Chondrocyte regulation by mechanical load

The effects of load on articular cartilage are complex. Dynamic loading of cartilage is associated with slight cell and tissue deformation as well as cyclical fluctuations in the hydrostatic pressure of cartilage and in fluid movement. Static loading results in expression of fluid from the tissue, concentrating extracellular matrix macromolecules and consequently increasing the concentrations of cations, reducing extracellular pH and increasing extracellular osmolarity. Each of these alterations is implicated in regulating the synthetic response of chondrocytes to load. However, the mechanisms by which these changes affect matrix turnover are poorly understood. In this review we consider how load may affect chondrocyte behaviour through its influence on membrane transport processes and thus on the intracellular environment.