Question
If a transfemoral prosthesis user switches to a higher heel shoe than what the device was originally aligned to, what is the user likely to experience?
Answer
We would break it down and first consider which plane of motion this is affecting. In this instance, the sagittal plane motion is in question. Too high of a heel is going to drive the knee into flexion, and the user is going to experience an instability of the knee. It is going to cause the knee to either feel like it is going to collapse, or it will make the patient feel that they have to really use their hip extensors to stabilize the knee. Even a quarter-inch of change in heel height can have a profound effect on the alignment.
What we can do is have the patients bring their shoes in. We can put heel wedges or forefoot wedges in the shoes to balance them so that they all react the same way for the prosthetic foot. They do not have to have the heel height adjustable foot. They can come in with their sneakers and flats, and we can accommodate anywhere in the range of a quarter of an inch to a half of an inch of heel height difference. When I say heel height, I am talking about heel rise. It is the difference between the thickness of the shoe in the front and the heel of the shoe in the back. I have seen shoes that have very thick soles, but they are very flat inside. There is not a real heel rise.
Let’s say that the patient was originally fit in a sneaker. The rule of thumb is that if they were to wear a very flat shoe with no heel, we need to put heel wedges in both shoes. We cannot just put it on the prosthetic side because it will actually change the heel height of the prosthesis. If a wedge goes in one shoe, it has to go in both shoes if it is under the heel because that will change the effective length of the prosthesis. Conversely, if they were fit in flats and they wanted to go into a sneaker, and it was causing too much of an anterior lean, then we could put a forefoot wedge under the front of the foot. That would tip the prosthesis back into neutral. In that case, we would not need a forefoot wedge in the contralateral side.
