Computer Analysis: Supinator 1 (3D Views)
(Notes on reading
these images)
3-Dimensional Pressure Graphs
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Bare Foot |
Foot with Traditional Rigid Orthotic |
Foot with Silicone Dynamic Orthotic |
| 3-D Horizon view |
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| 3-D Tilt view |
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The next way to look at this dynamic foot pressure is in 3D. The
images above are different representations of the pressure maps that we
just discussed. These pictures use the same color scale as the pressure
maps: blue represents low pressure, red represents high pressure.
The intensity of pressure is also represented by the height of each peak.
In each of these pictures, the toes are on the right and the heel is on
the left. The Tilt views in the bottom row allow you to see the outline
of the foot. The Horizon views in the top row show the same information
but allow you to compare the height of the peaks.
The barefoot images on the left show how the pressure loads to the ground
for each part of the foot (heel, arch, mets and toes, including how and
when each met loads up) accumulating force until it peaks (maximum
pronation). We see the heel making contact, the arch is very low in
pressure and the ball of the foot registers significant pressure.
In the middle, with the patient's rigid orthotic, we see a high impact
at the heel but this is due to the hardness of the orthotic. The space
in front is the arch which shows no pressure because it is being carried
in a pre-set position by the orthotic and cannot register any force to
the ground. The front of the foot (ball) still shows significant but improved
pressure. What we see in these graphs that we did not see in the 2D pressure
map picture is how the pressure under the 5th metatarsal is significantly
higher. This means that the 5th metatarsal is carrying more than its fair
share of the load and this is why we see a reduction in pressure in other
areas.
As we look at the foot with the SDO (Horizon view) we see greatly reduced
pressure across the forefoot. We also see the arch playing a role
in the weight carrying capacity of the full load as indicated by the slighly
higher pressure in this area. We can see a softer heel contact indicating
the heel's reduced range of pronation. We see good balance and distribution
of weight and forces (do not be confused with the toes, the rise furthest
to the right) across the ball of the foot.
Let's compare this foot's function:
In the barefoot Horizon image, looking at the ball of the foot we identify
only the ground
reactive force (GRF) under the metatarsals. We see a small grouping
(meaning they are working together more as a unit-"the 5 metatarsals")
of the metatarsals close together (from front to back). In other
words we can see the individual "loading" of each metatarsal as it functions.
With the Horizon view of the rigid orthotic, the distance from front to
back widens (which is some loss in function) but does show reduction in
GRF (because of the function of the 5th metatarsal).
With the Tilt views, we can see a little more clearly. We see
that the foot with the rigid orthotic transferred the brunt of the weight
from the inside to the outside of the foot (the middle red peak).
The rigid orthotic forced the foot to carry more of the load there by causing
it to function pre-maturely. This view opens up the distance in the forces
from front to back (a lag in function) as they are peaking and you can
see how there is more force under the 5th and 4th metatarsals.
In the Tilt view for the SDO, we see a very close proximity (functioning
together) of all the mets peaking pretty much at the same time, sharing
the full load at the same time. A good indication of proper balance and
alignment.
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