Abstract: The invention relates to an artificial hip joint, in which the surfaces of both the socket and the ball of the joint are in the form of rotational bodies (rotational surfaces) deviating from the normal spherical shape. The rotational surfaces are in the form of Pascal's curve or screw rather than being spherical. In addition, provision is made such that an angular deviation .alpha. is present between the axis of the femoral throat of the thigh and the rotary axis of the ball of the joint when viewed from the top, such deviation preferably equal to 10.7.degree..+-.3.degree..

Abstract: 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.degree. 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.