Bone screw and fastening tool for same

• US 20030023243A1
• Filed: 07/17/2002
• Published: 01/30/2003
• Est. Priority Date: 07/27/2001
• Status: Active Grant

• Current Assignee: Biedermann Technologies GmbH & Co. KG
• Original Assignee: Biedermann Motech GmbH
• Inventors: Biedermann, Lutz, Harms, Jurgen
• Granted Patent: US 6,723,100 B2
• Time in Patent Office: Days
• US Class Current: 606/73
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7082 for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws driving other bone screws A61B17/8875
• CPC Class Codes: A61B 17/7091 for applying, tightening or removing longitudinal element-to-bone anchor locking elements, e.g. caps, set screws, nuts or wedges

Abstract

The invention relates to a bone screw and a tool for fixing same. A bone screw has a screw element (1), comprising a screw shank (2) and a screw head (3), a cylindrical receiver part (5) with a bore coaxial to the cylindrical axis coming from one end (8) of the cylinder, an opening (6) extending crosswise to the cylindrical axis for receiving a rod (16) to be connected to the bone screw, an inner thread (10) at one end (8) and a screw (13) cooperating with it and also an outer thread (11) at one end (8) and a nut (14) cooperating with it. Both threads (10, 11) are constructed as running in opposite directions. A fastening tool (21, 21′) acts as tool for fixing a bone screw, with a central shank (23), which is constructed at one end for engagement with a screw or nut and at its other end has a first handle (22), a sleeve-shaped shank (24), surrounding the central shank (23), which is constructed at one end for engagement with a screw or nut and at its other end has a second handle (25), both shanks (23, 24) being rotatable with respect to one another.

Claims

1. Bone screw with

a screw element (1) comprising a screw shank (2) and a screw head (3)

a cylindrical receiver part (5) for receiving a rod (16) with a bore coaxial to the cylindrical axis coming from one end (8) of the cylinder,

an opening (6) extending cross-wise to the cylindrical axis for receiving the rod (16) to be connected to the bone screw, an inner thread (10) at one end (8) and a screw (13) cooperating with it,

an outer thread (11) at one end (8) and a nut (14) cooperating with it,

characterised in that the two threads (10, 11) are constructed as running in opposite directions.

3. Bone screw according to claim 1 or 2, characterised in that the screw head (3) and the receiver part (5) are constructed in one piece.

4. Bone screw according to claim 1 or 2, characterised in that the opening (6) is constructed as a U-shaped recess open to one end (8).

5. Bone screw according to claim 1, characterised by a pressure element (18) acting on the screw head (3) of the inserted screw element (1), arranged in the receiver part (5) above the screw head (3).

10. Bone screw according to claim 1, characterised in that the nut (14) can be screwed on to the cylindrical receiver part (5) so far that it presses on the rod (16) and fixes this by means of pressure.

12. Fastening tool (21, 21′

) for fixing a bone screw according to one of claims 1 to 11, with a central shank (23) constructed at one end for engagement with a screw or nut and at its other end has a first handle (22),

a sleeve-shaped shank (24) surrounding the central shank (23), which is constructed at one end for engagement with a screw or nut and at its other end has a second handle (25), both shanks (23, 24) being rotatable against each other.

13. Fastening tool (21′

) according to the preceding claim, characterised in that

the central shank (23) is divided in the longitudinal direction into a first shank section (23a) and a second shank section (23b), between which gears with an input side connected to the first shank section (23a) and an output side connected to the second shank section (23b) are arranged, wherein the gears are constructed in such a way that the direction of rotation of a torque entering on the input side is reversible on the output side and wherein the gears have a gear housing (30) to which the sleeve-shaped shank (24) is connected as fixed against rotation, so the input torque introduced into the first shank section (23a) can be diverted as an oppositely directed output torque on the second shank section (23b) of the central shank (23) and/or as an output torque directed the same way as the input torque on the sleeve-shaped shank (24).

14. Fastening tool (21′

) according to the preceding claim, characterised in that the gear housing (30) forms the second handle, so that a torque introduced via the first handle (22) or the gear housing (30) can be transferred to the central shank (23) and the sleeve-shaped shank (24) in opposite directions in each case by fixing the first handle (22) or the gear housing (30) at desired proportions.

15. Fastening tool (21′

) according to claim 12 or 13, characterised in that

the first shank section (23a) of the central shank (23) is held as rotatable by a first bore (32a) provided in the gear housing (30) and is connected at the end as fixed against rotation to a first toothed wheel (37), the second shank section (23b) of the central shank (23) is held as rotatable by a second bore (35a) provided in the gear housing (30) and is connected at the end as fixed against rotation to a second toothed wheel (38), and at least one third toothed wheel (41, 42), which is in engagement with the first and second toothed wheel (37, 38), is held as rotatable in the gear housing (30).

16. Fastening tool (21′

) according to the preceding claim, characterised in that the third toothed wheel (41, 42) is held as rotatable on a shaft (34) standing perpendicular to the axis of the two shanks (23, 24).

17. Fastening tool (21′

) according to one of the two preceding claims, characterised in that a fourth toothed wheel (42) is provided, arranged opposite the third toothed wheel (41).

18. Fastening tool (21′

) according to the preceding claim, characterised in that the shaft (34) extends from one side of the gear housing (30) to the other side and the third and fourth toothed wheels (41, 42) are jointly held thereon.

19. Fastening tool (21′

) according to one of claims 15 to 18, characterised in that the toothed wheels (37, 38, 41, 42) are constructed as bevel wheels.

2. Bone screw with

a screw element (1) comprising a screw shank (2) and a screw head (3)

a cylindrical receiver part (5) for receiving a rod (16) with a bore coaxial to the cylindrical axis coming from one end (8) of the cylinder and an opening (6) extending cross-wise to the cylindrical axis for receiving the rod (16) to be connected to the bone screw, an inner thread (10) at one end (8) and a first screw (12) cooperating with it, which has a central bore (12a) with an inner thread (15), and a second screw (13′

) cooperating with the inner thread (15) for fixing the rod (16),

characterised in that the two threads (10, 15) are constructed as running in opposite directions.

6. Bone screw according to claim 2, characterised by a pressure element (18′

) acting on the screw head (3) of the inserted screw element (1), arranged in the receiver part (5) above the screw head (3).

7. Bone screw according to the preceding claim, characterised in that the pressure element (18′

) is constructed in one piece with the first screw (12).

8. Bone screw according to the preceding claim, characterised in that the pressure element (18′

) has a recess (18c′

) for receiving the rod (16), the depth of which in the axial direction is greater than the diameter of the rod (16).

9. Bone screw according to claim 2, further characterised by a snap ring (14′

) provided in the circumferential direction on the outer circumference of one end (8) of the receiver part (5).

11. Bone screw according to claim 2, characterised in that the second screw (13′

) can be screwed into the first screw (12) so far that it presses on the rod (16) and fixes this by means of pressure.