Investigation of mechanical behavior of articular cartilage by fibril reinforced poroelastic models.

The fibril reinforced poroelastic models have been found successful in describing some mechanical behaviors of articular cartilage in unconfined compression that were not understood previously, including the strong and nonlinear transient response, the strain-magnitude and strain-rate dependent cartilage stiffness and the depth-varying stresses and strains. It has been demonstrated that a better description for the mechanical behavior of cartilage is obtained by introducing a fibrillar matrix into a poroelastic model, in addition to the nonfibrillar matrix and water. This paper reports the development of the nonlinear fibril reinforced homogeneous and nonhomogeneous models and further explores the potentials of the models for investigation of cartilage mechanical response. Some comments are made in regard to further applications of the models and improved accuracy of the material representation.