一种髋关节计算机辅助建模新方法的研究

A Study on New Computer-aided Modeling Method of Hip Joint

目前导致人工髋部假体失效的主要原因在于假体松动以及因松动而造成的移位、脱位和折断。因此 ,有效地提高假体与骨结合面的长期稳定性是提高髋部人工关节置换术远期效果的关键。在过去的有关研究中 ,较多偏重于股骨上段髓腔的研究 ,而对髋臼尚停留在假设髋臼窝关节面为正球形凹面 ,臼假体的外形也基本上是半球形。本研究利用反求工程技术 ,通过测量得到完整的人体髋骨表面点云数据。然后对髋臼表面进行拟合误差分析 ,确定选用旋转椭球面拟合 ,结合优化技术 ,建立髋臼表面 CAD模型。通过比较分别用球面和旋转椭球面拟合的误差 ,可以得出旋转椭球面的拟合误差显著小于球面的拟合误差 。

The main reason of invalidation of prosthetic hip joint is the prostheses flexibility and shift, dislocation and disjunction. Promoting the long time stability of the prostheses is the key of improving the long term hip joint replacement effect. Former research work was focused on the upper segment of femur, and assumed the acetabulum cup to be a spheric concave, and the external form of acetabulum prostheses was basically semi spheric. This paper presents a method of acquiring the point data on the surface of the hip bone using the reverse engineering technology. By analyzing the acetabulum surface fitting error we use rotating elliptical surface to fit the acetabulum surface, together with the optimal technique to build up the CAD model of acetabulum surface. We compare the fitting error between the sphere fitting and rotating elliptical surface fitting and get the result that the rotating elliptical surface fitting error is smaller than the sphere fitting error, and the rotating elliptical surface can describe the shape of the acetabulum better.