手指的精細動作控制在人類日常生活扮演相當重要的角色。由於關節的活動，使拇指能與另外四根手指頭交互運動，進而可做出精準的對掌或抓取動作。指骨與掌骨骨折約佔所有骨折的10%。指骨骨間骨折一般處理的方式有骨釘、骨板、外固定器及副木。其主要問題在於骨折處癒合後，常發生關節僵硬，而使關節活動度受限，造成生活機能的不便。理想的固定方式，在於能儘早開始復健，又能提供適當的固定性，避免於復健活動時造成骨折移位的併發症，延長癒合時間。Suzuki學者所提出之動態外固定器，由K-pin及rubber所構成，在固定時提供牽引力，復健運動時產生額外牽引效果，有助於早期復健及適當固定兩方面考量。但是臨床上此固定器之相關尺寸、適合之固定位置與rubber 之角度對固定器結構與骨折處應力影響並無相關研究討論。本研究針對Suzuki學者所提出之動態外固定器，探討固定器於固定指骨骨間骨折時的固定器結構與骨折處的相關力學分析，並找出主要的影響因素。

首先由靜力學及材料力學推導外固定器固定指骨關節之牽引力學模型。接著由Solidworks建構指骨、側韌帶與K-pin之3D模型及CosmosWorks進行有限元素的模擬分析，探討在不同K-pin長度條件下，對結構及指骨的應力分佈與位移的影響。最後由不鏽鋼線受力實驗測試來與有限元素分析結果做比較。

模擬分析結果顯示：Suzuki 動態外固定器中K-pin長度影響著牽引力的大小，當固定於中間指骨與近端指骨的K-pin長度過長，皆會造成結構變形增加，而降低其牽引效果。數學模型結果顯示：當固定於中間指骨的K-pin位置距離關節越遠，牽引力增加且使指骨移位的分力降低。

本研究結果建議在固定器的治療近端指骨骨間骨折時，固定位置要遠離中間指骨關節，固定於中間指骨K-pin長度短一點，使rubber的拉伸方向平行於中間指骨，動態外固定器能有較佳的效果。此研究能提供臨床醫師在使用動態外固定器固定指骨骨間骨折時的客觀參考依據，對於動態外固定器的設計與改善也是極具價值的參考資料。

Finger function plays an important role in the human life. The finger executes accurately opposition and grasping through the joint activities. Fractures of phalanges and metacarpals account for 10% of all bone fracture. Joint stiffness is the major problem of the healing intra-articular fractures on the proximal interphalangeal joint (PIP joint). The Suzuki dynamic external fixation device, consisting of K-pins and rubber, provides traction force for fracture restoration , ligament traction to release joint stiffness and enhance early rehabilitation for PIP joint range of motion. The purpose is to investigate biomechanics of the Suzuki dynamic external fixation on phalange intr1-articular fractures. The specific aims are to: (1) investigate the influence of K-pins length on stress and strain distribution on the device and phalanges: and (2) find better fixation position for this device.

Analytical model was developed to investigate the forces and moments of phalange fixation with the Suzuki dynamic external fixation device through static mechanics. A 3-D model of phalange, collateral ligament and K-pins was developed by CAD software SolidWorks. Finite Element Method (FEM) was used to analyze the stress distribution and displacement of K-pins and the articular surface in response to different lengths of the K-pin and phalange location by CosmosWorks. Finally, the mechanical testing was conducted on the Suzuki dynamic external fixation device to validate the FEM outcomes.

The analytical results illustrate that: (1) the longer the K-pin, the more structure deformation and the lower traction effect by FEM analysis; and (2) the far position of the K-pin fixed in proximal phalanx, the higher the traction force and the lower the partial vertically force.

The outcomes of this research have suggested the following design to the improved Suzuki dynamic external fixation: (1) the better fixation position is far away from PIP joint; (2) the length of K-pins in the Suzuki dynamic external fixation could be shorten; (3) the direction of rubber should be paralleled to the phalange to provide effective fixation.

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