骨板與髓內釘是股骨骨折復位手術中經常使用的內固定治療器具，由於股骨生理結構限制，幹骺處的骨折較不適合植入髓內釘治療。近年在輔以微創傷內固定手術技術下，應用鎖定式骨板治療骨折的方式被廣泛運用在人體各部位。然而，骨板疲勞斷裂問題依然存在於臨床治療上，過去研究人員曾遇過在相對較短的治療過程反覆發生骨板斷裂且位置皆相近的特殊案例，推測原因與選用骨板本身存有結構弱點和手術進行時醫師選用的螺絲配置有關。本研究目的有二：瞭解骨板破壞原理並比較骨折發生位置對骨板受力影響，藉以指出骨板最弱處以利後續修改；檢視螺絲配置並探討工作長度對骨板應變的分佈影響及原因。
　　研究之兩項目的均建立有限元素數值模型，並透過生物機械力學測試結果進行驗證與分析探討，比較在五種不同骨斷裂位置下之正向應變大小及分布狀況、軸向位移與整體剛度差異，最後依據建立之數值模型進行邊界條件微調與變形模式的探討，分析與歸納出在何種條件下骨板上的最大應力將隨工作長度增長而下降。
　　數值分析結果顯示鎖定式骨板最弱處與骨折位置相關，骨幹骨折由於高彎矩環境，在力學試驗與數值模型中皆測得最高的應力應變，選用骨板進行治療手段需特別謹慎；骨板治療是踝上骨折最適合的選擇，但較薄弱的幾何處需進行改善以增加使用壽命；較長的工作長度在特定邊界條件選擇下可降低骨板上的應變並增加骨折間隙處的軸向運動，刺激骨痂生長。
　　本論文研究建立之數值模型期望可做為骨科醫師臨床使用骨板之手術參考，並給予醫療器材設計人員於改良骨板設計參考之依據，及後續研究工作長度相關研究之邊界條件選擇。

　 Bone plates and intramedullary nails have been widely used as internal fixtures to treat long bone fractures in the lower body. Femoral metaphyseal fractures are not suitable for fixation with intramedullary nail due to its anatomy. With the Minimally Invasive Plate Osteosynthesis (MIPO) technology, plating treatment has been widely used in various fractures. Nonetheless, the risk of plate fatigue failure remains a problem in clinical surgery. We encountered a catastrophic case involving repeated plate breakage in similar positions during a short treatment process. The reason is speculated to be related to the structural weakness of the plate and the selection of short working length. This study has two purposes: first, to understand the principles of bone plate failure and compare the effects of different fracture locations on the plate; second, to examine the screw configuration and discuss the influence of working length on the plate.
Both studies established the finite element numerical models, which were verified by the experimental results of biomechanical tests. The comparison includes the normal elastic strain value, strain distribution, axial displacement, and overall structural stiffness among five models with different fracture locations. The discussion includes the boundary conditions and deformation modes, and the analysis and summary focus on the influence and occurrence conditions of the working length effect.
The numerical results indicated that the weakness of plate was related to fracture location. Due to the high bending environment, plating treatment for femoral shaft fractures should have been approached with more meticulousness. Plating was the golden standard for distal femoral fractures, but revising the weakest geometry is warranted. The present model could serve as a reference for orthopedics in clinical plating operations and as a basis for medical device manufacturers to improve plates. The comparison of boundary conditions settings in the study on working length could also assist future research work.

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