脊椎融合術一直以來是治療椎間盤退化的主要方法，但是許多臨床文獻指出，在術後觀察期發現，患者因為手術節段的活動度降低，使得鄰近節段發生補償現象進而加速鄰近節段退化，近年來，一些學者提出將剛性固定和動態固定結合成混合型固定，希望達到原有的穩定度還能減少鄰近節段退化的問題。然而過去的文獻並未完整說明何種混合型動態固定為較佳的選擇，因此本研究目的為利用有限元素分析法評估混合型動態固定系統的生物力學性能。
本研究選用T10-S1的胸腰椎三維有限元素模型，將L3-L4或L4-L5退化椎間盤移除並植入椎籠，在前彎、後彎、側彎和扭轉四種運動狀態下，求得各節椎間旋轉角度、後方固定器應力及鄰近節椎間盤應力等生物力學特性，探討不同種類的排列方法下，選擇最佳的雙節後方混合型固定及三節後方混合型固定作為治療方式。
分析結果顯示，退化節段和鄰近節段使用動態固定能夠有較接近完整脊椎的椎間旋轉角度，其中在雙節混合型後方固定中，退化節段搭配上端節段固定有較好的結果；在雙節混合型後方固定器的應力比較中發現，退化節段和上端節段皆為動態固定有最小的應力值，在三節混合型後方固定的比較中得知，退化節段為剛性固定搭配鄰近節段皆為動態固定能夠有效減緩後方固定器的損壞率；在鄰近節椎間盤應力的結果中發現，其較佳的固定方式和椎間旋轉角度結果有相同趨勢，因此皆使用動態固定能夠有效降低鄰近節承受的負載，本研究結果能夠提供臨床醫生在術前分析上做為選擇混合型後方固定器的參考。

Fusion has been the main treatment for degenerative disc disease (DDD). However, many clinical studies have showed that adjacent segment degeneration was observed after fusion surgery. To solve these problems, dynamic stabilizations were used to treat disc degeneration. In recent years, some researchers proposed to combine rigid and dynamic stabilization in the treatment of degenerative disc disease. Hybrid dynamic stabilization is designed to achieve the original stability and reduce adjacent segment degeneration. However, previous research did not specify what kind of hybrid dynamic stabilization is a better choice. The purpose of my study was to investigate which hybrid dynamic stabilization is the best combination to treat DDD.
A three-dimensional finite element model of the T10-S1 lumbar spine was used to evaluate biomechanics of various device including double hybrid stabilization and triple hybrid stabilization in comparison with intact spine. I remove degenerative disc at L3-L4 level or L4-L5 level and insert into the cage. The loading cases of flexion, extension, lateral bending and axial rotation were simulated. Intersegmental rotation, the von Mises stress of adjacent disc and the von Mises stress of posterior device were calculated and discussed at the index level and at the adjacent levels.
The results to double hybrid dynamic stabilization showed that the degenerative segments and the upper adjacent segments using dynamic stabilization can have a greater inter-segmental rotation. Posterior device with Dynesys has the lowest stress at the index level and the upper adjacent level. The von Mises stress of adjacent intervertebral disc has same trend to the inter-segmental rotation.
The results to triple hybrid dynamic stabilization showed that the degenerative segments and the adjacent segments using dynamic stabilization can have a greater inter-segmental rotation. Posterior device using rigid stabilization at the index level and using Dynesys stabilization at the adjacent level has the lowest stress. The adjacent intervertebral disc stress is closed to the intact spine with Dynesys at the index and adjacent levels.
Using the dynamic stabilization on double and triple hybrid posterior device can reduce the load on the adjacent segments. Finally, my research could help surgeons to understand the biomechanical performances of hybrid posterior stabilization.

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