Ankle-foot prosthesis for automatic adaptation to sloped walking surfaces
View Patent ↗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.
1. An ankle-foot prosthesis, comprising:
a) a foot plate including a rear portion and a forward deflectable portion;
b) an ankle frame including anterior and posterior portions and an apex portion;
c) said posterior portion of said ankle frame attached to said rear portion of said foot plate;
d) a yoke including front and rear end portions, and a fulcrum point therebetween;
e) said yoke pivotally connected to said apex portion of said ankle frame at the fulcrum point thereof and including a member for attaching to a prosthetic leg;
f) a hydraulic damper having a first end pivotally connected to the front end portion of said yoke and a second end pivotally connected to said posterior portion of said ankle frame;
g) a stiffness member disposed in parallel to said damper;
h) a fluid control circuit for controlling extension and compression of said damper;
i) said anterior portion of said ankle frame including a curved surface inclined upwardly relative to said foot plate and forwardly toward said forward deflectable portion of said foot plate; and
j) said curved surface forming a roll-over surface for limiting a dorsiflexion deflection of said forward deflectable portion of said foot plate by a direct engagement therewith.
2. The ankle-foot prosthesis of claim 1 , wherein:
a) said fluid control circuit includes a cutoff valve for allowing dorsiflexion and plantarflexion of the ankle.
3. The ankle-foot prosthesis of claim 2 , wherein:
a) said cutoff valve allows movement of the ankle during a gait cycle between prosthetic side toe off and the next prosthetic side foot flat.
4. The ankle-foot prosthesis of claim 2 , wherein:
a) said cutoff valve allows compression of said damper during a gait cycle at least between prosthetic side toe off and 0 to 0.13 seconds thereafter.
5. The ankle-foot prosthesis of claim 2 , further comprising:
a) at least one check valve for said fluid control circuit for allowing extension of said damper.
6. The ankle-foot prosthesis of claim 1 , further comprising:
a) at least one variable fluid-flow resistor for said fluid control circuit for adjusting hydraulic fluid resistance in plantarflexion.
7. The ankle-foot prosthesis of claim 1 , wherein:
a) said stiffness member comprises a spring or an elastic member.
8. The ankle-foot prosthesis of claim 7 , wherein:
a) said spring is selected from the group consisting of a compression spring, an extension spring, a compression tube spring, an extension tube spring, and a curved leaf spring.
9. The ankle-foot prosthesis of claim 1 , wherein:
a) said ankle frame is generally U-shaped in cross-section.
10. The ankle-foot prosthesis of claim 9 , wherein:
a) said hydraulic damper extends through said ankle frame.
11. The ankle-foot prosthesis of claim 9 , wherein:
a) said stiffness member comprises a spring disposed generally concentric with said hydraulic damper.
12. The ankle-foot prosthesis of claim 11 , wherein:
a) said stiffness member and said hydraulic damper extend through said ankle frame.