Biomedical Engineering Reference
In-Depth Information
Fig. 14
Bone structure stress distribution and displacement for an healthy foot in the standing
position
Fig. 15
Bone structure stress distribution (equivalent von Mises stress) for an obese foot for
standing position
For each gait stage, contacts will change according to how foot areas hit the
ground. Three gait cycle stance phase stages were simulated: heel contact (HC),
midstance (MS) and toe off (TO). For this, it is necessary to build either three 3D
models, one for each foot-ground contact position and corresponding three FEM
simulations if a static structural simulation is conducted, or only one model if
flexible dynamic simulation is chosen. In the situation illustrated in Fig.
13
,the
choice was a static structural simulation by analysing each gait stage chosen. For
midstance stage, it is possible to assume the foot is in pure compression just like
in standing position. Simulation results can be foot displacements, internal stress
distributions in bone structure, which are most interesting indicators to search for
healthy feet solutions (Fig.
14
).
These results were compared with similar simulation for an obese foot. In this
case, apart from bone structure internal stresses, plantar pressure and soft tissues
displacements were studied (Figs.
15
-
18
).
The knowledge and data obtained from these techniques are very important in
identifying critical foot areas, which will be relevant in the design and construction
of an orthosis in order to minimize plantar pressure, decreasing discomfort.
