- 學位論文
缺血性壞死股骨頭轉骨術之三維有限元素模擬
A three-dimensional finite element simulation of transtrochanteric rotational osteotomy for avascular necrotic femoral head
摘要
中 文 摘 要 對於年輕而較具活動性的股骨頭缺血性壞死之病患而言，轉子間轉骨術是髖關節置換術之外的另一可選擇之外科手術，此手術的概念是將位於重量承載區之股骨頭壞死區域轉移到非重量承載區，以減輕壞死區上之應力，進而延緩股骨頭的塌陷。本研究之目的為探討: 一、不同轉骨角度對降低壞死區應力的效率；二、壞死區材料性質的改變對應力分佈的影響；三、球頭塌陷與壞死區大小的相關性。利用標準人造股骨之電腦斷層(CT)掃描影像，以產生完整股骨之實體模型與六面體有限元素網格。藉由完整的股骨模型建立27個轉骨模型，以模擬3種不同壞死區範圍(60°, 100°, 115°)股骨之九個轉骨角度。將單腳站立之負載條件設定於所有的27組模型中，並使用有限元素分析軟體MARC2001完成模型之分析。經由計算得到所有27組模型中之應力分佈與壞死區之平均蒙麥斯應力。結果顯示，壞死區上之平均應力將隨著轉骨角度的增加而降低，且前轉之應力百分比低於後轉。60°壞死區於不同前轉角度之應力百分比為: 45%, 13%, 5%, 6%，於後轉為: 54%, 19%, 11%, 8%。對於較小範圍之壞死區，其應力百分比降低的速度比大壞死區快。比較不同大小之壞死區應力分佈顯示，較大的壞死區擁有較廣的高應力區域，較小的壞死區則在壞死區與健康骨界面上擁有較高的應力。本研究概約地提供不同大小的壞死區在不同轉骨術角度下對降低壞死區應力的效率。並且可以觀察壞死區在轉骨前與轉骨後之應力分佈。本研究之結果可作為醫師進行轉骨術之術前規劃時之參考。
並列摘要
英 文 摘 要 ABSTRACT Transtrochanteric rotational osteotomy (TRO) is an alternative surgical procedure besides total hip replacement for younger and more active patients of femoral head avascular osteonecrosis (AVN). The concept of the procedure is to move the weight-bearing necrotic area to a non-weight-bearing region by TRO, and to reduce the stress on the necrotic zone. Then it can prevent progressive collapse of the femoral head. The purpose of this study was to investigate (1) the efficiency of different rotation angles of TRO, (2) the stress redistribution with different ON properties and (3) collapse associated with ON lesion size. CT image data of a standardized composite femur was used to create the intact femoral solid model and the hexahedral finite element mesh. Based on the intact model, 27 models simulating nine different angles of TRO together with three different ON regions (60°, 100°, 115°) were created. A single leg stance loading condition was applied to each of the 27 models and finite element analyses were performed using the MARC2001 finite element software. The stress distribution and the average von Mises stress on the ON region for each of the 27 models were calculated. Results showed that the average stress on the ON region decreased as the rotation angle increased. The percent stress ratio for anterior rotation was lower than that of posterior rotation. The percent stress ratios for different anterior rotations for 60° ON region were: 45%, 13%, 5%, 6% and for different posterior rotations were: 54%, 19%, 11%, 8%. The percent stress ratios for smaller ON region decreased faster than that of larger ON region. The comparisons of different ON regions showed that larger ON region has more extensive high-stress region and smaller ON region has higher stress on the ON-bone interface. This study provides a general view of the efficiency for different angles of rotational osteotomy with different extent of ON regions. Also, the stress redistribution of the ON region before and after osteotomy can be observed. The results can be used as a guideline for pre-surgical planning for surgeons performing TRO.