3D Printed Prosthetics for (realatively) cheap.

[Napoleon the Clown]

Yeah, there's a sock. It helps with comfort and it can also help for generally keeping the stump warm. That's actually something that can be of concern, so even ignoring friction from the prosthetic a sock can be helpful.

There's been a lot of looking at using air-filled sacks in the sockets of prosthetics to help give a stable fit while maximizing comfort. That can help, to a degree, with changes in the stump's general size and shape. There's quite a bit of effort being made in implants that can give a prosthetic a good anchor point, which would help a lot with reducing friction and everything else. There are limits to the stress such implants can undergo, though. Too much stress and the bone can split. For a prosthetic arm, this wouldn't be as much an issue. Legs, though? Important consideration.

[Zeropoint]

Hmm... I wonder if using the 3D printer to make a custom mold, then using conventional injection molding or something similar, would result in a similarly priced, but more durable, prosthetic.

Oh yes, there are LOTS of ways to use a 3D printer to create parts that are not themselves 3D printed. Making the molds directly, as you suggested, is one way to do it. Another is to use the 3D printed positive part to make a mold for some kind of investment casting, in plastic or metal. You could also just use the 3D printing as rapid prototyping, and then use CNC machining techniques once you've got the design and sizing finalized, since you'll have a CAD model of the desired form at that point.

[salm]

From my experiences last term, I can tell you that at least some forms of 3D printed plastic can be reasonably strong in the direction of the filaments, but they have a grain, like wood, and like wood are much weaker against tensile stresses perpendicular to the filaments.

By filaments in this case, I'm referring to the strands of plastic laid down by the print head--they don't bond to each other as well as I'd believed up to that point.

The more professional 3D printers don´t work with filament. Laser sintering builds up the objects out of layers of powder treated by a laser. These objects don´t have this "wood" property.
I´d expect such prosthetics to be laser sintered rather than extruded.
On the other hand I´ve made plenty of really stable objects with my home built reprap extruder and I think other than size there´s nothing that would prevent me from printing a reasonably stable hand prosthetic like that.

[Broomstick]

The problem with sintering methods of 3D printing is that they're much more expensive right now than extrusion.

Having little experience with 3D computer controlled manufacturing, I think a lot of people don't realize the enormous number of variables involved, like what sort of material is being used for extrusion/sintering/whatever.

You also have to consider what the prosthetic is being used for - back when I worked in the medical insurance industry we had a person who qualified for high-tech C-leg prosthetic but who refused it for an older model with no power whatsoever. You see, he liked duck-hunting. A lot. And a C-leg would never survive in that environment, but a more primitive leg would. A prosthetic is a balance between application, durability, utility, and weight.

[salm]

The problem with sintering methods of 3D printing is that they're much more expensive right now than extrusion.

Having little experience with 3D computer controlled manufacturing, I think a lot of people don't realize the enormous number of variables involved, like what sort of material is being used for extrusion/sintering/whatever.

You also have to consider what the prosthetic is being used for - back when I worked in the medical insurance industry we had a person who qualified for high-tech C-leg prosthetic but who refused it for an older model with no power whatsoever. You see, he liked duck-hunting. A lot. And a C-leg would never survive in that environment, but a more primitive leg would. A prosthetic is a balance between application, durability, utility, and weight.

Sintering isn´t that expensive anymore. I got something sintered a couple of months ago and it is quite afordable. All the "mainstream" 3D printing services like Shapeways use laser sintering for example.

[Broomstick]

OK, then, good news.

Now, how available is that technology for the third world or remote places?

[Zeropoint]

Salm, you make a good point. The term "3D printing" covers a range of technologies, each with their own strengths and weaknesses.

[biostem]

I'd be interested to know if it's harder or easier for someone who wasn't born with a limb, versus someone who lost a limb, to adapt to using one of these. I'd also assume that a child would more easily pick up or get used to using a prosthetic, (though I suppose there are many factors that would cause this to vary from person to person - like having to cope with the trauma if you lost the limb, or if there were secondary injuries).

[salm]

OK, then, good news.

Now, how available is that technology for the third world or remote places?

You read about projects like that here and there. I remember one in particular when after the earth quake in Haiti Doctors Without Borders flew in a couple of 3D printers to produce cheap arms and legs.

[biostem]

OK, then, good news.

Now, how available is that technology for the third world or remote places?

You read about projects like that here and there. I remember one in particular when after the earth quake in Haiti Doctors Without Borders flew in a couple of 3D printers to produce cheap arms and legs.

Can you begin the process of manufacturing a replacement limb, even if the stump is still healing? I'd think you'd have to wait until the wounded part fully heals, any swelling goes down, and any sort of raised suture areas/scars smooth out/tighten up.

[salm]

DWB are still there, so i guess there´s been enough time for the healing process.
Perhaps it makes sense to print a bunch of parts you know you are going to need anyways in larger quantities and then just print an adapter from stump to prosthetic as soon as the healing process is finished?

[Broomstick]

I'd be interested to know if it's harder or easier for someone who wasn't born with a limb, versus someone who lost a limb, to adapt to using one of these. I'd also assume that a child would more easily pick up or get used to using a prosthetic, (though I suppose there are many factors that would cause this to vary from person to person - like having to cope with the trauma if you lost the limb, or if there were secondary injuries).

Because there's a learning process involving balance and muscle memory kids do tend to adapt better than adults, or at the very least quicker. However, since successful adaption often (but not always) involves the brain being able to map the body image of a missing limb onto a prosthetic people born without a limb don't always adapt to using one. Who can and can't adapt varies enormously and unpredictably. I know of a woman who successfully adapted to a below the knee leg prosthetic in her late 90's, but there are people in their 20's who never manage it. It's not just about the technology of the limb, it's also about the person accepting the limb, the quality of their rehabilitation, and so forth.

Young kids have the additional problem that they are growing so they need frequent replacements as they grow. If they can't get that they might give up using a prosthetic rather than struggling with one that no longer fits. That's another reason to bring down the cost.

[biostem]

Young kids have the additional problem that they are growing so they need frequent replacements as they grow. If they can't get that they might give up using a prosthetic rather than struggling with one that no longer fits. That's another reason to bring down the cost.

I wonder if they have prosthetics that can either be extended or easily added to, to accommodate a child's growth, instead of needing a total replacement.

[Broomstick]

To some extent, yes - a prosthetic leg can be made with a main support that can be gradually extended over time, as one example. However, the socket the stump fits into has to be custom fitted and as a child grows the stump will gradually change size and shape (this can even occur in adults over time) rendering the socket useless. Sometimes the socket be replaced. So a prosthetic can be made to accommodate some growth, but not to the degree a child would change over long time periods, and changing out/replacing some of the parts also carries a cost.