Effect of Stress Relaxation on Layer Thickness of Articular Cartilage due to Dynamic Loadings

Abstract

Articular cartilage is the bearing material of diarthrodial joints as hydrated soft material such as knee, hip, shoulder, and etc. Then articular cartilage has exceptional lubricating properties and low coefficient of friction that greatly assist its function in synovial joints. Some studies of cartilage lubrication have hypothesized that pressurization of the interstitial fluid may contribute predominantly to reducing the friction coefficient at the contact interface of articular layers. In this paper, we present the response of interstitial fluid pressurization within hydrated soft material of cartilage, which accounts for the cartilage defects. For the computation model, we have chosen an axisymmetric model with two uniformly thick cartilage layers and solved by using finite element method. This model demonstrates that a simultaneous prediction of compression experiments of articular cartilage were under stress relaxation and dynamic loading. For the experimental results, we found that the increased fluid concentration of the tissue’s solution can be achieved the minimum friction coefficient. Furthermore, it is observed that the friction coefficient does not remain constant under various loads or fluid concentration and correlation analyses that the equilibrium value depends in part on the compressive strain in the cartilage.