人體腰椎隨著年紀增長經常產生各種退化性疾病，最有效的治療手段便是採取手術治療。其中，腰椎椎間融合術(LIF)是最為普遍的手術方法之一，以及植入棘突間裝置的非融合手術也在近年被經常使用。透過電腦模擬分析，有助於進一步了解手術行為在生物力學上的影響。過往模型在材料性質的決定上，多半是依照骨骼結構各自給定材料參數。近年來，也出現了基於 CT 影像的亨氏單位(HU)對模型元素分配材料性質的方法。然而，很少研究針對這兩種材料性質設定方法進行比較，且模型幾何多半經過簡化。因此本研究目的，是使用基於 CT 影像建立的患者特異性之人體胸腰椎有限元模型，了解不同的骨骼材料性質之設定方式，對於完整模型與手術模型的生物力學之影響和差異。
本研究透過 Amira 針對 CT 影像初步建立出 T10-S 三維胸腰椎表面模型，並透過 Freeform 和 Geomagic Wrap 進行表面平滑處理並輸出實體模型，最後於 Ansys
Workbench 2022 R1 上進行有限元素分析。在完整模型的基礎上，建立 TLIF 腰椎
融合模型和棘突間裝置運動保存模型，並使用三種骨骼材料模式：Material mapping、Solid 和 Shell 進行設定。模型上的椎骨元件和植體皆為線彈性及等向性材料，椎間盤則採用 Mooney-Rivlin 公式定義之超彈性材料，韌帶部份以僅受拉伸彈簧元件來模擬。接觸條件除了小面關節為摩擦接觸，其他部份均為固定連結。邊界負載條件部份將薦椎底部視為固定端，以 400N 之從動負載模擬人體上半身重量，並於 T10頂面給定位移控制產生屈曲、伸展、側向彎曲及軸向旋轉之運動行為。結果部份針對椎間旋轉角度、椎間盤應力、小面關節壓力及植體應力等面向進行探討。
從分析結果來看，本研究預測之活動範圍(ROM)與過往研究相似。椎間旋轉角度和椎間盤應力的表現在三種骨骼材料模式之間，均有很高的相似度，而小面關節壓力的表現則出現較大的差異，並同時受到模型品質、接觸條件及關節間隙等多方因素影響。腰椎融合模型在手術節段(L3-L4)具有較低的椎間旋轉角度及椎間盤應力，在鄰近節段的椎間旋轉角度及椎間盤應力則相對較高。運動保存模型相對於腰椎融合模型，在手術節段具有較好的椎間旋轉角度及椎間盤應力之表現。腰椎融合模型的植體應力相對的遠低於運動保存模型。針對三種骨骼材料模式進行相關性比較，實體元素模型比起薄殼元素模型，更加能夠表現出近似於骨骼材料映射模型的結果。骨骼材料映射模型的分析水準，更加接近真實人體生物力學實驗的表現。

The most effective treatment strategy for the human lumbar degenerative diseases is surgery. Computer simulation is one of the effective methods for understanding the biomechanics of various surgical treatment strategies. However, only some studies have considered the bone material distribution based on computed tomographic scan images. Thus, this study aims to develop patient-specific finite element models of the human thoracolumbar spine and investigate the biomechanical outcomes of the thoracolumbar
spine with intact, lumbar fusion, and motion preservation conditions.
A three-dimensional thoracolumbar spine model was established based on CT images using ANSYS Workbench. Three different bone material models were considered and discussed, including the material mapping model, the solid element model, and the shell element model. Besides, one intact and two treated thoracolumbar spine models were developed. The treaded models included the lumbar fusion model and the motion preservation model. Six types of human spinal movements with a follower load of 400 N
were considered as the loading condition. In postprocessing, the intersegmental rotation, disc stress, facet joint pressure, and implant stress were analyzed and discussed. The results show that the range of motion predicted by the present study was similar to that of the past studies. The lumbar fusion model revealed lower intersegmental rotation and disc stress at the index level and higher intersegmental rotation and disc stress at the adjacent level compared to the intact model. The motion preservation model has better intersegmental rotation and disc stress than the lumbar fusion model. The implant stress of the lumbar fusion model is lower than that of the motion preservation model. Compared to the three bone material mapping methods, the solid element model could provide closer results to the material mapping model than the shell element model. The material mapping model, which considers the actual material distribution of the human thoracolumbar spine, was suggested.

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