單側式骨外固定器主要包含兩種功能，一種為骨折復位，另一種為提供軸向動態對位。骨折復位可確保斷骨在指定位置，軸向動態對位能提高骨頭癒合率，改善骨痂形成及骨頭重建。同時，外固定器可利用增加自由度之方式，滿足軸向動態對位，但使用過多的鉸接關節，則關節之間的連桿長度亦會增加，影響手術時的操作性。
本文研究目的是參考Dynafix和Orthofix骨外固定器之設計，並根據文獻所提出達到骨折復位和軸向動態對位之準則，將Orthofix骨外固定器在軸向動態對位調整上之不足，透過在遠端關節下方增加側向自由度，設計出修正型骨外固定器。利用齊次轉換矩陣建構運動鍊方程式，計算各個關節的調整範圍。並在多個數值解中，研究滿足軸向動態對位之機構與關節設計，運用電腦模擬骨外固定器模型，驗證數值解在骨折復位過程與軸向動態對位之準確性。
分析結果得知，Dynafix、Orthofix、概念型、修正型骨外固定器調整範圍可由齊次轉換矩陣求出，經由電腦模擬方式達到骨折復位。骨外固定器之軸向動態對位，除了要滿足軸向動態設計概念準則外，當骨外固定器在中立狀態，斷骨之相對位置正好是關節運動方向時，亦可滿足軸向動態對位；或骨釘為垂直打入斷骨且垂直於近端伸縮關節之狀態，亦可滿足軸向動態對位。本文亦探討對四種骨外固定器之機構設計、關節自由度數目和排列、數值解分析於臨床上之影響。

Reduction and axial dynamization of bone fracture are two important functions in application of unilateral external fixator. Fracture reduction is to ensure that the broken bones are in the specified location. Axial dynamization is to enhance bone healing, callus maturation, and bone remodeling. Meanwhile, the external fixator can be used to increase degrees of freedom to benefit the axial dynamization. However, the excessive use of articulated joints affects the surgical operations.
The purpose of this study is to develop a fixator design while satisfying all criteria of adjustability for reduction and alignment of axial dynamization. The modified external fixator with one more lateral degree of freedom at the distal joint was designed to remedy the disadvantage of Orthofix external fixator for achieving axial dynamization. Homogeneous transformation matrix was utilized to form kinematic chain equations for Dynafix, Orthofix, conceptual, and modified external fixators. The adjustment of each joint was calculated, and the constraints of axial dynamization of institutions and joint design should be met. By using computational modelling, the numerical solutions were verified accurately in both fracture reduction and axial dynamization.
For four fixators, the adjustment ranges of the joints can be solved by the homogeneous transformation matrix to achieve fracture reduction. However, for the external fixator that does not fulfill the design criteria but achieves axial dynamization, there are some special conditions: (1) the movements of the broken bones and joint are in the same direction; or (2) bone screws should be inserted orthogonally to the broken bone and the telescopic joint should be parallel to proximal broken bone.
For the mechanism designs of four external fixators, the influence of degrees of freedom of joints on clinical operations is numerically analyzed in this study as well.

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