Contact creep of biphasic cartilage layers

Integral transform methods are used to solve the contact creep problem between two identical cylindrical biphasic cartilage layers bonded to rigid impermeable subchondral bone substrates. The biphasic model employed for cartilage consists of a binary mixture of an incompressible porous-permeable solid phase and an incompressible fluid phase. Solutions are obtained as a function of time, from the instantaneous to the equilibrium responses of the tissue. A significant result of this analysis is that under application of a step fond, fluid pressurization may support upward of 96 percent of the total applied load for move congruent joints, shielding the solid colla gen-proteoglycan matrix of the tissue from excessive stresses during physiological loading durations. The protection imparted by interstitial fluid pressurization to the solid collagen-proteoglycan matrix of cartilage is investigated, and the influence of material properties and osteoarthritic changes on the potential loss of this protective effect is discussed.