Shear load transfer in high and low stress tendons.
Shear load transfer in high and low stress tendons.
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DOI：
10.1016/j.jmbbm.2015.01.021
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发表时间：
2015-05
影响因子：
3.9
通讯作者：
Vanderby R Jr
中科院分区：
文献类型：
--
作者：
Kondratko-Mittnacht J;Duenwald-Kuehl S;Lakes R;Vanderby R Jr
肌腱是关节运动和稳定性的组成部分，因为它的功能是将负荷从肌肉传递到骨骼。它具有各向异性的纤维分层结构，通常在其纤维/纤维束的方向上加载。当关节运动旋转插入部位或局部损伤破坏纤维/束时，内部载荷分布发生改变，可能导致纤维间（或束间）剪切。具有不同微观结构（螺旋与线性）的肌腱可能会以不同的方式重新分配载荷。本研究探讨了剪切力如何通过在肌腱的相对侧上产生撕裂伤（范围为肌腱宽度的约20-60%）来重新分配大鼠尾肌腱（具有线性微结构的低应力肌腱）和猪屈肌腱（具有螺旋微结构的高应力肌腱）中的轴向载荷，以产生各种大小的剪切力。使用偏振光显微镜对束状取向的差异进行定量。出乎意料的是，这两种肌腱类型保持约20%的撕裂前应力值后，重叠削减60%的肌腱宽度（没有完整的纤维端到端），这表明剪切应力转移可以贡献更多的整体肌腱强度和刚度比以前报道的。两种肌腱类型的所有结构参数随撕裂深度的增加而线性下降。尾部肌腱有一个更快的下降后撕裂的弹性应力和模量参数，以及一个更线性和不太紧密包装的束状结构，这表明位置肌腱可能不太适合通过剪切机制重新分配负载。
Tendon is an integral part of joint movement and stability, as it functions to transmit load from muscle to bone. It has an anisotropic, fibrous hierarchical structure that is generally loaded in the direction of its fibers/fascicles. Internal load distributions are altered when joint motion rotates an insertion site or when local damage disrupts fibers/fascicles, potentially causing inter-fiber (or inter-fascicular) shear. Tendons with different microstructure (helical versus linear) may redistribute loads differently. This study explored how shear redistributes axial loads in rat tail tendon (low stress tendons with linear microstructure) and porcine flexor tendon (high stress with helical microstructure) by creating lacerations on opposite sides of the tendon, ranging from about 20-60% of the tendon width, to create various magnitudes of shear. Differences in fascicular orientation were quantified using polarized light microscopy. Unexpectedly, both tendon types maintained about 20% of pre-laceration stress values after overlapping cuts of 60% of tendon width (no intact fibers end to end) suggesting that shear stress transfer can contribute more to overall tendon strength and stiffness than previously reported. All structural parameters for both tendon types decreased linearly with increasing laceration depth. The tail tendon had a more rapid decline in post-laceration elastic stress and modulus parameters as well as a more linear and less tightly packed fascicular structure, suggesting that positional tendons may be less well suited to redistribute loads via a shear mechanism.