Abstract:
This paper provides a comprehensive technical overview of the strategies and challenges associated with creating accurate three-dimensional (3D) finite element (FE) models of ligaments for biomechanical analysis. The authors detail a complete workflow, beginning with the acquisition of 3D ligament geometry from medical imaging sources like MRI and CT, and discuss the nuances of image segmentation and FE mesh generation using solid (hexahedral) or shell elements. A significant portion of the review is dedicated to the constitutive modeling of ligaments, summarizing their complex mechanical behavior—which is anisotropic, nonlinear, and viscoelastic—and reviewing the various mathematical models used to represent these properties.
A novel and critical contribution of the paper is the detailed presentation of a method to apply in situ strain to FE models. This technique uses a multiplicative decomposition of the deformation gradient and an iterative update algorithm to accurately represent the baseline tension that exists in ligaments within a joint, which is crucial for predicting realistic stresses. The paper strongly emphasizes the need for rigorous verification and validation, outlining a framework that includes mesh convergence studies, sensitivity analyses, and direct comparison of model predictions with subject-specific experimental data. The authors conclude by identifying key areas for future research, such as developing multiaxial failure criteria and better understanding the role of the ligament-bone insertion site.
