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標題: | 椎體撐開器及其植入設備開發 Development of an Expandable Intravertebral Body Cage and Implant Apparatus |
作者: | Yu-Ning Wang 王毓甯 |
指導教授: | 王兆麟(Jaw-Lin Wang) |
關鍵字: | 脊椎壓迫性骨折,椎體撐開器,可擴張,微創手術, Vertebral Compression Fracture,intravertebral body cage,expandable,minimally invasive surgery, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 背景簡介: 骨質疏鬆症是高齡化社會嚴重的課題,而脊椎壓迫性骨折為骨質疏鬆症患者最常見的併發症之一。壓迫性脊椎骨折成因為骨骼支撐力降低,導致患者出現劇烈背痛、椎骨變形等症狀,嚴重影響患者日常活動能力及生活品質。近年來患者多以手術治療,以達到快速又有效的治療成果,目前主要的手術治療方式為椎骨整形術及椎體後凸成形術。椎骨整形術是將具有高應力之骨水泥注入骨折處以增強脊椎骨支撐力,以達到穩定的效果;而椎體後凸成形術是將氣囊植入至椎體中製造一空腔,再注射骨水泥。此二種手術療法對於患者緩解疼痛十分有效,但手術仍存在骨水泥溢流等臨床風險,因此出現一新想法,即設計一具有撐開功能之椎體撐開器裝置,將其留置於椎骨中,再以骨水泥固定。目前市面上之椎體撐開器之市場反應良好,惟其價格昂貴且僅有垂直擴張之功能,使其撐開效果受侷限,故本研究將參考並改良此類撐開器裝置,設計一可使用微創手術方式植入之椎體撐開器,其具備雙向之變形功能,可由小體積植入體內後再加以擴張,以達成穩定支撐椎體之功能。
目的: 本研究將設計一可用於微創手術之椎體撐開器及其植入設備。此椎體撐開器須具備可變形之功能,能夠在植入前以外徑5.5 毫米、長度26.5 毫米以內之小體積進入微創手術傷口,在植入椎骨後進行垂直之方向擴張至至少10 毫米,以矯正椎節高度,並進行水平方向之擴張,以增加撐開器支撐之椎體範圍。 材料與方法: 本研究選擇鈦合金作為椎體撐開器之材料,不鏽鋼作為植入桿件之材料,白塑鋼作為其他植入設備之材料。本研究設計出多個撐開器版本,使用有限元素分析法模擬其變形狀況及分析結構強度。藉由重複設計、模擬、修改不斷優化設計,最終以光敏性樹脂及鈦合金打樣撐開器,配合精密加工製造植入設備作測試。 結果: 本研究就撐開器系統之設計主要可分為四個版本,版本一由38個零件組合而成,其目的為利用連桿機構模擬擴張情形,確認此構想之可行性。透過植入桿件偏心驅動後,其垂直方向及水平變形幅度分別可達135% 及239%,且可控制轉向角度,模擬結果功能性十分良好,已確認機構可行,故將多件連桿、轉軸所組成之撐開器主體簡化為一體成形撐開器作為版本二。版本二以一體成形設計,克服無法定型及零件數量過多的問題,打樣結果顯示水平方向擴張佳,但尚未觀察出垂直方向擴張時,水平擴張之轉角處即斷裂無法承力,其功能未達預設規格要求且斷裂將導致嚴重潛在風險。版本三針對撐開器外形作修改,其垂直方向及水平變形幅度分別可達117% 及67%,其功能已達預設規格要求,但外形導致其不易向外側撐開,易向內側塌陷損壞。版本四亦針對撐開器外形作修改,以有限元素法模擬擴張情形,其垂直方向及水平變形幅度分別可達176% 及12%,功能已達預設規格要求。以3D列印機打樣撐開器放大至1.25倍之測試結果,其垂直方向及水平變形幅度分別可達124% 及 25%。以金屬打樣原始大小之撐開器,其測試結果呈現僅前端擴張之V字型,不符合模擬結果對稱擴張之形狀。版本五為最終版本,針對版本四金屬打樣之結果修改撐開器外形,其垂直及水平變形幅度分別可達44% 及 7%。金屬打樣之測試結果,呈現前端高後端低之平行四邊形,不符合模擬結果對稱擴張之形狀。 結論: 版本四及版本五雖可成功模擬對稱擴張,但變形幅度尚未達到規格要求,未來可嘗試將撐開器設計具有初始角度以增加擴張幅度;此外亦可加入轉向功能,由醫師主動控制植入方向及角度,將其放置到最合適的位置,達到最佳的臨床效果。另外,版本四及版本五之金屬打樣結果與模擬結果相異,皆無法對稱變形,推測為特定機構參數或金屬加工誤差導致,未來可嘗試將撐開器修改為四連桿機構之形式,以確保達到對稱擴張之功能。 Background: Osteoporosis is a serious problem for an aged society, and vertebral compression fractures (VCFs) are one of the most common complications caused by osteoporosis. VCFs are due to strength weakening of vertebra. The fractures can cause some symptoms such as severe back pain and vertebrae deformity resulting in reduced quality of life and functionality. In recent years, vertebroplasty and balloon kyphoplasty, which are both minimally invasive methods, have been used to treat VCFs. In vertebroplasty, bone cement is injected into the vertebral body to stabilize it. In balloon kyphoplasty, a balloon is inserted to raise the vertebral body height, and then the bone cement is injected to stabilize vertebral body. These two surgery methods have positive impacts on pain relief; however, there are problems including cement leakage which increase clinical risk. The present study investigates a novel surgical device system to treat VCFs. When inserted into the vertebral body, the device expands symmetrically. After it restores the vertebral height, bone cement is injected to stabilize the device. Current expandable implant, such as SpineJack® (Vexim), is the most commonly used expandable device nowadays. However, it is too expensive and it can only expand in one direction. Therefore, there is still room for improvement. Objective: The aim of this study is to design an implant surgery apparatus for minimally invasive surgery and an implant device with expandable function. The device should be less than 5.5 mm in diameter and 26.5 mm in length, and thus can be used in minimally invasive surgery. After inserted, the device should be expanded to 10 mm in height to restore the height of vertebra, and expanded in the horizontal direction to increase supporting area for the vertebral body. Material and Methods: This study uses titanium alloy as the material for the intravertebral body cage, and uses stainless steel and photosensitive resin as the material of implant apparatus. The device is designed for multiple versions. Finite element analysis is applied to simulate the deformation and analyze the structural strength. Then the device is optimized through design, simulation and numerous revisions. Lastly, the device is prototyped with photosensitive resin via 3D printer and with titanium alloy via precision manufacturing, and the implant apparatus is prototyped via precision manufacturing. Results: This study contains four distinct versions of the expandable implant device. The mechanism of version 1 is composed of 38 parts. The aim of version 1 is to confirm feasibility of mechanism motion via simulation. The simulation result shows that the device expands symmetrically, and its deformation ratio in the vertical and horizontal directions could be 135% and 239% respectively, thereby meeting the specification, and its insert angle can be controlled. The simulation results show positive feasibility. As a result, the mechanism of version 1 is simplified to version 2. Version 2 is a one-piece design simply composed of 4 parts. However, the corners of the design are so weak that they rupture before being expanded vertically. Version 3 is a modified form of Version 1. The device expands symmetrically, and its deformation ratio in vertical and horizontal directions could be 117% and 67%, thereby meeting the specification. However, its structure tends to deform inward instead of being expanded outward. Version 4 is created by modifying appearance of version 3. By performing finite element analysis to simulate the expansion, the device expands symmetrically, and its deformation ratio in vertical and horizontal directions could be 176% and 12%, meeting the specification. The version 4 is prototyped by 3D printer with size of 1.25 times. It expands asymmetrically, and its deformation ratio in vertical and horizontal directions are 124% and 25%, respectively. Besides, it is also prototyped in the original size with titanium alloy. It expands asymmetrically in the shape of “V”, different from the symmetrical shape being expected. Version 5 is the final version of the design created by modifying appearance of version 4. By performing finite element analysis to simulate the expansion, the device expands symmetrically, and its deformation ratio in vertical and horizontal directions could be 44% and 7%, which expansion is not enough for meeting the specification. In addition, the version 4 is prototyped with titanium alloy. It expands asymmetrically in the shape of parallelogram, different from the symmetrical shape being expected. Conclusion: Though version 4 and version 5 of design can be simulated expanding successfully, however, their expansion doesn’t meet specifications yet. Besides, the prototyping sample of both version 4 and version 5 are not expanded symmetrically as the result of simulation. The future work is to increase expansion and improve expansion form by adding an initial angle and four bar linkage mechanism into the design to ensure the expansion function. In addition, the design can also be optimize by adding a function of rotating freely. By this function, the device can be inserted to the human body with a controlled angle instead of being limited by the shape of vertebral body. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/77825 |
DOI: | 10.6342/NTU201704191 |
全文授權: | 有償授權 |
顯示於系所單位: | 醫學工程學研究所 |
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