NONLINEAR-INTERACTION BETWEEN CARTILAGE DEFORMATION AND INTERSTITIAL FLUID-FLOW

The movement of interstitial fluid through articular cartilage and its influence on the creep behavior of the tissue due to a unit step load function has been investigated. Experimental results show that the hydraulic permeability of articular cartilage depends on both the axial compressive strain on the tissue sample, as well as the driving pressure difference maintained across the specimen. These experimental results have been utilized in a known theory of a deformable and permeable material used to describe the behavior of articular cartilage. The creep-like behavior of the cartilage in compression has been analytically treated. It has been determined that the nonlinear interaction between the hydraulic permeability of the tissue and the compressive strain on the tissue retards the progress of the consolidation of the cartilage during uniaxial compression. However, the equilibrium displacement of the articular surface as t yields infinity depends only on the elastic constant of the parallel spring and dashpot viscoelastic behavior of the solid component of the tissue.