Ankle-foot prosthesis for automatic adaptation to sloped walking surfaces
Inventors
Hansen, Andrew H. • Nickel, Eric A.
Assignees
US Department of Veterans Affairs • University of Minnesota System
Publication Number
US-11129734-B2
Publication Date
2021-09-28
Expiration Date
2033-09-10
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Abstract
An ankle-foot prosthesis includes a foot plate, an ankle frame attached to the foot plate, a yoke pivotally connected to the ankle frame and including a member for attaching to a leg, a damper having a first end connected to the yoke and a second end connected to the ankle frame, and a control mechanism for switching the damper between low and high settings.
Core Innovation
The invention concerns an ankle-foot prosthesis designed for automatic adaptation to level and sloped walking surfaces, primarily for use by lower limb amputees to improve walking stability and comfort. The prosthesis includes a foot plate with a rear and a forward deflectable portion, an ankle frame attached to the foot plate, a yoke pivotally connected to the ankle frame for leg attachment, a hydraulic damper connected between the yoke and ankle frame, a stiffness member disposed in parallel to the damper, and a fluid control circuit to control damper extension and compression.
The ankle frame's anterior portion includes a curved surface inclined upwardly relative to the foot plate, forming a roll-over surface to limit dorsiflexion deflection of the foot plate by direct engagement. The damper's compression and extension damping values are controllable, allowing a high extension damping during stance to lock the ankle in a plantar flexed position and low extension damping at toe-off to allow return to a neutral or dorsiflexed position for swing phase. This design enables the foot to "find the surface" automatically on every step, adapting to different slopes for walking and providing a stable mode for standing or swaying tasks.
Claims Coverage
The patent includes one independent claim describing the main inventive features of the ankle-foot prosthesis.
Ankle-foot prosthesis structure and components
An ankle-foot prosthesis comprising a foot plate with rear and forward deflectable portions; an ankle frame with anterior, posterior, and apex portions; posterior ankle frame attached to rear foot plate; a yoke with front and rear ends and a fulcrum point pivotally connected to the ankle frame apex and including a leg attachment member.
Hydraulic damper and stiffness member configuration
A hydraulic damper pivotally connected between the front end of the yoke and the anterior portion of the ankle frame, with a stiffness member disposed in parallel to the damper.
Fluid control circuit with dorsiflexion control
A fluid control circuit controlling extension and compression of the damper, including an anterior ankle frame curved surface forming a roll-over surface that limits dorsiflexion by direct engagement with the foot plate forward deflectable portion.
The claim covers an ankle-foot prosthesis integrating specific structural components, a hydraulic damper paired with a stiffness member, and a fluid control circuit designed to control ankle movement and adapt to walking surfaces by limiting dorsiflexion and adjusting damping.
Stated Advantages
Allows a user to have a more natural and comfortable gait.
Provides energy-efficient walking.
Features a simple design using fewer parts, requiring low or no maintenance.
Compact and more durable compared to systems with many mechanical parts prone to failure.
Resists or prevents undesirable backward swing that could lead to imbalance or injury.
Quieter, lightweight, less clumsy, and more user-friendly.
Automatically adapts to different sloped walking surfaces on every step.
Easily switches into a stable mode suited for standing or swaying tasks, such as washing dishes.
Documented Applications
Use by lower limb amputees to ambulate over various sloped terrain with improved stability and safety.
Allows users to perform standing and swaying tasks more stably.
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