Energy Storage and Return (ESAR) Prosthesis

Abstract

The engineering evolutionary process of the prosthesis for people with transtibial amputation is synergistically linked with relevant scientific discovery regarding the gait cycle. During the 1980s a major breakthrough was made in terms of the role of the ankle-foot complex during the gait cycle. During the terminal aspect of stance phase powered plantar flexion imparts a substantial level of mechanical energy to the gait cycle. In tandem with the decade of this discovery the concept of the Energy Storage and Return (ESAR) prosthesis progressively evolved. Preliminary energy storage and return prostheses incorporated an elastically deflectable keel in the prosthetic foot aspect. This design would store a portion of energy during the impact of stance initiation with a subsequent release during the terminal aspect of stance. Later versions of energy storage and return prostheses would incorporate the effective length from the foot assembly to the socket as energy storing and releasing medium. As the standard energy storage and return prosthesis lacks the capacity to temporally control the release of elastically stored potential energy, the incorporation of mechatronic subsystems facilitated the controlled release of stored energy. The Controlled Energy Storage and Return (CESR) incorporate a microelectronics package and clutch mechanism for controlling the timed release of stored mechanical energy. Prostheses that apply energy storage and return have been the subject of considerable testing and evaluation, which have demonstrated improvements both qualitative for the user and quantitative in terms of gait analysis techniques.