Ristaniemi A, Torniainen J, Stenroth L, Finnilä M A J, Paakkonen T, Töyräs J, Korhonen R K
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
J Mech Behav Biomed Mater. 2020 Apr;104:103639. doi: 10.1016/j.jmbbm.2020.103639. Epub 2020 Jan 17.
Mechanical material properties of ligaments originate from their biochemical composition and structural organization. However, it is not yet fully elucidated how biochemical contents vary between knee ligaments and patellar tendon (PT) and how they relate with mechanical properties. The purpose of this study was to compare water, collagen, proteoglycan and elastin contents between bovine knee ligaments and PT and correlate them with tensile material properties. Hydroxyproline (collagen), uronic acid (proteoglycan) and elastin contents per wet and dry weights were measured using colorimetric biochemical methods for bovine knee ligament and PT samples (n = 10 knees). Direct comparison and correlation with multiple linear regression were performed against biomechanical properties measured in our earlier study. Anterior cruciate ligament (ACL) and PT exhibited lower hydroxyproline content per wet weight compared with other ligaments (p < 0.05). Cruciate ligaments had higher uronic acid content per dry weight compared with collateral ligaments (p < 0.05). Posterior cruciate ligament had higher elastin content than ACL (p < 0.05). Higher hydroxyproline content per wet weight implied higher Young's modulus, strength and toughness. Quantitatively, higher elastin content per wet weight predicted higher toe region nonlinearity and Young's modulus whereas higher uronic acid content per dry weight predicted lower Young's modulus, yield stress and toughness. Differences between ligaments in biochemical composition highlight differences in their physiological function and loading regimes. As expected, collagen content showed similar trend with stiffness and strength. The predictive role of proteoglycan and elastin contents on the mechanical properties might indicate their important functional role in ligaments.
韧带的力学材料特性源于其生化组成和结构组织。然而，膝关节韧带和髌腱（PT）之间的生化成分如何变化以及它们与力学特性有何关系，目前尚未完全阐明。本研究的目的是比较牛膝关节韧带和PT之间的水、胶原蛋白、蛋白聚糖和弹性蛋白含量，并将它们与拉伸材料特性相关联。使用比色生化方法测量牛膝关节韧带和PT样本（n = 10个膝关节）的湿重和干重中的羟脯氨酸（胶原蛋白）、糖醛酸（蛋白聚糖）和弹性蛋白含量。与我们早期研究中测量的生物力学特性进行直接比较，并通过多元线性回归进行相关性分析。前交叉韧带（ACL）和PT的湿重羟脯氨酸含量低于其他韧带（p < 0.05）。十字韧带的干重糖醛酸含量高于侧副韧带（p < 0.05）。后交叉韧带的弹性蛋白含量高于ACL（p < 0.05）。湿重羟脯氨酸含量越高，杨氏模量、强度和韧性越高从定量角度来看，湿重弹性蛋白含量越高，预测的趾区非线性和杨氏模量越高，而干重糖醛酸含量越高，预测的杨氏模量、屈服应力和韧性越低。韧带之间生化组成的差异突出了它们生理功能和负荷状态的差异。正如预期的那样，胶原蛋白含量与刚度和强度呈现相似趋势。蛋白聚糖和弹性蛋白含量对力学性能的预测作用可能表明它们在韧带中具有重要的功能作用。
