The shaft has an anchoring area (27, 29) which is arranged inside a femur in order to anchor the prosthesis into bone and a head area which is axially adjacent to the anchoring area on a near side. The maximum cross-sectional dimension of a head area is at the most equal and, in particular, smaller than the maximum diameter of the anchoring area in such a way that the maximum cross-sectional dimension of the shaft (11) is in the anchoring area.
