[The stress in femoral prosthesis: a study of the importance of the diaphyseal support and horizontal setting (author's transl)].

This study by strain-guauge methods trends to estimate relative stress in the fresh, adult human cadaver femur, before and after implantation of a cement-free (madreporique) prosthesis with a trochantero-diaphyseal support. In contrast with Blaimont, Oh and Harris statements (after insertion of a conventional femoral component with an oblique setting over the femoral neck and a short stem, the pattern of strain in the proximal part of the femur is reversed compared with that in the intact femur, the maximum strain occuring around the tip of the prosthesis rather than at the calcar femorale), the Authors found that a dihedral foundation--with an horizontal setting of the prosthesis over the calcar--, and a long stem do not reverse the normal pattern of strain in the femur. This biological balance is necessary to bone-ingrowth development for implant anchoring. This "in vitro" study does not deal with this bony fixation but intends to approximate the initial static requirements, just after the uncemented prosthetic insertion, for such a bone ingrowth.