Self-tapping screw for small-bone surgery

Self-tapping screw for small-bone surgery, particularly of the Barouk screw type, comprising:

• a threaded proximal head (2) and a threaded distal shank (3),
• the pitch of the screw thread on the proximal head being shorter than the pitch of the screw thread on the distal shank, and
• an internal passage (4) in the manner of a cannula, wherein,
• the distal shank (3) is threaded over its entire length to meet the threaded head (2),
• the distal end of the distal shank has milled portions forming angularly equidistant self-tapping faces (5, 5a, 6, 6a) on first distal threads,
• at least two milled portions, preceding said self-tapping faces (5, 5a, 6, 6a) and forming angularly equidistant faces (9, 10) about the longitudinal axis of the screw and having respectively common perpendicular faces (5a, 6a) with the taping faces that with the internal passage, determine at least two notches (11) in the end of the internal passage, and
• angularly offset milled portions (7, 8) determine with said perpendicular faces (5a, 6a) at least two self-boring cutting edges (5b, 6b) at the distal end of the screw, and
• milled portions at the distal end of the screw thread of the head, and located aside from milled portions forming angularly equidistant self-tapping faces (12 to 15, 12a to 15a) on first threads of the proximal screw thread, form angularly equidistant chamfered faces (16–19), the chamfered faces determining boring edges (12b–15b), and
• the milled portions are preceded by a short groove (2b) which follows the distal screw thread.

A self-tapping surgery screw, comprising:

• a threaded proximal head (2);
• a threaded distal shank (3), the shank threaded over the entire overall length thereof;
• a relief groove (2b) directly connecting the head to the shank, a maximum diameter of the relief groove being less than a maximum diameter of the shank;
• an axial canal (4) formed throughout the entire overall length of the head, relief groove, and the shank;
• a socket (20) in the head, the socket shaped to take a screwing tool end;
• a first self-boring part located at the terminal end of the shank and including at least two self-boring cutting edges (5b, 6b) at the distal end of the shank, and at least two milled portions forming angularly equidistant faces (9, 10) about the longitudinal axis of the shank that together with the axial canal define at least two notches (11) in the terminal end of the axial canal;
• and
• a second self-boring part located at an end of the head adjacent the relief groove and opening to the relief groove.