Two-blade intervertebral cage

Abstract

The present invention relates to intersomatic cages. The cage comprises an element 10 with two opposite 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 integral with the base making with the flat face 52 of the base an angle a different from zero and ninety degrees; the cavity 14 comprising two walls each consisting of three portions, the two portions bordering the central part 14-c making with the latter an angle substantially equal to a, the blades 31, 32 being mounted integral with 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 intersomatic cages with at least two blades capable of being interposed between two vertebrae to replace 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 for locking this element with at least one of the two vertebrae by means of two blades in order to obtain the fixing of the cages by osteosynthesis.

[0002] Intersomatic cages are known which comprise a disc and means for locking this disc with at least one of the two vertebrae between which it is placed, these locking means being constituted by one or two blades capable of pivoting so that their ends are planted in the bony element of the vertebrae. Such an embodiment with two blades parallel to each other and perpendicular to the planes of the opposite faces of the disc is for example described and illustrated in FR2955483.

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

[0004] More specifically, the present invention relates to an intersomatic cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae, comprising: an element having the general shape of a disc comprising two substantially parallel opposite faces and a lateral wall connecting these two opposite faces, the two said opposite faces being capable of coming into contact respectively with the two vertebral bodies and substantially defining two facial planes containing these two faces, said element comprising a substantially central opening opening onto 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 relative to said axis of rotation;and means for controlling the rotation of said shaft, characterized in that: each blade is made up of a base, one of the faces of which is substantially flat, and two half-blades secured to two opposite points of this base, making with its flat face an angle α relative to a plane perpendicular to said axis of rotation, said angle α being different from zero and ninety degrees, and that said cavity has 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 with it an angle substantially equal to said angle α, the axis of rotation intersecting said central part, making with it substantially a right angle, the blades being mounted secured 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 characteristics and advantages of the invention will appear during the following description given with reference to the attached drawings for illustrative but in no way limiting purposes, in which:

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

[0007] [Fig.2] represents a side view of the first embodiment of the cage intersomatic according to the invention in accordance with [Fig.l], in which the blades are in the extended position,

[0008] [Fig. 3] represents a top view of a second embodiment of the cage intersomatic according to the invention, and

[0009] [Fig.4] represents, in schematic form, an 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 for such a cage to comprise 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 embodiment described may comprise several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated comprises several elements of identical function 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 on its own, without any specific particular mention concerning it, a set of structural characteristics, these characteristics may be taken, for the definition of the object of the protection requested, 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 "substantially" is associated with a qualifier of a given means, this qualifier must be understood in the strict or approximate sense.

[0013] With reference to the attached figures, the present invention relates to an intersomatic cage capable of being interposed between two vertebral bodies to replace 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 comprising two substantially parallel opposite faces 11, 12 and a lateral wall 13 connecting these two opposite faces, these two opposite faces being capable of coming into contact respectively with the two vertebral bodies of the vertebrae VI, V2 and substantially defining two facial planes containing them.

[0015] The element 10 comprises a substantially central opening opening onto the two opposite faces 11, 12, this opening constituting a cavity 14. Means for locking this element 10 with the two vertebral bodies are also provided. These locking means are constituted by at least 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.

[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 comprises means for securing the two blades 31, 32 with the shaft 48 so that the plane of these blades makes a determined angle relative 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, also well known in themselves from the prior art.

[0018] According to the present invention, each blade 31, 32 is made up of a base 51, one 52 of whose faces is substantially flat, and two half-blades 31-1, 31-2; 32-1, 32-2 integral with 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 characteristic of the invention, the cavity 14 comprises two opposite walls 14-1, 14-2, each of these opposite walls being made up of at least three successive portions, each portion being substantially planar, the two portions bordering the central portion 14-c making with it an angle substantially equal to said angle a, the axis of rotation 100 intersecting this central portion 14-c making with it substantially a right angle, the blades 31, 32 being mounted integral with the shaft 48 so that the planar 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 characteristic 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 said blades a so-called “divergent” position, as seen more particularly in Figures 1 and 2.

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

[0022] According to another characteristic 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 an angle of negative value, the cavity advantageously has a cross-section substantially in the shape of a rectangle, the large sides of which are substantially in a concave V.

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

[0025] The element 10 can be made for example of Titanium, Peek (i.e. polyetherethercet one) or the like. As for the blades and shaft, they are made for example of Titanium or stainless steel or the like.

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

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

[0028] In particular, it is for example specified 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 having a slight curvature substantially in the shape of a spoon.

Claims

1. Claims Intersomatic cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae (VI, V2), comprising: an element (10) having the general shape of a disc comprising two substantially parallel opposite faces (11, 12) and a lateral wall (13) connecting these two opposite faces, the two said opposite faces being capable of coming into contact respectively with the two vertebral bodies and substantially defining two facial planes containing these two faces (11, 12), said element comprising a substantially central opening opening onto 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 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 (31, 32) to said shaft (48) so that the plane of these blades makes a determined angle relative to said axis of rotation (100); and means for controlling the rotation of said shaft (48), characterized in that: each blade (31, 32) consists of a base (51) one (52) of whose faces is substantially flat, and two half-blades (31-1, 31-2; 32-1, 32-2) secured to two opposite points of this base (51) making with its flat face (52) an angle α relative 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; of these opposite walls being made up of at least three successive portions, each portion being substantially planar, the two portions bordering the central portion (14-c) making with it an angle substantially equal to said angle a, the axis of rotation (100) intersecting this said central portion (14-c) making with it substantially a right angle, the blades (31, 32) being mounted integral with said shaft (48) so that the planar 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).

2. Cage according to claim 1, characterized in that said angle a 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.

3. Cage according to claim 2, characterized in that said cavity has a cross-section substantially in the shape of a diabolo.

4. Cage according to claim 1, characterized in that said angle a has a 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 said blades a so-called "convergent" position.

5. Cage according to claim 4, characterized in that said cavity has a cross-section substantially in the shape of a rectangle, the large sides of which are substantially in a concave V.

6. Cage according to one of the preceding claims, characterized in that the value of the angle a is of the order of twenty degrees of angle.

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