(iii) Proximal fixation stems yield optimal fixation

Abstract

Distal fixation with extensively porous-coated stems has demonstrated good fixation, but a high incidence of proximal stress-shielding. Proximal femoral fixation was developed to load the femur proximally to avoid the problem of stress-shielding. First generation proximal fixation stems had a high percentage of thigh pain and loosening. Second generation designs with mechanical fixation only in the diaphysis (smooth distal stems) improved fixation, but still demonstrated a relatively high incidence of thigh pain. It is now evident that biologic fixation is required in the diaphysis. Still, proximal fixation must occur in the cortical bone of the proximal femur. Stems with a geometry that primarily load the proximal femur, and yet achieve biologic (osseous) fixation in the diaphysis, result in ‘transitional stress transfer’ to the femur. Contemporary designs that employ these principles are successful in providing durable fixation, a low incidence of thigh pain, and avoid the problem of stress-shielding.