带有颅底的全颈椎三维有限元模型的建立及分析

The establishment and analysis of a finite element model of the whole cervical spine plus the skull base

目的:建立带有颅底的全颈椎三维有限元模型并验证模型有效性,为分析颈椎疾患的生物力学机制提供帮助。方法:选取一31岁健康男性志愿者进行颈椎(包括颅底)薄层CT扫描,并将CT原始数据以Dicom格式存贮。运用建模软件Simpleware3.0把CT数据转化为STL格式数据,通过Geomagic 8.0对数据中的图像进行修补、去噪、铺面并转化为NURB曲面模型,得到带有颅底的全颈椎(C0-C7)三维有限元实体模型。应用软件Hypermesh 9.0进行前处理,包括接触定义、网格划分、材料属性设定及载荷与边界条件设定。应用Abaqus 6-9-1大型有限元计算软件进行计算,将屈曲、伸展、左右侧弯和左右旋转工况下的活动范围(ROM)与Panjabi的实验数据进行比较,对模型进行验证。结果:建立的正常全颈椎三维有限元模型共包含664026单元,228557节点,具有逼真的几何外观。通过与Panjabi的实验数据进行对比验证,发现该模型在屈伸、侧弯及旋转工况下的ROM与Panjabi的数据基本一致,只有在C2-C3旋转活动度方面存在差异(6.03°vs 3°±2.5°,P<0.05)。结论:所建立的带有颅底的正常全颈椎三维有限元模型满足有限元分析的几何相似性和力学相似性,可用于颈椎的生物力学分析。

Objectives： To establish a three-dimensional finite element model of the cervical spine plus skull base, and to evaluate its mechanism of the cervical spine disease. Methods： A 31-year-old healthy male volunteer underwent cervical thin-section CT scans. And the raw data of the CT scans were stored in Dicom format. Then the CT data were transferred into STL format by using modeling software Simpleware 3.0. And NURB surface model was obtained after data repair, noise removal and pavement under the help of Geomagic 8.0. Finally a full cervical spine（C0-C7） finite element model was established. Pre-processings, including interaction definition, meshing and the set-up of material properties, load and boundary, were done by using Hypermesh 9.0. Calculations were performed by using Abaqus 6-9-1, large finite element calculation software. The ROMs in flexion, extension, lateral bending and rotation were compared with the data reported by Panjabi in order to validate the model. Results： The final intact cervical spinal model consisted of 664026 elements and 228557 nodes. The model had the same similarity and profile as the clinical case, and the ROMs in flexion, extension, lateral bending and rotation were consisted by the data reported by Panjabi, there was difference only in C2-C3 rotary motion（6.03° vs 3°±2.5°,P〈0.05）. Conclusions： The normal three-dimensional finite element model of the cervical spine plus the skull base meet the standards required in finite element analysis including geometric and mechanical similarities. Thereafter, the model can be used for biomechanical analysis of the cervical spine.