股骨近端及人工髖關節之有限元素網格自動生成

　　　　　有限元素法是了解人工髖關節植入前後應力改變狀況的最佳方法。 人工關節設計 師可利用有限元素分析之結果來評估並修改人工關節之設計，進而提高人工髖關節植入人體 後之成功率。由於股骨形狀及材料特性極不規則，因此有限元素網格建立不易且費時。本研 究提出一套股骨與人工髖關節的實體模型建立法及有限元素網格自動生成法，用於快速且細 密地建立股骨及人工髖關節之有限元素模型。本研究利用 CT 影像擷取股骨皮質骨及疏鬆骨 之內外輪廓並由電腦輔助設計程式取得人工髖關節之外輪廓，將輪廓資料輸入 NUAGES 電腦 軟體，使用 Delaunay 三角形生成法建立表面三角形模型與四節點四面體有限元素網格。網 格之有限元素分析使用商業有限元素軟體 ANSYS，並評估網格之收斂性。使用本研究之網格 生成法建立股骨與人工髖關節之有限元素網格，將可大幅降低網格生成所需的時間。
　　　　　Finite element method is currently the most appropriate method to understand the femoral stress distribution before and after implantation of a hip prosthesis. From the finite element analysis results, prosthesis design engineers can evaluate and modify the implant designs and hopefully to increase the success rate for the implantation. Due to the highly irregular geometry and material properties of the femur, it is rather difficult and time consuming to build finite element models for the femur and the prosthesis. In this study, a procedure for automatically generating surface models and finite element meshes of a proximal femur and implant is described. CT scan images were used to obtain the inner and outer contours of the cortical bone and cancellous bone on each section of the femur and the prosthetic contours were obtained from a CAD program. The contours were then input to a computer program-NUAGES which based on the Delaunay triangulation algorithm for generating triangular surface models and four-node tetrahedral finite element meshes. Finite element analyses for these meshes were performed using a commercial finite element analysis package-ANSYS and the convergence of the meshes were tested. By using the mesh generation procedure described in this study, the mesh generation time can be greatly reduced when performing finite element analyes for the femur and implant systems.