Lubrication of human joints — a microcontinuum approach

Abstract

The present understanding of human joint lubrication is not complete. Earlier work, based on the classical continuum theory, failed to explain the observed effective increase in viscosity near the solid boundary. The microcontinuum approach represents a more realistic model for explaining the complex mechanism occurring in human joints. The behaviour of the synovial fluid, which contains long-chain hyaluronic acid molecules, is considered to be governed by micropolar fluid theory. The hip joint is approximated by a spherical bearing. The salient feature of this study is an increase in effective viscosity. This theory also establishes theoretically that for a diseased or damaged joint the load capacity and the response time decrease. This decrease may result in pain with diseased rheumatoid joints.