As a result of this discussion, the other night I got my ski boots out (it's autumn here), pulled out a liner, and dug out the Surefoot footbed, and compared it with my new orthotic.
The Orthotic starts its correction a lot sooner, under the heel. My podiatrist explained (and showed ) how if you start the correction almost directly under the ankle, the line of foot bones line up properly, so the whole foot operates. While I was sitting down, with one hand he poked these bones into where they should be, and with the other hand bent my big toe right back. i've had almost no bendability in my big toes since highschool.
I should be able to run again, since I now have "pushoff" with my foot and toes.
The Surefoot footbed, otoh, does nothing until it rises up in the arch area. The Surefoot guy (he was an older guy and obviously had the foot knowledge) also put a little quarter-sized lump under the lining, a little above where the middle of teh ball of the foot is. This helped with some toe nerve problems.
I put the Surefoot and the Orthotic on the floor and stood with one foot on each. The Orthotic picks up the foot from a much earlier point, and lines my whole leg up. The Surefoot one basically pushes up the arch only, and my leg was allowed to rotate inward. I remember when they made this footbed, the Surefoot guy spent a lot of time lining my foot up, pushing the ankle around and holding it in a certain position. But what my podiatrist said makes sense. When the foot is placed on the ground, the problems are already occuring. If the foot is totally unweighted, the problems are not occuring.
I was able to put my orthotic in the boots (the orthotic does not extend to the ball of the foot, it's a 2/3 length one), but felt more pressure over the top of the foot as the orthotic has re-introduced the arch I am meant to have.
I might introduce them to my skiing gradually. What I expect is that my knock-kneed stance will disappear, but I'll have to re-learn my edging. Getting an outside edge will be much quicker and easier (rather than the long journey it has been), and getting an inside edge will be a much cleaner affair as I'm not already flopped in on the arch.
My lower back and left hip and knees are already feeling happier. I'll save a fortune in knee strapping tape as I'll no longer have to tape my kneecaps into place. And for anyone with dodgey feet and leg problems, I'll be suggesting unweighted correctional orthotics!