Prosthetic device for the tarsal joint

Claim 1

A partial prosthesis for the human tarsal joint, comprising a first rigid member of synthetic plastic material, substantially block shaped, having an exposed concavely curved first surface of part-cylindrical shape, and a support surface facing away from said first surface and including a plurality of discrete trapezoidal-shaped projections of different sizes extending over the entire support surface, substantially diverging in a direction away from said support surface; a second rigid member of metallic material, substantially plate-shaped and of substantially trapezoidal outline, having an exposed convexly curved second surface of part cylindrical shape with a radius of curvature different from that of said first surface, and a support surface facing away from said second surface and including a plurality of discrete trapezoidal-shaped projections substantially diverging in a direction away from said support surface provided on only a center portion of said support surface; whereby said first rigid member is adapted to be fastened to the head of the tibia, and said second rigid member is adapted to be fastened to the talus so that said first and second members engage each other in line contact and have limited freedom of lateral displacement along the line of contact.