Adaptable Ankle-Foot Prosthesis

NU 2006-132B

Inventors

Dudley Childress

Andrew Hansen*

Steven Gard

Brian Ruhe

Ryan Williams

Short Descriptions

Prosthetic and Orthotic Ankle-Foot Device, adaptable to changing grades & heel heights

Abstract

Northwestern researchers have designed several prototypes that significantly improve upon currently available passive ankle-foot prostheses. Their invention automatically adapts to different surface slopes and to shoes of different heel heights without electrical or active components. The Adaptable Ankle-Foot Prosthesis utilizes stiffness properties that mimic the natural behavior of an able-bodied foot and ankle for normal self-selected walking speeds. It sets its effective alignment in early stance phase, adapting automatically to surface slopes, and plantarflexes beyond a neutral position during the unloading phase of gait. After toe off, it brings the ankle back into a neutral or slightly dorsiflexed position to provide toe clearance during the swing phase. The ability of the system to store and release energy from a plantarflexed position should increase the return of stored energy to the leg, and thereby reduce the amount of energy needed for walking. This feature may in turn help prosthesis and orthosis users to walk at consistently faster speeds. Lastly, the ability of the ankle to adapt its alignment automatically to surface slopes should improve the stability of prosthesis and orthosis users, providing safer and more enjoyable ambulation on uneven terrain.

Applications