[Critical observations and the loads on femoral head replacement and the femoral bone calculated for a support in 3 points (author's transl)].

In their attempts at calculation of forces acting on a femoral head implant and the forces transmitted to the bone, some authors have assumed support of the implant in a few distinct points. It can be shown, however, that forces thus calculated very much depend on the direction and point of action of the supporting forces assumed arbitrarrily. The suggestion to implant a prosthesis in a "valgus" position cannot be justified by results obtained by the method in question. The change in the resultant force at the hip joint due to positioning in "varus" or "valgus" has not been taken into account by previous authors. In the valgus position of the femoral head prosthesis the resultant hip force is up to 33% greater than that in a "varus" position.