Characterization of the mechanical behavior of human knee ligaments: A numerical-experimental approach
Characterization of the mechanical behavior of human knee ligaments: A numerical-experimental approach
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DOI：
10.1016/0021-9290(95)00040-2
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发表时间：
1996-02-01
影响因子：
2.4
通讯作者：
Kauer, JMG
中科院分区：
文献类型：
--
作者：
Mommersteeg, TJA;Blankevoort, L;Kauer, JMG
在膝关节运动期间，膝关节韧带的纤维束以募集模式不均匀地加载，这取决于插入部位的连续相对方向。这些纤维束的长度、取向和机械性能各不相同。因此，韧带整体的刚度特性在膝关节运动过程中是可变的。本研究的目的是表征这种可变的机械行为。假设为此目的，必须将韧带机械地视为多束结构，其中考虑纤维束特性的可变性，而不是一维结构。为了验证这一假设，对韧带的骨-韧带-骨制剂进行了一系列单向亚失效拉伸试验，其中相对插入方向是不同的。对于每个单独的测试样本，这一系列拉伸测试均使用数学韧带模型进行模拟。从几何角度来看，该模型由多个线元素组成，其中插入和方向是基于解剖学的。在数学优化过程中，通过将模型的可变刚度特性与测试系列的可变刚度特性进行拟合来识别线单元的未知刚度和募集参数。因此，获得了集中参数，该参数将韧带的机械行为描述为相对插入方向的函数。这种识别方法适用于所有四个膝关节韧带。在所有情况下，实验结果和计算机模拟之间都获得了令人满意的拟合，尽管十字韧带的残余误差 (1.0-2.4%) 低于副韧带 (3.7-8.1%)。研究发现，具有三个或更少线元的模型对几何参数非常敏感，而具有超过 7 个线元的模型则存在数学冗余。 4 和 7 行元素之间几乎没有发现差异。结论是，目前的韧带模型可以真实地模拟人体膝关节韧带的可变拉伸行为。由此验证了以下假设：必须将膝关节韧带视为多束结构，以便充分表征其机械行为。
During knee-joint motions, the fiber bundles of the knee ligaments are nonuniformly loaded in a recruitment pattern, which depends on successive relative orientations of the insertion sites. These fiber bundles vary with respect to length, orientation and mechanical properties. As a result, the stiffness characteristics of the ligaments as a whole are variable during knee-joint motion. The purpose of the present study is to characterize this variable mechanical behavior. It is hypothesized that for this purpose it is essential to consider the ligaments mechanically as multi-bundle structures in which the variability in fiber bundle characteristics is accounted for, rather than as one-dimensional structures. To verify this hypothesis, bone-ligament-bone preparations of the ligaments were subjected to series of unidirectional subfailure tensile tests in which the relative insertion orientations were varied. For each individual test specimen, this series of tensile tests was simulated with a mathematical ligament model. Geometrically, this model consists of multiple line elements, of which the insertions and orientations are anatomically based. In a mathematical optimization process, the unknown stiffness and recruitment parameters of the line elements are identified by fitting the variable stiffness characteristics of the model to those of the test series. Thus, lumped parameters are obtained which describe the mechanical behavior of the ligament as a function of the relative insertion orientation. This method of identification was applied to all four knee ligaments. In all cases, a satisfactory fit between experimental results and computer simulation was obtained, although the residual errors were lower for the cruciate ligaments (1.0-2.4%) than for the collateral ligaments (3.7-8.1%). It was found that models with three or less line elements were very sensitive to geometrical parameters, whereas models with more than 7 line elements suffered from mathematical redundancy. Between 4 and 7 line elements little difference was found. It is concluded that the present ligament models can realistically simulate the variable tensile behavior of human knee ligaments. Hereby the hypothesis is verified that it is essential to consider the ligaments of the knee as multi-bundle structures in order to characterize fully their mechanical behavior.