Articular cartilage has high water content from 70 to 80% and biphasic property. Articular cartilage is composed of chondrocytes and an extracellular matrix. Extracellular matrix is mainly composed of proteoglycan and collagen, and produced by chondrocytes to provide scaffold to chondrocytes and support load to cartilage. The structural component of the tissue is inhomogeneous and anisotropy. Consequently, cartilage tissue shows complicated viscoelastic behavior to mechanical stimuli because of depth-dependent and time-dependent interstitial fluid flux and stress-strain behaviors. Therefore it is necessary to consider not only the average tissue property but also the local one to explain mechanical and functional behavior. In this study, we created articular cartilage tissue model in unconfined compression test under constant total deformation or constant load and simulated stress relaxation and creep behaviors using finite element method based on biphasic theory.
