FIELD: medicine.SUBSTANCE: medical device implantable into a human or animal body or used to reinforce a human or animal hard tissue to implant a separate implant comprises a shell element configured to contact to the living hard tissue and/or material substituting the hard tissue during surgical intervention； the above shell element has a long slot forming a long canal extending from the proximal end of the shell element in the distal direction, and a group of passages in the wall of the above canal. The medical device also comprises a diluting element insertable or inserted into the long canal and at least partially diluted under the effect of energy applied from the proximal side so that the diluted material outflows through the passage in the wall from the long canal into the structural elements of the hard tissue and/or material substituting the hard tissue； the medical device is characterised by a guide construct comprising a structure varying in dependence to an azimuth angle in relation to the long axis of the long canal so that to direct different parts of the diluted material to different of the above passages； the guide construct comprises the main part of the guide construct, and a separation part projecting in the proximal direction from the above main part of the guide construct； the separation part comprises at least one wall projecting in the proximal direction from the above main part of the guide construct. The method for fixing the medical device in a human or animal body comprises the following stages: providing the shell element with the long slot forming the long canal extending from the proximal end of the shell element in the distal direction； the wall of the above canal has a group of passages； providing the diluted material； bringing the shell in contact with the human or animal hard tissue and/or material substituting the hard tissue； pressing the diluted material in the distal direction to the guide construct when it is at least partially
