Regional nutrition and cellularity of the meniscus. Implications for tear and repair.

The knee menisci are relatively avascular and must rely to a large degree on synovial sources of nutrition. Lack of nutrition may lead to degenerative changes and may inhibit any potential repair capabilities of the menisci. Continuous passive motion applied to the knee stimulates greater activity and/or transport of nutrients to the meniscal fibrochondrocytes. However, in an avascular model, solutes within the synovial fluid are lost by their convective transport from the joint. Regional differences in transport of a low molecular weight nutrient like sodium sulphate exist such that cells in the central core region of the meniscus are poorly supplied with nutrients by the synovial fluid and/or are less active. These conditions may be the cause of a relatively high incidence of degenerative changes in the central core region.