A Comparison of Friction Measurements of Intact Articular Cartilage in Contact with Cartilage, Glass, and Metal

Abstract

The goal of this study was to develop a method of friction testing utilizing cartilage counter surfaces with a complete subchondral bone plate and compare the results to the cartilage on glass and metal (steel) counter surfaces. Articular cartilage surfaces with the underlying subchondral bone intact were not isolated through plug removal. Friction testing was completed using a tribometer (n=16). The coefficient of friction (COF) was measured between the proximal articular surfaces of the second carpal bone when brought into contact with the articular surface of the distal radial facet. The COF of the distal radial facet was obtained with glass and metal counter surfaces. Cartilage-cartilage interfaces yielded the lowest COF when a normal force of 5N and 10N was applied. No statistically significant increase in COF was noted for any combination when an increased normal force was applied (10N), although an increase was observed when glass and metal was in contact with cartilage. COF significantly increased when comparing the cartilage counter surface to metal under an applied load of 5N (p=0.0002). When a 10N load was applied, a significant increase in the COF was observed when comparing the cartilage counter surface to both the glass and metal counter surfaces (p=0.0123 and p < 0.0001 respectively). Results have shown that the described methodology was accurate, repeatable, and emulates physiologic conditions when determining the friction coefficient. The determined COF of cartilage against cartilage is significantly lower than cartilage against metal or glass.