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Figure 1: In the frontal plane mark a line along the lower ½ of the tibia that aligns with the 2nd digit (this will give a good indication of the subtalar
neutral position). Sit patient on a chair with legs 90 degrees to floor.
Place left foot on left side of foam box. Place heel about 1 inch from the
back edge of box and centre foot in the middle of the foam. |
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Figure 2: Place left thumb in the inner-space of the navicular & talus
bones on the left foot. And index finger on the left side of the talus.
This way you can feel for neutral position. Next turn left box lid
counter-clock wise, which will pronate the heel or clockwise which will
supinate the heel. Then stop turning the box when you find that the
navicular & talus are properly aligned in subtalar neutral. |
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Figure 3: Picture shows heel and in-step in neutral position. In 80% of
all feet you will find that the fore foot has a varus deformity. The first,
second, & third metatarsals will be above the top of the foam (Drawing in
figure 3) Later when the fore foot is pushed down you must keep the angle
all the way down to bottom of box. (See figure 5) |
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Figure 4: After setting the foot in neutral the right hand should still be
in place on in-step. Then place your left hand on the patients left knee.
With both hands push knee and in-step straight down until heel is at the
bottom of the box. (Make sure the anterior lines are still in good
alignment). |
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Figure 5: The left hand should still be on left knee. Place right back
part of palm over the heads and if your hand is narrower than the foot be
sure to use the lateral part of palm on the fifth metatarsal and the rest of
palm on 4, 3, & 2. This is in order to feel the fifth metatarsal when it
stops at the bottom of the box. Next push all of the metatarsal heads down
keeping your palm at the same angle the fore foot was in when you set the
foot in neutral. (see third picture) until the fifth metatarsal stops
approximately 2 inches at the bottom of the box. Do not roll across the
heads and push the first metatarsal down. |
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Figure 6: Push the toes down. |
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Figure 7: Place the index finger on the cuboid and push a little just to
seat it. |
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Figure 8: Note: Heel is approximately 2 inches down in the foam and the
fifth metatarsal is 2 inches down, and the in-step is in line with the
medial side of the leg. (see figure 4) |
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Figure 9: Cast right foot on right side of box using left thumb on navicular & talus inner-space and repeat all the previous steps |
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Figure 10: Shows a proper cast, the heel and the lateral side of the fifth
metatarsal is approximately 2 inches down at the bottom of the foam. And the
first metatarsal is ¼ inch off the bottom of the box, which matches the fore
foot deformity when the foot was first set in neutral as in figure 3. It's
important to keep your palm at the angle the fore foot is in when the heads
are pushed down. |
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Figure 11: The plaster cast shows where the ¼ inch post was added into the cast
to fill in the missing space. This balances the varus in the fore foot, so
your patient can toe off evenly and walk more in the middle of the foot. It
helps to maintain good alignment in the knee and hip. |
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Figure 12: When an impression is taken by simply stepping into the box, it
is impossible to know how much to raise and correct the foot. The reason you
must cast in subtalar neutral is as equally important as the reason for
giving your patient an orthotic. You want to control and correct the
patient's foot. For the orthotic to be made properly, we must receive an
accurate impression of the foot. When you send in a corrected foot we can
make an orthotic to compensate for the corrections. |
