Lee Andrea H, Szczesny Spencer E, Santare Michael H, Elliott Dawn M
Department of Biomedical Engineering, University of Delaware, United States.
Department of Orthopaedic Surgery, University of Pennsylvania, United States.
Acta Biomater. 2017 Jul 15;57:363-372. doi: 10.1016/j.actbio.2017.04.011. Epub 2017 Apr 21.
Tendon pathology is associated with damage. While tendon damage is likely initiated by mechanical loading, little is known about the specific etiology. Damage is defined as an irreversible change in the microstructure that alters the macroscopic mechanical parameters. In tendon, the link between mechanical loading and microstructural damage, resulting in macroscopic changes, is not fully elucidated. In addition, tendon damage at the macroscale has been proposed to initiate when tendon is loaded beyond a strain threshold, yet the metrics to define the damage threshold are not determined. We conducted multi-scale mechanical testing to investigate the mechanism of tendon damage by simultaneously quantifying macroscale mechanical and microstructural changes. At the microscale, we observe full recovery of the fibril strain and only partial recovery of the interfibrillar sliding, indicating that the damage initiates at the interfibrillar structures. We show that non-recoverable sliding is a mechanism for tendon damage and is responsible for the macroscale decreased linear modulus and elongated toe-region observed at the fascicle-level, and these macroscale properties are appropriate metrics that reflect tendon damage. We concluded that the inflection point of the stress-strain curve represents the damage threshold and, therefore, may be a useful parameter for future studies. Establishing the mechanism of damage at multiple length scales can improve prevention and rehabilitation strategies for tendon pathology.
Tendon pathology is associated with mechanically induced damage. Damage, as defined in engineering, is an irreversible change in microstructure that alters the macroscopic mechanical properties. Although microstructural damage and changes to macroscale mechanics are likely, this link to microstructural change was not yet established. We conducted multiscale mechanical testing to investigate the mechanism of tendon damage by simultaneously quantifying macroscale mechanical and microstructural changes. We showed that non-recoverable sliding between collagen fibrils is a mechanism for tendon damage. Establishing the mechanism of damage at multiple length scales can improve prevention and rehabilitation strategies for tendon pathology.
肌腱病理学与损伤相关。虽然肌腱损伤可能由机械负荷引发，但对其具体病因知之甚少。损伤被定义为微观结构的不可逆变化，这种变化会改变宏观力学参数。在肌腱中，机械负荷与微观结构损伤之间导致宏观变化的联系尚未完全阐明。此外，有人提出当肌腱负荷超过应变阈值时会引发宏观层面的肌腱损伤，但尚未确定定义损伤阈值的指标。我们进行了多尺度力学测试，通过同时量化宏观力学和微观结构变化来研究肌腱损伤的机制。在微观层面，我们观察到原纤维应变完全恢复，而原纤维间滑动仅部分恢复，这表明损伤始于原纤维间结构。我们表明，不可恢复的滑动是肌腱损伤的一种机制，并且是束状层面观察到的宏观线性模量降低和趾区延长的原因，而这些宏观特性是反映肌腱损伤的合适指标。我们得出结论，应力 - 应变曲线的拐点代表损伤阈值，因此可能是未来研究的一个有用参数。确定多长度尺度下的损伤机制可以改善肌腱病理学的预防和康复策略。
肌腱病理学与机械诱导的损伤相关。如工程学中所定义，损伤是微观结构的不可逆变化，会改变宏观力学性能。尽管微观结构损伤和宏观力学变化很可能存在，但这种与微观结构变化的联系尚未建立。我们进行了多尺度力学测试，通过同时量化宏观力学和微观结构变化来研究肌腱损伤的机制。我们表明，胶原原纤维之间不可恢复的滑动是肌腱损伤的一种机制。确定多长度尺度下的损伤机制可以改善肌腱病理学的预防和康复策略。
