Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Department of Mechanical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, 55455, USA.
Biomech Model Mechanobiol. 2018 Feb;17(1):133-145. doi: 10.1007/s10237-017-0949-8. Epub 2017 Aug 18.
The facet capsular ligaments encapsulate the bilateral spinal facet joints and are common sources of painful injury due to afferent innervation. These ligaments exhibit architectural complexity, which is suspected to contribute to the experimentally observed lack of co-localization between macroscopic strain and microstructural tissue damage. The heterogeneous and multiscale nature of this ligament, combined with challenges in experimentally measuring its microscale mechanics, hinders the ability to understand sensory mechanisms under normal or injurious loading. Therefore, image-based, subject-specific, multiscale finite-element models were constructed to predict the mechanical responses of the human cervical facet capsular ligament under uniaxial tensile stretch. The models precisely simulated the force-displacement responses for all samples ([Formula: see text]) and showed promise in predicting the magnitude and location of peak regional strains at two different displacements. Yet, there was a loss of agreement between the model and experiment in terms of fiber organization at large tissue stretch, possibly due to a lack of accounting for tissue failure. The mean fiber stretch ratio predicted by the models was found to be significantly higher in regions that exhibited anomalous fiber realignment experimentally than in regions with normal realignment ([Formula: see text]). The development of microstructural abnormalities was associated with the predicted fiber-level stretch ([Formula: see text]), but not with the elemental maximum principal stress or maximum principal strain by logistic regression. The multiscale models elucidate a potential mechanical basis for predicting injury-prone tissue domains and for defining the relationships between macroscopic ligament stretch and microscale pathophysiology in the subfailure regime.
关节囊侧韧带包裹着双侧脊柱小关节，由于有传入神经支配，它们是疼痛损伤的常见来源。这些韧带具有复杂的结构，这被怀疑是导致宏观应变与微观组织损伤之间缺乏共定位的实验观察结果的原因。该韧带具有异质和多尺度的性质，再加上在实验中测量其微观力学的挑战，阻碍了对正常或损伤负荷下感觉机制的理解能力。因此，构建了基于图像的、个体特异性的、多尺度有限元模型，以预测人颈椎关节囊侧韧带在单轴拉伸下的力学响应。这些模型精确地模拟了所有样本的力-位移响应([Formula: see text])，并在预测两个不同位移处的峰值区域应变的幅度和位置方面表现出了良好的前景。然而，在大组织拉伸时，模型与实验之间在纤维组织方面的一致性丧失，这可能是由于缺乏对组织失效的考虑。模型预测的纤维拉伸比在实验中显示异常纤维重新排列的区域显著高于正常重新排列的区域([Formula: see text])。微观结构异常的发展与预测的纤维级拉伸有关([Formula: see text])，但与元素最大主应力或最大主应变无关，这是通过逻辑回归得出的。多尺度模型阐明了在亚失效状态下预测易受伤组织域以及定义宏观韧带拉伸与微观病理生理学之间关系的潜在力学基础。
