According to the process, a series of n images, distributed along the receiving bone, in parallel transverse planes, are produced by scanography or NMR, the different images are standardised and standardised images of the contour of the medullary canal are deduced therefrom, several smoothing steps are carried out, along an ellipse, on the standardised images of the contour and, along a parabole, on projections of the n centres of the ellipses so as to determine an anatomical axis, and then various parameters of the smoothing ellipses; a simplified shape of an implant 10, adapted to the medullary canal, is reconstructed from the smoothing ellipses and the implant 10 is machined by means of a numerically controlled milling cutter using numerical information relating to the simplified form. <IMAGE>
