Prosthetic knee joint for attachment to a natural or prosthetic leg

摘要

A femur-engaging upper base and a tibia-engaging lower base of a prosthetic knee joint are positively interconnected by an inextensible and incompressible coupling mechanism allowing the two bases to swing vertically between two relative limiting positions about 135 apart, one of these limiting positions corresponding to a substantial alignment of the femur with the tibia. Throughout the swing, a more forwardly located first point (A) and a more rearwardly located second point (B) on the upper base are held at a substantially fixed distances from a more rearwardly located third point (D) and from a more forwardly located fourth point (C) on the lower base, respectively, these four points thus constituting the fulcra of a four-bar kinematic linkage. The coupling mechanism may be realized with a pair of intersecting rigid links hinged to the bases, arcuate guides in cheek plates for studs laterally projecting from the bases at the aforementioned four points, confronting projections on the bases rollingly engaging each other along curved ridges substantially conforming to the centrodes for the coupler motion of the four-bar linkage, or some combination thereof. Where crossed links are used, their hinges may be constructed as universal joints allowing limited relative rotation of the bases about an axis lying in the swing plane, such rotation being impeded by a link-engaging detent in the position of alignment between femur and tibia.