Intervertebral cage

Abstract

The present invention relates to intervertebral cages that can be placed between two vertebral bodies. The cage comprises an element 10 delimited by two opposing faces 11, 12 delimiting a space 26, a first linking means for securing the element 10 to a first vertebral body without the element 10 being secured to the other vertebral body, and a second linking means for securing the element 10 to the other vertebral body after it has been secured to the first vertebral body, the first linking means comprising a rotation shaft 40, a blade portion 41, and means for mounting the first blade portion 41 on the shaft 40 such that they are in engagement with one another, the second linking means comprising a second blade portion 45 mounted on the shaft 40 so that it pivots in the opposite direction to, and independently of, the first portion 41, in order for these two portions to be implanted successively in the two vertebral bodies, respectively.

Description

[0001] Intervertebral cage

[0002] The present invention relates to intervertebral cages suitable for being interposed between two vertebrae in replacement of the 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 the two vertebrae by means of blades in order to obtain the fixation of the intervertebral cages on the vertebrae by osteosynthesis.

[0003] Intervertebral cages are known to include a disc and means of locking this disc with the two vertebrae between which it is placed, these locking means being made up of blades capable of pivoting so that their ends are embedded in the bony element of the vertebrae.

[0004] Such a cage is described and illustrated in FR2955483, as well as in US2010 / 016968, US2010 / 280619, US2007 / 270961, W02009 / 070721 and WO2014 / 145527. It gives good results but does not allow for the practical correction of cases such as spondylolisthesis, namely the case where the vertebrae are not aligned.

[0005] Therefore, the present invention aims to create an intervertebral cage that overcomes the disadvantages of the prior art cages mentioned above while facilitating the work of practitioners.

[0006] More specifically, the present invention relates to an intervertebral cage suitable for interposing between a first vertebral body and a second vertebral body in place of the intervertebral disc initially present between these two vertebral bodies, the cage comprising: an element having the general shape substantially of a disc having two substantially parallel opposite faces, the two said opposite faces being suitable for coming into contact respectively with the two vertebral bodies by defining two facial planes containing these two faces to delimit a space between these two faces, a first means of connection suitable for securing said element with the first vertebral body without said element being secured with the second vertebral body and a second means of connection suitable for securing said element with the second vertebral body after it has been secured with said first vertebral body,characterized by the fact that the first means of connection comprises:

[0007] • a shaft mounted for rotation relative to said element,

[0008] • at least a first portion of the blade, • means for mounting said first portion of the blade cooperatively on said single shaft so that it is capable of assuming all positions between a first position and a second position, the first position being that in which, according to a first angular position of said shaft relative to said element, said first portion of the blade is entirely contained within the space, the second position being that in which, according to a second angular position of said shaft relative to said element after a rotation of said shaft in a first direction of rotation, said first portion of the blade emerges at least partially from a first side of said space, and that the second means of connection comprises:

[0009] • at least one second portion of the blade,

[0010] • means for mounting said second portion of blade in cooperation with said shaft so that it is able to take all positions between a first position and a second position, the first position being that in which, according to a first angular position of said shaft with respect to the element, said second portion of blade is entirely contained in space, the second position being that in which, according to a second angular position of said shaft with respect to said element after a rotation of said shaft in a second direction of rotation opposite to said first direction of rotation of said shaft, said second portion of blade emerges at least partially from the second side of said space, opposite to said first side of said space.

[0011] 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:

[0012] Figure 1 represents a schematic top view of a preferred embodiment of the intervertebral cage according to the invention.

[0013] Figure 2 represents a portion of the cage according to the invention in the embodiment shown in Figure 1, in a first configuration considered to be the initial configuration.

[0014] Figure 3 represents the same part of the cage according to the invention as that shown in Figure 2, but in a second configuration. Figure 4 represents the same part of the cage, but in a configuration considered to be final. Figure 5 represents four very schematic views referenced chronologically (1) to (4) illustrating a method of implanting the interbody cage according to the invention for, in particular, the treatment of spondylolisthesis.

[0015] It is specified that, in this 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.

[0016] It is also specified that, for the purposes of the invention, the term "blade portion" used in the present description is defined, for greater understanding, in relation to the known blades of prior art cages 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 able to be implanted respectively in the two vertebral bodies of two consecutive V1 and V2 vertebrae.

[0017] The term "blade portion" used in this description refers to a single portion of this blade that is suitable for implantation in only one of the two vertebrae. The structure of such a blade portion, as defined herein, is clearly illustrated in the drawings accompanying this description.

[0018] With regard to the attached figures, the present invention relates to an intervertebral cage suitable for being interposed between two vertebral bodies V1, V2 in replacement of the intervertebral disc originally located between these two vertebral bodies.

[0019] The cage according to the invention comprises an element 10 suitable for being interposed between a first vertebral body V1 and a second vertebral body V2 in replacement of the intervertebral disc initially present between these two vertebral bodies.

[0020] Element 10 has the general shape substantially of a disc having two substantially parallel opposite faces 11, 12, the two opposite faces being able to come into contact respectively with the two vertebral bodies V1, V2 by defining two facial planes containing these two faces 11, 12 to delimit a space 26 (Fig. 5(4)) included between these two faces.

[0021] The cage further comprises a first means of connection suitable for securing element 10 with the first vertebral body V1 without this element 10 being secured with the second vertebral body V2 and a second means of connection suitable for securing this element 10 with the second vertebral body V2 after it has been secured with said first vertebral body V1.According to the invention, the first connecting means comprises a shaft 40 mounted for rotation relative to the element 10; at least a first portion of a blade 41, means for mounting this first portion of a blade 41 cooperatively on the shaft 40 so that it is able to take any position between a first position and a second position, the first position being that in which, according to a first angular position of this shaft 40 relative to the element 10, the first portion of the blade 41 is entirely contained within the space 26, the second position being that in which, according to a second angular position of the shaft 40 relative to the element 10 after a rotation of said shaft in a first direction of rotation, said first portion of the blade 41 emerges at least partially from a first side of said space 26.

[0022] As for the second connecting means, it comprises at least a second portion of blade 45, means for mounting this second portion of blade 45 in cooperation with the shaft 40 so that it is capable of assuming any positions between a first position and a second position, the first position being that in which, according to a first angular position of the shaft relative to the element 10 (which may be the same as that mentioned above), this second portion of blade 45 is entirely contained within the space 26, the second position being that in which, according to a second angular position of the shaft relative to the element

[0023] 10 after a rotation of this tree in a second direction of rotation opposite to the first direction of rotation of this same tree, the second portion of blade 45 emerges at least partially from the second side of space 26 which is opposite to the side of space 26 from which the first portion of blade 41 emerges.

[0024] 11 is mentioned that these first and second means of attachment are capable of being operational independently of each other, as will be shown below in the continuation of this description.

[0025] According to another feature of the invention, the means for mounting said first 41 and second 45 blade portions in cooperation with the shaft 40 comprise means for driving the rotation of the first blade portion 41 when the shaft 40 undergoes a rotation in the first direction of rotation, without driving the second blade portion 45 into rotation, and means for driving the rotation of the second blade portion when the shaft 40 undergoes a second rotation in the opposite direction to the first direction of rotation, without driving the first blade portion 41 into rotation.According to the invention, the means for driving the rotation of at least one of the first and second portions of the blade relative to the element 10 are constituted by the fact that one of the first and second portions of the blade is mounted in rotation on the shaft via a free rotation bearing in cooperation with coupling means comprising an oblong slot 51 made in the shaft 40 or in the bearing and a finger 52 mounted projecting on the bearing or on the shaft, so that this finger 52 is able to travel the oblong slot 51 so that, according to a direction of rotation of the shaft 40, one of the first and second portions of the blade is subjected to a rotation when the finger comes against an end of the oblong slot 51.

[0026] The means for rotating the two portions of the blade advantageously have functional structures identical to that defined above for only one of the two portions of the blade 41, 45 and illustrated in figures 2-4.

[0027] It is specified that these oblong slots 51 can be formed in a plane perpendicular to the axis of the shaft 40 (as illustrated in Figures 2-4), but that they can also be formed in a plane with a certain inclination to the axis, the means for mounting the blade portion onto the shaft 40 being adapted accordingly. These oblong slots can also have a curved profile. Moreover, and most preferably, the element 10 has a substantially central through cavity 30 (Figure 1) opening onto the two opposite faces 11 and 12 of the element 10, the first and second connecting means being located at least partially within this cavity 30, as schematically illustrated in Figure 1.

[0028] The cage thus defined above finds a particularly advantageous application in the correction of spondylolisthesis between two consecutive vertebrae V1, V2.

[0029] Figures 2 to 4 illustrate the operation of the means for pivoting the portions of the blade in the embodiment described above.

[0030] Figure 2 illustrates the original position of the two blade portions 41, 45, a position defined as their first position in space 26, with the fingers 52 arranged in the slots 51 as illustrated in this figure.

[0031] When the shaft 40 is rotated clockwise (dextrorsum), Figure 3, the blade portion 41 rotates, but not the blade portion 45, since the finger 52 travels along the slot 51 made in this portion of the blade 45 without moving it. When the shaft 40 is rotated counterclockwise (sinistrorsum), Figure 4, the blade portion 45 rotates, but not the blade portion 41, since the finger 52 travels along the slot 51 made in this portion of the blade 41 without moving it.

[0032] The final position, defined as the second position above, is illustrated in Figure 4, in which it is easy to understand that the two portions of blade 41, 45 were successively implanted in the two vertebral bodies V1, V2, to obtain a result which will be explained below with regard to the four diagrams in Figure 5. It is stipulated that, in the description made above, only one portion of blade 41, 45 is mentioned on either side of the rotation shaft 40.

[0033] However, according to an advantageous and preferred embodiment, at least one of the two connecting means, preferably both, further comprises another portion of blade, figure 1, and means for mounting this other portion of blade in cooperation with the rotation shaft so that it is able to take any position between a first position and a second position, as defined above.

[0034] These other portions of the blade being preferably substantially opposite each other on the same side of this tree, making a non-zero angle between them, allows for a wedge-effect fixation after their implantation in the vertebral body.

[0035] Figure 5 represents in a very schematic way a method of implanting the cage according to the invention in the case of the treatment of a deformity of a vertebral column such as spondylolisthesis or similar between two consecutive vertebrae V1, V2, for example following an accident.

[0036] This process will be described more particularly in the case of the embodiment according to the figure.

[0037] Figure 5(1) represents a first step in the process: the placement of element 10 in place of the intervertebral disc which was located between the two vertebrae V1, V2.

[0038] Figure 5(2) represents a second step in the procedure: fixing element 10 to only one of the two vertebrae, in this case vertebra V1, by rotating the two blade portions referenced 24 and 28 in Figure 5. These two blade portions are located on the same side of the rotation shaft 40 and are both implanted in the vertebral body V1. In this second step, element 10 is not fixed to vertebra V2. Figure 5(3) represents a third step in the procedure: translating the second vertebra V2 until it is positioned along the original physiological axis of the spine, so as to relieve the patient's pain.

[0039] Figure 5(4) illustrates the final step of the procedure: the fixation of element 10 to the other vertebra, in this case vertebra V2, by rotating the two remaining blade portions. These two remaining blade portions are located on the same side of the rotation shaft 40 and are both implanted in the vertebral body V2. With element 10 fixed to the two vertebral bodies V1 and V2 aligned with each other, the patient's pain relief is sustained.

Claims

DEMANDS [Claims 1] An intervertebral cage adapted to be interposed between a first vertebral body (V1) and a second vertebral body (V2) in replacement of the intervertebral disc initially present between these two vertebral bodies, the cage comprising: an element (10) having the general shape substantially of a disc having two substantially parallel opposite faces (11, 12), the two said opposite faces being adapted to come into contact respectively with the two vertebral bodies (V1, V2) by defining two facial planes containing these two faces (11, 12) to delimit a space (26) included between these two faces, a first connecting means adapted to secure said element (10) with the first vertebral body (V1) without said element (10) being secured with the second vertebral body (V2), and a second connecting means adapted to secure said element (10) with the second vertebral body (V2) after it has been joined to the said first vertebral body (V1),characterized by the fact that the first means of connection comprises: • a shaft (40) mounted for rotation with respect to said element (10), • at least one first portion of the blade (41), • means for mounting said first portion of blade (41) cooperatively on said shaft (40) so that it is capable of assuming any position between a first position and a second position, the first position being that in which, according to a first angular position of said shaft (40) relative to said element (10), said first portion of blade (41) is entirely contained within space (26), the second position being that in which, according to a second angular position of said shaft (40) relative to said element (10) after a rotation of said shaft in a first direction of rotation, said first portion of blade (41) emerges at least partially from a first side of said space (26), and that the second connecting means comprises: • at least one second portion of the blade (45), • means for mounting said second portion of blade (45) in cooperation with said shaft (40) so that it is capable of assuming any positions between a first position and a second position, the first position being that in which, according to a first angular position of said shaft relative to the element (10), said second portion of blade (45) is entirely contained within the space (26), the second position being that in which, according to a second angular position of said shaft relative to said element after a rotation of said shaft in a second direction of rotation opposite to said first direction of rotation of said shaft, said second portion of blade (45) emerges at least partially from the second side of said space (26), opposite said first side of said space (26). [Claims 2] Cage according to claim 1, characterized in that the means for mounting said first (41) and second (45) blade portions in cooperation with said shaft (40) comprise means for driving the rotation of said first blade portion (41) when the shaft (40) undergoes a rotation in the first direction of rotation, without driving the second blade portion (45) into rotation, and means for driving the rotation of the second blade portion when the shaft (40) undergoes a rotation in the opposite direction of said first direction of rotation, without driving the first blade portion (41) into rotation. [Claims 3] Cage according to claim 2, characterized in that the means for driving the rotation of one of the first and second portions of blade are constituted by the fact that said one of the first and second portions of blade is mounted in rotation on the shaft via a free bearing in cooperation with coupling means comprising an oblong slot (51) made in the shaft (40) or in the bearing and a finger (52) mounted projecting on the bearing or on the shaft, so that this finger (52) is able to travel through said oblong slot (51) so that, according to a direction of rotation of said shaft (40), one of the first and second portions of blade is subjected to a rotation when said finger comes against an end of said oblong slot (51). [Claims 4] Cage according to any one of the preceding claims, characterized in that said element (10) comprises a substantially central through cavity (30) opening respectively onto the two said opposite faces (11, 12) of said element (10), said first and second connecting means being located at least partially in said cavity (30). [Claims 5] Cage according to any one of the preceding claims, characterized in that it finds application in the correction of spondylolisthesis between two consecutive vertebrae (V1, V2).

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