intervertebral cage

Abstract

The present invention relates to intervertebral cages. The cage comprises an element 10 including at least one locking blade 20, means for rotating the blade 20 about an axis 21 so that the blade is able to assume any position between a first position and a second position P2, these means for rotating the blade including a shaft 24 rotatably mounted relative to the element about the axis 21, and means for connecting the blade to the shaft 24, these means including a male spherical zone 31 formed in cooperation with the shaft 24, a through-hole 32 formed in the blade 20, having the shape of a female spherical zone 33 able to pivot relative to the zone 31 through a given central angle Ad, and means for securing the blade 20 to the shaft 24. Figure 1

Description

Title of the invention: intervertebral cage

[0001] The present invention relates to intervertebral cages suitable for being interposed between vertebral bodies as a replacement for intervertebral discs.

[0002] Such an intervertebral cage is already known, the one described and illustrated in FR2955483 in the name of the same Applicant.

[0003] This intervertebral cage is essentially characterized by the fact that it comprises a shaft for rotating an anchoring blade in a plane forming a first angle with the planes passing respectively through the two opposite faces of a substantially disc-shaped element. This angle is, in this embodiment, different from ninety degrees and, as a result, the blade has a certain inclination with respect to the axis of the rotation shaft.

[0004] The technical problem that can arise with this embodiment of such a cage is essentially the realization of the whole, and therefore the assembly of the shaft and the blade according to the desired inclination.

[0005] The present invention therefore aims to remedy this situation by proposing a solution which facilitates in particular this realization and which, in addition, can offer possibilities for more easily obtaining different values ​​of inclination of the blade with respect to the axis of the rotation shaft.

[0006] More specifically, the present invention relates to an intervertebral cage suitable for being interposed between two vertebral bodies in place of 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 suitable for coming into contact respectively with the two vertebral bodies and defining substantially two planes which contain them; at least one locking blade, the overall width of this 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 blade around an axis so that this blade is able to take all positions between a first position and a second position, the first position being that in which the blade is entirely contained within 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 blade emerges from this space, these means for rotating the blade comprising a shaft mounted to rotate relative to the element around said axis and means for connecting the blade with said shaft, characterized by the fact that the means for connecting the blade with said shaft comprise a zone; male spherical zone produced in cooperation with said shaft, the radius of this male spherical zone having a determined value, a through-hole produced in said blade, the inner wall of which has the shape of a female spherical zone, the radius of this female spherical zone having a value at least equal to the value of the radius of the male spherical zone so that said female spherical zone is able to pivot relative to said male spherical zone according to a given central angle value, and means for securing said blade with said shaft in a given angular position relative to said axis of rotation.

[0007] 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:

[0008] Figure 1 shows a diagram, according to a first cross-sectional plane, of a first embodiment of the cage according to the invention.

[0009] Figure [Fig. 2] represents a diagram, along a second cutting plane perpendicular to the first cutting plane, of the first embodiment,

[0010] Figure 3 shows a diagram illustrating the principle of a second embodiment of the cage according to the invention, and

[0011] Fig. 4 represents this second preferred embodiment of the cage according to the invention in more detail, applying the teaching of Fig. 3.

[0012] 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 described embodiment may comprise several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated comprises several elements with identical functions 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.

[0013] It is specified that when, in the present description, an expression defines by itself, without any particular specific mention concerning it, a set of structural characteristics, these characteristics may be taken, for the definition of the object of the protection sought, when this is technically possible, either separately, or in total and / or partial combination.

[0014] It is further specified that, in the present 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.

[0015] It should also be noted that, across all four figures, the same references designate the same means having the same function, regardless of their graphical representation.

[0016] Furthermore, it is clearly specified that, by "spherical zone", it is understood that the portion of the surface of a sphere contained between two parallel planes which intersect this sphere, and that a diametrical plane is a plane which passes through the center of the sphere.

[0017] Furthermore: two spherical zones, male and female respectively, can be said to be complementary when they are able to pivot relative to each other without their respective spherical surfaces necessarily sliding on each other, it being possible that there may be between them a non-zero space, but of a small enough value for these two surfaces to still be considered, in the sense of the present invention, as complementary.

[0018] As mentioned above, the present invention relates to intervertebral cages suitable for being interposed between two vertebrae in place of the intervertebral disc originally located between these two vertebrae.

[0019] According to the present invention, the cage comprises an element 10 having the general shape of a disc comprising two substantially parallel opposite faces 11,12 and a lateral wall connecting the two opposite faces, these opposite faces being able to come into contact respectively with the two vertebral bodies and defining substantially two planes which contain them; at least one locking blade 20, the overall width of this 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 the blade 20 about an axis 21 so that this blade is able to take any position between a first position PI and a second position P2, the first position PI being that in which the blade is entirely contained within the space defined between the planes of the two opposite faces 11, 12 and the second position P2 being that in which at least one end 22 of the blade emerges from this space, these means for rotating the blade comprising a shaft 24 mounted rotatably relative to the element about the axis 21 and means for connecting the blade with the shaft.

[0020] According to one feature of the invention, the means for linking the blade with the shaft comprise: a male spherical zone 31 made in cooperation with the shaft, the radius of this male spherical zone having a determined value; a through bore 32 made in the blade 20, the inner wall of which has the shape of a female spherical zone 33, the radius of this female spherical zone having a value at least equal to the value of the radius of the male spherical zone 31 so that the female spherical zone is able to pivot relative to the male spherical zone 31 according to a given center angle value Ad; and means for securing the blade 20 with the shaft 24 in a given angular position relative to the axis of rotation 21.

[0021] The male spherical zone can be mounted in cooperation with the shaft 24 of dif The shaft can be manufactured in various ways, either as a single piece with the shaft by machining, casting, etc., or independently and then attached and fixed to the shaft in different ways, for example by welding or similar means, possibly in one or more combinable parts. Furthermore, preferably, this male spherical zone 31 is substantially centered on the axis 21 of the shaft 24.

[0022] Figures 2 and 3 illustrate a first embodiment applying the general definition of the cage structure according to the invention made above.

[0023] According to this first embodiment, the cage comprises two substantially complementary spherical zones 31, 33 whose contacting spherical surfaces are capable of sliding against each other. Consequently, the two spherical zones have substantially the same radius of curvature. However, the radius of the female spherical zone will be very slightly greater than the radius of the male spherical zone, so as to ensure the pivoting of the two zones relative to each other.

[0024] With this structure, the blade 20 can therefore be positioned according to a desired angle relative to the axis 21 of the rotation shaft 24, so as to obtain a result as for example explained in the document FR2955483 mentioned above.

[0025] Once the blade 20 has been positioned as desired, an orifice 40 is drilled, or is pre-drilled, through the blade 20, for example in a laterally raised portion, as shown in Figures 1 and 2, possibly also through the male spherical area 31 and the shaft 24, and a pin 41 is pressed into this orifice. Thus, the blade 20 and the shaft 24 are firmly joined together.

[0026] In this illustrated embodiment, the female spherical zone 33 is a zone defined between two bases located on either side of its diametral plane. However, according to another embodiment, this female spherical zone 33 may have a structure whose diametral plane is located outside the portion of space defined between these bases.

[0027] Furthermore, in the embodiment according to these figures 1 and 2, the male spherical zone 31 is made according to a sphere made up of an assembly of at least two pieces, so as to be able to be more easily introduced into the female spherical zone 33.

[0028] It is understandable, however, that it is not easy to introduce and / or make a male sphere into a portion of a female sphere, as mentioned above, to obtain an embodiment according to Figures 1 and 2. Figure 4 illustrates a second embodiment of the cage according to the invention, which largely overcomes this problem.

[0029] This embodiment according to [Fig.4] is an application of the present invention, given by way of example, with two blades 20, 20' on the same shaft 24, these two blades 20, 20' each defining an anchoring plane, these two planes making between them, advantageously preferably a non-zero angle, as explained in FR2955483 mentioned above.

[0030] The means for linking the blade 20' to the rotation shaft 24 have similar, if not identical, characteristics to those defined above for linking the blade 20 to the shaft 24.

[0031] For understanding the structure according to the realization of [Fig.4], reference is made to the teaching of [Fig.3].

[0032] In this second embodiment, the male and female spherical zones 31, 33 each have at least one thread 51, 52 (of a relatively small width compared to that of the element 10). These two threads are substantially complementary so as to be able to cooperate with each other, the thread of the female spherical zone also bordering a hollow groove 53, preferably spherical with substantially the same radius as that of the male spherical zone 31 taken at the top of the thread 51, in which the thread 51 of the male spherical zone 31 is able to be positioned.

[0033] For this reason, the width of the thread 51 of the male spherical zone 31 is advantageously less than the width of the groove 53.

[0034] In this way, when the thread 51 passes the thread 52, it falls into the groove 53. In this position, the female spherical zone 33 can move relative to the male spherical zone 31 according to at least two degrees of freedom.

[0035] The representation of [Fig.3] shows, in part and in continuous lines, the male spherical zone 31 Zsm outside the female spherical zone 33 before the cooperation of the two threads 51, 52 with each other and, in broken lines, the male spherical zone 31 Zsm in the female spherical zone 33 after the thread 51 has passed the thread 52 and is positioned in the groove 53.

[0036] In this position, as illustrated in [Fig.3], the blade 20 can therefore pivot in the solid angle Ad and take the desired angular position relative to the axis 21.

[0037] It should be noted that, in this case, the two spherical male zones Zsm and female zones Zsf may have radii of different values, but this embodiment must be considered as included in the definition of the present invention.

[0038] In the representation according to this [Fig.3], the female spherical zone 33 can pivot in a solid angle Ad with a relatively large amplitude in a plane parallel to that of the threads 51, 52 and with a smaller amplitude in a plane perpendicular to these two threads, this amplitude then being a function of the difference between the width of the groove 53 and the width of the thread 51.

[0039] It should be specified that, although, on [Fig.4], the blades 20, 20' are slightly distant from the wall of the element 10, they can, in another embodiment, be positioned very tightly, and even under pressure, against the wall of this element 10.

[0040] From the description given above, it is evident, particularly to those skilled in the art, that the cage according to the present invention has many advantages over cages of the prior art.

Claims

1.

2.

3. Demands Intervertebral cage suitable for interposition between two vertebral bodies in place of the intervertebral disc originally located between the two vertebrae, comprising: an element (10) having the general shape of a disc comprising two substantially parallel opposite faces (11, 12) and a lateral wall connecting said two opposite faces, these opposite faces being suitable for coming into contact respectively with the two vertebral bodies and defining substantially two planes which contain them; at least one locking blade (20), the overall width of this 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 blade (20) about an axis (21) so that this blade is able to take any position between a first position (PI) and a second position (P2), the first position (PI) being that in which the blade is entirely contained within the space defined between the planes of the two opposite faces (11, 12) and the second position (P2) being that in which at least one end (22) of the blade emerges from this space, these means for rotating the blade comprising a shaft (24) mounted rotatably relative to the element about said axis (21) and means for connecting the blade with said shaft (24), characterized in that the means for connecting the blade with said shaft comprise:; • a male spherical zone (31) formed in cooperation with said shaft (24), the radius of this male spherical zone having a determined value, • a through-hole (32) formed in said blade (20), the inner wall of which has the shape of a female spherical zone (33), the radius of this female spherical zone having a value at least equal to the value of the radius of the male spherical zone (31) so that said female spherical zone is able to pivot relative to said male spherical zone (31) by a given central angle (Ad), and • means for securing said blade (20) with said shaft (24) in a given angular position relative to said axis of rotation (21). Cage according to claim 1, characterized in that said female spherical zone (33) has two bases. Cage according to claim 2, characterized in that the two bases are located on either side of the diametrical plane of said female spherical zone (33).

4. Cage according to any one of the preceding claims, characterized in that the means for securing said blade (20) with said shaft (24) in a given angular position with respect to said axis of rotation (21) comprise an orifice (40) made in said blade and said shaft, optionally in said male spherical zone (31), and a pin (41) suitable for being inserted into said orifice (40).

5. Cage according to any one of the preceding claims, characterized in that said male and female spherical zones (31, 32) each have at least one thread (51, 52), the two threads being substantially complementary and able to cooperate with each other, the thread (52) of said female spherical zone bordering a hollow groove (53) in which the thread (51) of the male spherical zone (31) is able to be positioned after being screwed into the thread (52) of said female spherical zone (32).

6. Cage according to any one of the preceding claims, characterized in that said male spherical zone (31) is made up of an assembly of at least two parts.

7. Cage comprising at least one other blade (20') and other means for linking said other blade (20') with said shaft (24), said other means having the characteristics as defined in at least one of the preceding claims.

8. Cage according to claim 7, characterized in that the two blades (20, 20') each define an anchoring plane, these two planes making a non-zero angle between them.

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