髓腔改变对股骨近端假体-骨界面应力的影响

目的 建立股骨近端假体-骨界面应力有限元分析模型.并对中国成年人股骨近端正常受力、翻修过程中扩髓条件下进行静态有限元分析.方法 运用逆向工程与有限元的理论.对CT图像采用了滤波、边界提取、二值化等方法进行处理,所得数据用CAD软件经过曲线重构、曲面重构、实体重构,加工出股骨应力模型.将不同载荷施加与假体-骨界面,改变股骨骨皮质的厚度、假体长度等参数,进行静态模拟应力分析.结果 建立起以国人股骨为基础的有效的假体-骨界面应力分布规律三维有限元模型.股骨的受力主要集中在小转子和大转子之间的股骨距分布区域,并且随着载荷的增加而递增;假体增粗至原来的120%时,股骨最大应力已经接近极限应力值.结论 构建的解剖型股骨假体-骨界面三维有限元模型,几何相似性好.模拟应力分析结果提示接受关节置换的患者应该尽量避免登山等接近加载量极限的活动;对于髓腔骨缺损严重的翻修患者提倡应用骨移植材料.谨慎采用增粗假体固定.

Three-dimensional finite element analysis modeling of the post-implanting femur and statics analysis of femur prothesis bone interface

Objective To establish the 3-dimention finite element model of implant in proximal femur bone-prosthesis areas and analyze proximal femur of chinese adult men under normal stress, medullary cavity enlargement and prothesis enlength conditions. Methods Using contra-direction engineering and finite element theory,CT data were processed through image filter-wave,border-extract,bi-tite change.then gone through curve-reconstitution,cyrto-face and entity reconstitution by CAD software and obtain model.parameters such as load volume,femur cortex depth .which were changed in model and computed static stress. Results The 3-dimention finite element model based on Chinese man was established.Femoral suffering area concentrates mainly on femur calar between lesser trochanter and greater trochanter.Femur maximum stress is nears to ultimate when prothesis enlarges to 120% of normal size. Conclusion The model is similar to femur bone geometry and promising to analysis clinical problem in total hip arthroplasty replacement. These results suggest that patients who receive total hip arthroplasty replacement should avoid some activities such as climbing.on the other hand, Operator should advocate to make use of bone grafts and take care of femur medullary cavity enlargement under severe bone defect in meduallary cavity.