K. Mabuchi et al., RELATIONSHIP BETWEEN THE CONFORMITY AND THE LUBRICATING ABILITY OF SYNOVIAL JOINTS, Clinical biomechanics, 13(4-5), 1998, pp. 250-255
Objective. To relate conformity of sliding surfaces with the lubricati
ng ability of synovial joints. Design. Measurement of start-up frictio
n in the stifles of various animals. Assessment of conformity by Hertz
ian contact area. Background. Past studies showed that the start-up fr
iction in synovial joints sharply increased with the loading duration.
The reasons why the friction increased and why the increasing rate is
different in different joints were, however, not found. Methods. Nine
stifle joints from various animals were used. A robotic arm was used
to give the compressive force and the sliding motion to the joint. Sta
rt-up friction was measured by a universal force sensor. The principal
curvatures of the sliding surfaces were directly measured by a radius
-gauge. Hertzian contact area was calculated from the principal curvat
ures of the sliding surfaces. Results. The duration until the friction
al coefficient reached 0.1 was related to the Hertzian contact area. C
onclusion. The conformity of sliding surfaces is related to the lubric
ation ability in synovial joints. The squeeze-film mechanism plays an
important role in joint lubrication.