Cyclic loading moves the peak stress to the cartilage surface in a biphasic model with isotropic solid phase properties

Experimental indentation studies of articular cartilage have shown the initiation of fibrillation at the cartilage surface. To date, isotropic biphasic models have failed to support this observation. This study presents the results of applying cyclic loading to an isotropic biphasic cartilage indentation model using an FE based solution procedure. The model incorporated a contact dependent flow algorithm to prevent fluid movement across contacting regions. The results show that under the application of cyclic loading the location of key peak solid phase stresses move from the base of the cartilage layer to the surface and thus to the region of experimentally observed cartilage surface failures