脊柱為人體當中支撐體軸並提供軀體的活動度功能，對於因脊椎病變失去脊椎穩定性的患者，臨床上用椎弓骨釘來進行脊椎復位與矯正；對老化而產生脊椎骨質疏鬆患者而言，術後因骨釘與疏鬆的海綿骨之界面強度不足而難以達到穩定與固定的效果。因此本研究的目的為改良一般骨釘的結構設計使其適用於骨鬆椎骨，藉此提高骨釘的穩定度，減少術後骨釘之鬆動或移位。 本研究以有限元素模擬方法，分析探討一般骨釘及配合骨水泥骨釘植入骨鬆椎骨內固定的生物力學表現，並以不銹鋼316L及鈦合金Ti-6Al-4V的降伏強度以及學者文獻來對照模擬的結果。 有限元素模擬之結果顯示，新型骨釘結構強度與一般L1骨釘相同；新型骨釘在滲漏槽邊角有些微應力集中，加入骨水泥覆蓋滲漏槽後應力值會降低，但海綿骨與骨水泥接觸部分的應力值會提高。Pull-out testing模擬結果顯示：骨釘的位移量無顯著差別，原因是所施加的拉力超過骨鬆椎骨能承受的pull-out strength；骨釘主要發生破壞的受力情形由彎矩負載(flexion)發生。 未來研究方向建議：1. 以臨床骨鬆椎骨做為樣本，建立符合實際骨鬆椎骨的3D模型，以期能有符合實際情況的模擬結果，2. 以臨床骨鬆椎骨做實驗分析，驗證有限元素模擬結果。

Spine support body axis and provide active function. For the patients who lost spinal stability because of pathologic disease treated by pedicle screw to reduction and correction in clinical. For the osteoporotic patients, it was difficult to treat in stable effect due to lack of enough strength between pedicle screw and cancellous bone. The purpose of this research was to improve the structure of the normal pedicle screw for osteoporotic spine to increase the stability of pedicle screw and prevent loosening . Finite element method was used to analyze the biomechanical behavior with normal pedicle screw and improved pedicle screw combined bone cement into osteoporotic spine. In addition, stresses distribution of stainless steel 316L and titanium Ti-6Al-4V after simulation was investigated by using material yielding strength and literatures to compare the results. The analytical results illustrate that (1) the strength of improved pedicle screw is the same as normal pedicle screw, (2)improved pedicle screw has few stress concentration at corner of seepage hole, it reduce after adding bone cement into screw and cover all of seepage hole. But stress raise at cancellous bone with contact region of cement, (3)pull-out testing discover no difference of screw’s deformation, because of applying pull-out force too high, it exceeds pull-out strength of osteoporotic vertebra, the pedicle screw is failure by flexion loading. Future works suggest that (1)take osteoporotic vertebra to build 3D model in clinical, it will has more accurate results, (2) to proceed experiment by osteoporotic vertebra to verify finite element simulate results.

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