Biomedical Engineering Reference
In-Depth Information
Fig. 5.74
Joints of the metatarsus
ground, enabling a harmonic swing of the leg. In contrast, during running, the joints
work synchronously (synchronous flexion or extension) during the complete stance
phase. The leg rotation mainly results from hip extension and knee flexion.
FE-Models: The finite element models depicted in Fig.
5.71
, including the
complete anatomy of the right leg, were generated. They are based on HMC-data,
combined with the previously introduced FE-models, Figs.
5.60
,
5.61
,
5.62
,
5.63
,
5.64
, and
5.65
, as well as appropriate boundary conditions at the knee and hip
joint, together with characteristic ground reaction force. The Figs exemplarily
show the bi-pedal initial stance phase for walking and the mono-pedal stance
phase for running. A superposition of the simulation results with the respective
video sequences are in good agreement, Figs.
5.68
a (right) and
5.69
(right).
To control the positions of individual toes during the foot roll, an upright-MRI
device was employed to generate in vivo images of the foot in five characteristic
angle positions during the stance phase, Fig.
5.72
. These images were initially
planned as boundary information to be used in the finite element model, but were
rejected due to insufficient image resolution. To date, no feasible non-invasive in
vivo approach exists to gain information about the transiently changing relative
positions of the bones of the human foot during motion.
Modelling of the Foot Joints: To model the four foot joints, namely the upper
ankle joint, the lower ankle joint, the talonavicular joint and the naviculocuboidea
joint, cf. Fig.
5.73
, the single cartilage layers were modelled to achieve a realistic
