As you mentioned in the pm, this may be of interest for other people too, so I will post it here again.
Just to make it absolutely clear, the craft skills needed to do this kind of stuff and the theoretical background knowledge are completly different from what a normal leatherwork knows. If you try stuff like this to do yourself you do this at your own risk. You can make things worse when trying to make an orthopedic shoe and have no clue what your are doing
Ok so here ya go,
There are basically three places where you can adjust a shoe to orthopedic needs.
First is the front and heel stiffeners. Do you have problem with your toes (I.e. are they moving sideways or bending up or down). If not don't care about. You can make a normal toe stiffener. If yes, there are a few variation of the toe stiffener that fit different needs. The heel stiffener is not important when you have a normal last. Special heal stiffeners need usually a leg last which means the last represent the foot and a part of the leg. With a last like that you make boots that have special formed heal stiffeners.
For example: The X-ray of your leg looked as if you cant move your ankle joint at all. If this is the case the heel stiffeners are not important at all. If you have a little movement left in your ankle, this movement will most likely cause pain when walking. In this case you would make a boot over an leg last with a heel stiffener that is at least 20cm in height and that goes over both of your ankles. This stiffener would make your ankle completly unmovable. Which reduces pain but makes walking difficult but that will be handled at another point.
Second thing you can adjust is the insole. Here I need to explain in detail a little more. As far as I know, in english you use the word insole for both the sole that is attached the last (where the welt will be attached) and those soles that you can put into a normal shoe, that support your arches. The one that I'm talking about is a little different. It can support the arches and reduce the force of impact when the heel hits the ground. Its possible to give the heel more stability too and a few other things If you are interested in this just let me know then I will explain in more detail but basically you build up this insole at the bottom of your last by putting cork under it. You need eight millimeter normal cork and eight millimeter soft cork (or sometimes called microcork). This is a special cork that is soft and thermoplastic. It's of a lighter color than normal cork and the cork particles are much finer. If you are interested in this I will describe the process of building up this kind of insole in more detail. Nice thing about this insoles is that you can add the height difference of your legs to them as you did now permanently under one of your lasts.
Last thing you can adjust to your need is the bottom of your shoe. I.e. the sole and heel. There are different things you can do with a normal sole to make it fot different needs. Lets look at your leg again as an example.
Since your ankle can't move your foot, you won't Be able to bend down and raise it like a healthy foot which is important for walking. When I walk I have the foot raised just before the heel touches the floor. Then I lower the foot until the Balls touch the ground. Then I lower it more and bent it down over the big toe to get the force that I need to do the next step. If I am right you are not able to walk this way without problem so you need to make your shoes In a way that helps you doing this.
You can achieve that by using the leverage effect. Take a look at your last. Lift it up a little at the back as if there would be a heel. Now look from the side.Your last touches the ground at the point where the balls are (more or less) and rise from this point to the toes.
Before you attach the last sole to your shoe, the walking sole, you can now add a layer of material 0.8-1 centimeter to your shoe. This additional material you will grind on a belt sander in a way that the point where the shoe touches the ground is not the balls anymore but lies 1-2 centimeter behind the balls. From that point to the front you try to get a slightly curve. You know you got the curve right when you press your shoe down at the front with a finger and it rolls very smoothly to the most front part Of your shoe. After that you attach your normal walking sole. This replaces the force you need to bend down your foot and lift it in the air to make the next step. Of course you need to add the same amount of material to the heel to make your shoe stand right. In addition you can slightly round of the back part of your heel before attaching the last heel piece. You always do this on both shoes.
Here is a picture of the sole to make it more clear
http://www.grifka.de...id=40&Itemid=82
And one of the rounded heel
http://www.grifka.de...id=40&Itemid=82
Best wishes