An energy-recovering prosthetic foot

[unixronin]

Mechanically speaking, the human lower leg/ankle/foot is not just a support and a locomotive system, but also a shock absorber and energy recovery system.  In all, the human leg from the knee down actually recovers up to two thirds of the energy required to take each step.  A significant part of this energy recovery actually takes place in the foot.

Delft University of Technology in the Netherlands and the University of Michigan have recently developed an almost entirely mechanical prosthetic foot designed to recover energy in the same way that an undamaged foot and ankle does.  It's not perfect, and it's still in development, but it reduces the metabolic penalty of walking with an immobilized ankle and an otherwise undamaged lower leg from 23% above normal with a conventional rigid prosthesis to 14% above normal with the mechanical active prosthesis.  In other words, it cuts energy loss by almost half.  The paper also notes that there is added energy expenditure associated with the additional mass of the simulatore boot device used, so energy recovery in actual a[pplication could potentially be even better.  (Interestingly, the active prosthesis actually increases push-off energy by 7% above normal.  This offers the implication, unstated in the paper, that users of the active prosthetic might be able to save additional energy once they get used to walking with it.)

At the moment, it's purely a research device, not ready for medical application yet.  But it's an interesting development that shows a lot of future promise.  There may yet come a time when I need one of these myself.

Comments

[ithildae]

Let us hope that less drastic measures will be available for you to better use your natural hardware.

[unixronin]

I'm really hoping the regeneration research projects show fruit.

[masgramondou.livejournal.com]

You might recall that S African footless sprinter at the Beijing Olympics who had springy paddle thing to run on.

http://www.lifeinthefastlane.ca/man-with-no-legs-wins-battle-to-run/offbeat-news

And that energy recovery trick is almost certainly why the faster runners are toe-strikers not heel-strikers.

[unixronin.livejournal.com]

There's another runner with "cheetah legs", a woman whose name escapes me now. Not only is she fast, she's astoundingly graceful.

My ability to run was ruined for years by a school PT instructor who relentlessly drilled "HEEL TO TOE, HEEL TO TOE!" into everyone. But eventually I relearned to run on my toes (and learned that when I did so, I could keep up with a horse for short distances).