AU2004277356A1

AU2004277356A1 - Intervertebral implant

Info

Publication number: AU2004277356A1
Application number: AU2004277356A
Authority: AU
Inventors: Jean-Jacques Martin; Frederic Sgier
Original assignee: Fixano SA
Current assignee: Fixano SA
Priority date: 2003-10-02
Filing date: 2004-09-27
Publication date: 2005-04-14
Also published as: DE602004006289D1; EP1675535A1; CA2541002A1; ATE361043T1; WO2005032432A1; BRPI0415012A; FR2860428A1; KR20060092259A; FR2860428B1; EP1675535B1; JP2007507265A

Abstract

The invention relates to an intervertebral implant (1) with two juxtaposed walls (2) in the form of a "U", which are connected to each other along the edges thereof by an intermediate wall (3), with a small degree of elastic flexibility, said intermediate wall (3), being deformable such as to permit a movement of said juxtaposed walls (2) with relation to each other. According to the invention, the implant (1) is of such a size that the lateral branches (2a) of said juxtaposed walls (2) can be engaged to both sides of the spinal cord (100) by the posterior route and can be inserted between vertebral plateaus of the two vertebra (101) being treated, in the lateral zones of said plateaus.

Description

VERIFICATION OF TRANSLATION I, Kenneth G. Finney, of Level 26, 239 George Street, Brisbane, Queensland 4000, Australia, state that the attached document is a true and complete translation of International Patent Application No. PCT/FR2004/002434 to the best of my knowledge and belief CULLEN & CO. KENNETH G. FINNEY Date: 21 April 2006 WO 2005/032432 1 PCT/FR2004/002434 INTERVERTEBRAL IMPLANT The present invention relates to an intervertebral implant. Insertion of a rigid implant, hollow inside, between the bodies of two vertebrae is known. The functions of such an implant are to reestablish the distance and anatomical position of these vertebrae in the event of a collapsed disk, and to bring about relative immobilization of these vertebrae by growth of bone cells through the implant. Complete immobilization of the vertebrae with respect to each other has the drawbacks of reducing the patient's mobility and overstressing the joints immediately below and above. Also, US 2002/077702 Al teaches provision of an intervertebral implant with two juxtaposed U-shaped walls connected to each other at one of their edges by an intermediate wall with a slight degree of elastic flexibility, this intermediate wall being deformable so as to allow mobility of said walls juxtaposed with each other. This document describes an implant that can be implanted either alone or with another identical implant and can be installed near the edge of the verbebral plate of a vertebra. The upper and lower branches of this implant are separated two at a time by slots of limited widths. This implant does not restore the anatomical space between two vertebrae nor does it restore appropriate functional play of these vertebrae. The goal of the present invention is to overcome these essential drawbacks. The implant to which it relates has, in known fashion, two U-shaped juxtaposed walls connected to each other at one of their edges by an intermediate wall having a slight degree of elastic flexibility, said intermediate wall being deformable so as to allow mobility of said juxtaposed walls with respect to each other. According to the invention, the implant is dimensioned such that the side branches of said juxtaposed walls can be engaged posteriorly on either side of the spine and can be inserted between the vertebral plates of the two treated vertebrae in the lateral zones of these plates. When the implant is installed, the side branches of said juxtaposed walls abut the vertebral plates of the treated vertebrae, reestablishing their anatomical distance and repositioning them. Because of the deformability of said intermediate wall, these juxtaposed walls can move relative to each other to preserve the mobility of the vertebrae, thus preventing the patient's movements from being limited and the intervertebral disks immediately above and below from being overstressed.

WO 2005/032432 2 PCT/FR2004/002434 The intermediate wall can be designed to allow mobility of said juxtaposed walls in only one or two planes, namely, after implantation, the sagittal plane, the frontal plane, and/or the plane perpendicular to the axis of the spine. Preferably, however, this intermediate wall is deformable so as to allow mobility of said juxtaposed walls in three planes, namely, after implantation, the sagittal plane, the frontal plane, and the plane perpendicular to the axis of the spine. The side branches of said juxtaposed walls are advantageously dimensioned such that, after posterior installation of the implant between the vertebral plates of the two treated vertebrae, said intermediate wall is at the level of, or slightly anterior to, the former position of the facets of the treated vertebrae before installation of the implant, said installation involving resection of these facets. This positioning of the intermediate wall is the most appropriate for optimal mobility of the vertebrae. In particular, the intermediate wall can in particular have a rounded shape when viewed from the side, i.e., in the sagittal plane after installation. The implant also has a substantially U shape when viewed from the side. This intermediate wall can in particular have a rounded shape when viewed in a plane parallel to said juxtaposed walls, favoring its deformability in this plane. This deformability in this plane allows, after installation, mobility of the vertebrae rotationally with respect to each other in the axis of the spine. At least one of the juxtaposed walls can have a degree of elastic deformability to allow not only deformability of said intermediate wall but also extensive mobility of these juxtaposed walls with respect to each other. The implant is advantageously made of a single piece of material, preferably titanium or titanium-including alloy. The juxtaposed walls can have protuberances for engagement with the vertebral plates. These protuberances lock the implant into position and prevent the risk of the implant being expelled due to the repeated movements of the vertebrae. These protuberances can in particular be in the form of ribs projecting from the outer faces of said juxtaposed walls and disposed transversely to said side branches. These ribs can in particular have a triangular cross section defining a sharp upper edge.

WO 2005/032432 3 PCT/FR2004/002434 Advantageously, the implant overall has a "soft" shape, i.e., it has no sharp angles that could injure the surrounding tissues. The outer side edges of said juxtaposed walls can thus have convex shapes and the indentation delimited by these juxtaposed walls can have a round shape. In this way, the implant has a rounded and slightly "horse-shoe" shape. The free ends of said side branches can also be rounded in shape. The invention will be understood, and other features and advantages thereof will emerge, by reference to the attached schematic drawings that show, in a non-limiting manner, a preferred embodiment of the implant to which it relates. Figure 1 is a perspective view; Figure 2 is a perspective view from another angle; Figure 3 is a side view; Figure 4 is a plan view; Figure 5 is an end-on view; and Figures 6 to 8 are perspective views, after implantation between two vertebrae, from three different angles. Figures I to 5 show an intervertebral implant 1 having two juxtaposed walls 2 and an intermediate wall 3. The implant 1 is made of a piece of titanium-vanadium alloy. The two juxtaposed walls 2, in plan views (see Figure 4), are U-shaped and connected to each at their edges by wall 3. As can be seen in Figures 6 to 8, the implant 1 is dimensioned such that the indentations 4 that delimit the walls 2 allow engagement of this implant 1 posteriorly on either side of the spine 100 and engagement of the side branches 2a formed by these indentations 4 between the vertebral plates of the two treated vertebrae 101 in the lateral zones of these plates. The implant I is also dimensioned such that, after installation, said intermediate wall 3 is in or slightly behind the position formerly occupied by the facets 102 of the vertebrae 101 before installation of the implant 1, said installation involving resection of these facets 102. As can be seen in Figure 3, the intermediate wall 3 is rounded when viewed from the side, i.e., in the sagittal plane after implantation. It is also rounded viewed in a plane parallel to the juxtaposed walls 2, as can be seen in Figure 4.

WO 2005/032432 4 PCT/FR2004/002434 The juxtaposed walls 2 also have four pairs of ribs 5 projecting from their outer faces and disposed transversely to said side branches 2a. These ribs 5 have a triangular cross section defining an upper sharp edge. With reference to Figures 1, 2, and 4, it appears that the implant 1 overall has a "soft" shape, i.e., with no sharp angles that could injure the surrounding tissues. The external side edges 2b of said juxtaposed walls 2 have convex shapes, the indentations 4 have a rounded bottom 2c, and the free ends of the side branches 2a have a rounded shape. Overall, the implant has a slightly "horse-shoe" shape. In practice, as can be seen in Figures 6 to 8, the facets 102 and the two spinous processes 103 of the vertebrae 101 are resected to create a space for passage of the implant 1. This implant I can thus be engaged in this space posteriorly until the side branches 2a of the walls 2 are inserted between the vertebral plates of the vertebrae 101. This engagement is made possible by the indentations 4 which create sufficient clearance to eliminate any risk of contact between the implant I and the spine 100. In the implantation position, the wall 3 is located at the former position, before resection, of the facets 102, or slightly behind this position, and the ribs 5 rest on the plates to eliminate any risk of the implant retreating or being expelled by the repeated movements applied to it by the vertebrae 101. The juxtaposed walls 2 and the intermediate wall 3, because of the material of which they are made and because of the shape of wall 3, have a slight degree of elastic flexibility so that mobility of said juxtaposed walls 2 is possible in three planes, namely, after implantation, in the sagittal plane (that of Figure 3), in the frontal plane (that of Figure 5), and in the plane perpendicular to the axis of the spine (that of Figure 4) for mobility of the vertebrae rotationally with respect to each other in the axis of the spine. As can be seen from the foregoing, the invention provides an intervertebral implant I having the crucial advantage of reestablishing the anatomical distance between the vertebrae 101 and ensuring anatomical repositioning of these vertebrae, while allowing these vertebrae to move with respect to each other because of the deformability of said intermediate wall 3 and the juxtaposed walls 2. The mobility of the vertebrae, thus preserved, prevents the patient's movements from being limited and avoids overstressing the intervertebral disks immediately above and below.

WO 2005/032432 5 PCT/FR2004/002434 It goes without saying that the invention is not confined to the embodiment described above as an example but extends to all the embodiments covered by the attached claims.

Claims

1. Intervertebral implant (1) with two U-shaped juxtaposed walls (2) connected to each other at one of their edges by an intermediate wall (3) having a slight degree of elastic flexibility, said intermediate wall (3) being deformable such as to allow mobility of said juxtaposed walls (2) with respect to each other, characterized in that it is dimensioned such that the side branches (2a) of said juxtaposed walls (2) can be engaged posteriorly on either side of the spine (100) and can be inserted between the vertebral plates of the two treated vertebrae (101) in the lateral zones of these plates.

2. Intervertebral implant (1) according to Claim 1, characterized in that the intermediate wall (3) is deformable so as to allow mobility of said juxtaposed walls (2) in three planes, namely after implantation, the sagittal plane, the frontal plane, and the plane perpendicular to the axis of the spine.

3. Intervertebral implant (1) according to Claim 1 or Claim 2, characterized in that the side branches (2a) of said juxtaposed walls (2) are dimensioned such that, after posterior installation of the implant (1) between the vertebral plates of the two treated vertebrae (101), said intermediate wall (3) is at the level of, or slightly anterior to, the former position of the facets (102) of the treated vertebrae (101) before installation of the implant (1), said installation involving resection of these facets (102).

4. Intervertebral implant (1) according to one of Claims 1 to 3, characterized in that the intermediate wall (3) has a rounded shape when viewed from the side, i.e., in the sagittal plane after installation.

5. Intervertebral implant (1) according to one of Claims 1 to 4, characterized in that the intermediate wall (3) has a rounded shape when viewed in a plane parallel to said juxtaposed walls (2).

6. Intervertebral implant (1) according to one of Claims 1 to 5, characterized in that at least one of the juxtaposed walls (2) has a degree of elastic deformability.

7. Intervertebral implant (1) according to one of Claims I to 6, characterized in that it is made of a single piece of material, preferably titanium or titanium-including alloy.

8. Intervertebral implant (1) according to one of Claims I to 7, characterized in that the juxtaposed walls (2) have protuberances (5) for support against the vertebral plates. WO 2005/032432 7 PCT/FR2004/002434

9. Intervertebral implant (1) according to one of Claims 1 to 8, characterized in that its overall shape has no sharp angles that could injure the surrounding tissues.

10. Intervertebral implant (1) according to Claim 9, characterized in that the outer side edges (2b) of said juxtaposed walls (2) have convex shapes and in that the indentation (4) delimited by these juxtaposed walls (2) has a round shape.