Continuum‐Mechanical Modelling of Hip Cartilage under Physio‐Dynamical Loading

Abstract

Articular cartilage is a very resilient material which lines the bony ends in synovial joints and has a gel‐like hydrated structure reinforced by a collagen fibre network. Despite its high load‐bearing and almost frictionless low‐wear capabilities, the high dynamical contact loads acting on cartilage can cause degenerative changes inside the tissue, whose internal structure hardly regenerates due to its avascular nature. One goal of the presented research is the appropriate modelling of the chemo‐mechanical behaviour of such materials under physio‐dynamical loading to foster the principle understanding of articulating joint mechanics. In particular, the tissue is described as a charged biphasic solid‐fluid aggregate based on the well‐founded Theory of Porous Media (TPM) against the background of large strain inelastic multi‐field continuum mechanics. The description of the inherent tissue heterogeneities over the cartilage thickness starting from the outer contact surface to the underlying bone layer as well as the strong anisotropic behaviour remains a challenge. The numerical treatment of the coupled PDE system is carried out in the framework of the mixed Finite Element Method (FEM) applying an efficient implicit monolithic solution procedure allowing the computer‐based analysis of a realistic hip joint contact. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)