Towards a Standardised Method for Visualisation of Stress Distribution at the Cartilage-Bone Interface

The degeneration of articular cartilage is one of the most common causes of pain and disability in middle-aged and older people. In this context, osteoarthritis is a well-known clinical syndrome related to cartilage degeneration. The degeneration of normal articular cartilage is not simply the result of aging and mechanical wear. Pathological loads may also increase the risk of degeneration of normal joints, and individuals who have an abnormal joint anatomy or inadequate muscle strength probably have a greater risk of degenerative joint disease. The goal of this contribution is to investigate the influence of cartilage degeneration on the stress pattern at the cartilage-bone interface. In this connection, articular cartilage is described as a highly anisotropic and heterogeneous charged biphasic solid-fluid aggregate in the framework of the Theory of Porous Media (TPM). After calibration of the model under physiological loading conditions, the results of a sensitivity analysis of the model parameters are presented. Realistic boundary conditions are applied on the cartilage surface of the femoral head obtained from multibody dynamics calculations. Use is made of the Hertzian contact theory for the contact pressure distribution. The applicability of a new rendition technique to visualise simulation results based on a standardised stereographic projection of the von Mises stresses along the curved cartilage-bone interface is introduced. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)