T.A. Schmidt Ph.D. and R.L. Sah M.D., Sc.D.
The lubrication of articulating cartilage surfaces in joints occurs through several distinct modes. In the boundary mode of lubrication, load is supported by surface-to-surface contact, a feature that makes this mode particularly important for maintenance of the normally pristine articular surface. A boundary mode of lubrication is indicated by a kinetic friction coefficient being invariant with factors that influence formation of a fluid film, including sliding velocity and axial load. The objectives of this study were to (1) implement and extend an in vitro articular cartilage-on-cartilage lubrication test to elucidate the dependence of the friction properties on sliding velocity, axial load, and time, and establish conditions where a boundary mode of lubrication is dominant, and (2) determine the effects of synovial fluid (SF) on boundary lubrication using this test. The authors conclude that a boundary mode of lubrication was achieved in a cartilage-on-cartilage test configuration. Synovial fluid functioned as an effective friction-lowering boundary lubricant for native articular cartilage surfaces.
Osteoarthritis and Cartilage, Volume 15, Issue 1,