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標題: | 低強度超音波刺激對肌腱機械性質之影響 Effect of Low Intensity Ultrasound Stimulation on Mechanical Properties of Tendon Fascicle |
作者: | Chun-Feng Lai 賴淳風 |
指導教授: | 王兆麟 |
關鍵字: | 大鼠尾巴肌腱,機械性質,低能量脈衝式超音波,超音波治療, Rat tail tendon,mechanical properties,low-intensity ultrasound,therapeutic ultrasound, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 目的:研究大鼠尾巴肌腱的機械性質與黏彈性,並探討大鼠尾巴肌腱在低強度超音波刺激下可能的改變。
背景簡介:肌腱的主要功能為連結與制動關節,連接在肌肉與骨骼之間。超音波對軟組織的熱效應已被廣泛應用於復健及治療之中,能夠舒緩疼痛並且提高關節自由度。但超音波如熱效應外,包括孔蝕(Cavitation)現象及表面振波等,都已被廣泛應用於工業界中,前者可以造成微結構的破壞,後者則在工業中應用於聲波潤滑。因此本研究希望能夠在降低超聲波熱能的影響下,對軟組織之機械性質與黏彈性做討論,希望能夠建立軟組織的微結構,包含膠原纖維之間的關聯等,在超音波照射下的所造成的改變。 材料與方法:(一)大鼠尾巴肌腱束抽取:大鼠在 12 周大時犧牲,本研究取得其尾巴作為實驗試樣。在小心地劃開大鼠尾巴皮膚及破壞椎體連接後,將肌腱束從大鼠尾巴遠端抽出。每條肌腱束被分為四段,一段長約 35 mm,每兩段被作為控制組與實驗組的成對試樣。每段皆透過光學顯微鏡照相,並量測截面積。實驗中另有三組鼠尾肌腱,透過藥物及酵素清洗取得純化的膠原纖維。(二)超音波系統設置:超音波系統由輸入端至輸出端,依序由波形產生器、RF 功率放大器、電功率計及其感測器、匹配電路到超音波探頭組成。超音波能量輸出透過聲功率計量測,在實驗環境中有 70 mW/cm2 的強度。(三)力學測試:力學測試以拉伸速率分為三組,依序分別為低應變速率組(0.01 mm/s)、中應變速率組(0.1 mm/s)及高應變速率組(0.8 mm/s)。在每一組不同的應變速率組中,又分別使用兩種不同的式樣,其中一種為鼠尾肌腱,另一組則為由鼠尾肌腱純化的膠原纖維。每組力學測試皆經過一固定 2%的應變大小,重複荷重測試五次,再執行拉斷測試。控制組與實驗組的不同,在於力學測試時超音波刺激的有無。 結果:(一)拉伸應變速率:控制組中,低應變速率的線性模數較其他兩組來得低,能量損失較其他兩組高,最大應力隨負荷所損失的比例,也是較其他兩組低。實驗組中有相同的趨勢,但不是每組皆有顯著差異。(二)面積影響:大鼠尾巴肌腱的隨面積增加而減少,從 200 MPa(面積大於 0.1 mm2),到 1200 MPa(面積小於 0.05 mm2)不等。藉由縮小截面積的範圍,各機械性質的標準差都可以被大幅降低(50%降至15%)。(三)超音波的影響:在所有的資料中,超音波刺激與控制組之間並沒有顯著差異,標準差過大。在縮小截面積所帶來的影響後,取截面積在 0.05 至 0.09 mm2之間(直徑為 300±25 um),會發現超音波在高應變速率組造成了顯著差異(p<0.05)。 (四)為節省實驗試樣,此研究中所使用的大鼠尾巴取自台大醫工所醫用陶瓷及複合材料實驗室,大鼠皆曾有過施打 OA 誘導高尿酸紀錄,然而在已知文獻回顧中,並不會影響肌腱力學性質。 結論:大鼠尾巴肌腱的力學性質,包括線性模數、最大應力以及能量損失等,對速率及面積的影響,已在本研究中完成。然而因為大鼠肌腱束的截面積變異,使模數與應力的標準差非常大。低能量超音波僅在高拉伸速率,也就是等同於生理負荷速度時,線性模數有顯著的降低。 Objective: To study the mechanical and viscoelastic properties of the tendon, and to investigate the differences in those properties under low intensity ultrasound stimulation. Summary of background data: The main function of the tendon is to connect and drive joints, and it lies between the muscle tissue and bone. Rat tail tendon grows parallel along with the tail, and are dispersed peripherally around vertebrate. Each tendon can be separated partly into 4 or 5 tendon fascicles. The effect of ultrasound, especially the thermal effect, has been well studied and widely used in therapeutics. Cavitation and surface acoustic waves have not been studied to the same extent as thermal effect despite their common appearance in industry. Cavitation can lead to micro structure damage and surface acoustic waves can reduce the friction force between two layers (acoustic lubricant) thus prompting this investigation. This study aims to investigate if the stimulation of low intensity ultrasound, which would not raise the temperature in tissue, would affect the mechanical and viscoelastic properties of tendon tissue. Methods: (1) Preparation of rat tail tendon: 12-week old rats were examined in this study. Rat tails were cut off from rats after they were sacrificed. After peeling off skin from tail, tendon fascicles were carefully pulled out from the distal end of the tail. Each tendon fascicle was equally divided into 4 parts. Two parts of the tendon fascicle were assigned to the intact group and the other 2 were assigned to experiment group. All of the tendon fascicles had pictures taken transversely in order to measuring their cross sectional area. Some of the rat tail tendons were immersed in enzymes to extract the pure extracellular matrix and collagen fibers from the tendon. (2) Setup of ultrasound system listed from the input to the output terminal: Ultrasound system was built with function generator, radio frequency amplifier, radio frequency power meter and its sensor, impedance matching circuit and ultrasound probe. The power of ultrasound was measured by the ultrasound acoustic meter, and then intensity was calculated after dividing power by the surface area of ultrasound probe. In this study, 70 mW/cm2 ultrasound intensity is delivered from the probe. (3) Mechanical testing protocol: There are three different groups depending on the cyclic loading rate, low strain rate (0.01 mm/s), middle strain rate (0.1 mm/s) and high strain rate (0.8 mm/s). In the high strain rate group, both rat tail tendon and purified collagen fibers bundles were examined. All the specimens underwent a 2% constant-strain cyclic load for 5 times. After cyclic loading, ramp to failure was conducted to determine the mechanical properties in linear region. The only difference between control group and experimental group is that there is an ultrasound stimulation during the loading. Result: (1) The average tangent modulus in the low strain rate group was higher than those in the mid strain rate group and the high strain rate group, but the average energy loss and max stress reduction rate is lower than those in mid strain rate group and high strain rate group. (2) The modulus of the rat tail tendon decreases while the cross section area increases. It ranges from 200 MPa (area greater than 0.1 mm2) to 1200 MPa (area less than 0.05 mm2). By grouping data points with smaller range of area, the relative standard deviation of modulus and max stress are reduced from 50% to 15%. (3) With all data points included, there is no significant difference between the intact group and experiment group. With the data points chosen with area in between 0.05 mm2 and 0.09 mm2, there is a significance in the high strain rate group between intact group and experiment group. Conclusion: The mechanical and viscoelastic properties of rat tail tendon were investigated. However, the variance of cross sectional area leads to a great standard deviation in modulus. Low intensity ultrasound only significantly reduces tangent modulus in high strain rate group when the variance of cross sectional area. Keywords: Rat tail tendon, mechanical properties, low-intensity ultrasound, therapeutic ultrasound |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/71951 |
DOI: | 10.6342/NTU201804094 |
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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