An evaluation of the quasi-linear viscoelastic properties of the healing medial collateral ligament in a goat model
An evaluation of the quasi-linear viscoelastic properties of the healing medial collateral ligament in a goat model
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DOI：
10.1023/b:abme.0000017539.85245.6a
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发表时间：
2004-03-01
影响因子：
3.8
通讯作者：
Debski, RE
中科院分区：
文献类型：
--
作者：
Abramowitch, SD;Woo, SLY;Debski, RE
在山羊模型中研究了孤立性损伤后12周愈合的内侧副韧带（MCL）的粘弹性特性。采用股骨-MCL-胫骨复合体实验测定了在5%应变下愈合的MCL的应力-应变关系、静态和循环应力-松弛行为。这些实验数据与Fung（1972）的准线性粘弹性（QLV）理论结合使用，以表征该组织的简化松弛函数G(t)(由常数C， tau（1)和tau(2)描述）和弹性响应sigma(e)(epsilon)（由常数A和B描述）。结果发现，愈合后mcl的应激松弛率明显高于假手术对照组（49.0 +/- 12.1% vs. 26.5 +/- 8.1%, p < 0.05）。与假手术对照组相比，愈合mcl的常数A x B的乘积，即应力-应变曲线的初始斜率，显著低于假手术对照组（32.9 +/- 15.8 MPa vs. 118.8 +/- 48.3 MPa; p < 0.05）。无量纲常数C，即粘性响应的大小，在愈合的mcl中几乎是三倍，而常数tau(1)在两组之间相似（分别为0.80 +/- 0.43 s和0.89 +/- 0.52 s）。愈合MCL的恒定tau(2)显著低于对照组（1269 +/- 38 s vs. 1845 +/- 431 s; p < 0.05），表明应力松弛较早达到平台期。这些用于描述愈合MCL的QLV理论常数通过预测循环应力松弛实验中的峰值应力，验证了本实验中使用的应变水平（一致性为4.5%）。理论确定的值与实验测量的值非常吻合。因此，本研究表明，QLV理论可以成功地用于描述愈合早期MCL的粘弹性行为。
The viscoelastic properties of the healing medial collateral ligament (MCL) at 12 weeks after isolated injury were investigated in a goat model. The stress-strain relationships, static and cyclic stress-relaxation behaviors of the healing MCL up to 5% strain were determined experimentally using a femur-MCL-tibia complex. These experimental data were used in combination with the quasi-linear viscoelastic (QLV) theory of Fung (1972) to characterize the reduced relaxation function, G(t) (described by constants C, tau(1), and tau(2)) and the elastic response, sigma(e)(epsilon) (described by constants A and B) of this tissue. It was found that the percentage of stress relaxation for the healing MCLs was significantly greater than those for sham-operated controls (49.0 +/- 12.1% vs. 26.5 +/- 8.1%, respectively; p < 0.05). The product of constants A x B, i.e. the initial slope of the stress-strain curves, was found to be significantly lower for healing MCLs compared to those for sham-operated controls (32.9 +/- 15.8 MPa vs. 118.8 +/- 48.3 MPa; p < 0.05). The dimensionless constant C, i.e. the magnitude of the viscous response, was nearly three times greater for healing MCLs, while constant tau(1) was found to be similar between the two groups (0.80 +/- 0.43 s vs. 0.89 +/- 0.52 s, respectively). Constant tau(2) for the healing MCL was significantly less than the controls (1269 +/- 38 s vs. 1845 +/- 431 s; p < 0.05) indicating that the stress relaxation reached a plateau earlier. These constants of the QLV theory used to describe the healing MCL were validated for the strain level utilized in this experiment ( congruent to 4.5%) by predicting the peak stresses during a cyclic stress-relaxation experiment. The theoretically determined values closely matched the experimentally measured values. Thus, this study demonstrates that the QLV theory could be successfully used to describe the viscoelastic behavior of the MCL during the early phases of healing.