EP1890655A1

EP1890655A1 - Device insertable between two successive vertebras

Info

Publication number: EP1890655A1
Application number: EP06764776A
Authority: EP
Inventors: Hassan Razian
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-15
Filing date: 2006-06-13
Publication date: 2008-02-27
Also published as: FR2887138A1; FR2887138B1; WO2006134262A1

Abstract

The invention relates to a device insertable between two successive vertebras. According to said invention, the device is essentially characterised in that it comprises two main parallel plates (1, 2) which are arranged on two planes perpendicular to an axis (3) for defining a space (4) therebetween, elastic body means (5) which are inserted between the plates (1, 2) into the space therebetween and which are expandable in a direction perpendicular to the axis (3) when a compression torque is applied to the elastic body means in the direction of the axis (3) and means (10) for controlling the displacement of the two plates (1, 2) in a position parallel thereto along said axis (3). Said invention can be used in the form of an intersomatic cage and/or prosthesis for replacing an intervertebral disc.

Description

DEVICE THAT CAN BE INTERCALED BETWEEN TWO CONSECUTIVE VERTEBRA

The present invention relates to devices capable of being inserted between two consecutive vertebrae, which find a particularly advantageous application both as an intervertebral cage and as replacement prosthesis of an intervertebral disc.

It is known that, according to the trauma suffered by a spine, Practitioners are led to perform two kinds of intervention. When the trauma concerns only an intervertebral disc and the two consecutive vertebrae surrounding this disc are in good condition, the Practitioner can opt for the replacement of the disc by a prosthesis whose functionality is substantially equivalent to that of the original disc, it that is to say leaving the two vertebrae the ability to move relative to each other in rotational and / or translational movements.

On the other hand, when the trauma is more important, the Practitioner can choose to join the two consecutive vertebrae together by osteosynthesis. To do this, the intervertebral disk is partially or completely destroyed and replaced by an intervertebral cage generally associated with an osteosynthesis promoting element, for example a bone graft.

There are currently two types of devices that make it possible to perform these interventions, with, for each type, a relatively large range of products to respond to each case of intervention, which requires a large stock of products. It is therefore conceivable that the cost of these devices is relatively high.

By way of example, the device according to US Pat. No. 5,653,763 may be cited. The cage according to this document essentially comprises two rigid plates pivotally mounted relative to one another on hinge means and on means for pivoting said two plates so that their ends farthest from the hinge means move away from each other. With this cage, the majority of the distraction forces between the two consecutive vertebrae between which is interposed the cage is applied to the free ends of the two plates. These forces are therefore distributed over a small surface of the vertebral bodies. Also, the object of the present invention is to provide a device capable of being inserted between two consecutive vertebrae which, although of very simple structure and involving an easy implantation technique, can be used both as an intervertebral cage and as replacement prosthesis of an intervertebral disk, which overcomes the disadvantages mentioned above cages of the prior art.

More specifically, the present invention relates to a device adapted to be inserted between two consecutive vertebrae, characterized in that it comprises: ^• two main plates substantially parallel to each other and arranged in two planes substantially perpendicular to a given axis to delimit an inter-plate space,

^• means of elastic body interposed between the two main plates in said inter-plate space, the said means of elastic body being capable of following dilating a direction perpendicular to said given axis when a pair of compressive forces next applied thereto said given axis, and

^• means for controlling the movement of the two main plates parallel to themselves along said given axis. Other characteristics and advantages of the invention will appear in the course of the following description given with reference to the accompanying drawings for illustrative but not limiting purposes, in which:

FIGS. 1 and 2 show a first embodiment of the device according to the invention adapted to be inserted between two consecutive vertebrae, FIG. 1 being a perspective view in a cavalier view, FIG. 2 a side view,

FIG. 3 represents, in side view, a second embodiment of the device according to the invention,

FIGS. 4 and 5 show a third embodiment of the device according to the invention, FIG. 4 being a view from above and FIG.

FIG. 6 represents a view from above of a fourth embodiment of the device according to the invention.

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 regardless of 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 represent four embodiments of the object according to the invention, but that there may be other embodiments that meet the definition of this invention.

Referring to all of Figures 1 to 6, the device according to the invention adapted to be inserted between two consecutive vertebrae comprises two main plates 1, 2 substantially parallel to each other and arranged in two planes substantially perpendicular to a given axis 3 to delimit a interplate space 4, elastic body means 5 interposed between the two main plates in this inter-plate space, these elastic body means being able to expand along at least one direction perpendicular to the given axis 3 when a force pair compression is applied thereto along this axis, and means 10 for controlling the displacement of the two main plates 1, 2 parallel to themselves along the given axis 3.

In their rest configuration, the elastic body means 5 are relaxed and their volume is entirely, or almost, contained in the inter-plate space 4. However, even in the rest configuration, they will advantageously be slightly compressed to exert a torque of forces respectively on the two main plates 1, 2 and thus obtain good cohesion between the constituent elements of the device.

As for the means 10 for controlling the displacement of the two main plates 1, 2 parallel to themselves along the given axis 3, they are advantageously constituted by a threaded rod 11, means 12 for mounting one end 13 of the rod threaded in free rotation directly or indirectly on a first 1 of the two main plates 1, 2, and a threaded orifice 15 made in an element 17 connected to the second main plate 2, the threaded rod being mounted screwed into this threaded orifice 15 .

It is specified that, by threaded rod in the sense of the present description, it is understood any kind of threaded rod, regardless of the direction and value of the pitch of the thread. Thus, this rod may comprise two successive threads, a first thread for, at first, to obtain a fast advance of the rod 11 relative to the second plate 2, and a second for a slower advance, for example to proceed as finely as possible to the final adjustment of the distance separating the two main plates 1, 2 and therefore the swelling of the elastic body means 5 as will be explained below. In both embodiments according to FIGS. 1 to 3, the end 13 of the threaded rod 11 is mounted in free rotation in the first main plate 1 in a direct manner, for example by a through-hole 16, being supported in 19 by a screw head or the like. The shoulder 19 is, in this embodiment, located on the face of the first main plate 1 which is outside the inter-plate space 4. As for the element 17 linked to the second main plate 2 in which is made the threaded orifice 15, it is constituted by the central portion of the second main plate.

Thus, by turning the threaded rod 11 in the direction of its screwing into the threaded orifice 15, the distance between the two main plates 1, 2 decreases, the elastic body means 5 are compressed and expand towards the outside of the inter-plate space 4 to emerge more or less depending on the importance of screwing the threaded rod.

In the case of the embodiment according to Figures 4 and 5 wherein the threaded rod is mounted in free rotation in the first main plate 1 indirectly, the means 12 defined above are constituted by a first auxiliary plate 20 arranged substantially parallel to the two main plates 1, 2 and on the same given axis 3, and by holding means 21 of this first auxiliary plate 20 relative to the first main plate 1 outside the inter-plate space 4 and facing the outer face of the second main plate 2 not located in the inter-plate space.

According to an advantageous embodiment, the means 21 for holding the first auxiliary plate 20 outside the inter-plate space 4 consist of at least one tab 22, 25 and means for securing the two ends 23, 24 of the tab 22 together. , Respectively on an edge of the first auxiliary plate 20 and an edge of the first main plate 1, so that the tab 22, 25 is situated outside the inter-plate space 4.

According to an advantageous possible embodiment, the assembly formed of the first plate 1, the lug 22, 25 and the first auxiliary plate 20 is made in one piece, by forming, bending, welding, molding or other techniques. In addition, preferably, the width of the tab 22, 25 taken in the direction perpendicular to the given axis 3 is at most equal, if not equal, to the height of the inter-plate space 4 taken along the same direction .

It is preferable that the device further comprises means 30 for guiding the second main plate 2 in a displacement advantageously of translation and indexing its displacement with respect to the tab 22, 25.

According to an advantageous embodiment, these means 30 are constituted, FIG. 4, by a longitudinal groove 31 made in the lug 22, 25 along the given axis 3 and a lug 32 secured to the second main plate 2 so as to plunge into the groove 31 and go through it when the second main plate 2 moves relative to the first main plate 1 along the given axis 3. The length of the groove is determined to limit the displacement of the second main plate.

In this embodiment, the threaded rod is mounted screwed into the second main plate 2, and in free rotation in the first auxiliary plate 20 by a through hole 18 made in this auxiliary plate 20, being supported at 39 by a head of screw or the like. However, in this embodiment, the shoulder 39 is located in contact with the face of the auxiliary plate which is opposite the outer face of the second main plate 2. Thus, by turning the threaded rod in the direction of its screwing in the second main plate 2, the distance between the two main plates 1, 2 decreases and the elastic body means 5 are compressed and expand outward to emerge more or less from the inter-plate space 4, in as a function of the importance of screwing the threaded rod 11 into the second main plate 2. However, as in the embodiment illustrated in FIG. 6, it is possible for the threaded rod to be screwed indirectly into the second main plate. 2 and in free rotation in the first main plate 1 directly.

In this embodiment, the element 17 connected to the second main plate 2 and in which is made the threaded orifice 15 is constituted by a second auxiliary plate 60 disposed substantially parallel to the two main plates 1, 2 and on the same axis given 3, and by holding means 61 of the second auxiliary plate 60 relative to the second main plate 2, outside the inter-plate space 4 and facing the face exterior of the first main plate 1 not located in the interplate space 4.

According to an advantageous embodiment, these means 61 for maintaining the second auxiliary plate 60 outside the inter-plate space 4 consist of at least one lug 64, 65 and means for securing the two ends of the lug 64, 65 respectively on an edge of the second auxiliary plate 60 and an edge of the second main plate 2, so that the tab 64, 65 is located outside the inter-plate space 4.

But also, very preferably, the means 12 for mounting the end 13 of the freely rotating threaded rod on the first main plate 1 comprise ball or similar means 62 allowing the first main plate 1 to pivot according to a axis of rotation 63 perpendicular to the given axis 3, at a given angle β, FIG. 6. When the device is inserted between two consecutive vertebrae, this axis 63 will be perpendicular to the faces of the vertebral bodies of the two vertebrae.

Preferably, as in the embodiment according to FIG. 4, the device according to this embodiment illustrated in FIG. 6 comprises means, not illustrated in this FIG. 6, for guiding the first main plate 1 in a displacement advantageously of translation. and indexing its displacement relative to the tab 64, 65.

The description made above refers to a single tab, but it is preferable, for the reliability and rigidity of the device, that the latter comprises two tabs 64, 65 flanking the inter-plate space 4, as in the method of embodiment according to Figure 4. Throughout the description above, reference is made to resilient body means 5 interposed between the two main plates.

These elastic body means 5 may be constituted in different ways, depending on the possible applications of the device. They are for example constituted, FIGS. 1, 2, 4, 5 and 6, by at least one leaf spring 40, the two ends of which are respectively integral with the two main plates 1, 2, this leaf spring advantageously being prestressed in bending of so that its convex face 41 is turned towards the outside of the inter-plate space 4. Such a blade can be of any shape, for example in the form of a lamella as illustrated, or hemispherical or the like. Of course, for greater security and to balance the action of the elastic body means, it is advantageous, as shown in these five figures, that these elastic body means 5 consist of at least two pairs of leaf springs 40 located on either side of the inter-plate space 4 so that the convex faces 41 of the blades come into contact with the vertebral bodies of the two vertebrae, and whose ends are two by two respectively integral with the two main plates 1, 2 .

But these elastic body means 5 can also be constituted, as illustrated in FIG. 3, by a plurality of rings 50 made of elastic material mounted or stacked against one another in the inter-plate space 4 and substantially centered on the given axis 3.

In addition, the device may also comprise means for promoting anchoring, for example lamellae, in the bone body of the vertebrae. These means may consist of lugs, pins and / or undulations on the convex face of the lamellae. These means are well known in themselves and have not been represented.

It is specified that, more particularly in the case of the embodiments illustrated in Figures 1, 2 and 3 the device may further comprise means for defining a minimum distance between the two main plates 1, 2. These means can be of any type but, advantageously, as shown schematically in Figure 2, they may be constituted by a body 51 in the form of olive or the like which is slidably mounted on the rod portion 11 between the two main plates.

With the description given above, it clearly appears that the device according to the invention can be used, either as an intervertebral cage between two consecutive vertebrae, or as replacement prosthesis of the intervertebral disc located between these two vertebrae.

When the Practitioner wants to use the device as a replacement prosthesis for a damaged intervertebral disc, he places it between the two vertebrae in the same way as a prosthesis of the prior art and, by varying the tension of the elastic body means 5, like the leaf springs 40 which will emerge more or less from the inter-plate space 4, it can adjust the distance between the vertebral bodies of the two vertebrae and allow these two vertebrae to move relative to each other. other in movements substantially identical to their original movements, when separated by the undamaged disk.

When the Practitioner wants to use the device as an intervertebral cage, he places it between the two vertebrae in the same way as a prior art intervertebral cage and, by adjusting the inter-plate distance, he varies the transverse expansion of the elastic body 5 and therefore the distance between the two vertebral bodies, until the desired distance to their joining by osteosynthesis. To achieve this result, by any means, the practitioner stiffens the cage to avoid, in particular, excessive flexing of the elastic body means and advantageously places, in the inter-plate space 4, for example a bone graft to promote the osteosynthesis between the two vertebrae.

It is mentioned that a same device according to the invention can be used, initially as replacement prosthesis of an intervertebral disc, and in a second time as inter somatic cage after having been stiffened at least partially and after the introduction of a bone graft.

The embodiment illustrated in FIG. 6, which comprises ball-and-socket means 62 for linking the end 13 of the threaded rod 11 with the first main plate 1, has a further advantage over the embodiments according to the other FIGS. at 5.

Indeed, in the case where one of the two vertebrae is rotated relative to the other about an axis perpendicular to the longitudinal axis of the spine, it occurs in the space between the two bodies. consecutive vertebrae, a slight nip on one side and an opening on the other side. As a result, the two blades on the same side will be more compressed than the two blades on the other side. With the embodiment according to FIG. 6, the ball-and-socket means 62 allow a rotation of the first main plate 1 around the axis 63 defined above, which induces a decompression of the two blades situated on the pinch side and a compensating compression. on the side of the opening.

With reference to FIG. 6, if the pinching occurs on the H side, the first main plate 1 takes the position Ph. If the pinching occurs on the B side, the plate 1 takes the Pb position, the two positions Ph and Pb being illustrated in broken lines in this figure 6.

Claims

1. Device adapted to be inserted between two consecutive vertebrae, characterized in that it comprises: ^• two main plates (1, 2) substantially parallel to each other and arranged in two planes substantially perpendicular to a given axis (3) to delimit an inter-plate space (4),

• elastic body means (5) interposed between the two main plates in said inter-plate space, said elastic body means being able to expand in a direction perpendicular to said given axis (3) when a pair of forces of compression is applied to the elastic body means along said given axis, and

Means (10) for controlling the displacement of the two main plates (1, 2) parallel to themselves along said given axis (3).

2. Device according to claim 1, characterized in that the means (10) for controlling the displacement of the two main plates parallel to themselves along said given axis are constituted by:

A threaded rod (11), means (12) for mounting one end (13) of the freely rotating threaded rod in a first (1) of the two first and second main plates (1, 2), and

• an element (17) connected to said second main plate (2) in which is made a threaded orifice (15), the threaded rod being mounted screwed into said threaded orifice.

3. Device according to claim 2, characterized in that said means (12) for mounting one end (13) of the threaded rod in free rotation in a first (1) of the first and second main plates (1, 2), are constituted by a through hole (16) formed in said first main plate (1).

4. Device according to one of claims 2 and 3, characterized in that said element (17) connected to said second main plate (2) in which is realized a threaded orifice (15) is constituted by the central portion of said second main plate (2).

5. Device according to claim 2, characterized in that said means (12) for mounting one end (13) of the threaded rod in free rotation in a first (1) of the first and second main plates (1, 2), are constituted by:

^• first an auxiliary plate (20) disposed substantially parallel to the two main plates (1, 2) and the same given axis (3), said rod being mounted to rotate freely in a through bore (18) formed in said first auxiliary plate (20), and

^• means (21) for maintaining said second auxiliary plate (20) relative to said first main panel (1) and facing the outer face of the second main plate (2) not situated in said inter-plate space (4 ), said threaded orifice (15) being formed in said second auxiliary plate (20).

6. Device according to claim 5, characterized in that the means (21) for maintaining said second auxiliary plate (20) relative to said first main plate (1) and opposite the outer face of the second main plate ( 2) not located in said inter-plate space (4) are constituted by at least one tab (22, 25) and means for securing the two ends (23, 24) of the tab (22, 25) respectively on one edge of the first auxiliary plate (20) and an edge of the first main plate (1), so that the tab (22, 25) is located outside the inter-plate space (4).

7. Device according to one of claims 5 and 6, characterized in that it comprises means (30) for guiding the second main plate (2) in its displacement relative to the first main plate (1) and for indexing its displacement relative to the leg (22, 25).

8. Device according to claim 7, characterized in that the means (30) for guiding the second main plate (2) in its movement relative to the first main plate (1) and to index its displacement by relative to the tab (22, 25), are constituted by a longitudinal groove (31) formed in said tab (22, 25) along said given axis (3), and a lug (32) integral with the second main plate (2). and arranged to dip into said groove (31) and run through it as said second main plate moves relative to the first main plate along said given axis (3).

9. Device according to claim 2, characterized in that said element (17) connected to said second main plate (2) in which is formed a threaded orifice (15) is constituted by: • a second auxiliary plate (60) arranged substantially parallel to the two main plates (1, 2) and on the same given axis (3), and

Means (61) for maintaining said second auxiliary plate (60) with respect to said second main plate (2) and facing the outer face of the first main plate (1) not located in said inter-plate space (4); ), said threaded orifice (15) being formed in said second auxiliary plate (20).

10. Device according to claim 9, characterized in that said means (12) for mounting one end (13) of the threaded rod in free rotation in a first (1) of the first and second main plates (1, 2), comprise ball-and-socket means (62) along an axis of rotation substantially perpendicular to said given axis (3).

11. Device according to one of claims 1 to 10, characterized in that said elastic body means (5) are constituted by at least one of the following bodies:

At least one leaf spring (40) whose two ends are respectively integral with the two main plates (1, 2), said leaf spring being biased in flexion so that its convex face (41) is facing outwards of said inter-plate space (4),

A plurality of rings (50) of elastic material mounted in said inter-plate space and substantially centered on said given axis (3).