Micromechanical properties of articular cartilage resilience under different compression conditions

doi:10.3969/j.issn.2095-4344.2017.20.006

Abstract

Abstract:

BACKGROUND: It is of great significance to study the resilience of articular cartilage for human daily routine and their match quality.
OBJECTIVE: To analyze the micromechanical properties of articular cartilage resilience under different loads and at time points.
METHODS: The swine cartilage samples coated with tracers were compressed using the MTF-100 tensile machine, and the cartilage compression and resilience were recorded by CCD. Images were processed using digital image correlation technology.
RESULTS AND CONCLUSION: During resilience, the strain value on the superficial surface of the cartilage was decreased most, successively followed by the middle layer and the deep layer, while the time of a decrease from 20%, 10% and 6% to 3% was similar. The longer the resilience time was, the more slowly the strain changed in different layers of the cartilage, but the ultimate strain was less than 1%. On the same layer under different compressive stress, the larger load caused faster strain change firstly, and then the smaller load brought about faster strain change. The effect of different continuous compressive time on the same layer of cartilage was similar with the load. These results showed that 90% resilience of the articular cartilage occurred within the first 15 minutes. The mechanical resilience of different layers of the articular cartilage has a close relationship with the loading and the loading time, and both compressive time and loading do harm to the resilience of articular cartilage. Besides, the cartilage will rebound to the state before compression.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Cartilage, Articular, Biomechanics, Elasticity, Tissue Engineering

CLC Number:

R318

Xu Xi-fan, Gao Li-lan, Men Yu-tao, Dong Pei-bei, Zhang Chun-qiu. Micromechanical properties of articular cartilage resilience under different compression conditions[J]. Chinese Journal of Tissue Engineering Research, 2017, 21(20): 3147-3151.

Figures/Tables 2

2.1 关节软骨不同层区压缩回弹整体应变变化图5显示了载荷分别为0.5 MPa和1 MPa，持续压缩20 min时关节软骨不同层区回弹时应变随时间的变化，可以看出实验曲线的走势。在载荷作用下，回弹时软骨浅表层回弹的应变减少幅度最大，中间层在浅表层和深层之间, 深层应变减少幅度最小。随着回弹时间的增大，软骨不同层区的应变值均呈现逐渐减小的趋势，最终趋于软骨压缩前的状态。同时随着载荷的增大，回弹的时间越趋于集中，即回弹前期的幅度越大。从图中也可以看出浅表层对载荷的增加最为敏感，中间层次之，载荷对深层的影响最小。关节软骨变形量最大的部分主要是浅表层和中间层，深层区变形很小，也说明关节软骨在合理的压载变形后，经过一定时间基本能回弹到原来的状态。如果载荷过大或载荷持续时间过长软骨的恢复会受到影响，长此以往软骨就会受到损伤，说明科学的作息对减少人体关节软骨的损害是有很大帮助的[15-16]。 2.2 不同载荷下关节软骨不同层区回弹应变变化图6显示了压缩时间为20 min，载荷分别为0.5 MPa和1 MPa作用下关节软骨不同层区回弹应变随时间的变化曲线。不同载荷下，相同层区应变曲线不重合但走势是一致的。由图可以看出浅表层的回弹曲线最为圆滑，深层波动最大，且载荷的大小对浅表层的影响最大，对深层的影响最小，中间层介于两者之间。相同层区不同载荷作用下，在回弹开始时，压缩载荷越大，软骨回弹应变变化越快；在回弹后期，压缩载荷越小，软骨回弹应变变化越大。但随着时间的增长，软骨应变变化均趋于缓慢。从最终的回弹情况可以看出，压缩载荷小的回弹性能要好些。以上可以说明不同压缩载荷对关节软骨不同层区的回弹有一定的影响。 2.3 不同压缩时间下关节软骨不同层区回弹应变变化图7显示了载荷为1 MPa，压缩时间分别为20 min和60 min的作用下关节软骨不同层区回弹应变随时间的变化曲线。由图可以看出压缩时间长对浅表层的回弹影响较小，对深层区的影响最大，中间层在两者之间，说明负载时间长会优先破坏深层区的软骨结构。在不同压缩时间下，相同层区应变曲线不重合；相同层区不同压缩时间作用下，在回弹开始时，压缩时间越长，软骨回弹应变变化越快；在回弹后期，压缩时间越短，软骨回弹应变变化越快。但随着时间的增长，软骨应变变化趋于缓慢。从最终的回弹情况可以看出，压缩时间短的回弹性能要好些。以上可以说明不同压缩时间对关节软骨不同层区的回弹也有一定的影响。"

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