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標題: | 遠端橈骨骨折骨外固定器生物力學分析及幾丁聚醣在大範圍骨組織缺損之研究 Mechanical Analysis of Wrist External Skeletal Fixator and The Application of Chitosan in Large Bony Defect |
作者: | Chih-Hao Chang 張志豪 |
指導教授: | 王兆麟 |
關鍵字: | 遠端橈骨骨折,骨外固定器,機械分析,骨缺損,幾丁聚醣,骨形成因子,化學鍵結,指引性組織再生, distal radius fracture,external skeletal fixator,mechanical analysis,bone,chitosan,chitosan membrane,guided tissue regeneration (GTR),rhBMP-2,surface modification, |
出版年 : | 2010 |
學位: | 博士 |
摘要: | 第一部分
遠端橈骨骨折是最常見的骨折,約佔所有骨折的10%。而手腕部骨外固定器常被用來治療遠端橈骨骨折。骨外固定器雖然已有許多相關研究,但大多是以下肢的骨外固定器為研究材料,卻不常見手腕骨外固定器的研究。由於手腕部骨外固定器所負擔的生理受力與臨床要求皆不同於下肢的骨外固定器,且大部分的手腕部骨外固定器產生的併發症均與其中的鋼釘有關,故對於手腕部骨外固定器中的鋼釘進行機械分析實有更進一層研究的必要。 在本研究中,我們設計了三個不同的模型來做實驗測試:機械模型、cadaver模型及人體活體模型。我們量測在不同的受力情形下,手腕部骨外固定器中各個鋼釘的形變量,用以代表其受力。我們發現,在手腕部的骨外固定器中,主要受力的鋼釘為最遠端第2掌骨頭的鋼釘及最靠近骨折處的橈骨鋼釘。而位於第2掌骨基座的鋼釘最易鬆脫,而最近端的橈骨鋼釘負擔多變代償性受力的功能。 根據本研究的結果,我們提出了改善手腕部骨外固定器鋼釘的設計與位置的新想法與觀念,希望藉此能避免有關手腕部骨外固定器鋼釘併發症的產生,造福病患。 第二部分 大範圍骨缺損對骨科或牙科而言,一直是一個令人非常頭痛的問題。骨腫瘤、骨髓炎、嚴重骨質疏鬆症,嚴重牙周病引起齒槽骨流失等疾病,都會有此問題,而許多方法被用來處理此一情形。自體骨移植為最常見,也最有效的方法,但它有來源不足,數量有限及多一道傷口的困擾;異體骨移植,來自其它人類捐贈的骨頭,可達到填充骨缺損的目的,但它有來源不足、數量有限及潛在性傳染疾病的困擾。於是近年來,隨著組織工程科學的發展,及生醫材料的進步,許多的生物材料備發展出來,用以解決此一骨缺損的問題,這是近年來最有發展的科學領域之一。 本研究的主要目的是利用幾丁聚醣的生物可吸收性及無毒性的特殊性質,嘗試結合骨形成生長因子,來做為骨填充物的生醫材料。藉由對幾丁聚醣的高度操作技術處理,我們成功的發展出新的生醫技術,可以把骨形成生長因子(BMP-2)成功與幾丁聚醣做一共價鍵的結合。這個突破以往生長因子只能以物理吸附性質存在於高分子材料中。於是我們可以製造出穩定、緩慢釋出作用,且效果長久的生長因子攜帶支架,並且將之做成薄膜形式,達到所謂指引性組織再生(guided tissue regeneration)的目的。 part 1 Wrist external fixator is widely used in unstable type of distal radius fracture. Although there are many studies about the mechanical analysis of external fixators, there are few papers talking about the mechanical analysis of wrist external fixators. Wrist external fixators are quite different from the external fixators used in the lower extremity. They do not need to bear the body weight. They cross the wrist joint composed of complex carpal bones and ligaments. Usually, wrist external fixators are more slender and less bulky than the ones used in the lower extremity. In most studies for external fixators, they used the mechanical model and finite element model to analyze. The data of true human specimen is deficiency. In our study, we analyzed the loading force to the pins of wrist external fixator in situation of mechanical model, cadaver model, and in vivo human model. The strains of the pins were recorded and analyzed. In the mechanical model, the strains of all pins are proportional to the loading force. The most distal 2 pins afforded compression force and the most proximal 2 pins afforded tension force. In the cadaver model and in human model, the strain of the pin located at the 2nd metacarpal base was near zero. It means this pin afforded minimal force. Loosening of this pin happened frequently. Soft tissues of the wrist joint absorbed partial force and they resulted in the reduction of the strain of all pins. The pins inserted at the radius bone are equally important. When they are assembled together within one clamp, the force will concentrate on one pin. The other pin will afford minimal strain. The mechanical model is an ideal model for analysis of external fixators either upper extremity or lower extremity. But there are some differences when external fixator applied to the real human. Soft tissues and anatomical characteristics of human specimen are the major factors. The most distal pin is very important in WEF because the second pin always loosened. The proximal two pins are the same important. Because they are assembled in one clamp, one pin afforded most force usually and the other pin is mild when the force applied. The force distribution is asymmetry. Usually, the pin near the wrist joint will afford most force. Our study helps to understand true loading condition to the pin of wrist external fixator and the fact that there are differences between 3 models. part 2 Large bony defect is a difficult condition in orthopedics and dental field. There are many situations resulting in this condition. Large bone tumors, osteomyelitis, severe osteoporosis, and severe periodontitis are met frequently. Usually, the doctors will transplant the autogenous bone from the patient himself or take the allogenic bone from the donors to fill this defect. But there are many potential problems for these two choices. Transmitted disease and limited sources are the most problems we will meet. Recently, artificial biomaterial science developed and got a great progression and improvement for bony substitutes. Many biomaterials were mentioned, studied, and used. This is a rather new field and has a large potential development. This project is majorly concerned with the invention of the new biomaterials based on chitosan nature polymer in combination with biomolecules for various biomedical applications. The novel technique of combining chitosan with biomolecules such as growth factors used in this project consists in chemical immobilization rather than physical method. The growth factors or other biomolecules immobilized on chitosan are expected to carry the long–term release effect rather than short-term one in the physically adsorption system. The product concept of this research is to immobilize the growth factor to the chitosan scaffold to achieve the osteo-inductive and osteo-conductive effects. In this study, we applied the chitosan scaffold with immobilized growth factors to bone regeneration and found the positive results. The potential of surface covalently-bonded rhBMP-2 biodegradable chitosan membrane was examined for guided tissue regeneration (GTR) applications. The chitosan surface-bonded rhBMP-2 membrane has the potential as a bioactive material for GTR. |
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