When the International Olympic Committee approved the prosthetic blades that replace Oscar Pistorius’s artificial legs when running, they set a precedent that could be hard to manage down the line. What was the committee’s criteria for approving them, and why should one prosthetic be allowed and not another? There’s no definitive answer yet, but it’s a safe bet that a rocket-powered prosthetic ankle probably won’t make the cut.

Developed by researchers at the University of Alabama, the ankle strikes the perfect balance between being lightweight, but also providing enough power to allow the wearer to walk with a natural gait. The prosthetic uses an artificial muscle actuator that’s powered like a rocket using a liquid fuel known as a monopropellant. In essence, it would work kind of like the pistons in your car’s engine using tiny controlled explosions to generate extra energy that facilitates easier walking.

But not surprisingly there’s still a few kinks to work out. Hot exhaust would have to be safely vented, excess heat would need to be managed, and of course the prosthetic would need a reliable way to store and refuel the monopropellant. So the researchers don’t expect to see the artificial ankle in use until 2016 at the earliest, but they’re confident it will eventually look and function exactly like a real human limb. [University of Alabama via Medgadget]