Connection device for osteosynthesis

• US 6,432,109 B1
• Filed: 02/05/2001
• Issued: 08/13/2002
• Est. Priority Date: 03/31/1998
• Status: Expired due to Fees

• Current Assignee: Societe de Genie Medical SGM
• Original Assignee: Societe de Genie Medical SGM
• Inventors: Desrousseaux, Jean-François, Mathevon, Henri, Letendart, Joël, Cordonnier, Denis, Stahl, Philippe
• Primary Examiner(s): Smith, Jeffrey A.
• Application Number:
  US09/647,404
• Time in Patent Office: 554 Days
• Field of Search: 606/61, 606/60
• US Class Current: 606/264
• CPC Class Codes: A61B 17/7041 with single longitudinal rod offset laterally from single row of screws or hooks A61B17/7044 takes precedence
• CPC Class Codes: A61B 2090/037 with a frangible part, e.g. by reduced diameter

Abstract

The ostheosynthesis connection device of the invention is designed to connect a screw for implanting in the spine to a vertebral support rod. The screw is constituted by a bottom first threaded portion, a head having flats and a curved base, and a top second threaded portion in line with the first. A nut having a curved base is suitable for co-operating with the second threaded portion. For connection with the screw, a connection piece has a hole of inside diameter that is greater than the outside diameter of the second threaded portion of the screw, and around said hole it has curved top and bottom bearing faces such that the connection piece is locked in position relative to the screw once the nut has been tightened by the curved base of the nut bearing against the top bearing face thereof and by the bottom bearing face being clamped against the curved base of the head of the screw.

Claims

1. An osteosynthesis connection device for a vertebral support rod, the device comprising:

a) a screw suitable for implanting in a spine, said screw comprising a bottom first threaded portion for implanting in the spine, a head having flats and a curved base, a top second threaded portion in line with the first threaded portion, and a locking nut suitable for co-operating with said second threaded portion and having a curved base, the screw having a central axis not lying in a same plane as a central axis of the vertebral support rod when implanted;

b) a connection piece having a bottom bearing face and a top bearing face, said connection piece having, for connection with the screw, a hole of an inside diameter greater than an outside diameter of said second threaded portion of the screw; and

c) means for locking the vertebral support rod onto said connection piece, wherein said connection piece is locked in position on said screw once said locking nut has been tightened by said curved base of said locking nut bearing against said top bearing face of said connection piece, and by said bottom bearing face of said connection piece bearing against said curved base of said head of said screw;

said curved surfaces of said bases of said head of said screw, of said locking nut, and of said top and bottom bearing faces of said connection piece being portions of spheres all having their centers in the same position, one of said top and bottom bearing faces being convex, and the other being concave, thereby enabling said connection piece to rotate relative to said screw.

2. The connection device according to claim 1, wherein said means for locking said connection piece on said vertebral support rod comprises:

a) a locking piece having a first passage for the vertebral support rod, a second passage for a portion of the connection piece, said first and second passages being substantially perpendicular and sharing a common inside volume in which said rod and said connection plate can come into contact, and a threaded third passage opening out into said inside volume of said first or second passage; and

b) a set screw suitable for screw engagement in said third passage to lock said vertebral support rod and said connection piece in position by clamping said set screw, said rod, said connection piece, and said locking piece against one another.

3. The connection device according to claim 2, wherein the portion of said connection piece is designed to slide in said second passage of said locking piece and is a plate of substantially rectangular section with rounded sides, said second passage being shaped to enable said locking piece to slidably move and fit on said portion of said connection piece where the portion of the connection piece extends beyond said curved bearing faces.

4. The connection device according to claim 2, wherein said first passage for said vertebral support rod is of oblong cross-section, thereby allowing said support rod to move a little in a height direction prior to said set screw being tightened and enabling an already curved rod to be passed therethrough.

5. The connection device according to claim 2, wherein said locking piece is a cylindrical piece, said first and second passages extending along diametral directions that are perpendicular to each other, and said third passage being formed in one of the two circular faces of the cylinder and opening out into the inside volume of said first passage.

6. The connection device according to claim 2, wherein said connection piece has an abutment-forming element for said locking piece while the locking piece is free to slide, prior to said set screw being tightened.

7. The connection device according to claim 2, wherein the connection piece is constructed and arranged to form an abutment for said locking piece while the locking piece is free to slide, prior to said set screw being tightened.

8. The connection device according to claim 1, wherein said top second threaded portion of said screw is suitable for being broken off.

9. The connection device according to claim 8, wherein the second threaded portion is constructed and arranged to present a zone of weakness suitable for breaking.