A Biphasic Multiscale Investigation of the Biomechanical Microenvironment of Articular Cartilage

Osteoarthritis (OA) is a debilitating joint disease that involves the degeneration of articular cartilage. Although much research has been conducted at the macroscale level, the microscale level is poorly understood. This thesis investigated the micromechanical environment of cartilage cells that is thought to regulate cell metabolic activity.The cell microenvironment was studied at six distinct locations using a multiscale post-processing approach. Microscale sub-models were developed with biphasic poroviscoelastic (BPVE) fibril-reinforced materials and tested under axial quasi-static indentation and physiological cyclic sliding.Elevated principal and shear strains, and decreased fluid pressurization were found with simulated cartilage degeneration. Maximum intracellular compressive (19%) and shear strain (15%) occurred in the superficial zone of OA chondrocytes under sliding loads. Different loading modes resulted in different strains and fluid pressures between cartilage grades that may affect cell metabolism, suggesting that use of non-physiological loads in studies of cartilage could result in erroneous conclusions.