颅颈交界区不稳定三维有限元模型的建立

Construction of an unstable three-dimensional finite element model in the craniovertebral junction

目的建立颅颈交界区[枕骨髁(C0)～C2]不稳定的三维有限元模型,并验证其有效性。方法在国人解剖学数据基础上选取1例健康成年男性志愿者,对C0～C2进行CT连续薄层扫描,导入相应软件进行三维几何模型重建,优化模型结构,生成骨性三维有限元模型,补充建立相关韧带结构。设定载荷1.5 N.m测定各脊柱节段单位(C0～C1、C1～C2)的前屈、后伸、侧屈、旋转的三维运动范围,位于文献测试结果范围内认为模型建立成功。删减横韧带、寰枕、寰枢关节囊的单元结构,模拟相应损伤,建立颅颈交界区不稳定模型,并进行有限元网格划分。再次测量各脊柱节段的三维运动范围,若较正常运动范围增大,则认为模型构建成功。结果成功建立正常成人颅颈交界区的三维有限元模型,整个模型共包括86 050个节点和55 371个单元。模型与实体组织具有良好的几何相似性。通过对单元结构的删减,各脊柱节段活动范围均较正常增大,成功建立颅颈交界区不稳定的三维有限元模型,共包括82 650个节点和53 370个单元。结论成功建立颅颈交界区不稳定三维有限元模型,该模型具有较高的真实性,可以用于相关生物力学试验研究。

Objective To establish and validate an unstable 3-D finite element model in the craniovertebral junction.Methods Sectional images of the occipital condyle（C0）-C2 were obtained from CT scans of a healthy male adult.The 3D geometric model was constructed by the combination of software Mimics10.0 and Freeform5.0.The osseous finite element model was developed with Ansys10.0.The structure of ligament was established supplementarily based on the osseous model.3-D motion range of flexion,extension,lateral flexion and rotation was detected by setting load of 1.5 N.m in the segmental units（C0 ～ C1,C1 ～ C2）.The test results,which were within the range of literature,were considered successfully constructed.The unstable model in the craniovertebral junction was constructed by deleting unit structures of transverse ligament,atlanto-occipital,atlantoaxial joint capsule,and simulating the damage,and then finite element mesh was divided.Three-dimensional motion range was measured again in the spinal segments.If a normal range of motion increased,then the model was constructed successfully.Results The three dimensional finite element model in the craniovertebral junction of normal adult was successfully constructed.The whole model consisted of 82 650 nodes and 53 371 elements.The model and real structure of organism showed a good geometrical similarity.The range of segmental activities was increased compared to the normal by deleting the unit structures.The unstable three-dimensional finite element model of the successful simulation of craniovertebral junction included a total of 82 650 nodes and 53 370 units.Conclusion The unstable three-dimensional finite element model in the craniovertebral junction was successfully constructed,which can simulate the biomechanical condition and facilitate the further biomechanical research.