Prosthetic ankle joint mechanism

A prosthetic foot and ankle assembly comprising a combination of

• a foot component, and
• an ankle joint mounted to the foot component and having a fixed range of dorsi-plantar flexion during walking, the ankle joint comprising a joint mechanism providing resistance to ankle flexion, wherein the joint mechanism comprises:
• a hydraulic piston and cylinder assembly having a piston which is movable so as to define a pair of variable-volume chambers, one chamber located on each side of the piston, and which is constructed and arranged to provide hydraulic damping continuously over the range of dorsi-plantar flexion, and
• a valve arrangement controlling the flow of hydraulic fluid between said chambers, the valve arrangement comprising first and second adjustable valves, respectively comprising first and second orifices each adjustable in area for independently presetting dorsi-flexion damping resistance and plantar-flexion damping resistance respectively such that during walking said first orifice is preset to provide said hydraulic damping at a first setting whenever the ankle joint is flexed in a dorsi-flexion direction and said second orifice is preset to provide hydraulic damping at a second setting whenever the ankle joint is flexed in a plantar-flexion direction,
• wherein the joint mechanism includes a first flexion limiter that limits dorsi-flexion of the joint mechanism to a dorsi-flexion limit and a second flexion limiter that limits plantar-flexion of the joint mechanism to a plantar-flexion limit, thereby defining said fixed range of dorsi-plantar flexion, the first and second flexion limiters comprising mechanical end stops of the joint mechanism, wherein the fixed range of dorsi-plantar flexion has a magnitude between 6degrees and 16degrees, and wherein the joint mechanism is structured and arranged such that the hydraulic damping provided by the hydraulic linear piston and cylinder assembly is non-electronically controlled.

A prosthetic foot and ankle assembly comprising a combination of:

• a foot component, and
• an ankle joint mounted to the foot component and having a fixed range of dorsi-plantar flexion during walking, the ankle joint comprising a joint mechanism providing resistance to ankle flexion, wherein the joint mechanism comprises:
• a hydraulic linear piston and cylinder assembly having a piston which is movable so as to define a pair of variable-volume chambers, one chamber located on each side of the piston, and which is constructed and arranged to provide hydraulic damping continuously over the range of dorsi-plantar flexion, and
• a valve arrangement controlling the flow of hydraulic fluid between said chambers, the valve arrangement comprising first and second adjustable valves, respectively comprising first and second orifices each adjustable in area for independently presetting dorsi-flexion damping resistance and plantar-flexion damping resistance respectively such that during walking said first orifice is preset to provide said hydraulic damping at a first setting whenever the ankle joint is flexed in a dorsi-flexion direction and said second orifice is preset to provide hydraulic damping at a second setting whenever the ankle joint is flexed in a plantar-flexion direction,
• wherein the joint mechanism includes a first flexion limiter that limits dorsi-flexion of the joint mechanism to a dorsi-flexion limit and a second flexion limiter that limits plantar-flexion of the joint mechanism to a plantar-flexion limit, thereby defining said fixed range of dorsi-plantar flexion, the first and second flexion limiters comprising mechanical end stops of the joint mechanism, and wherein the joint mechanism is structured and arranged such that the hydraulic damping provided by the hydraulic linear piston and cylinder assembly is non-electronically controlled,
• a lower end of the ankle joint being pivotally mounted to the foot component at a first pivotal connection about which said fixed range of dorsi-plantar flexion occurs, and a lower end of the linear piston and cylinder assembly being pivotally connected to the foot component at a second pivotal connection displaced in an anterior-posterior direction from the first pivotal connection, an upper end of the ankle joint having a pyramid alignment interface for connection to a shin component defining a shin axis, wherein a central axis of the pyramid alignment interface, a central axis of the linear piston and cylinder assembly, and the second pivotal connection are all substantially in linear alignment with the shin axis when the pyramid alignment interface is connected to the shin component.