Prosthetic implant having segmented flexible stem

A prosthesis for implanting into a bone having a cavity, the prosthesis comprising:

• a body;
• and
• a stem fastened to the body at a proximal end and extending longitudinally away from the body to form a distal end, the stem comprising an elongated core and a plurality of segments extending outward from the core, the core and the segments consisting essentially of a microstructurally consistent implant material, the stem having an outer layer that at least partially contacts an inner surface of the cavity of the bone when the prosthesis is implanted into the cavity of the bone, the segments being spaced apart so as to define a transverse groove surrounding the core between adjacent segments, the longitudinal length of at least one segment being greater than the longitudinal length of each groove, wherein the longitudinal length of at least two transverse grooves varies such that the stiffness of the stem varies from the proximal end to the distal end of the stem.