Contact creep of biphasic cartilage layers

Integral transform methods are used to solve the contact creep problem betw een two identical cylindrical biphasic cartilage layers bonded to rigid imp ermeable subchondral bone substrates. The biphasic model employed for carti lage consists of a binary mixture of an incompressible porous-permeable sol id phase and an incompressible fluid phase. Solutions are obtained as a fun ction of time, from the instantaneous to the equilibrium responses of the t issue. A significant result of this analysis is that under application of a step fond, fluid pressurization may support upward of 96 percent of the to tal applied load for move congruent joints, shielding the solid colla gen-p roteoglycan matrix of the tissue from excessive stresses during physiologic al loading durations. The protection imparted by interstitial fluid pressur ization to the solid collagen-proteoglycan matrix of cartilage is investiga ted, and the influence of material properties and osteoarthritic changes on the potential loss of this protective effect is discussed.