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標題: | 疲勞負載與休息對椎間盤流變性質的影響 Effect of Fatigue and Rest on the Rheological Properties of Intact Intervertebral Disc |
作者: | Tzu-Cheng Lin 林子誠 |
指導教授: | 王兆麟 |
關鍵字: | 椎間盤,疲勞負載,潛變測試,滲透性,聚合模數, disc,fatigue,creep test,permeability,aggregate modulus, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 目的:探討疲勞負載次數與休息對椎間盤流變性質的影響。
背景:疲勞負載是引發下背痛的主要因子之一,並且影響椎間盤水分的含量及黏彈性行為的表現。文獻上指出,長期的疲勞負載會造成椎間盤力學性質改變,推測是椎間盤微結構破壞而改變椎間盤水分進出情形。然而,實際機制仍有待詳盡地探討,因此探討疲勞負載與休息對椎間盤流變性質的影響,有助於了解因疲勞負載所引起的脊椎病變機制。 材料與方法:使用六個月大的豬隻腰椎運動單元作為試樣(L1-L2,L3-L4,共十副),每副試樣在疲勞負載前先經過一次潛變測試,於食鹽水中休息24小時後,依序進行「疲勞負載-休息-潛變測試-休息」的實驗流程,五次循環後即完成一組實驗。潛變測試時間為1小時,負載力量為420N;疲勞負載的大小為190至590N (平均為420N),頻率為5Hz。五次疲勞負載時間依序為0.5、1、2、3、4小時(次數:9,000、18,000、36,000、54,000、72,000次);休息時,將試樣浸泡於生理食鹽水溶液中24小時。以線性位移計量測計錄試樣於潛變測試中的高度改變,擷取頻率為2Hz,並使用雙相(固液相)線性模型對椎間盤於潛變期間的高度變化量進行聚合模數(HA,類似材料之楊氏係數)、滲透性(k)的擬合。實驗結束後,將椎間盤沿著中央冠狀面及矢狀面切半觀察內部結構改變。 結果:椎間盤高度在承受0.5小時(9000次)的疲勞負載後所下降的高度並無法藉由浸泡24小時食鹽水溶液完全回復,且隨著疲勞負載時間的增加,無法回復的高度量愈多。椎間盤在承受10.5小時的疲勞負載後,聚合模數並無顯著性的改變,滲透性則會隨著疲勞負載時間增加而明顯地下降,直到疲勞負載時間達到3小時以上才不再降低。實驗後從椎間盤的橫剖面可發現靠近椎間核內側的椎間環有明顯的扭曲變形現象,有些甚致產生斷裂。 結論:椎間盤因為疲勞負載所流失的水分無法藉由浸泡生理24小時食鹽水的過程中完全回復。隨著疲勞負載時間的增加,椎間盤的滲透性會明顯地下降,聚合模數則無顯著性改變。椎間盤受到10.5小時的疲勞負載後,內側椎間環產生扭曲或斷裂,但外側椎間環並沒有出現肉眼可觀察到的損傷。 Objective: To evaluate the effect of the duration of fatigue loading and the rest on the rheological properties of healthy porcine intervertebral disc. Summary of Background Data: Fatigue loading can induce the low back pain by altering the water content and viscoelastic behaviors of the intervertebral disc. Long term fatigue loading was suspected to result in changes of material properties due to the irreversible failure. However, the mechanical properties of disc fluid flow (i.e., the rheology) within the disc have not been fully discussed yet. The understanding of effect of fatigue loading and rest on the disc rheological properties can be beneficial to delineate the mechanism of fatigue loading induced spinal disorders. Methods: Ten porcine lumbar motion segments (L1-L2,L3-L4) without posterior elements were applied with fatigue loading (190~590N) at 5 Hz for 0.5, 1, 2, 3, and 4 hours (9,000, 18,000, 36,000, 54,000, 72,000 cycles), respectively. A creep test using 420 N was applied after a 24 hours saline immersion post fatigue loading. The axial deformation during creep phase was curve-fitted with linear biphasic model to obtain the aggregate modulus (HA) and permeability coefficient (k). After the fatigue loading, the disc was sectioned along sagittal and coronal plane to find the structure changes of anulus fibrosus and nucleus pulposus. The paired-t test was performed to evaluate the change of disc height, HA, and k after a series of fatigue loading and 24 hours rest. Results: The height of intervertebral disc was not recovered by a 24 hours rest after fatigue loading. The permeability decreased significantly with the duration of fatigue loading, while the aggregate modulus remained the same. The ruptured inner fibrosus were found after fatigue loading. Conclusion: A 24 hours rest is not able to fully restore the fluid loss during fatigue loading. The increase of duration of the fatigue loading reduces the disc permeability and damages the structure of inner anular fibrosus. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/9636 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 醫學工程學研究所 |
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