摘要
膝下截肢義肢承筒的製作在臨床上沒有一定的準則。對於膝下截肢的患者，義肢承筒為義肢中與人體殘肢接觸的部分，並且是負責義肢在人體下肢負荷時的穩定支撐及力量傳遞的介面。因此，殘肢與承筒間的介面壓力就顯得非常重要，截肢手術後因為下肢結構的改變，若設計不良就會導致殘肢受力不均，亦造成穿戴的併發症，導致其它功能上的代償，甚至需要二度截肢。電腦輔助設計和有限元素分析應用在膝下殘肢義肢承筒設計，可以為臨床輔具設計和膝下殘肢與軟墊(Liner)間的介面應力探討節省龐大的實驗及製作開支。
本研究建立殘肢的擬靜態有限元素模型(Quasi-Static Finite Element Model)並配合接觸與摩擦條件，經過非線性有限元素分析軟體MARC計算後，得到膝下殘肢與軟墊間介面正應力及剪應力在整個站立週期的分佈；分析結果與壓力量測實驗所得的數據做比較，了解非線性有限元素模型可以模擬整個站立週期在膝下殘肢與軟墊間介面正應力及剪應力的分佈。應力值達可接受範圍內的殘肢模型，即可作為設計製作承筒之依據。

關鍵字：義肢承筒、膝下截肢、介面應力、擬靜態、MARC、有限元素

Abstract
During designing a BK (below-knee) prosthetic socket, the interface pressures between stump and socket are the most important considerations. At the stance phase of gait cycle of an amputee wearing prosthesis, the prosthetic socket is expected to support and uniformly distribute the entire weight of the amputee. If the interface pressures at sensitive areas of the stump are too large, it will induce pain, discomfort and breakdown. The objective of this study is to use finite element analysis package to estimate and analyze the pressures between stump and socket at three different walking speeds.
In the study, a computer-aided software was employed to construct the CAD models of the stump, bone, and socket. Then, this assembly model is transferred to a finite element analysis system, MARC, which is capable of analyzing nonlinear problem. The quasi-static dynamic boundary condition is designated to simulate the whole stance phase of the gait cycle of an amputee wearing prosthesis, and also the contact conditions are also taken into consideration. After solving these three quasi static dynamic nonlinear finite element model, we could get the distribution of the interface pressures between stump and liner. These results were compared with the data from the measuring of experiment.
The results of this study may provide an objective information for prosthetist to design and fabricate the prosthetic sockets.
Keywords：Prosthetic socket, Interface stress, BK amputee, Contact, Finite element analysis, MARC, Quasi-Static

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