A porous implant model for a knee joint

A study of the lubrication mechanism occurring in knee joint replacement is presented. The idealized model has been shown to produce results consistent with those in normal situations. In the present problem viscoelastic fluid has been considered to represent the synovial fluid in the fluid-film region and purely viscous Newtonian fluid in the porous layer due to filtration. Because of exact solution not being possible for the governing non-linear partial differential equations, the perturbation method has been used to obtain approximate solutions. The effect of an increase in the viscoelastic parameter of the lubricant is similar to that of an increase in concentration of hyaluronic acid molecules in synovial fluid. Important deductions are made for load carrying capacity and coefficient of friction and it has been shown that the slip velocity plays an important role in maintaining the self-adjusting nature of human joints.