Knee unit for above-knee prosthetic leg

#This invention relates to a fluid controlled knee unit for an above-knee prosthetic leg and, more particularly, to a knee unit of the type described which in one form of the invention is operable for swing control and in another form of the invention is operable for stance control.

#In an above-knee prosthetic leg, the swing of the knee and shank of the leg is controlled in an effort to duplicate the function of a normal knee produced by the quadriceps and hamstring muscle group during the swing phase of gait. Stance control is used to lock the prosthetic leg to prevent buckling when the heel strikes a walking surface and to unlock the leg when the weight of an amputee is transferred from heel to toe.

#One of the primary problems in providing a satisfactory above-knee prosthetic leg involves swing control so that movement by the amputee at varying speeds can be comfortably accomplished. This can be achieved by fluid or friction controlled systems. Fluid controlled systems are advantageous in this regard since with friction systems the operation of the system is constant with respect to speed and therefore the amputee must make adjustments to the prosthetic leg to vary the speed of movement, as may be required.

#FIG. 1 is a diagrammatic representation generally illustrating an above-knee prosthetic leg incorporating the invention.

#FIG. 2 is a schematic representation particularly illustrating a form of the invention wherein a knee unit is arranged for swing control according to the invention.

#FIG. 3 is a schematic representation particularly illustrating a form of the invention wherein a knee unit is arranged for stance control according to the invention.

#With reference first to FIG. 1, an above-knee prosthetic leg is designated generally by the numeral 2. Prosthetic leg 2 includes a socket 4 of a suitable material such as plastic for receiving a leg stump 5 of an amputee, and which socket 4 is coupled by conventional means to the top of a knee cage 6. Knee cage 6 supports a knee control unit 7 which is arranged for swing control or phase control as will be hereinafter described. A pylon 8 is coupled to the bottom of knee cage 6 by conventional means and is coupled by likewise conventional means via a pyramid connector 10 to a prosthetic foot 12.

#FIG. 2 illustrates a knee control unit 7A for swing control in accordance with the invention. Thus, a pivot mount 16 which couples unit 7A to cage 6 (FIG. 1) is coupled via a length adjusting nut 18 to a piston rod 20. Piston rod 20 extends through a piston cap 22 via a bushing 24 and extends into a piston cylinder 26. A plunger block 28 within cylinder 26 is coupled to a piston 30. Piston cylinder 26 contains therein a suitable fluid 31 which may be, for purposes of illustration, a silicone oil. A valve body 32 is coupled to cylinder 26 and supports a flow control valve 34 via a seal 36.

#A bladder cylinder is designated by the numeral 38. A bladder 40 is disposed within bladder cylinder 38 and includes a bladder valve 42. A cap 44 and a cap seal 46 are coupled to bladder cylinder 12. A valve nut 48 is in threaded engagement with a valve housing 50.