The influence of articular surface incongruity on lubrication and contact pressure distribution of loaded synovial joints.
In the model intended for short-term loading (such as during the walking cycle) of a human synovial joint in the lower extremities, cartilage lubricated by Newtonian synovial fluid is considered to be incompressible elastic and subchondral bone is considered to be rigid. The model is non-diffusional, i.e. no interstitial fluid flow occurs across the articular surfaces. A simple plane strain case of the human ankle joint is considered. For high steady loading applied in the centre of the stationary tibial arc and for steady sliding of the talar arc, this model shows that individual physiological variations in the geometry of the articular surfaces have only a small effect on the contact stress distribution and the fluid film thickness. If this load is applied eccentrically in the tibial arc, the contact pressure distribution varies more with surface geometry, but the minimum fluid film thickness differs little from that for symmetric loading. The maximum contact pressure is placed eccentrically in this case, but its value is changed only little when compared to the central loading of the same value. In order to explain different distribution patterns of subchondral bone mineralization, it is anticipated that the total load peaks of periodic time-dependent loads are transmitted centrally in some incongruent joints and eccentrically in others.
Hlavácek
M
M
Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Vokoun
D
D
D000368:Aged; D000843:Ankle Joint / Q000502:physiology*; D002358:Cartilage, Articular / Q000502:physiology; D006801:Humans; D008153:Lubrication; D008875:Middle Aged; D008954:Models, Biological; D011312:Pressure; D012016:Reference Values; D013314:Stress, Mechanical; D013499:Surface Properties; D013583:Synovial Membrane / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology