Some things to consider:
Arch Height.
If you notice that the arches on your devices are coming out higher than the arch on the cast, it could be an indication that the core shells are not cooling down on the vacuum press.
The plastic should be left on the press until completely cooled. If if is taken off too soon, the material will curl up and the arches will seem higher.
Flexibility & Width.
The plastic has to be heated at the correct temperature and taken out of the oven at the right time.
If it is heated at too high of a temperature and/or left in the oven too long, the plastic could shrink up and thin out. This will make the shell seem more flexible than it should.
If it is heated at too low of a temperature or taken out of the oven too soon, it will not wrap around the perimeter of the cast completely and the heel will be wider than it should be.
How Arch Height Effects Flexibility.
Keep in mind that the higher arches will make the shell feel stiffer than the lower arches.
For example, you could have two patients, one with a Pes Cavus foot and one with a Pes Planus foot. They could be the same shoe size and same weight and you could use the same plastic thickness for both of them.
The higher arched Pes Cavus shell will feel stiffer than the low arch Pes Planus shell.
So just remember…. the more acute the curvatures are that the plastic is being formed to….the stiffer the shell will feel. By the same token, the milder the curvatures are that the plastic is molded to, the more flexible the shell will feel.
Stay tuned! We will be looking at frontal plane posting soon!
What do you think? Have you considered the variables at this step in the process?
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