Self-diffusion of water in cartilage and cartilage components as studied by pulsed field gradient NMR

Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) was used to investigate the self-diffusion behavior of water molecules in cartilage, polymeric cartilage components, and different model polymers. The short-time self-diffusion coefficients (diffusion time delta approximately/= 13 msec) are found to decrease steadily with decreasing water content. This holds equally well for cartilage and cartilage components. The short-time diffusion coefficients are subjected to a rather nonspecific obstruction effect and mainly depend on the water content of the sample. The long-time diffusion coefficients in cartilage (delta approximately/= 500 msec), however, reflect structural properties of this tissue. Measurements with varying observation times as well as experiments involving enzymatic treatment of articular cartilage suggest that the collagenous network in cartilage is likely to be responsible for the observed restricted diffusion.