Self-tapping screw for small-bone surgery

Claim 2

1 . 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 that of the distal shank, and an internal passage ( 4 ) in the manner of a cannula, characterized in that the distal shank ( 3 ) is threaded over its entire length to meet the threaded head ( 2 ), in that the distal end of the distal shank has, apart from milled portions forming angularly equidistant self-tapping faces ( 5 , 5 a, 6 , 6 a ) on the first distal threads, at least two milled portions forming angularly equidistant faces ( 9 , 5 a - 10 , 6 a ) about the longitudinal axis of the screw and such that they, with the cannula-type passage, determine at least two notches ( 11 ) in the end of this passage and, at least two self-boring edges ( 5 b, 6 b ) at the distal end of the screw, and in that the distal end of the screw thread of the head has, aside from milled portions forming angularly equidistant self-tapping faces ( 12 to 15 , 12 a to 15 a ) on the first threads of the proximal screw thread, milled portions forming angularly equidistant chamfered faces ( 16 - 19 ), determining boring edges ( 12 b - 15 b ) preceded by a short groove ( 2 b ) which follows the distal screw thread.

Claim 3

2 . Screw according to claim 1 , characterized in that the self-tapping milled portions ( 5 , 6 ) are preceded by milled portions ( 9 , 10 ) determining the notches ( 11 ) and also forming respectively common perpendicular faces ( 5 a, 6 a ) and in that angularly offset milled portions ( 7 , 8 ) determine, with the said perpendicular faces ( 5 a, 6 a ) the said cutting edges ( 5 b, 6 b ).

Claim 4

3 . Screw according to claim 1 , characterized by dimensions which lie in the following ranges: screw length: 10 mm to 60 mm head length 5-10 mm pitch of distal screw thread: between 1 and 3 mm pitch of proximal screw thread: between 0.8 and 2.5 mm diameter of the distal part (crest of thread): 2.5 to 5 mm.

Claim 5

4 . Set of several screws according to claim 1 , having different dimensions.

Claim 6

5 . Set according to claim 4 , characterized in that it contains a number of screws of different lengths, but having the same characteristics in terms of diameter and therefore diametral size and self-boring and self-tapping ability.

Claim 7

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

Claim 8

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

Claim 9

7 . Screw according to claim 6 characterized by dimensions which lie in the following ranges: screw length: 10 mm to 60 mm head length 5-10 mm pitch of distal screw thread: between 1 and 3 mm pitch of proximal screw thread: between 0.8 and 2.5 mm diameter of the distal part (crest of thread): 2.5 to 5 mm.

Claim 10

8 . Set of several screws according to claim 6 , having different dimensions.

Claim 11

9 . Set according to claim 8 , characterized in that it contains a number of screws of different lengths, but having the same characteristics in terms of diameter and therefore diametral size and self-boring and self-tapping ability.