[Anatomical and biomechanical considerations for medullary nailing (author's transl)].

By using X-ray films of 390 adult femurs and 15 cadaveric femurs of Japanese origin, and by measuring successive cross-sections the authors have made morphological and statistical analyses of the shape of the femoral medullary canal. These studies suggest new dimensions for the diameter of the reamer and the amount of contact area between nail and inner cortex. Furthermore it was found that the physiological antecurvature of the femur on the lateral view does not correspond with the prebending of the OA-nail. The authors made some mechanical experiments on four types of nails which are widely used today. As a consequence of these studies, the authors developed a new elastic nail for trial (Okayama-nail). This new type of nail greatly increases the area of contact with the inner femoral cortex. Obviously this nail satisfies better all of Kuentscher's originally mentioned requirements an intramedullary nail.