Abstract: A shoulder prosthesis includes a shaft and, at the head of the shaft, a member having a surface that is hemispherical and extends continuously beyond the base of the hemisphere with a smaller radius to provide, in use, at least 210.degree. of total rotation.

Abstract: A hip prosthesis comprises a generally cylindrical elongate shaft adapted for insertion into the femur of a subject, and a generally spherical head mounted on the shaft via a generally cylindrical neck, the dimensions of the head, neck and shaft being defined. The proximal end of the shaft is spaced by 0.5-1.5 cm from the plane normal to the longitudinal axis of the shaft and through the center of the head, to avoid abduction. The center of the head is offset by no more than 4.25 cm from the longitudinal axis of the shaft, to minimise damage to the subject during insertion of the prosthesis.