鎖定式骨板已經被廣泛地使用於治療股骨骨折，因其具有較好的結構剛度，以及較佳的骨咬合能力，故已廣泛的用於股骨骨折外傷治療，尤其輔以微創鋼板內固定術(Minimally invasive plate osteosynthesis, MIPO)，更增加鎖定式骨板的優勢，但在臨床上仍會發現因應力集中所導致的骨板破斷，植入越多的鎖定螺絲可獲得越穩定的骨折固定穩定度，然而，植入較少的鎖定螺絲可減少骨骼肌肉組織的損傷，以及避免應力遮蔽(Stress shielding)問題，因此開始有人嘗試使用混合式的骨板，希望將兩種不同類型的螺絲優點結合在一起，先前的研究已探討各種不同型式的螺絲植入位置、數量與螺絲種類，但螺絲植入位置、種類與數量主要是依據臨床醫師的經驗，這些經驗尚未有具體的生物力學結果來佐證，且臨床上對於骨折固定之觀念已從絕對穩定(Absolute stability)改為相對穩定(Relative stability)因其對於骨折癒合有較大的幫助，因此本篇研究將使用有限元素分析軟體來比較結構較強的鎖定式骨板及新的混合式骨板並探討其生物力學現象，找出破壞之趨勢及避免破斷的方法來提供醫師做參考。
本研究使用目前被廣泛接受的股骨模型及市售的12孔鎖定式骨板以有限元素分析來評估鎖定式骨板與混合式骨板的生物力學特性，找出應力分布與結構穩定度的趨勢。而本研究中判斷其生物力學性能主要是依據植入物的最大軸向位移(穩定度)以及植入物之最大應力發生處此兩種結果來評估此結構的生物力學行為之優劣。
分析的結果顯示影響植入物應力的因素為工作長度(working length)，工作長度越長應力越低，植入物破壞機率也會降低，在結果中也發現到植入物的穩定度通常與應力成正比，越穩定的結構其應力也會越高，而將鎖定式骨板與混合式骨板做比較後發現在一樣的螺絲位置組合下混合式骨板的應力比鎖定式骨板的應力低非常多，其原因是因為非鎖定式的螺絲放置於近骨折處並不會縮短工作長度並使應力可以均勻的呈散開分佈，在醫學的角度上近骨折處使用非鎖定螺絲又可增加骨折斷面接觸的機率減少骨折癒合時間。
希望藉由本研究所得出的結果，可以幫助骨科醫師了解混合式骨板的生物力學特性，並做為在臨床上選擇使用骨板的參考依據。

Locking compression plate system with its advantages of higher construct stiffness and bone holding power has been widely used to treat femoral shaft fracture. The benefit of locking compression plate would be greatly improved if the minimally invasive plate osteosynthesis (MIPO) technique was applied. In clinical applications, we can still found that the implant failure cause by stress concentration, locking compression plate with a largest number of locking screws has excellent fixation stability. However, the omission of some locking screws can reduce the damage to bone and soft tissues and avoid stress shielding effects. Therefore, some research are try to use Hybrid plate, they hope to combine the advantage of two different types screws. Past studies have discussed the influences of screw position and number on the fixation stability. Unfortunately, the screw position and number of locking compression plate were determined by surgeon’s experience without experimental evidence.
The purpose of this study is to compare locking plate and hybrid plate by using Finite Element Analysis, and find out the trend of implant failure and how to avoid it.
The commercial 12 holes locking plate and the standardized femur model were used in this study. And use finite element software to evaluate the implant stability and implant strength. To determine the biomechanical characteristics of different screws combination, are the maximum von Mises stress of implant and maximum deformation of femur.
The results show that the working length is the most important parameter of implant strength and stability. We also found that implant strength and implant stability are conflict each other, it means when working length goes greater then the implant strength goes up but implant stability goes down. And the result also shows that hybrid plate’s stress is much less than locking plate when we place screws in same position, it because nonlocked screws do not interrupt working length so the stress goes down. In the clinical view, using nonlocked screws near the fracture side can help fracture bone contact, improve callus formation.
The results of this study wish to help surgeons to understand the biomechanical characteristics of locking plate and hybrid plate, and also provide evidence to support the use of hybrid plate.

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