Impact Of Proximal Femur Finite Element Analysis Aroused By Different Modeling Methods

Objective: To study the influence on the mechanical properties of the proximal femur finite element model aroused by different modeling methods.Method: DICOM files from the proximal femur specimens thin CT scan was imported in the materialise interactive medical image control system to reconstruct the three-dimensional proximal femur model, then the model was imported in the finite element analysis software after assigned by different modeling methods to compare stress and displacement under the same loading conditions.Result: 1.Three-dimensional model established by MIMICS and Hypermesh software have a high geometric similarity and mechanical similarity with proximal femur specimens, it may correctly reflect the problem in this study. 2.There are obvious distinction between the von mises stresses of different materials number,the von mises stresses from 2 copies and 400 copies were significantly different from the datasets of other number of copies. To ensure ease of operation and accuracy of the results, the material number of 10 copies is ideal. 3.The Stress cloud of The model established by CT gray-Assigned method is show that Stress in the femoral head is focused on the main line of trabecular bone, and stress Below the lesser trochanter is gradually focused on the backbone of cortical bone. With the different internal structure of the models, Stress distribution is different. The Model established by this method is consistent with the physical structure. However, The model established by Dichotomy bone Assigned method is show that Stress significantly concentrated in the cortical bone,and form a "bone envelope" or "ladder" phenomenon. 4.finite element analysis result of the model builted by CT gray assignment method showed a larger stress in the tantalum rod tip, play a supporting role. However,the stress still concentrated on cortical bone in the model builted by dichotomy bone assignment method. The stress of Cancellous bone and tantalum rod tip is blocked by cortical bone, and there is a clear "bone cladding" phenomenon. Dichotomy bone assignment method can not accurately describe the model entities, and it also affectthe results of the finite element analysis,selection of surgical approach and implant material,implant design and configuration service life.Conclusion: To the proximal femur, the modeling methods of CT gray-Assigned method with 10 copies of the materials accurately simulate the physical structure inside and outside of the proximal femur, It is close to the material properties of the femur complex situation and consistent with the biomechanical properties conducive for finite element analysis.