminarily develop a three-dimensional hexahedral finite element model of the upper cervical spine （C0-C3）.Subsequently,the movements of bending forward,dorsal flexion,rotation,lateroversion were generated through the assignment of materials,the constraint of boundary and the stimulation of models.The resultant data were imported into the ABAQUS 6.11 software for the analysis of the three-dimensional motion of each vertebral level.Finally,the stress nephogram of the model＇s three-dimensional range of motion （ROM） and stress distribution were compared with in vitro experiments and other published data for efficacy validation.Results An anatomically detailed three-dimensional hexahedral finite element model of the upper cervical spine was developed,which consisted of 30 550 nodes and 41 909 elements.The ROM and stress distribution coincided with the data from published literatures.Conclusion The finite element model of the upper cervical spine developed in this study appears to show high authenticity for use in clinically relevant biomechanic studies.