Ankle-Foot Prosthesis for Automatic Adaptation to Sloped Walking Surfaces

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.

What is claimed is: 
     
         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 rear end portion of said yoke and a second end pivotally connected to 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 said ankle-foot prosthesis.   
     
     
         3 . The ankle-foot prosthesis of  claim 2 , wherein:
 a) said cutoff valve allows movement of said ankle-foot prosthesis 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 extension 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 1 , further comprising:
 a) at least one check valve for said fluid control circuit for allowing compression 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 dorsiflexion, plantarflexion, or both.   
     
     
         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 1 , wherein:
 a) said spring comprises at least one 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 , further comprising first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper. 
     
     
         10 . The ankle-foot prosthesis of  claim 1 , further comprising first and second cutoff valves for said fluid control circuit, said first cutoff valve arranged in parallel with said second cutoff valve, said first cutoff valve for allowing plantarflexion of said ankle-foot prosthesis, said second cutoff valve for allowing dorsiflexion of said ankle-foot prosthesis. 
     
     
         11 . The ankle-foot prosthesis of  claim 1 , further comprising first and second variable fluid-flow resistors for said fluid control circuit, said first variable fluid-flow resistor arranged in parallel with said second variable fluid-flow resistor, said first variable fluid-flow resistor for adjusting hydraulic fluid resistance in plantarflexion, said second variable fluid-flow resistor for adjusting hydraulic fluid resistance in dorsiflexion. 
     
     
         12 . The ankle-foot prosthesis of  claim 1 , further comprising at least one variable fluid-flow resistor for said fluid control circuit, said at least one variable fluid-flow resistor for adjusting fluid resistance in plantarflexion. 
     
     
         13 . The ankle-foot prosthesis of  claim 2 , further comprising first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper. 
     
     
         14 . The ankle-foot prosthesis of  claim 2 , further comprising:
 at least one variable fluid-flow resistor for said fluid control circuit for adjusting hydraulic fluid resistance in plantarflexion; and   first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper.   
     
     
         15 . The ankle-foot prosthesis of  claim 2 , further comprising:
 first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper; and   first and second variable fluid-flow resistors for said fluid control circuit, said first variable fluid-flow resistor arranged in parallel with said second variable fluid-flow resistor, said first variable fluid-flow resistor for adjusting hydraulic fluid resistance in plantarflexion, said second variable fluid-flow resistor for adjusting hydraulic fluid resistance in dorsiflexion.   
     
     
         16 . The ankle-foot prosthesis of  claim 5 , further comprising a cutoff valve for said fluid control circuit for allowing dorsiflexion of said ankle-foot prosthesis. 
     
     
         17 . The ankle-foot prosthesis of  claim 6 , further comprising:
 first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper; and   a cutoff value for said fluid control circuit for allowing dorsiflexion of said ankle-foot prosthesis.   
     
     
         18 . The ankle-foot prosthesis of  claim 9 , further comprising first and second cutoff valves for said fluid control circuit, said first cutoff valve arranged in parallel with said second cutoff valve, said first cutoff valve for allowing plantarflexion of said ankle-foot prosthesis, said second cutoff valve for allowing dorsiflexion of said ankle-foot prosthesis. 
     
     
         19 . The ankle-foot prosthesis of  claim 9 , further comprising:
 first and second variable fluid-flow resistors for said fluid control circuit, said first variable fluid-flow resistor arranged in parallel with said second variable fluid-flow resistor, said first variable fluid-flow resistor for adjusting hydraulic fluid resistance in plantarflexion, said second variable fluid-flow resistor for adjusting hydraulic fluid resistance in dorsiflexion; and   a cutoff valve for said fluid control circuit for allowing dorsiflexion of said ankle-foot prosthesis.   
     
     
         20 . The ankle-foot prosthesis of  claim 9 , further comprising:
 first and second cutoff valves for said fluid control circuit, said first cutoff valve arranged in parallel with said second cutoff valve, said first cutoff valve for allowing plantarflexion of said ankle-foot prosthesis, said second cutoff valve for allowing dorsiflexion of said ankle-foot prosthesis; and   first and second variable fluid-flow resistors for said fluid control circuit, said first variable fluid-flow resistor arranged in parallel with said second variable fluid-flow resistor, said first variable fluid-flow resistor for adjusting hydraulic fluid resistance in plantarflexion, said second variable fluid-flow resistor for adjusting hydraulic fluid resistance in dorsiflexion.   
     
     
         21 . The ankle-foot prosthesis of  claim 12 , further comprising:
 first and second check valves for said fluid control circuit, said first check valve arranged in parallel with said second check valve, said first check valve for allowing compression of said damper, said second check valve for allowing extension of said damper; and   first and second cutoff valves for said fluid control circuit, said first cutoff valve arranged in parallel with said second cutoff valve, said first cutoff valve for allowing plantarflexion of said ankle-foot prosthesis, said second cutoff valve for allowing dorsiflexion of said ankle-foot prosthesis.