Biomedical Engineering Reference
In-Depth Information
Fig. 8. Orientation diagram of the magnitudes of angles between the axes of the femoral and
tibial diaphysis during the “flexion - extension - flexion“ cycle of the lower limb in relation
to the time percentage of the cycle
The total
thickness of the gap
between the opposite AC surfaces is only ca 50 μm, including
height roughness of the surfaces near both peripheral layers 2 x 2.5 μm
,
Fig. 4., Fig. 9.
(Petrtýl et al., 2010). In quiescent state, the AC surfaces are flooded with SF (synovial gel)
while during the leg motion (from flexion to extension and vice versa) synovial sol with the
relatively low viscosity is generated in SF in peripheral zones of AC. In other words,
due to
the effect of shear stresses
τ
xy
the viscosity η of SF decreases and synovial sol is generated.
Aggregations of macromolecules of hyaluronic acid decrease.
The most intense aggregations
are in places of the smallest SF velocities, i.e. in neutral (central) zone of SF between the AC
surfaces.
