Intervertebral cage

Abstract

The present invention relates to intervertebral cages. The cage according to the invention comprises an element 12 with two opposing faces 14, 15; a blade 13 driven in rotation about an axis 17 to take all positions between a position P1 and a position P2, the means for driving the blade 13 in rotation comprising a shaft 18 mounted rotatably relative to the element 12 about the axis 17, the blade being fixed to this shaft 18; an accessory part 20 fixed to the blade 13; a sliding ramp 21 made on the part 20; and controllable means 22 for applying a pressure force on the ramp 21 at a point 23 so as to rotate the blade between the position P1 and the position P2.

Description

Title of the invention: Intervertebral cage Technical field

[0001] The present invention relates to intervertebral cages capable of being interposed between two vertebrae to replace the intervertebral disc originally located between these two vertebrae. These cages are sometimes referred to as: intersomatic cages.

[0002] Intervertebral 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] According to this embodiment, the intervertebral cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae, comprises: an element having the general shape of a disc comprising two substantially parallel opposite faces and a lateral wall connecting these two opposite faces, these opposite faces being capable of coming into contact respectively with the two vertebral bodies and substantially defining two planes which contain them; means for locking the element with the two vertebral bodies,these locking means being constituted by a first blade and a second blade whose overall width measured in the 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 the first and second blades in planes 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 the first and second blades are entirely contained in the space defined between the planes of the two opposite faces, and the second position being that in which at least one end of each of the first and second blades emerges from this space,these means for driving in rotation respectively the first and second blades comprising respectively a first shaft and a second shaft mounted to rotate relative to the element around respectively the first and second axes, means for securing the first and second blades respectively with the first and second shafts so that their planes make a determined angle relative to the first and second axes, means for driving in rotation the first and second shafts comprising a drive gear mounted in cooperation respectively with these first and, second shafts and means for controlling the rotation of at least one of the shafts.

[0004] According to this known embodiment, the gear consists of a cardan connecting the first ends of the first and second shafts and substantially located at the point of intersection of the axes of these two shafts.

[0005] Such a gear consists of a disc having at its periphery a toothing consisting of a plurality of teeth. The gear in the case where the cage has two anchoring blades therefore has two toothed wheels which cooperate together so that one of them drives the other in rotation when one is controlled in rotation via the shaft on which it is mounted.

[0006] The space that encloses these gears is small (8 to 15mm wide) and the teeth of the gears are very small. Consequently, given the efforts that are necessary to make the blades penetrate the bony parts of the vertebrae, it may happen that the teeth break or shatter in the body of the patient who undergoes such an implantation.

[0007] It is very understandable that such an inconvenience should not occur.

[0008] Also, the present invention aims to produce an intervertebral cage which largely overcomes the drawback mentioned above.

[0009] More specifically, the present invention relates to an intervertebral 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 said two opposite faces, these opposite faces being capable of coming into contact respectively with the two vertebral bodies and substantially defining two planes which contain them, at least one first locking blade, the overall width of this first blade, measured in the plane substantially perpendicular to the two opposite faces, being at most equal to the distance separating these two opposite faces and its overall length measured in this same plane being greater than this distance;means for rotating said first blade about a first axis so that this first blade is able to take any position between a first position and a second position, the first position being that in which the first blade is entirely contained in the space defined between the planes of the two opposite faces and the second position being that in which at least one end of the first blade emerges from this space, these means for rotating the first blade comprising a first shaft mounted to rotate relative to the element about the first axis, and means for securing the first blade with said first shaft; characterized in that it further comprises: an ancillary part, means for securing said ancillary part with said first blade, a sliding ramp produced on said ancillary part and controllable means; to apply a pressure force to said sliding ramp substantially at one point so as to pivot said first blade between its first position and its second position.

[0010] 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:

[0011] [Fig. 1] represents a diagram illustrating the basic structure of the cage according to the invention,

[0012] [Fig. 2] represents, in cavalry perspective, a first industrial embodiment of the intersomatic cage according to the invention applying the teaching of [Fig. 1], and

[0013] [Fig. 3] represents, in cavalry perspective, a second industrial embodiment of the intersomatic cage according to the invention, also applying the teaching of [Fig. 1].

[0014] [Fig.4] represents, in cavalry perspective, a third industrial embodiment of the intersomatic cage according to the invention, also applying the teaching of [Fig.1].

[0015] 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.

[0016] 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.

[0017] 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.

[0018] It should also be noted that, in all three figures, the same references designate the same means having the same function, regardless of their graphic representation.

[0019] As mentioned above, the present invention relates to intervertebral cages capable of being interposed between two vertebrae to replace the intervertebral disc. originally located between these two vertebrae.

[0020] [Fig.l] represents the basic diagram of the cage according to the invention, emphasizing that this figure only illustrates a part of this cage, whereas figures 2 to 4 represent the cage in its entirety.

[0021] According to this principle figure 1, the present invention relates to an intersomatic cage capable of being interposed between two vertebral bodies (not shown) to replace the intervertebral disc originally located between the two vertebrae.

[0022] This cage comprises an element 12 having the general shape of a disc comprising two opposite faces 14, 15 which are substantially parallel and a lateral wall 16 connecting the two opposite faces, these opposite faces being capable of coming into contact with the two vertebral bodies respectively and substantially defining two planes which contain them.

[0023] The cage comprises at least one locking blade 13, called the “first blade” within the meaning of the present description. The overall width of this first blade, measured in the plane substantially perpendicular to the two opposite faces, is at most equal to the distance separating these two opposite faces and its overall length measured in this same plane is greater than this distance.

[0024] Means are also provided for rotating the first blade 13 about a first axis 17 so that it is able to take any position between a first position P1 (shown in solid lines) and a second position P2 (shown in broken lines), the first position P1 being that in which the first blade is entirely contained in the space defined between the planes of the two opposite faces 14, 15, and the second position P2 being that in which at least one end of the first blade emerges from this space. These means for rotating the first blade 13 comprise a first shaft 18 rotatably mounted relative to the element 12 about the first axis 17 and means for securing the first blade to this first shaft. These latter means are also known per se from the prior art.

[0025] According to a characteristic of the invention, the cage further comprises at least one additional part 20, means for securing this additional part with the first blade 13 (for example a weld or the like), a sliding ramp 21 produced on this additional part 20, and controllable means 22 for applying a pressure force on the sliding ramp substantially at a point 23 so as to pivot the additional part 20, and consequently the first blade 13 between its first position and its second position since the additional part is secured to this blade.

[0026] It is specified that the point 23 can slide on the ramp 21 when the pressure force is exerted constantly on the annex part via this ramp.

[0027] The element 12 may be a solid disc but may advantageously comprise, in a manner known per se, a substantially central cavity 10 advantageously passing through which opens respectively onto the two opposite faces 14, 15. All figures 2 to 4 represent a cage comprising such a cavity.

[0028] [Fig. 2] represents a first industrial embodiment of the cage according to the invention, in which the object of the invention is implemented twice. In this embodiment, the cage therefore comprises two locking blades 13, 13', and two ancillary parts 20.

[0029] In this first embodiment, as in the second and third embodiments with two blades 13, 13', the latter are advantageously shown located in the cavity 10.

[0030] In this [Fig.2], the cage is shown in its configuration when the two blades 13, 13' are in their second position P2.

[0031] According to an advantageous characteristic of the cage according to the invention illustrated in this [Fig. 2], the controllable means 22 for applying a pressure force are constituted by a pusher 24, for example a cylindrical rod preferably of revolution, one end 25 of which is capable of sliding on the sliding ramp 21 according to a linear translation of this pusher mounted in an orifice 26 made in the side wall 16 of the element 12, the axis 27 of this orifice 26 being secant with the sliding ramp over at least part of its translation. At the end of the stroke, the end of the pusher can be released from the ramp as illustrated in [Fig. 2].

[0032] It may indeed be advantageous that, as illustrated in this [Fig.2], the end of the pusher can, at the end of its travel, disengage from the ramp to position itself under the ramp, and thereby block the reverse rotation of the blade and be certain that it remains implanted in the bony part of the vertebrae.

[0033] [Fig. 3] represents a second industrial embodiment of the cage which also comprises two locking blades 13, 13', specifying that the cage is represented in its configuration where its blades are in their second position P2 after having been pivoted, namely the locking position of the cage with the bony portions of the vertebrae.

[0034] According to this embodiment, the controllable means 22 for applying a pressure force to the annex part 20 comprise a finger 30, for example a portion of cylindrical rod advantageously of revolution, capable of coming into contact with the sliding ramp 21 according to a rotational movement.

[0035] According to an advantageous characteristic of the cage according to the invention illustrated in this [Fig. 3], the controllable means 22 for applying a pressure force according to a rotational movement further comprise a second shaft 31 mounted along an axis 32 substantially collinear with the first axis 17 (because, in the sense of the present description, it can be slightly offset relative to this axis 17). The finger 30 is integral in offset of the end 33 of this second shaft 31 located in the cavity 10 so that this finger comes into contact with the sliding ramp 21 following the rotation of the second shaft and that, by pressing while sliding on the ramp, it causes the rotation of the first blade 13 between at least its first position PI and its second position P2.

[0036] In this second embodiment, the annex part 20 is advantageously made up of a portion of cylindrical rod, optionally of revolution, which is integral in offset directly or indirectly with the blade 13.

[0037] In this second embodiment, the cage may further comprise, as illustrated, a second locking blade 13' secured to the second shaft 31, in a manner known per se, the overall width of this second blade 13' measured in a plane substantially perpendicular to the two opposite faces 14, 15 being at most equal to the distance separating these two opposite faces and its overall length measured in this same plane being greater than this distance.

[0038] Very preferably, the first and second blades 13, 13' form a non-zero angle between them. The wedge effect created by their anchoring in the two vertebrae makes it possible to obtain optimum support of the cage between these vertebrae, as explained in the prior art.

[0039] To further optimize the installation of the cage, it is very advantageous for the two blades 13, 13' to be mounted tightly against the wall of the cavity 10.

[0040] In the industrial embodiments described above with reference to figures 2 and 3, the annex part 20 is located in the cavity 10. But it can be located in places other than in this cavity 10.

[0041] In the industrial embodiment illustrated in [Fig. 4], the ancillary part is located in a housing 40 made in the wall 16 of the element 12, advantageously at the intersection of the opening 19 made to mount the rotation shaft of a blade 13, 13' and another opening 41 made in this wall 16 of the element 12 substantially orthogonal to the axis of rotation 17 of the blade 13 with this opening 41 and parallel to the plane of the faces 14, 15 (but not intersecting the axis of rotation 17). This arrangement of the ancillary part is very advantageous due to its very small size and the resulting ease of controlling the rotation of the blade 13, 13'.

[0042] Indeed, according to this third embodiment, the controllable means 22 for applying a pressure force to the attached part 20 can be constituted by a threaded rod capable of being screwed into the hole 41, the wall of which is tapped accordingly.

[0043] The operating mode for the implantation of the cage according to the invention, whatever the embodiment described here, can be deduced without any difficulty from the present description and possibly from the content of the documents of the prior art. It will therefore not be developed further here.

[0044] The cage according to the present invention is particularly advantageous, in particular by the fact that it is possible to pivot the two blades, either by an anterior route called ALIF, or by an antero-lateral route called OLIF, or by a lateral route called XLIF, in complete safety and total reliability.

Claims

Claims

1. Intervertebral cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae, comprising an element (12) having the general shape of a disc comprising two opposite faces (14, 15) substantially parallel and a lateral wall (16) connecting said two opposite faces, these opposite faces being capable of coming into contact respectively with the two vertebral bodies and substantially defining two planes which contain them, at least one first locking blade (13), the overall width of said first blade, measured in the plane substantially perpendicular to the two opposite faces, being at most equal to the distance separating these two opposite faces and its overall length measured in this same plane being greater than this distance;means for rotating said first blade (13) around a first axis (17) located in a hole (19) made in the side wall (16) of the element (12) so that this first blade is able to take any position between a first position (PI) and a second position (P2), the first position being that in which the first blade is entirely contained in the space defined between the planes of the two opposite faces (14, 15), and the second position being that in which at least one end of the first blade emerges from this space, these means for rotating the first blade comprising a first shaft (18) rotatably mounted relative to the element (12) around the first axis (17), and means for securing the first blade to said first shaft;characterized by the fact that it further comprises an additional part (20), means for securing said first additional part with said first blade, a sliding ramp (21) produced on said additional part (20), and controllable means (22) for applying a pressure force on said sliding ramp (21) substantially at a point (23) so as to pivot said first blade between its first position (PI) and its second position (P2).;

2. Cage according to claim 1, characterized in that the controllable means (22) for applying a pressure force are constituted by a pusher (24) one end (25) of which is capable of sliding on said sliding ramp (21) according to a linear translation of this pusher in an orifice (26) made in said element (12), the axis (27) of this said orifice (26) being intersecting with said sliding ramp and not with said first axis (17).

3. Cage according to claim 1, characterized in that the controllable means (22) for applying a pressure force comprise a finger (30) capable of coming into contact with said sliding ramp in a rotational movement.

4. Cage according to claim 3, characterized in that the controllable means (22) for applying a pressure force according to a rotational movement further comprise a second shaft (31) mounted along an axis (32) substantially collinear with the first axis (17), said finger (30) being integral with offset from said second shaft so that this finger comes into contact with said sliding ramp (21) to cause the rotation of said first blade (13) between at least its first position (PI) and second position (P2) when said finger comes into contact with the sliding ramp following the rotation of the second shaft (31).

5. Cage according to one of claims 3 and 4, characterized in that the first annex part (20) is made up of a portion of cylindrical rod optionally of revolution which is integral in offset directly or indirectly with the first blade (13).

6. Cage according to one of claims 4 and 5, characterized in that it comprises a second blade (13') integral with said second shaft (31).

7. Cage according to claim 6, characterized in that the overall width of said second blade (13') measured in a plane substantially perpendicular to the two opposite faces (14, 15) 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.

8. Cage according to claim 7, characterized in that the first and second blades (13, 13') form a non-zero angle between them.

9. Cage according to one of claims 6 to 8, characterized in that the two blades are mounted tightly against the wall of said cavity.

10. Cage according to one of the preceding claims, characterized in that the element (12) comprises a cavity (10), said additional part (20) being located in one of the following places: in said cavity (10), in a housing (40) made in the wall (16) of said element (12), said housing being optionally obtained at the intersection of two holes made in this wall. 10

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