基于CT图像建立可供动态力学模拟分析的股骨头坏死有限元模型

Setting Up Finite Element Model for Dynamic Mechanical Analysis of Osteonecrosis of the Femoral Head Based on CT Images

目的:建立股骨头坏死的有限元模型,分析股骨头坏死的内部应力分布及力学特征,为股骨头坏死塌陷的预防提供生物力学依据。方法:选取标准成年男性左侧股骨头坏死自愿者1例,采用16排螺旋CT对患者双髋关节进行扫描,获得DICOM3.0格式的股骨头图像原始数据,利用Amira软件、Geomagic Studio软件、Ansys软件,建立坏死股头与正常股骨头有限元模型,分析慢步走时坏死股骨头与正常股骨头不同部位及不同骨质的力学特征。结果:建立坏死股骨头和正常股骨头三维有限元模型,分别根据是否区分皮质骨和松质骨,划分其总体节点数和单元数,并针对不区分和区分松质骨及密质骨的两类模型,分别计算总网格数为4 513 322和3 132 783的加密网格模型,二者在等效应力分布上趋势一致,最大等效应力相差4.3%.坏死股骨头模型最大应力值均小于正常股骨头模型,尤其是在区分松、密质骨时更为明显,最大应力值从52.110 3MPa降低到30.106 9MPa;坏死股骨头模型的最大位移值为1.006 9mm,明显大于正常股骨头模型的0.583 6mm.结论:建立了较好几何和物理相似性的、可重复应用、可供动态力学模拟分析的股骨头坏死有限元模型,相比正常股骨头建模,股骨头坏死模型建立时,将松质骨和皮质骨材料区分赋值更有必要。

Objective：To establish the finite element model of osteonecrosis of the femoral head （ONFH） ,and to analysis of internal stress distribution and mechanical features on ONFH,in order to provide biomechanical basis for prevention col- lapse of ONFH. Methods：Choosing one adult male volunteers with left ONFH and scanning bilateral hip joints of patients by using of GE Bright speed of 16-detector row spiral CT,to access original data of DICOM 3.00NFH and normal femo- ral head. Then the finite element model of normal femoral head and necrosis femoral head were established by Amira im- age analysis software,Geomagic Studio reverse engineering software,and Ansys finite element analysis software. The me- chanical characteristics of normal femoral head and ONFH in different parts,and different bone on walking were analyzed. Results：Establishment three-dimension finite element mode of normal femoral head and necrosis femoral head, in different finite element model, to divides the total number of nodes and the number of units. Based on the sensitivity of cortical bone and cancellous bone,distinguish between two kind＇s model of spongy bone and compact bone, and calculated total number of grid 4 513 322 and mesh model 3 132 783. They were the similar on the equivalent stress distribution,and the differ- ence between maximum equivalent stress is 4.3%. Maximum stress values of the necrosis femoral head model were less than the normal model,especially when loose,cortical bone scattering. Maximum stress was reduced from 52. 110 3 Mpa to 30. 106 9 Mpa. When loose,cortical bone ached, the model of the necrosis femoral head has a maximum displacement 1. 006 9 mm,significantly larger than the normal model of femoral head 0. 583 6 ram. Indirectly show the fact that necrotic bone has more collanse risk on the identical mechanical load. Conclusions.. We develop an ONFH finite element model withgood similarities on geometry and physical, repeatability and available for dynamic mechanical analysis. Compared with the model of health femoral head, when establishing the me- chanical model of the proximal femur with ONFH,it is nec- essary to individually assign the material properties for the cortical and cancellous bone respectively.