Analysis of Solute Transport in Cartilaginous Tissue Under Dynamic Unconfined Compression

Abstract

Transport of fluid and solutes through the extracellular matrix plays a key role in the nutrition and growth of cartilaginous tissues that lack blood supply. It has been found that the mechanical loading can alter the transport rates of solutes within cartilage [Bonassar, 2000; O’Hara, 1990; Quinn, 2002]. Dynamic compression may enhance the transport of large solutes (e.g., growth factors) within the tissue. Many theoretical analyses have been reported in literature on the transport of fluid and solutes, as well as physical signals (stress, strain, pressure, concentrations, and electrical potential) in cartilage under unconfined compression [Armstrong, 1984; Levenston, 1999; Mow, 2002]. However, little is known as to how the tissue fixed charge density (FCD) affects the transport of fluid and neutral solutes (e.g., glucose and IGF-1) in cartilage sample in dynamic compression. In this study, we numerically analyzed the transport of fluid and solutes, as well as the mechano-electrochemical signals within the cartilage sample in dynamic unconfined compression, using the finite element method (FEM). The objective of this study was to investigate the effects of FCD, loading frequency, and loading platens (permeable vs. impermeable) on the transport of fluid, ions, and neutral solutes within cartilage. This study is essential for the understanding of tissue nutrition and signal transduction mechanisms in cartilage subjected to mechanical forces.