股骨纵向受压时的应力分布特征分析

Stress Distribution Characteristics Analysis of Longitudinally Compressive Femurs

股骨是支撑人体的重要组成部分,其纵向受压是主要的外力作用形式.过大的荷载、意外的冲击、疲劳等可能造成股骨的断裂损伤,股骨颈开裂与折断是一种典型、高发的损伤形式,此时需要用人工假体代替损坏的部分股骨.为使假体与股骨结合性能接近于原股骨,必需研究掌握股骨的应力分布特征.股骨特别是两端因几何构造的复杂性,相应的应力情况也比较复杂.因受活体股骨及其实验技术的限制,有限元数值计算分析成为一种普遍采用的方法.但股骨上端部构造复杂、尺寸相对较小,往往缺乏可靠的计算结果,且股骨颈附近的有效测试数据相对较少.因此,需要进行全股骨纵向受压的应力分布特征特别是股骨颈附近应力特征的进一步研究.此外,假体植入后股骨的应力分布变化与假体的无菌性松动是一个切实的重要问题.论文基于股骨标本和假体植入鲜股骨纵向受压的多点应力测量结果,进行其有限元建模并计算分析.先基于股骨的CT扫描数据,利用MIMICS软件重建股骨的三维几何精确模型,再转入ANSYS软件划分单元,计算得到全股骨的应力分布结果,说明其分布特征及关键点的应力,并与实验结果比较说明结果的可靠性.然后,考虑股骨颈断裂损伤后的生物型金属假体植入情况,基于假体松动前的股骨实验结果,对于假体与股骨结合体计算分析其应力分布,说明假体植入对于股骨干应力分布的影响、及假体松动与应力遮挡现象.

Femurs are crucial components supporting bodies,which are often subjected to longitudinally compressive loads.Large loads can cause femoral damage such as femoral neck fracture,and then artificial prostheses are used for replacement and rehabilitation.To make the performance of the femur with prosthesis close to the original femur,the stress distribution characteristics of femurs need to be studied.The femur such as upper portion has geometric complexity and its stress distribution is complicated.The experimental technology for human femurs is restricted and then the finite element method is usually applied.However,there are less test results and reliable numerical results on stresses of the upper femur due to complicated structure and smaller size.The stress distribution of an entire femur,especially region near femoral neck under the longitudinal compression needs to be studied further.Moreover,the stress distribution change of the femur combined with prosthesis and the aseptic loosed move of the prosthesis are important problems.In this paper,the femur sample and femur with prosthesis under longitudinal compression are tested and analyzed by using the finite element method for stress distribution.First,the femoral geometric data are obtained by computer tomography(CT)scan,and the three-dimensional solid model of the femur is rebuilt by using MIMICS software.Numerical results on femoral stresses are obtained by using ANSYS software.The stress distribution and concerned point stresses are given and compared test results.Second,the femur combined with metal prosthesis is considered.Similarly,the stress distribution of the femur with prosthesis is tested and calculated by using the finite element method.The influence of the prosthesis replacement on the femoral shaft as well as the prosthesis loosed move and stress shielding is discussed.