Abstract

A prosthetic joint for replacing a metatarsal-phalangeal joint of a human toe has a head with a convex bearing surface that moves against the concave bearing surface of a base. The base is elliptical and formed by two different radii of curvature with a desired ratio. The head has a generally concave bone confronting surface with four different generally flat surface areas, one surface is horizontal and parallel to the longitudinal axis of the metatarsal bone, another extends approximately perpendicular thereto, and two others extend at angles to the longitudinal axis. The horizontal lower surface allows better distribution of vertical force and helps to resist separation of the head from the bone. The head exterior surface has four different regions formed by four different radii of curvature with desired ratios to one another. These four head surfaces allow the head and base to reproduce pivoting of a healthy toe joint. A method for installing the prosthetic joint is also disclosed.