FR2955483A1 - INTERSOMATIC CAGE - Google Patents

Abstract

The cage according to the invention comprises a disc 10 comprising two parallel faces 11, 12 and a side wall 13, at least one locking blade 31, 32 whose width measured in a plane 34 perpendicular to the two faces 11, 12 is at most equal to the distance separating these two faces and the length measured in the same plane 34 is greater than this distance, and first means 40-1 for rotating the blade 31, 32 in a first second plane 36, 37 making a first angle β, δ with the planes 42, 44 passing through the two faces 11, 12, different from ninety degrees, and so that the blade 31, 32 is able to take any position between two positions, a position in which the first blade is entirely contained in the space Esp defined between the two planes 42, 44, the other being the one in which at least one end of the blade emerges from the space Esp. Application to cages able to be interposed between two vertebrae in replacement of an intervertebral disc.

Description

INTERSOMATIC CAGE

The present invention relates to intersomatic cages adapted to be interposed between two vertebrae replacing the intervertebral disk originally located between these two vertebrae, of the type comprising an element having the general shape of a substantially cylindrical disk and means for blocking this element with at least one of the two vertebrae by means of one or two blades in order to obtain fixation of the cages by osteosynthesis.

Cages are known that 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 extremities are planted in the bone element of the vertebrae. Such an embodiment with two blades parallel and perpendicular to the planes of the opposite faces of the disk is for example described and illustrated in EP-A-1 674 053. These embodiments generally give good results, but may have disadvantages, for example the fact that they do not allow with certainty to flatten and maintain the two opposite faces of the cages on the facing faces of the vertebral bodies of the two vertebrae and the fact that, after the cages have been implanted, they do not prevent a possible displacement of the vertebrae, and therefore a distance from the cages with respect to the two vertebrae, which delays all the desired osteosynthesis.

Also, the present invention aims to provide an interbody cage which largely overcomes the aforementioned disadvantages of similar cages of the prior art and which, therefore, gives better results, especially by allowing a better permanent anchoring of the blades in the vertebrae and by providing a safer temporal connection of the opposite faces of the cage with the vertebral bodies of the two vertebrae between which such a cage must be implanted.

More specifically, the subject of the present invention is an intersomatic cage capable of being interposed between two vertebral bodies replacing the intervertebral disc originally located between the two vertebrae, comprising: an element having the general shape of a disc comprising two opposite faces substantially parallel and a side wall connecting the two said opposite faces, the two said opposite faces being adapted to come into contact respectively with the two vertebral bodies, and • locking means of said element with the two vertebral bodies, these locking means being constituted by at least one first blade whose overall width measured in a first plane perpendicular to said two opposite faces is at most equal to the distance separating said two opposite faces and the overall length measured in the same first plane is greater than this distance, characterized by the fact that it includes e n addition first means for rotating said first blade in a first second plane making a first angle with the third planes passing respectively by the two opposite faces, different from ninety degrees, and so that said first blade is capable of taking any position between two first and second positions, the first position being that in which the first blade is entirely contained in the space defined between the two third planes, and the second position being that in which at least one end of the first blade emerges from said space. According to another characteristic of the invention, said cage further comprises a second blade whose overall width measured in the first plane perpendicular to the two opposite faces is at most equal to the distance separating said two opposite faces and the length outside. all measured in the same first plane is greater than this distance, and second means for driving in rotation the second blade in a second second plane making a second angle with the third planes and an angle with the first second plane, these second means for driving in rotation the second blade being arranged so that the second blade is able to take any position between two first and second positions, the first position being one in which the second blade is entirely contained in the space defined between the two thirds planes, and the second position being that in which at least one end of said second blade emerges from the t space.

Other features and advantages of the invention will emerge in the course of the following description given with reference to the accompanying drawings for illustrative but not limiting purposes, in which: FIG. 1 represents a cross-sectional schematic sectional view of an embodiment of FIG. the intersomatic cage according to the invention, and Figures 2 and 3 show a preferred embodiment, improved and industrial of the interbody cage according to the invention in accordance with the embodiment illustrated in Figure 1, Figure 2 being a view of perspective from above and Figure 3 being a side view. It is first of all specified that, in the figures, the same references designate the same elements, whatever the figure on which they appear and whatever the form of representation of these elements. Similarly, if elements are not specifically referenced in one of the figures, their references can be easily found by referring to another figure.

It is also stated that the figures essentially represent two embodiments of the object according to the invention, but that there may be other embodiments that meet the definition of this invention. It is furthermore 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 has several elements of identical function and if, in the description, it is not specified that the object according to this invention must obligatorily comprise a number particular of these elements, the object of the invention may be defined as comprising "at least one" of these elements.

Lastly, it is specified that when, in the present description, an expression defines, by itself, without a 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 technically possible, either separately, or in full and / or partial combination. The intervertebral cage according to the invention is able to be interposed between two vertebrae VI, V2 schematically mentioned in FIG. 1, replacing the intervertebral disk originally situated between these two vertebrae and damaged for any reason whatsoever, as a result of accident, illness, etc. The intervertebral cage comprises an element 10 having the general shape of a disk, like the one illustrated in FIGS. 2 and 3. This element 10 is delimited by two substantially parallel opposite faces 11, 12 (although these faces may be between them angulation, their planes forming a wedge as shown in Figure 3, but a low enough angulation so that they can be considered as contained in two substantially parallel planes, as mentioned in Figure 3) and a side wall 13 connecting the two opposite faces 11, 12, the two opposite faces 20 being adapted to come into contact respectively with the two vertebral bodies VI, V2. This element 10 is for example made, but not exclusively, PEEK (in English "PolyEthylEtherKetone" - in French "poly (ether-ether ketone)"]. The cage further comprises means 20 for locking the element 10 with the two vertebral bodies VI, V2. These locking means 20 are constituted by at least a first blade 31, 32 whose overall width measured in a first plane 34 perpendicular to the two opposite faces 11, 12 is at most equal to the distance separating these two opposite faces and 30 the overall length measured in the same foreground is greater than this distance. According to a first important characteristic of the invention, the cage further comprises first means 40-1 for rotating the first blade 31, 32 in a first second plane 36, 37 making a first angle R, 8, FIG. with the two thirds planes 42, 44 passing respectively through the two opposite faces 11, 12, different from ninety degrees, and so that the first blade 31 or 32 is able to take any position between two first and second positions , the first position being that in which it is entirely contained in the space Esp defined between the two third planes 42, 44, and the second position being that in which at least one of its ends emerges from the space Esp.

With the embodiment described above, the fact that the blade 31, 32 makes with the third planes 42, 44 an angle R, different from ninety degrees allows it to occur, between the opposite faces 11, 12 of the element 10 and the blade, a wedge effect in the vertebral bodies that prevents the two vertebrae VI, V2 at least to move away from these two opposite faces 11, 12. And this, especially as these two opposite faces 11, 12 are generally covered with pins or the like, Figures 2 and 3, which are anchored in the vertebral bodies. According to an advantageous and complementary feature of the invention, the cage comprises a second blade 32, 31 whose overall width measured in the first plane 34 perpendicular to the two opposite faces 11, 12 is at most equal to the distance separating these two said opposite faces and the overall length measured in the same first plane is greater than this distance, and second means 40-2 for rotating the second blade 32, 31 in a second second plane 37, 36 forming a second angle 8, f3 with the third planes 42, 44 and an angle α with the first second plane 36, 37. These second means 40-2 for rotating the second blade 32, 31 are arranged so that the second blade is adapted to take any position between two first and second positions, the first position being that in which it is entirely contained in the space Esp defined between the two third planes 42, 44, and the second position is nt the one in which at least one of its ends emerges from this space Esp. In Figures 1 and 3, the two blades 31, 32 are shown in their second position. In Figure 2, they are shown in their first position. According to another embodiment, as illustrated in the figures, the cage is arranged in such a way that the first and second second planes 36, 37 form between them a non-zero angle α. This embodiment is advantageous because it secures the fixation of the cage between the vertebrae even more than the two embodiments described above. Indeed, in this case and when each of the first and second second planes 36, 37 makes, with the third planes 42, 44, an angle R, 8 different from a right angle, the two blades 31, 32 forming between them a As a non-zero angle, between them and the two opposite faces 11, 12 of the element 10 there are three wedge effects in the vertebral bodies respectively defined by the three angles R, 8 and a. According to a still more advantageous embodiment, and therefore preferential, the first and second second planes 36, 37 are arranged so that their line of intersection Di, FIG. 3, makes with the third planes 42, 44 a non-zero angle, optionally worth about fifteen degrees. In FIG. 1, this straight line Di is parallel to the third planes 42, 44 and therefore perpendicular to the plane of FIG. 1. In this embodiment, when the two blades 31, 32 are rotated to penetrate the vertebral bodies, the two ends of the two blades which are the closest 31-p, 32-p are getting closer and the two ends 31-e, 32-e of the two blades 31, 32 which are the farthest apart are moving away, resulting in variable corner effects on each vertebra VI, V2 and tends to bring the two vertebrae VI, V2 of the two opposite faces 11, 12, and thus to press them and hold them against these two faces. It is specified that, in all the embodiments described above, the blades may be flat or have for example a slight curvature to better penetrate the vertebral bone bodies of the vertebrae VI, V2. According to one embodiment which may be advantageous for certain applications of the cage according to the invention, the first and second means 40-1, 40-2 for rotating respectively the first and second blades 31, 32 respectively comprise two first and second shafts 46, 47 rotatably mounted in the element 10 respectively around two first and second axes 48, 49, these first and second axes being substantially concurrent, either strictly in the mathematical sense or at a distance from one of the other of a value low enough to allow, within the meaning of this description, to define them as substantially concurrent. These first and second means 40-1, 40-2 for rotating respectively the first and second blades 31, 32 further comprise means for securing the first and second blades 31, 32 respectively with the first and second shafts 46, 47 so that their planes are respectively substantially perpendicular to the first and second axes 48, 49, and means for rotating the first and second shafts 46, 47.

According to a possible and advantageous embodiment, these means for rotating the first and second shafts 46, 47 comprise a cardan gear connecting the first ends of the first and second shafts 46, 47 situated substantially at the point of competition of the first and second shafts. , 49, and means for rotating one of the first and second shafts 46, 47. These cardanic means are, in their simplest embodiment, constituted for example by a fork 50 with at least two branches connected by a base, means for connecting the base to one of the first and second shafts 46, 47 so that said shaft is not located between the two branches, and a finger 52 secured to the other of the first and second trees, the fork 50 and the finger 52 then being respectively connected to the first ends of the first and second shafts 46, 47 so that the finger 52 plunges relatively freely between the branches of the fork 50, that is to say that i It can be displaced laterally when the fork is rotated, for example, so that rotation of one of the first and second shafts 46, 47 causes rotation of the other shaft. In an embodiment which is often preferred, such as that illustrated in the figures, at least one of the first and second shafts 46, 47, in this case the shaft 46 in FIG. 1, opens, by its second end. 54, on the side wall 13 of the element 10. In this way, it is possible to easily rotate simultaneously the two blades 31, 32 by means of a suitable instrument via the end 54 which emerges from the side wall 13 , and thus to simultaneously anchor the ends of the blades 31, 32 in the vertebral bodies of the two vertebrae VI, V2. According to another possible and advantageous embodiment which is not specifically illustrated, but merely evoked in phantom in FIG. 2, the means for rotating the first and second shafts 46, 47 may be constituted by the fact that the first shaft 46, 47 emerges, by a 54 of its ends, on the side wall 13 of the element 10 and that the element 10 further comprises an orifice 70 (in broken lines in FIG. 2) coaxial with the axis 49, 48 of the second shaft 47, 46, this opening 70 opening, by one of its ends 71, on the side wall portion 13 of the element 10 which emerges the first shaft by its second end 54 and being open at its other end 72 next to the second tree. According to this last embodiment, to achieve the locking of the element 10 on the vertebrae VI, V2, we begin by rotating the blade 31 to anchor it in the two vertebrae. After this movement, it no longer cuts the orifice 70 and allows the passage of an instrument shaft, such as that of a screwdriver or the like, from the outside of the element 10 to the blade 32, to make rotate it from its first position to its second position as previously defined. In this case, it is possible to rotate the two blades 31, 32, but one after the other, whereas, with the embodiment described above, the two blades can be rotated simultaneously through the gear to gimbal. The blades 31, 32 may be respectively located in slots made in the element 10, these slots being for example of the same type as those illustrated in the prior document referenced in the preamble of the present description. However, according to a very preferential embodiment, as illustrated in FIGS. 1 and 2, it is possible, in the element 10, to have a through-hole 60 open on the two third planes 42, 44 and having sections taken in planes parallel to each other and perpendicular to these two third planes 42, 44, of substantially trapezoidal shape, the small and large bases being located respectively in the two third planes 42, 44 and the two oblique faces 66, 67 connecting the two bases being respectively parallel at the first and second second planes 36, 37.

The two blades 31, 32 are then of shorter length respectively than the oblique faces 66, 67 and are respectively mounted on the first and second shafts 46, 47 so as to be located in the through-hole 60 and substantially pressed against these two faces oblique, or very close to them, to be guided and supported by them. When the straight line Di defined before, with the third planes 42, 44, a non-zero angle, it is advantageous that this through-hole 60 is arranged so that its sections, taken in planes parallel to the two third planes 42, 44, they also have a substantially trapezoidal shape, these sections also having a continuously increasing value between the two third planes 44, 42, as shown in FIG. 2, in order to guide the two blades when they come closer or move away to obtain the result described above.

Claims (12)

REVENDICATIONS1. An intersomatic cage adapted to be interposed between two vertebral bodies (V1, V2) to replace the intervertebral disc originally located between the two vertebrae, comprising: • an element (10) having the general shape of a disc having two substantially parallel opposed faces (11, 12) and a side wall (13) connecting the two said opposite faces (11, 12), the two said opposite faces being able to come into contact respectively with the two vertebral bodies (V1, V2), and • means locking (20) of said element (10) with the two vertebral bodies (VI, V2), these locking means (20) being constituted by at least a first blade (31, 32) whose overall width measured in a first plane (34) perpendicular to said two opposite faces (11, 12) is at most equal to the distance separating said two opposite faces and the overall length measured in the same first plane is greater than this distance, characterized e in that it further comprises first means (40-1) for rotating said first blade (31, 32) in a first second plane (36, 37) at a first angle ((3, 5) with the third planes (42, 44) passing respectively through the two opposite faces (11, 12), different from ninety degrees, and so that said first blade (31, 32) is able to take any position between two first and second positions, the first position being one in which the first blade is entirely contained in the space (Esp) defined between the two third planes (42, 44), and the second position being that in which at least one end of the first blade emerges from the said space (Esp). 2. Cage according to claim 1, characterized in that it further comprises a second blade (31, 32) whose overall width measured in the first plane (34) perpendicular to the two opposite faces (11, 12) is at most equal to the distance separating these two said opposite faces and the overall length measured in the same first plane is greater than this distance, and second means (40-2) for driving in rotation the second blade (31, 32) in a second second plane (36, 37) making a second angle (5, R) with the third planes (42, 44) and an angle (a) with the first second plane, these second means (40-2). for rotating the second blade (31, 32) being arranged so that the second blade (31, 32) is adapted to assume any position between two first and second positions, the first position being that in which the second blade is fully contained in the space (Esp) defined between the two third planes (42, 44), and the second position being that in which at least one end of said second blade emerges from said space (Esp). 3. Cage according to claim 2, characterized in that the first and second second planes (36, 37) are between them a non-zero angle (a). 4. Cage according to one of claims 2 and 3, characterized in that each of the first and second second planes (36, 37), with the third planes (42, 44), an angle (R, 5) different from a right angle. 5. Cage according to one of claims 2 to 4, characterized in that the first and second second planes (36, 37) are arranged so that their line of intersection (Di) with the third planes (42, 44) a non-zero angle, optionally a value of about fifteen degrees. 6. Cage according to one of claims 2 to 5, characterized in that the first and second means (40-1, 40-2) for rotating respectively the first and second blades (31, 32) comprise respectively: Two first and second shafts (46, 47) rotatably mounted in said element (10) respectively about two first and second axes (48, 49), said first and second axes being substantially concurrent and making respectively with the third planes (42); , 44) of the third and fourth respectively complementary angles of the first and second angles (R, 5), • means for securing the first and second blades (31, 32) respectively with the first and second shafts (46, 47) so as to that their planes are respectively substantially perpendicular to the first and second axes (48, 49), and • means for rotating said two first and second shafts (46, 47). 7. Cage according to claim 6, characterized in that the means for rotating the two first and second shafts (46, 47) comprises a cardan gear connecting the first ends of the first and second shafts (46, 47) located substantially at the point of competition of the first and second axes (48,49), and means for rotating one of the first and second shafts (46,47). 8. Cage according to claim 7, characterized in that the cardan gear is constituted by: • a fork (50) with at least two branches connected by a base, • means for connecting said base to one of first and second shafts (46, 47) so that said shaft is not located between the two branches, and • a finger (52) integral with the other of the first and second shafts, • said fork (50) and said finger (52) being respectively connected to the first ends of the first and second shafts (46, 47) so that said finger (52) freely plunges between the legs of said fork (50) and so that the rotation of one of the first and second shafts (46,47) rotate the other shaft. 9. Cage according to one of claims 6 to 8, characterized in that at least one of the first and second shafts (46, 47) opens, by its second end (54), on the side wall (13). ) of the element (10). 10. Cage according to one of claims 2 to 9, characterized in that said element (10) has a through-hole (60) opening on the two third planes (42, 44), said piercing through having sections, taken in planes parallel to each other and perpendicular to the two third planes (42, 44), of substantially trapezoidal shape, the small and large bases being situated respectively in the two third planes (42, 44) and the two oblique faces (66, 67) connecting the two bases being respectively parallel to the first and second second planes (36, 37), and that the two blades (31, 32) are respectively of length less than that of said oblique faces (66, 67) and are respectively mounted on the first and second shafts (46, 47) so as to be located in said through-hole (60) and substantially pressed against both of said two oblique faces (66, 67). 11. Cage according to claim 10, characterized in that said through-hole (60) is furthermore arranged so that its sections, taken in planes parallel to the two third planes (42, 44), are of substantially trapezoidal shape, these sections having a continuously increasing value between the two third planes (42, 44). 12. Cage according to claim 5, characterized in that the means for rotating the two first and second shafts (46, 47) are constituted by the fact that the first shaft (46, 47) opens, by a (54) its ends, on the side wall (13) of the element (10) and that they comprise an orifice (70) made in said element (10) coaxially with the axis of the second shaft (47, 46) , said opening opening, by one of its ends (71), on the side wall portion (13) of the element (10) in which opens (54) the first shaft and open at its other end (72) facing of the second tree.