Abstract: Implantable device, such as a femoral head prosthesis, with a body (12) of biocompatible material shaped to suit its medical function, which forms an internal cavity (16) and has open apertures (18) that lead from the cavity (16) to the outside. The cavity (16) serves to receive spongiosa or other biological material into which the tissue that surrounds the implanted device is intended to grow through the apertures (18). The device is provided with at least two electrodes (30, 32), at least one of which is located in the cavity (16) spaced apart from the inside of the body (12) that forms the cavity (16). The electrodes are provided with an arrangement for supplying a low-frequency alternating voltage, so that by means of the supplied voltage a low-frequency electrical alternating field and a low-frequency alternating current, whereby the tissue growth is promoted, are created inside the cavity (16).