Patent ID: 7883548

Claim:
A prosthetic knee joint mechanism comprising first and second knee parts which are rotatable relative to each other in joint flexion and joint extension, and a load-activated knee-stabilizing device for resisting joint flexion during a stance phase of the walking gait cycle, the stabilizing device comprising means defining a fluid-filled fluid displacement chamber associated with the first knee part and a piston which is connected to the second knee part so as to be driven by rotation of the second knee part relative to the first knee part and which is so arranged within the chamber that it divides the chamber into first and second variable volume chamber parts which are interconnected by a fluid passage, the stabilizing device further comprising a valve associated with the fluid passage and including a valve member which is movable within a housing between a stabilizing position in which the valve member at least restricts fluid flow through the passage so as to resist joint flexion and an open position in which fluid can flow through the passage to allow joint flexion, wherein the valve member is movable towards its open position in response to fluid pressure in the interconnecting passage upstream of the valve member caused by application of a flexion torque to the knee joint mechanism, and wherein the stabilizing device includes a stance phase weight-responsive valve control arrangement which, in use, operates in response to patient loading to at least resist movement of the valve member in the direction of its open position thereby to cause the mechanism to resist joint flexion during the stance phase.