Calibration of the shear wave speed-stress relationship in ex vivo tendons
Calibration of the shear wave speed-stress relationship in ex vivo tendons
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DOI：
10.1016/j.jbiomech.2019.04.015
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发表时间：
2019-06-11
影响因子：
2.4
通讯作者：
Thelen, Darryl G.
中科院分区：
文献类型：
--
作者：
Martin, Jack A.;Schmitz, Dylan G.;Thelen, Darryl G.
最近有研究表明，肌腱的横波速度直接依赖于轴向应力。因此，波速可以用来推断肌腱载荷，前提是波速-应力关系可以校准，并且在各种载荷条件下保持稳健。本研究的目的是研究加载速率和流体浸泡对离体肌腱波速-应力关系的影响，并评估潜在的校准技术。测量了20根猪指屈肌腱在循环（0.5、1.0和2.0 Hz）或静态轴向载荷下的波速和轴向应力。方波速度与应力高度相关(r(avg)(2) = 0.98)，对加载速率不敏感（p = 0.57）。比例常数为有效密度，它反映了肌腱组织的密度和邻近流体增加的额外有效质量。在盐水浴中，肌腱振动的有效密度平均为1680 kg/m(3)，加上质量效应，盐水浴中的波速平均比空气中的低22%。当使用肌腱特异性校准参数时，预测应力与实测应力的均方根误差为0.67 MPa（最大应力的6.7%）。当基于10根肌腱的组编译数据进行校准时，这些误差增加到1.31 MPa（最大应力的13.1%）。这些结果支持了基于线性校准关系的波速平方计算肌腱绝对应力的可行性。(C) 2019 Elsevier Ltd.版权所有。
It has recently been shown that shear wave speed in tendons is directly dependent on axial stress. Hence, wave speed could be used to infer tendon load provided that the wave speed-stress relationship can be calibrated and remains robust across loading conditions. The purpose of this study was to investigate the effects of loading rate and fluid immersion on the wave speed-stress relationship in ex vivo tendons, and to assess potential calibration techniques. Tendon wave speed and axial stress were measured in 20 porcine digital flexor tendons during cyclic (0.5, 1.0 and 2.0 Hz) or static axial loading. Squared wave speed was highly correlated to stress (r(avg)(2) = 0.98) and was insensitive to loading rate (p = 0.57). The constant of proportionality is the effective density, which reflects the density of the tendon tissue and additional effective mass added by the adjacent fluid. Effective densities of tendons vibrating in a saline bath averaged 1680 kg/m(3) and added mass effects caused wave speeds to be 22% lower on average in a saline bath than in air. The root-mean-square error between predicted and measured stress was 0.67 MPa (6.7% of maximum stress) when using tendon-specific calibration parameters. These errors increased to 1.31 MPa (13.1% of maximum stress) when calibrating based on group-compiled data from ten tendons. These results support the feasibility of calculating absolute tendon stresses from wave speed squared based on linear calibration relationships. (C) 2019 Elsevier Ltd. All rights reserved.