Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Canada; Biomedical Engineering Graduate Program, University of Calgary, Canada; McCaig Institute for Bone and Joint Health, University of Calgary, Canada.
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Canada; Biomedical Engineering Graduate Program, University of Calgary, Canada; McCaig Institute for Bone and Joint Health, University of Calgary, Canada.
J Biomech. 2021 May 7;120:110345. doi: 10.1016/j.jbiomech.2021.110345. Epub 2021 Mar 1.
Patellar tendinopathy is a common overuse injury in sports such as volleyball, basketball, and long-distance running. Microdamage accumulation, in response to repetitive loading of the tendon, plays an important role in the pathophysiology of patellar tendinopathy. This damage presents mechanically as a reduction in Young's modulus and an increase in residual strain. In this study, 19 human patellar tendon samples underwent cyclic testing in load control until failure, segmented by four ramped tests where digital image correlation (DIC) was used to assess anterior surface strain distributions. Ramped tests were performed prior to cyclic testing and at timepoints corresponding to 10%, 20%, and 30% of cyclic stiffness reduction. Young's modulus significantly decreased and cyclic energy dissipation significantly increased over the course of cyclic testing. The DIC analysis illustrated a heterogeneous strain distribution, with strain concentrations increasing in magnitude and size over the course of cyclic testing. Peak stress and initial peak strain magnitudes significantly correlated with the number of cycles to failure (r = 0.65 and r = 0.57, respectively, p < 0.001); however, the rates of peak cyclic strain and modulus loss displayed the highest correlations with the number of cycles to failure (r = 96% and r = 86%, respectively, p < 0.001). The high correlation between the rates of peak cyclic strain and modulus loss suggest that non-invasive methods to continuously monitor tendon strain may provide meaningful predictions of overuse injury in the patellar tendon.
髌腱病是排球、篮球和长跑等运动中常见的过度使用损伤。微损伤的积累，对肌腱的反复加载反应，在髌腱病的病理生理学中起着重要作用。这种损伤在力学上表现为杨氏模量的降低和残余应变的增加。在这项研究中，19 个人髌腱样本在负荷控制下进行循环测试，直到失效，通过四个斜坡测试分段，其中数字图像相关（DIC）用于评估前表面应变分布。斜坡测试在循环测试之前进行，并且在对应于循环刚度降低 10%、20%和 30%的时间点进行。杨氏模量在循环测试过程中显著降低，循环能耗显著增加。DIC 分析表明应变分布不均匀，随着循环测试的进行，应变集中的幅度和大小都在增加。峰值应力和初始峰值应变幅度与失效循环数显著相关（r = 0.65 和 r = 0.57，分别为 p < 0.001）；然而，峰值循环应变率和模量损失率与失效循环数的相关性最高（r = 96%和 r = 86%，分别为 p < 0.001）。峰值循环应变率和模量损失率之间的高度相关性表明，连续监测肌腱应变的非侵入性方法可能对髌腱过度使用损伤提供有意义的预测。
