Study on the law of static solute transport in degenerated cartilage

Results indicate that mass transport within cartilage exhibits pronounced anisotropy along the surface pathway, with molecular concentrations showing significant gradients across cartilage thickness and effective diffusion coefficients decreasing sharply from superficial to deep layers. The effective diffusion coefficients in all cartilage layers decrease by >50 % as molecular weight increases from 400 Dalton to 150 kDa. The larger molecules (LMT) exhibit lower diffusivity than smaller ones (SMT) across all layers. In the side pathway, molecular concentrations remained nearly constant between superficial, intermediate, and deep layers, forming gradients primarily along the width (i.e., diffusion direction), indicating minimal influence of interlayer structure on diffusion behavior. In the composite pathway, mass transfer patterns resembled the surface pathway, with clear concentration gradients forming along the thickness while maintaining uniformity across the width, demonstrating significant differences in transport efficiency among the different molecules. It was also demonstrated that cartilage degeneration significantly enhances the transport efficiency of solutes across all molecular weight ranges when diffused via the composite patrway. The results provides valuable references for optimizing OA drug delivery systems and enhancing intra-articular drug retention time.