Solute transport in biological tissues is a fundamental process of supplying nutrients to tissue cells. Due to the avascular nature of cartilage, nutrients have to diffuse into the tissue to exert their biological effects. Whilst significant research efforts have been made over last decade towards understanding the solute transport behavior within the cartilage, the effect of dynamic loading on the transport process is still not fully understood. By treating cartilage as a homogeneous tissue, recent theoretical studies generally indicate that physiologically relevant mechanical loading could potentially enhance solute uptake in cartilage. However, like most biological tissues, articular cartilage is actually an inhomogeneous tissue with direction-dependent mechanical properties (such as aggregate modulus and hydraulic permeability). The inhomogeneity of tissue mechanical properties may have considerable influence on solute transport, and thereby need critical investigation. Using an engineering approach, a quantitative theoretical model has been developed in this study to investigate the solute transport behavior in cartilage in consideration of its material inhomogeneity. Using a cylindrical cartilage disk undergoing unconfined cyclic deformation as a case study, the model results demonstrate that inhomogeneous cartilage properties could potentially influence the magnitude and profile of interstitial fluid velocity and pressure throughout the cartilage. Furthermore, the enhancement of solute transport by dynamic loading is depth-dependent due to the inhomogeneous distribution of material properties.
EXPERIMENTAL INVESTIGATIONS ON SOLUTE TRANSPORT BEHAVIOR ASSOCIATED WITH HYDRAULIC PROPERTY OF UNDERGROUND DAM
