US Patent 7625409 Ankle prosthesis

A fixed-bearing ankle prosthesis may include tibial and talar components whose articulating surfaces directly contact one another. The tibial component defines medial and lateral concave condylar facets separated by a convex central portion. The talar component includes medial and lateral convex condyles separated by a concave central portion. The condyles each have a single radius of curvature in a medial-lateral plane such that each condyle has a circular-arc cross-section continuously extending from the respective medial or lateral edge of the talar component to the concave central portion. The medial-lateral radii of the condyles are smaller than corresponding radii of the condylar facets.