The majority of protheses available today that replace the lower leg, ankle, and foot are passive devices that store energy in an elastic element (similar to a coiled spring) at the beginning of a step and release during push-off to give you some added boost. While this type of prosthetic is energy efficient, it doesn't replicate the full power we get from our muscles. In order to provide that kind of energy an actuator is required, and these are often heavy and bulky. Researchers at Belgium's Vrije Universiteit Brussel have streamlined the technology in a device they call the AMP-Foot (Ankle Mimicking Prosthetic Foot).
Read the full article: AMP-Foot 2.0 prosthesis mimics human ankle's spring