Boundary lubricating ability of synovial fluid in degenerative joint disease.

The boundary lubricating ability of eleven synovial fluids was measured in a miniaturized latex--glass test system. The specimens were obtained at necropsy from knees in which the degree of degenerative joint disease varied from none to very severe. The lubricating ability of the fluid was independent of the viscosity over a wide range of shear rates. It was not diminished even in advanced lesions. In two additional fluids, the mucin clot was poor; the lubricating ability of one of these was compromised. Thus, although degenerative joint disease, during its quiescent stages, is not associated with defective synovial lubrication, the possibility that transient defects might lead to cartilage wear during life has not been excluded. The measurements are believed to be valid indicators of boundary lubricating ability under physiological conditions despite the fact that the test surfaces were not cartilaginous and the loading was relatively low (up to 47 pounds per square inch).