A Bargain In Bionic Knees

You probably don’t want to lose a leg, but if you have to there are many options now that were unthinkable not long ago. That is, if you can afford them. A microprocessor knee — a prosthetic with some smarts in it — can run anywhere from $25,000 to well over $100,000. However [Lucas Galey], a PhD candidate at the University of Texas El Paso in a recent paper claims to be able to produce a comparable artificial knee for under $1,000. If the paper is too long to read, Amplitude has a good summary including what it means to people who need them.

Of course, the cost of making something like this is almost incidental. The cost of approvals, testing, and other factors mean that even with about $500 in parts, the retail price would be much higher. Probably not $25,000, though.

In the device is an Arduino and some sensors that monitor the user’s gait among other things. Apparently [Lucas] volunteers with an organization called LIMBS International that provides prosthetics to people in developing nations. His design in an outgrowth of a low-cost passive knee developed by the organization. That knee, however, doesn’t meet Federal standards, so you can’t get one in the United States.

We know of at least one 3-D printed prosthetic leg. We’ve also looked more than once at mind controlling prosthetic devices.

17 thoughts on “A Bargain In Bionic Knees

  1. >You can’t get a LIMBS passive knee in the United States, as it doesn’t meet federal standards for healthcare technology

    Do you need that to sell prosthetics in US? or only to get on a list of products covered by insurance? Because even the “cheapest” $25K will be >$1K in deductibles. Similar to how people pay more out of pocket for insurance covered hearing aids than over the counter products in Asia.

    1. In the US, no company can make/market/sell a medical device without FDA approval. People could make one for themselves, but even a non-profit would be breaking federal regulations if they made one for others.

      1. This is entirely correct. I know that the FDA process costs a lot of money, and you have to show safety, otherwise you leave yourself open to a lot of litigation. FDA approval of a lot of systems requires not only showing that the device itself meets guidelines, but also that the manufacturing process meets the right guidelines for the type of device.

  2. Also, wouldn’t a large proportion of the cost of a prosthetic knee be that of “installation”? You have to have an orthopaedic surgeon and a long time in an operating theatre, and their time isn’t cheap.

    1. I believe they’re proposing a prosthetic knee joint for patients who already has an above-knee amputation. No additional surgery required.

      When I worked in an ER in the 80’s, an old man came in with a homemade below-knee prosthetic made from a pine branch, tire rubber, roofing tin, and mule harness. His pants leg had polished the pine bark like glass. He was understandably proud of it. Speaks to health care accessibility issues, but it was still a pretty cool hack.

  3. course, the cost of making something like this is almost incidental. The cost of approvals, testing, and other factors mean that even with about $500 in parts, the retail price would be around $750 or probably much higher.

    Maybe stop blaming government regulations for your corporate greed?!

    1. Annual company registrations alone with FDA are many thousands of dollars, and requires a facility to be approved for making them. Device approval applications also have large fees, excluding the very high cost of putting together all the documentation for the registration applications. Unless relatively large numbers were being made, it would be cost-prohibitive, just on the registration & approvals side.

      1. Thousands. And large fees. And very high cost

        These corporations that have millions in profits doing it, they’re just… Fake news? Lucky? If making prosthesis is such a bad deal in terms of regulation, where did all of that money come from?

        1. That’s the whole point of the article isn’t it? Many companies sell these devices for large sums, partially because they have to pay regulations, but also partially because that’s what people are willing to pay. The proposed device is supposed to offer a cheaper alternative for people in need.

  4. It seems to me that these type of organizations should take a page out of the book of gun companies to skirt stupid regulations. They should sell 80% kits with all the parts and instructions for finishing.

    1. Huh, that’s a really interesting idea, maybe a really good one.

      A lot of FDA regulations are there mainly to make sure only large incumbent corporations can enter lucrative medical markets. It’s the same with any government regulations. Unfortunately, without government regulation, corporations will do absolutely monstrous things if they think they can get away with it, or have a monopoly. So there isn’t a clear solution.

  5. You can get around FDA clearance for medical devices if you do not actually distribute the product, and only have the plans up somewhere like GitHub. See the OpenAPS system, and similar setups for using a self-built android app to control an insulin pump based upon data from a continuous glucose meter.

    I suspect though that a company that just sold pre-made or pre-printed parts for something like this in the US would get in trouble with the FDA.

    The FDA for good reason insists upon robust testing before products are made available to the public.

    1. “The FDA for good reason insists upon robust testing before products are made available to the public.”
      But … why, though? At least in this case? I mean, I understand for drugs, and internal implants and stuff – those sorts of things are the very definition of “user inaccessible”. But as far as I can tell, these prosthetics don’t go inside the body at all – they just have a glove that goes around the stump.
      So what is the failure mode for just letting any random person make such a device? The leg collapses? That’s no more risk than a ladder, and you don’t need an FDA license for that. The stump-glove bit rubs the skin raw? First, that seems like something that the user could be trusted to check on themselves. Second, maybe I’m underestimating the complexity of the process, but the glove bit seems very possible to just make a silicone mold of.
      I’m not saying we should go back to some wild west of medical devices. I just honestly don’t see what would be so bad in this particular case.

      1. I have a friend that is going through the process of getting both legs fitted for prosthetics, she had her legs
        removed below the knee. And she has had to go through many many fittings for the mold to fit her leg. The size of her leg changes a lot each over a very short time while it adapts to the fit in the new legs. The more she does the more times she has had it remade. Eventually the leg will stop shrinking at a certain point. She has gone through 6 or 7 new leg cups (for lack of a better term). It is a slow process to do it right. Part of the cost is the rehab and learning how to walk again. The first couple of times she only worn the in bed and in her wheelchair around the house. Then she got another set that she was able to slowly put weight on while she was sitting on the edge of the bed. You have to let the leg get used to the different pressure point of the cup, because it used to being supported by the skeletal muscles. And yes her leg was rubbed raw many many times, but they keep making new ones to refine the fit, Anyway the point of it only costing $500 is a little unrealistic and a kit would be out of the question. It’s not you can just strap a new limb on and start walking. With all the multiple casting and molds that would have to be made you would eat up $500 pretty quick. So the lower mechanical parts of the leg are nothing compered to the cost of getting the fit right. So I don’t really think $25,000 it too much for all the work being done. I think my friends are about $50,000 for both below the knee. I applaud his skill and design effort, but I’m sure he adapted an already the cup from a much more expensive custom fitted one.

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