Artificial joint

The invention relates to an artificial joint (3), in particular for replacement of an upper ankle joint, with a first main joint surface (1) forming a joint socket (4), in particular for replacement of the tibia, consisting of a principal functional plane of the joint (3) corresponding to the sagittal plane. parallel, concave curvatures is constructed and with a with the main joint surface (1) in operative connection passing second joint surface (2) as part of a particular the talus replacing condyle (5) with in the main functional plane convex curvatures (7, 8, 9, 10), which are matched to the first main joint surface (1). In order to achieve at the same time a high load capacity and optimal mobility of the joint (3) as a function of the respective joint position, the radii of the curvatures (7, 8, 9,