Some help with a Prosthetic Ski Leg?

[Tech Tonics]

Hey all,

I make limbs for amputees. These days I mostly specialize in Upper Limb Prosthetics, but I still see a lot of my old lower limb patients.

I have this patient who I’ve been working with for nearly 10 years. He’s a badass. Amputated just above the knee.


Mostly he skis 3-track (so one ski and outrigger ski poles) and he RIPS. If you ski Wolf Creek or Telluride or Purg regularly, you may have seen him going REALLY fast.



I made him a ski rig a few years ago. He’s way better at 3 tracking but the forces he’s putting on his one leg are crazy and he won’t be able to ski the way he does on one leg forever.



More importantly, he can’t tour without a prosthesis. (He has done the one ski, and double pole plants style but that’s just not practical)



He’s done some bc skiing with Fritschi’s but weight is a major concern. His prosthesis fits awesome (I made it!) but we still want to make it light as possible

Years ago I got him a custom ski foot. It’s made in Utah and has a DIN sole. See pics below. This keeps him from having to transfer energy from his prosthesis to the boot



Can anyone think of a way to modify this so that it’ll work with tech bindings?



Thanks.

[XXX-er]

after lots of drinks, giving it very careful thot for at least 30 seconds

chop a tech boot down and bolt the sole to the foot

[Conundrum]

Dude. Kudos to you both. That is some inspiring stuff. Seems like a boot maker could hooks you up some materials and knowledge given what you’re trying to do.

[MakersTeleMark]

Use a pivoting tele binding.

[warthog]

Never toured with skins, but I would think you should be able to set up some sort of cotter pin that goes through the entire front of the binding and then through the "Toe" of the "foot". Thinking horizontally vs vertically, though either way should work. Horizontally, the entire setup would work like a hinge when the back of the binding isn't engaged. If the ski coming off is necessary, maybe make the cotter pins out of something that will break under extreme angles, and then have him carry lots of replacement pins.

Cotter pin isn't the right term though- I am thinking more of the long pins with a flip over bail, like you see used on hitch mount bike racks or trailer hitches.

[wickstad]

Maybe a dedicated climbing ski that can be exchanged out for the downhill ski at the top?

[XXX-er]

Use a pivoting tele binding.

how much dope would it take for that ^^ to work

[John_B]

Email CAST Touring and see what they recommend. https://casttouring.com/ They've got some experience adding tech fittings to boots. I'm sure the carbon fiber would be a challenge but maybe they have some thoughts.

[MakersTeleMark]

how much dope would it take for that ^^ to work

I think it's actually a rather simple, light, and dope idea.

[abraham]

Yeah, seems like cast would be the way to go for the downhill.

You might be able to attach a tech sole to a u shaped support that attaches to the top of the toe you have there. It would increase the stack height on one leg by a bit, but then you can remove it and use the din sole on the way down. Maybe a riser on the other toe might help negate the difference?

Another thought would be to have an attachment for a cotter pin instead of the tech toepiece

Of course if you could put tech fittings in the foot you have it would be great. But something nondestructive might be the way to go.

[I've seen black diamonds!]

Email CAST Touring and see what they recommend. https://casttouring.com/ They've got some experience adding tech fittings to boots. I'm sure the carbon fiber would be a challenge but maybe they have some thoughts.

That's a good place to start. You might also reach out to companies who make tech bindings boots and fittings and ask if there is anyone around is interested in lending some advice. That's the sort of challenge a lot of engineers would love. There are some mags who might have some knowledge or contacts , like Federico (designed the TLT 5), or Onenerdykid (Atomic).

Also if you want to harvest the fittings from my retired Maestrale RS's I'll send what's left of the to you.

Edit to add: this was a silly idea, but it wonder if it might be relevant to what you're working on:

https://www.wildsnow.com/6853/natura...ing-plate-nwp/





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[Lone Star]

I can't contribute anything other than

FKNA that is awesome, great work! You're gonna figure out a way to make it happen!

[pfluffenmeister]

I've skied a couple of runs with him at Wolf Creek and he is a ripper.

Was hiking the ridgeline up to Alberta Bowl and thought the guy that was way ahead of me had some weird poles? Whatever, head down and keep hiking.
Get to the top and the only other guy up there is on outriggers with one leg of his pants knotted above the knee (same green ones).
Asked him if he had already been down and he says : "Yeah, I've been down the right side. Going left now."
Cool.
Drops and kills it in 6-8" of wind affected pow.

Next lap I catch up to him at the saddle before the steep hike and he's screwing on a prosthetic with a running shoe on it that was in his backpack.
"I wondered if you had a leg in there!"
We hiked up together and he mentioned that he had done it without the prosthetic, but it wasn't the best.
He killed that run too.
Bus driver up there said he skis all the time.

Dude is an animal.

[old goat]

I assume the company that made the DIN foot doesn't make a tech foot? Everyone else is jumping on the BC bandwagon.

The amount of energy it takes to tour with an AK prosthesis is huge. Very impressive.

[Core Shot]

If you made the bottom plate aluminum It would be easy to drill toe holes for the uphill.

Not so good for downhill with soft aluminum. But you could use a shift binding for better downhill anyways.

On later thought, you could just modify the existing boot sole plate.
Drill the carbon fiber and insert a steel rod at the appropriate toe pin location. Countersink each end of that rod to match a tech toe.

Might be able to use a binding freedom or quiver killer insert screw for a cheaper fix?
Or salvage the tech toe inserts from an old boot and mold them into a new boot plate. I remember Lou Dawson or someone on the webs cut out a toe fitting, and the two metal pins are actually connected by a flat metal bar.

Either way, I would use Salomon shift bindings for safer downhill with mcgyver toe pins.

You could also just drill temporary countersink holes for the pins to see how it tours. The holes will wear out, but it would be a way to see how well it works before going too deep in fabrication. Worth a few laps, since a shift binding will be safe on the downhill, and uphill isn’t going to be dangerous.

[MakersTeleMark]

It's my understanding from the description that this would be just for uphill and that he prefers just one on the down. That is why I suggested a free pivot tele binding.

[Core Shot]

It's my understanding from the description that this would be just for uphill and that he prefers just one on the down. That is why I suggested a free pivot tele binding.

Ahhh. I missed that part.

Just use a snowshoe and fuck the skin track!

Seriously though if he’s not skiing down on it you don’t need much. The smallest shortest lightest ski that will hold in the skin track.

Might not even need a pivot binding. Just a pivot device. With heel lifters.

Could bolt a tele sole through those existing four bolts and use a tele tour binding. The lightest would be a three pin toe clamp. No need for heel cables etc.

[neufox47]

It's my understanding from the description that this would be just for uphill and that he prefers just one on the down. That is why I suggested a free pivot tele binding.

Finally a use for a snow shoe?

[Harvey44]

Hey all,

I make limbs for amputees...

I have nothing helpful to add.

You and your client are awesome and inspiring.

[old goat]

What's the mechanics of skinning with an AK prosthesis? I assume the amputated limb never gets out in front--or am I wrong? The little I know about AK prosthetics is way outdated--think Captain Ahab.. What I learned was that the prosthetic was swung forward with the pelvis to lock the knee, then it would support weight while the other leg took a step. But that wouldn't work going uphill. So I assume there's a modern solution.

[TBS]

after lots of drinks, giving it very careful thot for at least 30 seconds

chop a tech boot down and bolt the sole to the foot

Or similarly, can you get a set of replaceable tech toe & heel blocks from, for instance, Dynafit Titans? Then cut down/machine the existing metal “sole” plate to accept the blocks at the appropriate BSL?

Oh yea, and kudos to you for working on this project. Always amazed at the ingenuity of the adaptive community

[gregL]

Or similarly, can you get a set of replaceable tech toe & heel blocks from, for instance, Dynafit Titans?

I don't see why Titan, OG Cochise, or Quest Pro soles with tech fittings couldn't be ground flat and simply bolted on. Should be able to find some somewhere, even though they aren't currently for sale. If it's just for skinning up, or he intends to use a Shift or a Duke PT, you only need to replace the toes. Cool to help a badass be bad.

[old goat]

One thing that will be important--which TT already knows--is that whatever the solution is it has to preserve equal leg length.

[char_]

Why not just bypass the binding completely and have the prosthesis have the pivot? Might be tricky to make the attachment removable, but would eliminate lots of weight potentially.