Viscoelastic properties of the human medial collateral ligament under longitudinal, transverse and shear loading
Viscoelastic properties of the human medial collateral ligament under longitudinal, transverse and shear loading
复制标题
DOI：
10.1016/j.orthres.2004.06.002
复制
发表时间：
2005-01-01
影响因子：
2.8
通讯作者：
Weiss, JA
中科院分区：
文献类型：
--
作者：
Bonifasi-Lista, C;Lake, SP;Weiss, JA
韧带粘弹性控制能量的粘性耗散，从而控制损伤或灾难性失效的可能性。不同载荷条件下的粘弹性可能与组织的组织和各向异性有关。本研究的目的是量化的应变和频率依赖的粘弹性行为的人内侧副韧带（MCL）在拉伸沿着其纵向和横向方向，并在剪切沿着纤维方向。总体假设是，人类MCL将表现出方向依赖性粘弹性行为，反映了组织的复合结构组织。进行增量应力松弛测试，然后在三个不同的平衡应变水平下施加小正弦应变振荡。纵向的峰值和平衡应力-应变曲线。横向和剪切试验表明，组织的瞬时和长时间应力-应变响应在沿纤维拉伸、横向纤维拉伸和沿纤维剪切的加载条件之间显著不同。减少松弛曲线证明至少两个松弛时间的所有三个测试模式。1000 s后，松弛导致的应力为初始应力的60-80%。对于所有三种测试配置，在最低应变水平下，增量应力松弛进行得更快。动态刚度随试验模式和平衡应变水平变化很大，纵向和剪切试验中，随施加应变振荡频率的增加，动态刚度表现出适度但显著的增加。相位角不受应变水平（除了最低应变水平的纵向样品），但随着应变振荡频率的增加显着增加。测试类型对相位角没有影响。相位的增加以及因此在较高频率下的能量耗散可以保护组织在更快的加载速率下免受损伤。结果表明，韧带的长时松弛行为和短时动态能量耗散可能受不同的粘弹性机制控制，但这些机制在不同的载荷配置下对组织粘弹性的影响是相似的。(C)2004骨科研究学会。由爱思唯尔有限公司出版。保留所有权利。
Ligament viscoelasticity controls viscous dissipation of energy and thus the potential for injury or catastrophic failure. Viscoelasticity under different loading conditions is likely related to the organization and anisotropy of the tissue. The objective of this study was to quantify the strain- and frequency-dependent viscoelastic behavior of the human medial collateral ligament (MCL) in tension along its longitudinal and transverse directions, and under shear along the fiber direction. The overall hypothesis was that human MCL would exhibit direction-dependent viscoelastic behavior, reflecting the composite structural organization of the tissue. Incremental stress relaxation testing was performed, followed by the application of small sinusoidal strain oscillations at three different equilibrium strain levels. The peak and equilibrium stress-strain curves for the longitudinal. transverse and shear tests demonstrate that the instantaneous and long-time stress-strain response of the tissue differs significantly between loading conditions of along-fiber stretch, cross-fiber stretch and along-fiber shear. The reduced relaxation curves demonstrated at least two relaxation times for all three test modes. Relaxation resulted in stresses that were 60-80% of the initial stress after 1000 s. Incremental stress relaxation proceeded faster at the lowest strain level for all three test configurations. Dynamic stiffness varied greatly with test mode and equilibrium strain level, and showed a modest but significant increase with frequency of applied strain oscillations for longitudinal and shear tests. Phase angle was unaffected by strain level (with exception of lowest strain level for longitudinal samples) but showed a significant increase with increasing strain oscillation frequency. There was no effect of test type on the phase angle. The increase in phase and thus energy dissipation at higher frequencies may protect the tissue from injury at faster loading rates. Results suggest that the long-time relaxation behavior and the short-time dynamic energy dissipation of ligament may be governed by different viscoelastic mechanisms, yet these mechanisms may affect tissue viscoelasticity similarly under different loading configurations. (C) 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.