BONE SCREW

• US 20090281580A1
• Filed: 06/27/2007
• Published: 11/12/2009
• Est. Priority Date: 07/05/2006
• Status: Abandoned Application

• Current Assignee: Implants International Limited
• Original Assignee: Implants International Limited
• Inventors: Emannuel, Mohan
• Application Number:
  US12/307,314
• Publication Number:
  US 20090281580A1
• Time in Patent Office: Days
• US Class Current: 606/304
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts

Abstract

The cavity of a screw body presents a portion with an enlarged cross-section forming a chamber, positioned such that it is set back from the proximal surface of said head, over a sufficient distance so that first slots and first expandable portions which define these first slots constitute a gripping element to drive the screw in rotation. The expansion rod comprises a proximal head equipped with gripping element to drive it in rotation, intended to be found in the chamber in the non-expanded position of the screw head: The cavity has a first portion with a limited cross-section located at the expandable portions, this limited cross-section portion being intended to cooperate with the head to achieve expansion of the expandable portions while also defining a passageway having a cross-section sufficient to allow access, from the outside of the screw, to the gripping means comprised by the expansion rod.

Claims

1. Bone screw (1), of type “

expansion”

screw, comprising a tubular screw body (2) defining an axial cavity (5), which forms an expandable head (6) comprising first transverse radial slots (7), and an expansion rod (3) able to be moved in said cavity (5) so as to cause an expansion of the portions (8) of the screw body (2) defined by said slots (7), the screw body (2) and expansion rod (3) comprising threaded portions (11, 20) to allow movement of the expansion rod (3) in the screw body (2), characterized in that;

the cavity (5) of the screw body (2) presents a portion with an enlarged cross-section (16) forming a chamber, positioned such that it is set back from the proximal surface of said head (6), over a sufficient distance so that said first slots (7) and said first expandable portions (8) which define these first slots (7) constitute gripping means to drive the screw (1) in rotation;

said expansion rod (3) comprises a proximal head (21) equipped with gripping means (22) to drive it in rotation, intended to be found in said chamber in the non-expanded position of the screw head (6);

the cavity (5) of the screw body (2) has a first portion (15) with a limited cross-section located at the proximal zone of said first expandable portions (8), this limited cross-section portion (15) being intended to cooperate with the proximal head (21) of the expansion rod (3) to achieve expansion of said first expandable portions (8) while also defining a passageway having a cross-section sufficient to allow access, from the outside of the screw (1), to the gripping means (22) comprised by the expansion rod (3).

2. Screw (1) according to claim 1, characterized in that said proximal head (21) or the surface of said first limited cross-section area (15), or both, comprise(s) a surface appearance intended to prevent sliding of said proximal head (21) with regard to said first limited cross-section area (15) when this head (21) is located at this first limited cross-section area (15).

3. Screw (1) according to claim 2, characterized in that the surface of said first limited cross-section portion (15) is corrugated.

4. Screw (1) according to claim 1, characterized in that:

the body (2) of the screw comprises an expandable distal portion, meaning second slots (9) opening in the distal end of this screw body (2), defining second expandable portions (10);

the cavity (5) of the screw body (2) and the distal portion of the rod present respective portions (17, 23) intended to cooperate to achieve the expansion of said second expandable portions (10) when said proximal head (21) comes into contact with said first limited cross-section portion (15).

5. Screw (1) according to claim 4, characterized in that:

the cavity (5) of the screw body (2) presents a second limited cross-section portion (17) located at the distal zone of said second expandable portions (10), and

said expansion rod (3) comprises a limited cross-section area (23) intended to be found, in the unexpanded position, at the level of said second limited cross-section portion (17), and a distal zone having an enlarged cross-section relative to the cross-section of this limited cross-section zone (23), to carry out the expansion of said second expandable portions (10).

6. Screw (1) according to claim 1, characterized in that the distal end of said expansion rod (3) forms a tip developed such that it protrudes from the distal end of the screw body (2) in the unexpanded position.

7. Screw (1) according to claim 1, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

8. Screw (1) according to claim 2, characterized in that:

the body (2) of the screw comprises an expandable distal portion, meaning second slots (9) opening in the distal end of this screw body (2), defining second expandable portions (10);

the cavity (5) of the screw body (2) and the distal portion of the rod present respective portions (17, 23) intended to cooperate to achieve the expansion of said second expandable portions (10) when said proximal head (21) comes into contact with said first limited cross-section portion (15).

9. Screw (1) according to claim 3, characterized in that:

the body (2) of the screw comprises an expandable distal portion, meaning second slots (9) opening in the distal end of this screw body (2), defining second expandable portions (10);

the cavity (5) of the screw body (2) and the distal portion of the rod present respective portions (17, 23) intended to cooperate to achieve the expansion of said second expandable portions (10) when said proximal head (21) comes into contact with said first limited cross-section portion (15).

10. Screw (1) according to claim 2, characterized in that the distal end of said expansion rod (3) forms a tip developed such that it protrudes from the distal end of the screw body (2) in the unexpanded position.

11. Screw (1) according to claim 3, characterized in that the distal end of said expansion rod (3) forms a tip developed such that it protrudes from the distal end of the screw body (2) in the unexpanded position.

12. Screw (1) according to claim 4, characterized in that the distal end of said expansion rod (3) forms a tip developed such that it protrudes from the distal end of the screw body (2) in the unexpanded position.

13. Screw (1) according to claim 5, characterized in that the distal end of said expansion rod (3) forms a tip developed such that it protrudes from the distal end of the screw body (2) in the unexpanded position.

14. Screw (1) according to claim 2, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

15. Screw (1) according to claim 3, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

16. Screw (1) according to claim 4, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

17. Screw (1) according to claim 5, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

18. Screw (1) according to claim 1, characterized in that the threaded portion (20) of the expansion rod (3) presents a length such that, at the moment of the installation of the expansion rod (3) in the screw body (2), the engagement of this threaded portion (20) with the threaded portion (11) of the body screw (2) intervenes before said proximal head (21) meet said first limited cross-section portion (15).

19. Screw (1) according to claim 8, characterized in that:

the cavity (5) of the screw body (2) presents a second limited cross-section portion (17) located at the distal zone of said second expandable portions (10), and

said expansion rod (3) comprises a limited cross-section area (23) intended to be found, in the unexpanded position, at the level of said second limited cross-section portion (17), and a distal zone having an enlarged cross-section relative to the cross-section of this limited cross-section zone (23), to carry out the expansion of said second expandable portions (10).

20. Screw (1) according to claim 9, characterized in that:

the cavity (5) of the screw body (2) presents a second limited cross-section portion (17) located at the distal zone of said second expandable portions (10), and

said expansion rod (3) comprises a limited cross-section area (23) intended to be found, in the unexpanded position, at the level of said second limited cross-section portion (17), and a distal zone having an enlarged cross-section relative to the cross-section of this limited cross-section zone (23), to carry out the expansion of said second expandable portions (10).