In this work, we investigate differences in the mechanical and structural properties of tendon fascicle bundles dissected from different areas of bovine tendons. The properties of tendon fascicle bundles were investigated by means of uniaxial tests with relaxation periods and hysteresis, dynamic mechanical analysis (DMA), as well as magnetic resonance imaging (MRI). Uniaxial tests with relaxation periods revealed greater elastic modulus, hysteresis, as well as stress drop during the relaxation of samples dissected from the posterior side of the tendon. However, the normalized stress relaxation curves did not show a statistically significant difference in the stress drop between specimens cut from different zones or between different strain levels.

Using dynamic mechanical analysis, we found that fascicle bundles dissected from the anterior side of the tendon had lower storage and loss moduli, which could result from altered fluid flow within the interfascicular matrix (IFM). The lower water content, diffusivity, and higher fractional anisotropy of the posterior part of the tendon, as observed using MRI, indicates a different structure of the IFM, which controls the flow of fluids within the tendon.

Our results show that the viscoelastic response to dynamic loading is correlated with fluid flow within the IFM, which was confirmed during analysis of the MRI results. In contrast to this, the long-term relaxation of tendon fascicle bundles is controlled by viscoplasticity of the IFM and depends on the spatial distribution of the matrix within the tendon. Comparison of results from tensile tests, DMA, and MRI gives new insight into tendon mechanics and the role of the IFM. These findings may be useful in improving the diagnosis of tendon injury and effectiveness of medical treatments for tendinopathies.

在这项工作中，我们研究了从牛肌腱的不同区域解剖的肌腱束的机械和结构特性的差异。肌腱束的特性通过具有松弛期和滞后的单轴测试、动态力学分析 (DMA) 以及磁共振成像 (MRI) 进行了研究。具有松弛期的单轴测试显示更大的弹性模量、滞后以及在从肌腱后侧解剖的样品松弛期间的应力下降。然而，归一化应力松弛曲线在从不同区域切割的试样之间或不同应变水平之间的应力降没有显示出统计学上的显着差异。

使用动态力学分析，我们发现从肌腱前侧解剖的束束具有较低的储存和损失模量，这可能是由于束间基质 (IFM) 内流体流动的改变造成的。使用 MRI 观察到的肌腱后部的较低的含水量、扩散率和较高的各向异性分数表明 IFM 的不同结构，它控制着肌腱内的流体流动。

我们的结果表明，对动态载荷的粘弹性响应与 IFM 内的流体流动相关，这在 MRI 结果分析期间得到证实。与此相反，肌腱束的长期松弛受 IFM 的粘塑性控制，并取决于肌腱内基质的空间分布。拉伸试验、DMA 和 MRI 的结果比较为肌腱力学和 IFM 的作用提供了新的见解。这些发现可能有助于改善肌腱损伤的诊断和肌腱病药物治疗的有效性。