T 1ρ -based fibril-reinforced poroviscoelastic constitutive relation of human articular cartilage using inverse finite element technology

As one of the critical tissues for supporting and distributing loads in human joints, articular cartilage consists of a low density of chondrocytes and a large amount of extracellular matrix (ECM). The ECM is composed of water and solid matrix, which mainly contribute to the load-bearing capacity of cartilage under transient and equilibrium conditions, respectively (1,2). In the context of common joint diseases such as degenerative and posttraumatic osteoarthritis (OA), biochemical and molecular changes occur in the cartilage ECM: hydration, proteoglycan loss, and thinning and disruption of collagen are seen in the early stages of OA; and dehydration, disorganization of collagen network, and loss of cartilage become prominent in the late stages (3-5)