The invention concerns a device to be implanted and assembled in a patient, the device comprising a base part (1) with a liquefiable material, and comprising a nail or plate (85) for being inserted in an inner space of a tubular bone (45) for stabilizing a fracture of the tubular bone, the nail or plate comprising a non-liquefiable material. The device is to be assembled with a method that comprises providing a through opening (10) in the bone tissue (11) of the tubular bone (45), positioning the nail or plate (85) relative to the bone tissue (11), positioning the base part (1) in the through opening (10) such that a distal end or portion thereof is in contact with the nail or plate (85) or such that the base part reaches through a through opening of the nail or plate (85) and is in contact with an opposite wall of the tubular bone (45) and its proximal face is situated in the region of a proximal mouth of the opening (10), and pressing the base part (1) against the nail or plate (85) or the opposite wall and coupling mechanical vibration into the base part (1) for liquefying the liquefiable material of the based part and letting it fill a space between the based part (85) and the bone wall of the tubular bone (45), whereby said space forms a positive fit connection with the liquefiable material.
