Mommersteeg T J, Huiskes R, Blankevoort L, Kooloos J G, Kauer J M
Department of Anatomy and Embryology, University of Nijmegen, The Netherlands.
J Biomech. 1997 Feb;30(2):139-46. doi: 10.1016/s0021-9290(96)00096-6.
During knee motion, the fiber bundles of ligaments are nonuniformly loaded in a recruitment pattern which is different for successive knee-joint positions. As a result, the restraining functions of these ligaments are variable. To analyze the relative restraint contributions of the fiber bundles in different knee-joint positions, a new method was developed. Its application was illustrated for the cruciate ligaments of one knee-joint specimen. The methods developed to estimate bundle forces comprise five steps. First, the three-dimensional motions of a knee specimen are measured for anterior-posterior forces, using Röntgen Stereophotogrammetric Analysis. Second, bone-ligament-bone tensile tests are performed to evaluate the mechanical properties of these structures in several relative orientations of the bones. Third, multiple fiber bundles are identified in each ligament, based on the main fiber orientations. Fourth, the nonlinear force-length relationship of each functional bundle, as defined by a stiffness and a recruitment parameter, is determined by combining the multidirectional tensile tests with a multiline-element ligament model. Finally, the information obtained is combined in a whole-joint computer model of the knee, to determine the internal forces in the initial kinematic experiment, using an inverse dynamics approach. The technique appeared to be extremely time consuming and technologically involved. However, it was demonstrated to be useful and effective. The preliminary results reveal that the fiber bundle restraints are extremely sensitive to the knee flexion angle and the restraining forces are highly variable within the ligaments. For both cruciate ligaments, a gradual transition was demonstrated in load transfer from the posterior bundles to the more anteriorly positioned ones during knee flexion. Furthermore, it appeared that relatively high forces were carried by only a few fiber bundles at each flexion angle. Based on these preliminary results, it is concluded that the determination of forces in multiple ligament bundles is important for the understanding of failure mechanisms of ligaments. In particular, alternate loading of different fiber bundles suggests that successful operative reconstruction of the cruciate ligaments may not be achieved simply by a one-bundle preparation.
在膝关节运动过程中，韧带的纤维束以一种募集模式承受不均匀载荷，这种模式因膝关节的连续位置而异。因此，这些韧带的约束功能是可变的。为了分析不同膝关节位置的纤维束的相对约束贡献，开发了一种新方法。该方法在一个膝关节标本的交叉韧带中得到了应用。所开发的估计束力的方法包括五个步骤。首先，使用X射线立体摄影测量法测量膝关节标本在前后力作用下的三维运动。其次，进行骨-韧带-骨拉伸试验，以评估这些结构在骨骼的几个相对方向上的力学性能。第三，根据主要纤维方向在每条韧带中识别多个纤维束。第四，通过将多向拉伸试验与多线元韧带模型相结合，确定每个功能束由刚度和募集参数定义的非线性力-长度关系。最后，将获得的信息整合到膝关节的全关节计算机模型中，使用逆动力学方法确定初始运动学实验中的内力。该技术似乎极其耗时且技术复杂。然而，事实证明它是有用且有效的。初步结果表明，纤维束约束对膝关节屈曲角度极为敏感，韧带内的约束力高度可变。对于两条交叉韧带，在膝关节屈曲过程中，载荷从后束向前束的转移呈现出逐渐过渡的趋势。此外，似乎在每个屈曲角度只有少数纤维束承受相对较高的力。基于这些初步结果，可以得出结论，确定多条韧带束中的力对于理解韧带的失效机制很重要。特别是，不同纤维束的交替加载表明，仅仅通过单束制备可能无法成功进行交叉韧带的手术重建。
