A prosthetic implant having a fixation stem with varying stiffness is disclosed.
The stem comprises an elongated core and segments extending outward from the core.
The segments are spaced apart so as to define transverse grooves surrounding the
core between adjacent segments. The longitudinal length of the grooves, and the
materials used for the core and the segments are selected such that the stiffness
of the stem varies from the proximal end to the distal end. Typically, the stiffness
of the stem will be lower at the distal end such that the distal end of the stem
bears less force when loaded and thereby transfers more load to the proximal end
of the stem, which has a higher stiffness. As a result, stress shielding, in which
the load bypasses the proximal end of the stem, is minimized and bone resorption
adjacent the proximal end of the stem is decreased.
