Intervertebral cage

Abstract

The present invention relates to interbody cages. The cage comprises an element 10 comprising two opposite faces 11, 12, means for immobilizing the element 10, these means consisting of two blades 31, 32 and of means 40 for rotating the blades 31, 32 around a shaft 48 of axis 100, each of these blades 31, 32 comprising two planar half-blades 31-1, 31-2; 32-1, 32-2 joined together in pairs such that, for at least one of the two blades 31, 32, the two planes of the half-blades form a non-zero angle between them, these two blades being fixed on the shaft 48 in such a way that the planes of a half-blade 31-2, 32-2 form with the axis 100 a right angle, and that these two half-blades 31-2, 32-2 are fixed on the shaft 48 opposite each other.

Description

[0001] Intervertebral cage

[0002] 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 these cages on the vertebrae by osteosynthesis.

[0003] 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. The structure of the known cages comprises means which lock them as soon as they are implanted between two vertebrae. But this embodiment sometimes presents disadvantages for the proper resolution of the problem presented to the patient subject to this implantation.

[0004] Such cages are known, for example, from FR2955483, FR3136959, FR4299039 and US8545562. But none of these documents describes cages which include means enabling them to adapt automatically, in particular when they are implanted between two vertebrae, to the physiological shape of the spinal column in which they are to be placed.

[0005] The present invention therefore aims to produce a new intersomatic cage making it possible to at least partially overcome these drawbacks of previous intersomatic cages, while having a simple structure and not posing difficulties for its implantation, further facilitating the work of the practicing surgeon. More specifically, the present invention aims to produce 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; means for locking said element with the two vertebral bodies, these locking means being constituted by at least a first blade and a second blade and by means for driving said two blades in rotation relative to said element via a rotation shaft defined along an axis of rotation,characterized by the fact that the first blade comprises a half-blade: the second blade comprises a half-blade, each of these two half-blades being substantially defined in a plane, said cage further comprising means for fixing the half-blade of the first blade on said rotation shaft offset therefrom and so that its plane makes an angle with the rotation axis other than a right angle, means for fixing the half-blade of the second blade on said rotation shaft offset therefrom and so that its plane makes a right angle with the rotation axis, and that these half-blades of the first and second blades are fixed on either side of the rotation shaft.,

[0006] The present invention also aims to produce 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; means for locking the said element with the two vertebral bodies, these locking means being constituted by at least a first blade and a second blade, and by means for rotating the said two blades relative to the said element around a rotation shaft defined along an axis of rotation so that they are capable of taking 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, characterized in that a first of these two blades comprises two half-blades and the other second blade comprises a first half-blade, each of these three half-blades being substantially defined in a plane, the first blade further comprising means for fixing its two half-blades together so that the two planes of these half-blades make a first non-zero angle between them, and means for fixing its two half-blades on said rotation shaft so that the plane of one of them makes a right angle with the axis of rotation, the second blade further comprising means for fixing its half-blade on said shaft opposite the half-blade of the first blade which is not perpendicular to said axis, so that its plane,on the one hand makes a second non-zero angle with a plane perpendicular to the axis of rotation and on the other hand is not parallel to the plane of the half blade, which is opposite the first blade.,

[0007] According to another characteristic of the present invention, the second blade comprises a second half-blade substantially defined in a plane, means for fixing its second half-blade with its first half-blade and means for fixing it on said rotation shaft so that, on the one hand, the plane of its second half-blade makes a right angle with the axis, and on the other hand, this half-blade is substantially located opposite the half-blade of the first blade whose plane is perpendicular to said axis.

[0008] 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:

[0009] [Fig. 1] represents a top view of a preferred embodiment of the intersomatic cage according to the invention, in which the blades are in the retracted position, and [Fig. 2] represents a side view along the arrow F1 (figure 1) of the embodiment of the intersomatic cage according to the invention according to figure 1, in which the blades are in the extended position.

[0010] It is first of all 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. It is further specified that, within the meaning of the invention, the term "half-blade" used in the present description is defined, for greater understanding, in relation to the well-known blades of the cages of the prior art which are single-piece blades linked to a rotation shaft by having two portions located respectively on either side of this rotation shaft, so that these two portions are capable of being implanted respectively in the two vertebral bodies of two consecutive vertebrae V1 and V2.

[0011] The term "half-blade" used in the present description designates only one of these portions so that it is implanted in only one of the two vertebrae. The structure of such a half-blade thus defined is clearly apparent from the drawings attached to the present description.

[0012] Figures 1 and 2 schematically represent a preferred embodiment of the cage according to the invention. However, although schematic, this representation includes a large number of the structural characteristics of the cage according to the invention. The invention, in its primary function, relates to an intersomatic cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae V1, V2, comprising: an element 10 having the general shape of a disc; means for locking this element 10 with the two vertebral bodies, these locking means being constituted by at least a first blade and a second blade 31, 32 and by means 40 for driving them in rotation relative to the element 10 via a rotation shaft 48 defined along an axis of rotation 100.

[0013] More precisely, the cage, which is more specifically illustrated in the broken line frame Cl in Figure 2, is characterized by the fact that the first blade 31 comprises a half-blade 31-1 and the second blade 32 comprises a half-blade 32-2, each of these two half-blades being substantially defined in a plane.

[0014] The cage further comprises: means for fixing the half-blade of the first blade on the rotation shaft offset from the latter and so that its plane makes an angle with the rotation axis other than a right angle; means for fixing the half-blade of the second blade on the rotation shaft offset from the latter and so that its plane makes a right angle with the rotation axis, these half-blades of the first and second blades being fixed on either side of the rotation shaft.

[0015] 11 is clearly specified that the planes of the two half-blades respectively of the first blade 31 and of the second blade 32 may or may not be coincident. In the representation illustrated in frame C1, these two half-blades are not coplanar.

[0016] Figures 1 and 2 represent a preferred industrial embodiment of the intersomatic cage according to the invention capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae V1, V2, figure 2.

[0017] The cage according to this embodiment comprises an element 10 having the general shape of a disc delimited by two substantially parallel opposite faces 11,

[0018] 12 and a side wall 13 connecting these two opposite faces, these two opposite faces being able to come into contact respectively with the two vertebral bodies and substantially defining two facial planes containing these opposite faces 11, 12. The cage comprises means for locking the element 10 with the two vertebral bodies, these locking means comprising at least a first blade 31 and a second blade 32, and means 40 for rotating these two blades 31, 32 relative to the element 10 around a rotation 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 to be implanted in the bony part of the vertebrae.

[0019] According to a very preferred implementation of the cage according to the invention, the first 31 comprises two half-blades 31-1, 31-2 and the other second blade 32 comprises a first half-blade 32-1, each of these three half-blades being substantially defined in a plane.

[0020] The first blade 31 further comprises means for fixing its two half-blades

[0021] 31-1, 31-2 between them so that the two planes of these half-blades make a first non-zero angle between them, and means for fixing its two half-blades on the rotation shaft so that the plane of one 31-2 of them makes a right angle with the axis of rotation. These fixing means are well known in themselves and can be of any type, in particular like those mentioned in figure 1.

[0022] As for the second blade 32, it comprises means for fixing its first half-blade 32-1 on the shaft opposite the half-blade 31-1 of the first blade which is not perpendicular to the axis 100 so that its plane, on the one hand, makes with a plane perpendicular to the axis of rotation a second non-zero angle a' different from the first non-zero angle a and on the other hand is not parallel to the plane of the half-blade, which is opposite, the first blade.

[0023] As illustrated in Figures 1 and 2, this second blade 32 further comprises a second half-blade 32-2 substantially defined in a plane, means being further provided for fixing this second half-blade 32-2 with its first half-blade

[0024] 32-1 and means for fixing it to the rotation shaft 48 so that, on the one hand, the plane of this second half-blade makes a right angle with the axis 100, and on the other hand, it is substantially located opposite the half-blade 31-2 of the first blade 31, the plane of which is perpendicular to the axis 100.

[0025] According to an advantageous embodiment from the manufacturing point of view, it is preferable that the unaffected angles defined above are equal, for example of the order of twenty degrees of angle.

[0026] The embodiment illustrated in the figures has blades 31, 32 whose opposite half-blades 31-1, 32-1 are in a so-called "divergent" position, namely with their free ends further away from each other than their opposite ends which are close to the shaft 48. But it is clearly specified that these two half-blades 31-1 and 32-1 facing each other, respectively the first and second blades 31, 32 can be in a so-called "convergent" position, namely with their free ends closer to each other than their opposite ends.

[0027] According to the present description, when it is stipulated that a half-blade is defined in a plane, it is understood that this is its general shape, but that at least one of the half-blades of at least one blade may for example have the shape of a spoon for example slightly concave.

[0028] In addition, the element 10 may comprise a substantially central opening (figures 1 and 2) to constitute a cavity 14 open on the opposite faces 11, 12. In this case, the first and second blades 31, 32 are arranged according to one of the following three possibilities: both in the cavity, both outside the cavity, one in the cavity and the other outside.

[0029] As for the means mentioned above for fixing the blades on the shaft 48, they are known in themselves. Very schematically for example: the blades having axial holes of cylindrical polygonal cross section are positioned in the case where the element has a cavity, then the shaft of the male type complementary to the holes is introduced into them, and finally the blades are secured to the shaft by any means, for example a pin, a nut, etc. The element 10 can be made of Titanium or Peek (i.e. polyetheretherketone or similar). As for the blades and the shaft, they are for example made of Titanium or stainless steel or similar.

[0030] From the description given above, it is easily apparent that the cage according to the invention meets the aim of the present invention defined in the preamble.

[0031] In particular: referring more particularly to Figure 2, it can be seen that the two half-blades 31-1 and 32-1 make a non-zero angle between them (divergent position) and that, as a result, when they are implanted in the bony body of a vertebra, preferably an upper vertebra V1, they ensure, by wedge effects known in themselves, a firm connection of the disc 10 with this vertebra V1. When the two half-blades 31-2 and 32-2 (according to the invention, only one is possible, but two, as illustrated, are clearly preferable) are implanted in the vertebra V2, they are in planes parallel to each other, and also substantially to the longitudinal axis of the spinal column. Therefore, before the osteosynthesis takes place, they allow a slight translation of this V2 vertebra so that it can take a position that is as least traumatic as possible for the patient who has undergone this implantation.

Claims

Claims 1. Intersomatic cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae (V1, V2), comprising: an element (10) having the general shape of a disc; means for locking said element (10) with the two vertebral bodies, these locking means being constituted by at least a first blade and a second blade (31, 32) and by means (40) for rotating said two blades relative to said element (10) via a rotation shaft (48) defined along an axis of rotation (100), characterized in that: • the first blade (31) comprises a half-blade (31-1) • the second blade (32) comprises a half-blade (32-2), • each of these two half-blades being substantially defined in a plane, said cage further comprising: • means for fixing the half-blade of the first blade on said rotation shaft offset from the latter and so that its plane makes an angle with the rotation axis other than a right angle, • means for fixing the half-blade of the second blade on said rotation shaft offset from it and so that its plane makes a right angle with the axis of rotation, and that: • these half-blades of the first and second blades are fixed on either side of the rotation shaft.

2. Intersomatic cage capable of being interposed between two vertebral bodies to replace the intervertebral disc originally located between the two vertebrae (V1, 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);means for locking said element (10) with the two vertebral bodies, these locking means being constituted by at least a first blade and a second blade (31, 32), and by means (40) for rotating said two blades (31, 32) relative to said element (10) around a rotation 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, characterized by the fact that:; • a first of these two blades comprises two half-blades and the other second blade comprises a first half-blade, each of these three half-blades being substantially defined in a plane, • the first blade further comprising means for fixing its two half-blades together so that the two planes of these half-blades make a first non-zero angle between them, and means for fixing its two half-blades on said rotation shaft so that the plane of one of them makes a right angle with the axis of rotation, • the second blade further comprising means for fixing its half-blade on said shaft opposite the half-blade of the first blade which is not perpendicular to said axis, on the one hand so that its plane makes a second non-zero angle with a plane perpendicular to the axis of rotation and on the other hand so that its plane is not parallel to the plane of the half-blade, which is opposite, the first blade.

3. Cage according to claim 2, characterized in that the second blade comprises a second half-blade substantially defined in a plane, means for fixing its second half-blade with its first half-blade and means for fixing it on said rotation shaft so that, on the one hand, the plane of its second half-blade makes a right angle with the axis, and on the other hand, this half-blade is substantially located opposite the half-blade of the first blade whose plane is perpendicular to said axis.

4. Cage according to claim 3, characterized in that the unaffected angles are equal.

5. Cage according to claim 4, characterized in that the value of the undamaged angles is substantially of the order of twenty degrees of angle.

6. Cage according to one of claims 2 to 5, characterized in that the two half-blades facing each other of the first and second blades, which make a non-zero angle with respect to a plane perpendicular to the axis of rotation, are in one of the following two positions: convergent position, divergent position.

7. Cage according to one of claims 2 to 6, characterized in that at least one of the half-blades of at least one blade has a substantially spoon shape.

8. Cage according to one of the preceding claims 2 to 7, said element comprising a substantially central opening to constitute a cavity (14) open on said opposite faces (11, 12), characterized in that the first and second blades (31, 32) are arranged according to one of the following three possibilities: both in the cavity, both outside the cavity, one in the cavity and the other outside.

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