Two-bladed intervertebral cage

Abstract

The present invention relates to interbody cages. The cage comprises an element 10 with two opposing faces 11, 12 and a cavity 14; locking means 10 with the vertebral bodies comprising two blades 31, 32; means 40 for rotating these two blades around a rotation shaft 48; each blade comprising a base 51 and two half-blades fixed to the base by making an angle α other than zero and ninety degrees with the flat face 52 of the base; the cavity 14 comprising two walls each made up of three portions, the two portions bordering the central part 14-c making an angle substantially equal to α with it, the blades 31, 32 being mounted fixed to the shaft 48 so that the flat face 52 is in contact respectively with the central portion 14-c of the two walls 14-1, 14-2 of the cavity 14.

Description

Title of the invention: Two-blade intervertebral cage technical field

[0001] The present invention relates to interbody cages with at least two blades suitable for being interposed between two vertebrae in replacement of the intervertebral disc originally located between these two vertebrae, of the type comprising an element having the general shape of a substantially cylindrical disc and means of locking this element with at least one of the two vertebrae by means of two blades in order to obtain the fixation of the cages by osteosynthesis.

[0002] Interbody cages are known that comprise a disc and means for locking this disc to at least one of the two vertebrae between which it is positioned. These locking means consist of one or two blades capable of pivoting so that their ends are embedded in the bony elements of the vertebrae. Such an embodiment with two parallel blades perpendicular to the planes of the opposite faces of the disc is, for example, described and illustrated in FR2955483.

[0003] The implementation according to the document referenced above gives good results but the means to train these two blades in order to implant them in the bony part of the vertebrae are complex and require the practitioner to exert significant effort to accomplish their implantation.

[0004] More specifically, the present invention relates to an interbody cage suitable for being interposed between two vertebral bodies in place of the intervertebral disc originally located between the two vertebrae, comprising: an element having the general shape of a disc having two substantially parallel opposite faces and a lateral wall connecting these two opposite faces, the two said opposite faces being suitable for coming into contact respectively with the two vertebral bodies and defining substantially two facial planes containing these two faces, said element having a substantially central opening leading to the two opposite faces, this opening constituting a cavity;means for locking said element with the two vertebral bodies, these locking means being constituted by a first blade and a second blade whose overall width measured in a plane substantially perpendicular to the two opposite faces is at most equal to the distance separating these two opposite faces and the overall length measured in this same plane is greater than this distance; means for rotating said first and second blades, each in a plane of rotation, relative to said element around a shaft defined along an axis of rotation so that they are able to take any position between a first position and a second position, the first position being that in which they are entirely contained in the space defined between the two; facial planes and the second position being that in which at least one end of each of them emerges from said space; means for securing the first and second blades with said shaft so that the plane of these blades makes a determined angle with respect to said axis of rotation;and means for controlling the rotation of said shaft, characterized by the fact that: each blade consists of a base, one face of which is substantially flat, and two half-blades fixed at two opposite points of this base, making an angle α with its flat face with respect to a plane perpendicular to said axis of rotation, said angle α being different from zero and ninety degrees, and that said cavity comprises two opposite walls, each of these opposite walls being made up of at least three successive portions, each portion being substantially flat, the two portions bordering the central part making an angle substantially equal to said angle α with it, the axis of rotation intersecting this said central part at an substantially right angle with it, the blades being mounted fixed to said shaft so that the flat face of their base is in contact respectively with the central portion of the two walls of said cavity.

[0005] Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings, which are by way of illustration but in no way limiting, in which:

[0006] Figure 1 shows a top view of a first embodiment of the cage interbody according to the invention, in which the blades are in a retracted position,

[0007] Figure 2 shows a side view of the first embodiment of the cage interbody according to the invention in accordance with [Fig. 1], in which the blades are in the extended position,

[0008] Figure 3 shows a top view of a second embodiment of the cage interbody according to the invention, and

[0009] Figure 4 represents, in schematic form, one embodiment of a cage according to the invention comprising several possibilities of blades to illustrate the different characteristics of the cage according to the invention, without it being an obligation that such a cage include them all.

[0010] It is specified that, when, according to the definition of the invention, the object of the invention comprises “at least one” element having a given function, the described embodiment may comprise several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated comprises several elements with identical functions and if, in the description, it is not specified that the object according to this invention must necessarily comprise a particular number of these elements, the object of the invention may be defined as comprising “at least one” of these elements.

[0011] It is specified that when, in the present description, an expression defines by itself, without any particular specific mention concerning it, a set of structural characteristics, these characteristics may be taken, for the definition of the object of the protection sought, when this is technically possible, either separately, or in total and / or partial combination.

[0012] It is further specified that, in the present description, if the adverb "sensiblement" is associated with a qualifier of a given means, this qualifier must be understood in the strict or approximate sense.

[0013] With regard to the attached figures, the present invention relates to an interbody cage suitable for being interposed between two vertebral bodies in replacement of the intervertebral disc originally located between the two vertebrae VI, V2.

[0014] This cage comprises an element 10 having the general shape of a disc having two substantially parallel opposite faces 11, 12 and a lateral wall 13 connecting these two opposite faces, these two opposite faces being able to come into contact respectively with the two vertebral bodies of vertebrae VI, V2 and defining substantially two facial planes containing them.

[0015] The element 10 has a substantially central opening leading to the two opposite faces 11, 12, this opening forming a cavity 14. Furthermore, means for locking this element 10 to the two vertebral bodies are provided. These locking means consist of at least a first blade and a second blade 31, 32, the overall width of which, measured in a plane substantially perpendicular to the two opposite faces 11, 12, is at most equal to the distance separating these two opposite faces, and the overall length, measured in this same plane, is greater than this distance.

[0016] Means 40 are also provided for driving the two blades 31, 32 in rotation, each in a plane of rotation, relative to the element 10 around a shaft 48 defined along an axis of rotation 100 so that they are able to take any position between a first position and a second position, the first position being that in which they are entirely contained in the space defined between the two facial planes and the second position being that in which at least one end of each of them emerges from this space.

[0017] The cage includes means for securing the two blades 31, 32 to the shaft 48 such that the plane of these blades forms a predetermined angle with respect to said axis of rotation 100. These securing means can be of any type and are well known in themselves from the prior art. Means are also provided for controlling the rotation of this shaft 48, which are also well known in themselves from the prior art.

[0018] According to the present invention, each blade 31, 32 consists of a base 51, one face 52 of which is substantially flat, and two half-blades 31-1, 31-2; 32-1, 32-2 joined to two opposite points of this base 51 by making with its flat face 52 an angle a with respect to a plane perpendicular to the axis 100, this angle a being different from zero and ninety degrees.

[0019] According to another feature of the invention, the cavity 14 comprises two opposing walls 14-1, 14-2, each of these opposing walls being made up of at least three successive portions, each portion being substantially flat, the two portions bordering the central part 14-c making with it an angle substantially equal to said angle a, the axis of rotation 100 cutting this central part 14-c making with it substantially a right angle, the blades 31, 32 being mounted integrally with the shaft 48 so that the flat face 52 of their base 51 is in contact respectively with the central portion 14-c of the two walls 14-1, 14-2 of the cavity 14.

[0020] According to a feature of the invention, the angle a has a so-called "positive" value so that the free ends of the two half-blades 31-1, 31-2 which are opposite each other are located at a distance greater than that separating the two bases 51 of the two blades 31, 32, so as to give the said blades a so-called "divergent" position, as seen more particularly in figures 1 and 2.

[0021] In this case, with such a positive angle a, the cavity advantageously presents a cross-section substantially in the shape of a diabolo, [Fig.1].

[0022] According to another feature of the invention, the angle a has a so-called “negative” value so that the free ends of the two half-blades 31-1, 31-2 which are opposite each other are located at a distance less than that separating the two bases 51 of the two blades 31, 32, so as to give the blades a so-called “convergent” position, [Fig.3].

[0023] In this case, with such a negative angle, the cavity advantageously presents a cross-section substantially in the shape of a rectangle whose long sides are substantially in a concave V.

[0024] According to a preferred feature of the cage, the value of the angle a is on the order of twenty degrees of angle.

[0025] Element 10 can be made, for example, of titanium, PEEK (i.e., polyetherethercet one), or a similar material. As for the blades and shaft, they are made, for example, of titanium, stainless steel, or a similar material.

[0026] From the description given above, it appears that the cage has many advantages, in particular compared to that defined in FR2955483, namely: a simpler structure and easier to industrialize, larger free areas in the cavity which can therefore receive grafts or analogues.

[0027] It is further specified that some of the cage characteristics defined above can be taken individually or in combination, [Fig. 4] representing schematically a cage that would be capable of containing a plurality of these characteristics.

[0028] In particular, it is specified for example that the cage could, as illustrated in this [Fig.4], comprise in the same element 10 a group of diverging blades and a group of converging blades, doubled blades Ld, and even blades Le presenting a slight curvature substantially in the shape of a spoon.

Claims

1. Demands interbody cage suitable for interposing between two vertebral bodies in place of the intervertebral disc originally located between the two vertebrae (VI, V2), comprising: an element (10) having the general shape of a disc having two substantially parallel opposite faces (11, 12) and a lateral wall (13) connecting these two opposite faces, the two said opposite faces being suitable for coming into contact respectively with the two vertebral bodies and defining substantially two facial planes containing these two faces (11, 12), said element having a substantially central opening leading to the two opposite faces (11, 12), this opening constituting a cavity (14);means for locking said element (10) with the two vertebral bodies, these locking means being constituted by a first blade and a second blade (31, 32) whose overall width measured in a plane substantially perpendicular to the two opposite faces (11, 12) is at most equal to the distance separating these two opposite faces and the overall length measured in this same plane is greater than this distance; means (40) for rotating said first and second blades (31, 32), each in a plane of rotation, relative to said element (10) around a shaft (48) defined along an axis of rotation (100) so that they are able to take any position between a first position and a second position, the first position being that in which they are entirely contained within the space defined between the two facial planes and the second position being that in which at least one end of each of them emerges from said space;means for securing the first and second blades (31, 32) with said shaft (48) so that the plane of these blades makes a determined angle with respect to said axis of rotation (100); and means for controlling the rotation of said shaft (48), characterized by the fact that: each blade (31, 32) is made up of a base (51) of which one (52) of the faces is substantially flat, and of two half-blades (31-1,31-2; 32-1, 32-2) secured at two opposite points of this base (51) by making with its flat face (52) an angle α with respect to a plane perpendicular to said axis (100), said angle α being different from zero and ninety degrees, and that said cavity (14) comprises two opposite walls (14-1, 14-2), each;

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7. of these opposite walls being made up of at least three successive portions, each portion being substantially flat, the two portions bordering the central part (14-c) making with it an angle substantially equal to said angle a, the axis of rotation (100) cutting this said central part (14-c) making with it substantially a right angle, the blades (31, 32) being mounted solidly to said shaft (48) so that the flat face (52) of their base (51) is in contact respectively with the central portion (14-c) of the two walls (14-1, 14-2) of said cavity (14). Cage according to claim 1, characterized in that said angle has a positive value so that the free ends of the two half-blades (31-1,31-2) which are opposite each other are located at a distance greater than that separating the two bases (51) of the two blades (31, 32), so as to give said blades a so-called "divergent" position. Cage according to claim 2, characterized in that said cavity has a cross-section substantially in the shape of a diabolo. Cage according to claim 1, characterized in that said angle has a negative value such that the free ends of the two half-blades (31-1, 31-2) which are opposite each other are located at a distance less than that separating the two bases (51) of the two blades (31, 32), so as to give said blades a so-called "convergent" position. Cage according to claim 4, characterized in that said cavity has a cross-section substantially in the shape of a rectangle whose long sides are substantially concave V-shaped. A cage according to any one of the preceding claims, characterized in that the value of angle α is on the order of twenty degrees. A cage according to any one of the preceding claims, characterized in that at least one of the blades (31, 32) has a substantially spoon-shaped curvature.

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