Finite element (FE) modeling plays a well-established and increasingly significant role in analyses of articular cartilage at the organ, tissue, and cell scales: for example understanding the functional relationships among constituents, microstructure, and tissue function in diarthrodial joints. A constitutive model, the crux of an accurate FE model, formalizes the functional dependencies among physical variables (e.g., strain, stress, and energy), thereby providing the missing equations to close the system generated by the classical balance principals, while accounting for the specific behavior of cartilage. In the future, fully 3-D FE modeling of cartilage could provide clinical diagnostic tools for patient-specific analyses. Computational analyses of full, patient-specific knee joints under load, especially before and after surgical intervention, would facilitate: (1) investigating fundamental research questions, e.g., structure-function relationships, load support, and mechanobiological cellular stimuli; (2) assessing individual patients, e.g., assessing joint integrity, preventing damage, and prescribing therapies; and (3) advancing tissue engineering, i.e., building replacement materials for cartilage. Approaches to computational modeling generally aim to adopt the simplest possible formulation that can describe experimental data, yet the complexity of articular cartilage mechanics demands similarly complex models. This review discusses extant multi-phase, large-strain (i.e., finite-deformation) constitutive models for cartilage which have been implemented in 3-D nonlinear finite elements. These have paved the way toward 3-D patient-specific clinical tools and along with advances in the underlying continuum theories and computational methods provide the foundations of improved constitutive models for 3-D FE modeling of cartilage in the future.

有限元（FE）建模在器官，组织和细胞尺度的关节软骨分析中起着公认的作用，并且日益重要：例如，了解双髋关节的成分，微观结构和组织功能之间的功能关系。本构模型是精确有限元模型的关键，它使物理变量（例如，应变，应力和能量）之间的功能依赖性形式化，从而提供了缺失的方程式来关闭由经典平衡原理生成的系统，同时考虑了软骨的特定行为。将来，软骨的完整3-D FE建模可以为针对患者的分析提供临床诊断工具。在负载下对患者特定的完整膝关节进行计算分析，特别是在手术干预之前和之后，将有助于：（1）研究基础研究问题，例如结构-功能关系，负荷支持和力学生物细胞刺激；（2）评估个别患者，例如评估关节的完整性，预防损伤和开处方；（3）推进组织工程，即建造软骨的替代材料。计算建模的方法通常旨在采用可以描述实验数据的最简单的公式，但是关节软骨力学的复杂性要求类似的复杂模型。这篇综述讨论了现存的多相，大应变（即有限变形）的软骨本构模型，该模型已经在3-D非线性有限元中实现。