正常颈椎有限元模型建立及有效性验证

Establishment and validity verification of a finite element model of normal cervical spine

目的:建立颈椎C2~C7节段三维有限元模型,分析模型的生物力学特征,进行有效性验证。方法:招募一名健康志愿者为建模对象,利用64排螺旋CT进行颈椎连续性断层扫描,扫描区域设定为枕骨至C7椎体节段。将获得的图像数据DICOM文件导入至Mimics图像分割软件中,对颈椎骨性结构进行分割提取。在Geomagic studio软件中对获得的颈椎骨性结构模型进行去噪、光顺、修补填充等处理,拟合曲面实体,并偏移分割生成皮质骨与松质骨,将模型保存为STEP文件。在Solidworks软件中完成椎间盘髓核、纤维环及关节软骨结构的建立与模型的组装匹配。ANSYS Workbench软件中添加材料属性、接触关系、边界条件及载荷,测量颈椎在前屈、后伸、左右侧弯、左右旋转6种应力作用下位移变化。结果:成功建立颈椎C2~C7节段有限元模型,颈椎C2~C3屈伸、侧屈、旋转角度位移分别为7.2°、8.2°、5.3°,颈椎C3~C4屈伸、侧屈、旋转角度位移分别为7.2°、8.1°、6.2°,颈椎C4~C5屈伸、侧屈、旋转角度位移分别为8.1°、7.9°、7.8°,颈椎C5~C6屈伸、侧屈、旋转角度位移分别为6.9°、5.4°、5.2°,颈椎C6~C7屈伸、侧屈、旋转角度位移分别为5.7°、4.8°、3.7°,和既往颈椎生物力学模型测试结果基本一致。结论:本研究基于有限元建模软件成功建立正常颈椎有限元模型,该方法所建立的模型可靠,通过有效性验证,具备良好的生物力学性能。

Objective To establish a three-dimensional finite element model of cervical vertebrae C2-C7,and analyze its biomechanical characteristics for validity verification.Methods A healthy volunteer was recruited as the modeling object.The continuous CT scan of cervical spine was carried out with 64-slice spiral CT,with the scanning area set as the occipital bone to C7 vertebral vertebra.The DICOM files of the obtained images data were imported into Mimics image segmentation software for extracting the bony structure of cervical spine.After the cervical bony structure model was processed with Geomagic studio software(such as de-denoising,smoothing,patching and filling),curved solid was fitted and offset to generate cortical bone and cancellous bone,and the results were saved as STEP files.The establishments of nucleus pulposus,fibrous ring and articular cartilage,and the assembly and matching of models were completed in SolidWorks.The material properties,contact relationships,boundary conditions,and loads were assigned using Ansys Workbench.The displacements of cervical spine were measured under 6 kinds of stresses:forward flexion,backward extension,left and right lateral flexions,and left and right rotations.Results The finite element model of C2-C7 cervical vertebrae was successfully established.The angular displacements of C2-C3 in flexion and extension,lateral flexion,and rotation were 7.2°,8.2°and 5.3°,respectively,and those were 7.2°,8.1°,6.2°for C3-C4,8.1°,7.9°,7.8°for C4-C5,6.9°,5.4°,5.2°for C5-C6,5.7°,4.8°,3.7°for C6-C7,which were basically consistent with the previous biomechanical model test reports.Conclusion The finite element model of the normal cervical spine can be successfully established using finite element modeling software.The validation shows that the established model is reliable,with good biomechanical properties.