自動化有限元素分析流程於股骨柄設計之應用

Automation of Finite Element Analysis Procedures for the Application of Femoral Stem Design

廖富生(Fu-Sheng Liao)

指導教授 ： 陳文斌

中原大學/工學院/醫學工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500773

摘要

應力遮蔽效應是人工髖關節失敗的主要原因之一，以有限元素法評估人工髖關節之優劣是目前常見的方式，但以往有限元素前處理過程相當繁雜，需耗費冗長時間。因此，本研究有兩個目的：第一，希望能建立一套新的分析流程，縮短前處理時間；第二，以此流程分析股骨柄設計參數對於應力遮蔽效應的影響。
首先利用Amira軟體讀取人造股骨斷層掃描影像並建立實體模型，透過Solidworks軟體讀取模型再模擬手術植入人工股骨柄，最後用Cosmos做有限元素分析，Cosmos可以直接針對組合模型生成實體網格，以材料試驗機對人造股骨進行應變實驗，作為驗證Cosmos分析結果之依據。在股骨柄設計參數上，先針對股骨柄近端內側凹槽、外側凹槽、前後側凹槽、股骨柄中空處理及股骨柄末端錐度設定等參數獨立分析，再從初步分析結果中選擇較具影響性之參數，整合於股骨柄完成最後之設計。
在新流程的部分：Amira在建立股骨模型上，大幅度減少必須使用的軟體，省略了繁雜且重複性的步驟；Cosmos省卻修補網格程序，兩者的應用確實能大幅縮短有限元素前處理時間。設計參數的部分：初步結果顯示內側凹槽、中空及末端錐度此三種參數在股骨上的應力皆高於傳統式股骨柄，故選擇此三個參數做整合。整合股骨柄的股骨平均應力高於參數各自獨立的股骨柄，且在股骨近端及中段的應力明顯高於傳統式股骨柄，整合的股骨柄在減低應力遮蔽的效果上優於傳統式股骨柄。

關鍵字

人工髖關節 ； 應力遮蔽效應 ； 有限元素法

並列摘要

Stress shielding is considered to be one of the major reasons lead to total hip replacement failure. Finite element analysis has commonly been used to investigate the effect of stress shielding following hip replacement. However, the analysis procedure is very complex and time-consuming. Therefore, the objectives of the current study are in two folds: 1. to establish a new analysis procedure which can shorten the pre-processing time, 2. to perform parametric analsysis on the stress shielding effects of different hip stem designs.
An image-processing software (Amira) was used to process the sectional computed tomography images of a composite saw bone and to reconstruct the solid model of the bone. Then the solid model of the bone was transferred to a CAD program (Solidworks) to simulate the implantation of a hip prosthesis. Finally, the finite element analysis was performed using a finite element package (Cosmos) with the proper setting of boundary and loading conditions. The finite element analysis results were then validated with strain measurements on a composite saw bone loaded on an Instraon testing machine. The design parameters of the hip prosthesis investigated were: 1. medial flutes, 2. lateral flutes, 3. anterior-posterior flutes, 4. hollow interior portions, 5. distal tapers.
Results showed that, medial flutes, hollow interior portions and distal tapers were the effective parameters to reduce stress shielding effects. Therefore, when combining these three parameters on the hip stem design, the stress shielding effects can be minimized. Based on the current analysis procedures, the analysis time can be greatly shortened and the manual intervention can be minimized.

並列關鍵字

Stress shielding ； Hip prosthesis ； Total hip replacement ； Finite element analysis

參考文獻

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