Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, United States.
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
J Mech Behav Biomed Mater. 2021 Jun;118:104339. doi: 10.1016/j.jmbbm.2021.104339. Epub 2021 Mar 12.
Knee ligament injury diagnosis is achieved by a comparison between the laxity levels sensed by a clinician in the injured and healthy limb. This is a difficult-to-learn task that requires hands-on practice to achieve proficiency. The inclusion of a physical knee simulator with biomechanically realistic passive components such as knee ligaments could provide consistent training for medical students and lead to improved care for knee injury patients. In this study, we developed a material construct that is both adaptable to a physical knee model and capable of replicating the non-linear mechanical behavior of knee ligaments with the use of helically arranged acrylic yarn. The microstructure of four different types of acrylic yarn were measured and then tested under uniaxial tension. While the fiber twist angle was similar amongst the four yarn types (range = 17.9-18.8°), one yarn was distinct with a low ply twist angle (15.2 ± 1.6°) and high packing fraction (Φ=0.32±0.08). These microstructural differences yielded a lower toe length and higher stiffness and best corresponded to ligament mechanical behavior. We then made looped-yarn constructs to modulate the sample's toe length and stiffness. We found that the load-displacement curve of the construct can be tuned by changing the loop length and loop number of the looped-yarn constructs, matching the load-displacement curve of specific knee ligaments. This study shows how spun yarn can be used to replicate the mechanical behavior of knee ligaments, creating synthetic ligament constructs that could enable the construction of biomechanically realistic joints.
膝关节韧带损伤的诊断是通过比较临床医生在受伤和健康肢体上感觉到的松弛度来实现的。这是一项难以掌握的任务，需要实践操作才能熟练掌握。在物理膝关节模拟器中加入具有生物力学逼真的被动部件（如膝关节韧带）可以为医学生提供一致的培训，并改善膝关节损伤患者的护理。在这项研究中，我们开发了一种材料结构，它既适应物理膝关节模型，又能利用螺旋排列的丙烯酸纱线复制膝关节韧带的非线性机械行为。测量了四种不同类型的丙烯酸纱的微观结构，然后在单轴拉伸下进行了测试。虽然四种纱线类型的纤维扭角相似（范围为 17.9-18.8°），但有一种纱线的特点是低股扭角（15.2±1.6°）和高堆积率（Φ=0.32±0.08）。这些微观结构差异导致趾长较短、刚度较高，最符合韧带的机械行为。然后，我们制作了环形纱线结构来调节样品的趾长和刚度。我们发现，通过改变环形纱线结构的环长和环数，可以调整结构的载荷-位移曲线，使其与特定膝关节韧带的载荷-位移曲线相匹配。这项研究表明，如何利用纺制纱线来复制膝关节韧带的机械行为，从而制造出能够构建具有生物力学逼真性的关节的合成韧带结构。
