Lower limb prosthesis

Abstract

A lower limb prosthesis comprises an attachment section ( 10 ), a shin section ( 12 ), a foot section ( 14 ), a knee joint ( 16 ) pivotally connecting the attachment section ( 10 ) and the shin section ( 12 ), and an ankle joint ( 22 ) pivotally connecting the shin section ( 12 ) and the foot section ( 14 ). The knee joint includes a dynamically adjustable knee flexion control device ( 18 ) for damping knee flexion. The prosthesis further comprises a plurality of sensors ( 52, 53, 54, 85, 87 ) each arranged to generate sensor signals indicative of at least one respective kinetic or kinematic parameter of locomotion or of walking environment, and an electronic control system ( 100 ) coupled to the sensors ( 52, 53, 54, 85, 87 ) and to the knee flexion control device ( 18 ) in order dynamically and automatically to modify the flexion control setting of the knee joint ( 16 ) in response to signals from the sensors. When the inclination sensor signals indicate descent of a downward incline, the damping resistance of the knee flexion control device ( 18 ) is set to a first level during a major part of the stance phase of the gait cycle and to a second, lower level during a major part of the swing phase of the gait cycle. During an interval including a latter part of the stance phase, the knee flexion control device ( 18 ) is adjusted so that the damping resistance to knee flexion is between the first and second levels.

1 - 16 . (canceled) 
     
     
         17 . A lower limb prosthesis comprising:
 an attachment section,   a shin section,   a foot section,   a knee joint pivotally connecting the attachment section and the shin section, the knee joint including a dynamically adjustable knee flexion control device for damping knee flexion,   an ankle joint pivotally connecting the shin section and the foot section,   a plurality of sensors each arranged to generate sensor signals indicative of at least one respective kinetic or kinematic parameter of locomotion or of walking environment, and   an electronic control system coupled to the sensors and to the knee flexion control device in order dynamically and automatically to modify the flexion control setting of the knee joint in response to signals from the sensors, including from a first of the said sensors which is operable to generate inclination sensor signals indicative of ground inclination and from a second of the said sensors which is operable to generate speed sensor signals indicative of speed of locomotion,   wherein the arrangement of the sensors, the electronic control system and the knee flexion control device is such that when the inclination sensor signals indicate ascent of an upward incline, the damping resistance of the knee flexion control device increases as the speed of locomotion increases.   
     
     
         18 . A lower limb prosthesis as claimed in  claim 17 , wherein the knee flexion control device comprises a pneumatic piston mounted on a piston rod which is reciprocable in a pneumatic piston chamber having upper and lower parts on opposite sides of the pneumatic piston. 
     
     
         19 . A lower limb prosthesis as claimed in  claim 18 , wherein resistance of the pneumatic piston to flexion is controlled by a needle valve in a passage interconnecting the upper and lower parts of the pneumatic piston chamber, the needle valve being adjustable by an electrical stepper motor and an associated screw-threaded shaft connected to the needle member of the needle valve. 
     
     
         20 . A lower limb prosthesis as claimed in  claim 18 , wherein the pneumatic piston contains a pneumatic bypass passage including a non-return valve which is oriented such that the pneumatic piston provides negligible resistance to knee extension. 
     
     
         21 . A lower limb prosthesis as claimed in  claim 18 , wherein the knee flexion control device further comprises a hydraulic piston mounted on the piston rod which is reciprocable in a hydraulic piston chamber. 
     
     
         22 . A lower limb prosthesis as claimed in  claim 21 , wherein during a stance phase of a walking gait cycle, the knee flexion control device provides predominantly hydraulically controlled flexion and extension and during a swing phase of the walking gait cycle the knee flexion control device provides predominantly pneumatic controlled flexion. 
     
     
         23 . A lower limb prosthesis as claimed  claim 17 , wherein the ankle joint includes a dynamically adjustable hydraulic ankle flexion control device having a piston which is reciprocable in a cylinder to define upper and lower chambers which are linked by a pair of passages, the hydraulic ankle flexion control device being arranged to provide independent adjustment of dorsi-flexion and plantar-flexion damping resistance. 
     
     
         24 . A lower limb prosthesis as claimed in  claim 23 , wherein the electronic control system is further coupled to the ankle flexion control device in order dynamically and automatically to modify the flexion control setting of the ankle joint in response to signals from the sensors,
 wherein the arrangement of the sensors, the electronic control system and the ankle flexion control device is such that when the inclination sensor signals indicate ascent of an upward incline, the dorsi-flexion damping resistance of the ankle flexion control device decreases as the speed of locomotion increases.   
     
     
         25 . A lower limb prosthesis as claimed in  claim 24 , wherein the arrangement of the sensors, the electronic control system and the ankle flexion control device is such that when the inclination sensor signals indicate ascent of an upward incline, the plantar-flexion damping resistance of the ankle flexion control device increases as the speed of locomotion increases.