Why is it so hard to make a fake knee?

My brother has been in the medical engineering field for the last several years and has worked on things like DNA sequencing machines, surgical saws, and artificial lower legs for amputees (I’m told he’s actually quite competent too!). The project most interesting to me, though, was the fake the knee that he worked on a few years back.

The knee was designed to be a “smart” knee — meaning it would have software built in that would make it function like a real knee. It would be able to sense and react to movements so that it would move the way a regular (organically grown) knee does.

But there was a major problem when trying to program the software for the knees.

They had to try to get the knee to learn how the individual wearer walked so it could accurately predict when the person was going to, say, go up some stairs or step off a curb so that it could react accordingly.  But here was the problem.

The person wearing the knee never moved exactly the same way.

Once the knee had “learned” how the person moved, the person was already moving a different way. The position they slept in at night would change the way they walked.  Sitting for a while changed the way they walked. There was nothing that DIDN’T affect the way the person walked.

So the end result was that the smart knee’s software would get consistently confused and gradually lock up into the flexed position until it could be reset.

Not ideal.

The moral of the story is that it makes more sense to do as much as you can to keep the biological knee you’ve got before having it replaced with a smart knee or a dumb knee because no matter how good technology is, it’s extraordinarily hard to replicate the intricate system of coordination going in on your organically grown body!

Get your body working right. Keep your joints feeling right. Keep your OEM parts!


About the Author

Matt Hsu is a trainer and orthopedic massage therapist. He fought a long battle with chronic pain all over his body and won. He blends the principles he learned in his journey, empirical observations with clients, and relevant research to help others get their lives back.

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