A Comparison of the Flow Behaviour in Knee Articulations As a Function of the Friction Factor

In this work the flow behavior in the channel formed in the knee articulation is analyzed using Reynolds' equation. The comparison between natural and prosthetic knee is achieved through the evaluation of the corresponding friction coefficients which are added to the Reynold's equation. The friction coefficients are determined by relating them to the surface roughness, shear stresses, contact angles, work adhesion, and surface tension as described by Rabinowicz. The surface tension was evaluated theoretically by thermodynamic approach using the extended theory of xDVLO. SEM microscopy in human meniscus showed that its surface is formed by crests and valleys knitted on specific directions. For the synovial liquid-meniscus friction couple, as found out on the same SEM analysis, it was considered that the meniscus is a low permeability material and its influence neglected. It was found that slip could increase as the friction coefficient decreases.