Abstract A joint for an artificial limb which simulates a natural bicondylar joint such as a knee. It consists essentially of a pintle which articulates the upper and lower members and has a ball and socket connection at one end with both members and at the other end a non-slip rolling connection with one member and a journal bearing in the other member. The pintle is coupled to each member through a restraint or torque control unit such as a slipping friction clutch or a torsionally resilient unit. In the case of an artificial knee joint, the non-slip connection may either be with the tibia, in which case the axis of the pintle remains fixed relative to the femur and the tibia is twisted about its axis on the ball and socket pivot as flexion occurs; or the non-slip connection may be with the femur, in which case the axis of the pintle remains fixed in relation to the tibia but slews on the femur as flexion occurs. The relative proportion of tibial rotation to flexion is a function of the difference between the torques of the two couplings, whose characteristics at any point in the flexion/extension cycle can be varied by devices such as a one-way clutch, or cam control of the pressure of the slipping clutch.
A mechanical joint for an artificial limb to replace a natural limb having a bicondylar articulation between upper and lower limb members comprising rigid upper and lower limb elements eaCh having medial and lateral side walls which overlap the respective corresponding medial and lateral side walls of the other element with working clearance; a pintle constituting a transverse pivot interconnecting the said elements and pivotally supported at its lateral end by a common ball on the lateral side walls of the said elements and at its medial end by a journal bearing in the medial side wall of one of the said elements and by a non-slip bearing on one edge of a slot in the medial side wall of the other element, and separate restraint units coupling the pintle to the said upper and lower elements respectively.
Claim 2
Dependent Claim
138 words
A mechanical joint for an artificial limb to replace a natural limb having a bicondylar articulation between upper and lower limb members comprising rigid upper and lower limb elements eaCh having medial and lateral side walls which overlap the respective corresponding medial and lateral side walls of the other element with working clearance; a pintle constituting a transverse pivot interconnecting the said elements and pivotally supported at its lateral end by a common ball on the lateral side walls of the said elements and at its medial end by a journal bearing in the medial side wall of one of the said elements and by a non-slip bearing on one edge of a slot in the medial side wall of the other element, and separate restraint units coupling the pintle to the said upper and lower elements respectively.
Claim 3
Dependent Claim
22 words
A mechanical joint as claimed in claim 1 wherein the pintle is journalled at its medial end in the lower limb element.
Claim 4
Dependent Claim
22 words
A mechanical joint as claimed in claim 1 wherein the pintle is journalled at its medial end in the upper limb element.
Claim 5
Dependent Claim
21 words
A mechanical joint as claimed in claim 1 wherein the non-slip bearing is provided by a cam fixed on the pintle.
Claim 6
Dependent Claim
35 words
A mechanical joint as claimed in claim 1 wherein the common ball is formed on the pintle and the lateral side wall of each limb element has a socket embracing part of the said ball.
Claim 7
Dependent Claim
63 words
A mechanical joint as claimed in claim 1 wherein the common ball is fixed on the lateral side wall of one of the said limb elements, the pintle has a socket embracing part of the said ball and having a part-spherical external surface, and the lateral side wall of the other limb element has a socket embracing part of the said pintle socket.
Claim 8
Dependent Claim
19 words
A mechanical joint as claimed in clain 1 wherein one of the restraint units is a slipping frictional clutch.
Claim 9
Dependent Claim
19 words
A mechanical joint as claimed in claim 1 wherein one of the restraint units has a torsionally resilient characteristic.
Claim 10
Dependent Claim
62 words
A mechanical joint as claimed in claim 1 combined with a spasm lock for locking the joint in an emergency and comprising a positive detent engageable with both limb elements in the operative position and resiliently displaceable to the inoperative position against a viscous damping device whose resistance to displacement is a function of the rate of increase of the displacing force.