ABSTRACT
The purpose of this study was to design intramedullary femoral stems that will optimally distribute the stresses to the bone. It was postulated that an ideal distribution of stresses would occur if the femoral stem had the same shape as the canal. However, because of the curved nature of the canal it was not possible to insert a canal replica. To make insertion possible, certain areas on the stem must be removed. Cross-section of the femoral canal at 5 and 10mm intervals, were non-destructively obtained by computer assisted tomography and each outline was stored on computer disk. Close-fit stem shapes were generated by computer aided design. These close-fit hip stem designs significantly improved total and priority region stem-canal contact. Further investigation employing both theoretical analysis and laboratory experimentation will examine the strength of these stems and theirs stress distribution to the femur.