中文摘要

由於醫療科技與人類文明的進步造成全球高齡人口的增加，使骨質疏鬆症成為全世界第二大流行病學，導致骨質疏鬆相關脊椎病變患者劇增。在2000年全球共有4,400萬的人罹患骨質疏鬆症，脊椎骨折占了140萬人。臨床上以傳統骨釘來治療骨質疏鬆脊椎骨折，其椎弓骨釘固定系統在受力後常產生鬆脫(Pull-out)的情形，因此如何增加骨釘與海綿骨之界面強度來穩定骨質疏鬆的脊椎是臨床上常面對的難題。本研究目的為研發設計適用於骨鬆椎骨之骨水泥錨定型椎弓骨釘，其特定目標：(1) 設計研發3D骨泥錨定型椎弓骨釘模型；(2) 模擬分析骨泥錨定型椎弓骨釘植入三節椎體之生物力學特性。

本研究主要分為四個階段：(1) 依據功能性需求利用CAD進行設計適合骨鬆患者之骨泥錨定型椎弓骨釘，並進行雛型製作。(2) 利用椎弓骨釘配合骨水泥植入假骨進行骨水泥擴散實驗來驗証其可行性，並以長度、寬度及體積來量化其擴散分佈，且應用solidworks重建骨水泥擴散模型。(3) 利用MTS進行椎弓骨釘配合骨水泥植入假骨之生物力學抗拉強度測試共分為12組，探討各組間拉出強度及拉出能量並以One-way ANOVA分析其差異性。(4)以有限元素法模擬分析骨泥錨定型骨釘植入椎骨(包括至少三節椎骨)及灌入骨水泥生物力學特性。

結果顯示：(1)在抗拉強度下骨泥錨定型椎弓骨釘相較於傳統骨釘其最大應力增加5%，骨泥錨定型椎弓骨釘相較於傳統骨釘在總反作用力減少6%。在抗彎強度下骨泥錨定型椎弓骨釘相較於傳統骨釘其應力增加3%，但在位移下骨泥錨定型椎弓骨釘相較於傳統骨釘增加3%。(2)骨水泥的灌注對傳統骨釘、中空骨釘及錨定型椎弓骨釘的拉出強度與拉出能量皆有顯著性差異(P<0.05)。(3)椎弓骨釘配合骨水泥植入三節椎體模型之分析可得知傳統骨釘及骨泥錨定型椎弓骨釘當增加骨水泥的灌注時，可明顯的降低整體的最大應力27%至44%。

本研究結果建議在治療骨質疏鬆相關脊椎病變時，骨水泥錨定型椎弓骨釘配合骨水泥可有效的加強其固定效果，且骨水泥量愈多其固定效果愈佳。未來可針對本研究之骨泥錨定型椎弓骨釘進行cadver生物力學及動物實驗，以提供完整的資料作為臨床治療骨質疏鬆脊椎病變的另一種選擇。

Abstract

Because of improvement and development of the medical technology, the dramatic increase of aged population and associated osteoporosis has lead to increase patients with spinal trauma and related spinal disorder. In 2000, the America National Osteoporosis Foundation reported that there are over 140,000 vertebral fractures annually. The transpecicle screw system has been widely used to treat spinal disorder in the past two decades. Loosing or pullout of the pedicle screws occurs in cases of inadequate fixation strength between screw-bone interface,especially in patient with osteoporsis. However, it is a challenge to s perform for instrument on the osteoporotic spine. The purpose of study is to design and develop of bone cement anchoraged pedicle screw for osteoporotic spine. The specific aims are to: 1) design and development of bone cement anchoraged three-dimensional model of pedicle screw. 2) applying finite element method (FEM) to simulate and analyze the biomechanical characteristics of the inserted bone cement anchoraged pedicle screw and bone cement into the vertebre (including at least three vertebrae) for optimal design of the pedicle screw.

This study is divided into four stages: (1) applying computer aided engineering (CAE) to conceptual design a 3D bone cement anchoraged pedicle screw for osteoporosis, and prototype manufacture. (2) monitoring bone cement distribution patterns for pedicle screw types inserted into sawbone test block to prove the feasibility. The occupied space of different bone cement distribution is also quantitatively characterized for length, diameter, and volume by using a SolidWorks program. (3) pedicle screw with bone cement into sawbone test block of biomechanical tensile strength test conducted using MTS and divided into 12 groups. To evaluate the effect of different methods of the pedicle screw implantation on the stability of the fixation, one-way analysis of variance (ANOVA) is applied to compare the pullout strength and energy. (4) applying finite element method (FEM) to simulate and analyze the biomechanical characteristics of the inserted bone cement anchoraged pedicle screw and bone cement into the vertebra (including at least three vertebras).

The analytical results show that : (1) the bone cement anchoraged pedicle screw present a 5 % increase in tensile strength of the von mises stress compared with conventional pedicle screw and a 6 % increase in the total reaction force. The bone cement anchoraged pedicle screw a 3 % increase in bending strength of the von mises stress compared with conventional pedicle screw and a 3 % increase in the deformation. (2) A significant increase in the pullout failure strength of pedicle screws with PMMA bone cement augmentation relative to pedicle screws without bone cement augmentation is observed among each group ( P < 0.05 ). (3) traditional screw and bone cement anchoraged pedicle screw using PMMA bone cement augmentation will significantly reduce the overall von mises stress of 27 to 44 percent in pedicle screw and associate augmentation bone cement into the three vertebra model.

The outcomes of this research have suggested : the higher strength of pedicle screw fixation in osteoportic spine can be obtained with the larger amount of bone cement inject, but this may increase the risk of cement leakage. Future works suggest that bone cement anchoraged pedicle screw for cadver biomechanical and animal experiments for clinical treatment of osteoporosis an an alternative to spinal fracture to provide more complete information.

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