EP3836868A1

EP3836868A1 - Interosseous cage

Info

Publication number: EP3836868A1
Application number: EP19773135.9A
Authority: EP
Inventors: Hassan Razian
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-08-17
Filing date: 2019-08-13
Publication date: 2021-06-23
Also published as: WO2020035636A1; FR3084994A1; FR3084994B1; US20210338452A1

Abstract

The present invention concerns interosseous cages inserted between two bones O1, O2. The cage according to the invention comprises at least one body 10 with two support faces 11, 12, each support face being configured to come into contact with two bones, the body 10 being made of a first material having a given solidity, a through-cavity 20 produced in the body 10 opening onto the two faces 11, 12 and an insert 30 defined between two end faces 31, 32 and having a cross-section at most equal to the cross-section of the through-cavity 20 so that the insert is slid into the cavity, this insert also being configured so that its end faces are respectively in continuity with the two faces 11, 12 when said insert 30 is in the cavity 20, the insert being made of a second material that is more solid than the first material. The invention is applicable, in particular, to the production of intervertebral cages.

Description

Interosseous cage

The present invention relates to interosseous cages, namely cages capable of being implanted between two portions of bone with a view to firmly joining them by promoting their joining by osteosynthesis, which find particularly advantageous applications, but not exclusively, as cages intervertebral.

Many interosseous cages of this type are already known. They are essentially composed of a solid body, for example made of metal, comprising a through cavity in which is placed a bone graft or bone substitute which makes it possible to promote bone growth and therefore the connection between the two bone portions by osteosynthesis. .

There are also interosseous cages in which the solid body is made of a less solid material than metal, for example like that which is known by those skilled in the art under the name PEEK (polyetheretherketone).

An interosseous cage as defined above gives good results from an orthopedic therapeutic point of view, but can have drawbacks when it is inserted between two portions of bone which can be subjected to relatively high pressure forces. This is the case that can occur on a cage inserted between two vertebrae to replace a damaged intervertebral disc of the spine of a Patient who is still relatively young and physically strong. Indeed PEEK is not a material strong enough to always resist pressure forces.

Furthermore, PEEK, defined above, is a material which has the particularity of fusing with the bone medium. Therefore, the cage can sink at least partially into the bone and no longer play its role of wedge, that is to say spacer, to maintain the two portions of bone at the desired desired distance by the Practitioner.

Bone cages are already known, such as those which are described and illustrated in EP1414376 and US2015 / 073556. But these cages according to this prior art do not offer, either directly or indirectly, a solution to the problem mentioned above. Also, the present invention aims to achieve an interosseous cage which, although having a simple and inexpensive structure, overcomes the

disadvantages mentioned above of similar cages of the prior art.

More specifically, the present invention relates to an interosseous cage capable of being interposed between two portions of bone for the purpose of joining them together.

osteosynthesis, which has at least the characteristics defined in the

claim 1 appended.

Other characteristics and advantages of the present invention will appear during the following description given with reference to the drawings annexed by way of illustration, but in no way limiting, in which:

Figures 1 and 2 show, in two sectional views, a very schematic embodiment of the interosseous cage according to the invention, Figure 1 being a section referenced / - / in Figure 2, and Figure 2 is a section referenced // - // in FIG. 1, and

FIG. 3 is a perspective view of an embodiment of an essential element of the object of the invention, namely the insert which appears in FIGS. 1 and 2.

It is firstly specified that, by “solid material” within the meaning of the present invention, is meant a material which has a structure, a quality which allows it to withstand wear and / or breakage risks and / or tear and / or rupture, etc. under the pressure forces of a given intensity.

Thus, for the definition of the present invention, mention may be made, in the description and in the appended claims, of at least one pair of materials, one of which is more solid than the other according to the definition above.

With reference to the appended figures, the present invention relates to an interosseous cage capable of being inserted between two portions of bone 01, 02 with a view to joining them by osteosynthesis.

According to this invention, the cage comprises at least one body 10 delimited by two opposite bearing faces 1 1, 12, each bearing face being configured to be able to come into contact with a corresponding face of one of the two bone portions, this body 10 being made of a first material having a given solidity.

The cage also includes a through cavity 20 produced in the body 10 and opening onto the two bearing faces 11, 12, and an insert 30 defined between two faces ends 31, 32 and having a cross section at most equal to the cross section of the through cavity 20 so that this insert is able to be slid into the cavity.

This insert is further configured so that its end faces are respectively substantially in continuity with the two bearing faces 11, 12 of the body 10 when the insert 30 is in the through cavity 20.

The insert is made of a second material which is stronger than the first material.

It has been mentioned above that the insert 30 is configured so that its end faces 31, 32 are respectively substantially in continuity with the two bearing faces 11, 12 of the body 10 when the insert 30 is in the through cavity 20. However, according to another embodiment, this insert is configured so that its end faces 31, 32 are respectively slightly set back from the two bearing faces 11, 12 of the body 10 when the insert 30 is in the through cavity 20.

This withdrawal can be advantageous to allow the passage of a cutting blade to cut the trabecular bays which, after a certain time after the implantation of such a cage, connect the cancellous bone with the insert 30. This

intervention can be done in the case, for example, of a resumption of operation after a revision of the bone structure.

Also, it is advantageous that, to these recesses defined above, correspond slots or the like in the body 10 to allow the passage of the cutting blades so that they easily reach these recesses.

This characteristic above is very advantageous because, during the insertion of the cage between the two bone portions 01, 02, it is then certain that at least one portion of the two end faces of the insert does not either not projecting from the bearing faces 11, 12 of the body, and that the end faces of the insert do not damage the bony faces of the bone portions 01, 02 against which the two faces will bear opposite of the cage (ie the bearing faces 11, 12 of the body 10 and the end faces 31, 32 of the insert 30).

According to a preferred characteristic, the insert 30 has a porous structure, even more advantageously for example a porous honeycomb structure. Even more preferably, the honeycomb structure comprises at least one continuous channel 35 opening onto the two ends of the insert.

According to another preferred characteristic, the cross section of the insert 30 can be equal to that of the cavity. In this case, the insert 30 and the body 10 can be made in one piece by being molded in production, one with or on the other.

According to another particularly advantageous embodiment, as illustrated in FIG. 3, the insert 30 is arranged, with respect to the embodiment according to FIGS. 1 and 2, to present an increased elasticity in a direction 50 substantially perpendicular to the two faces of opposite supports 11, 12, so that, when this insert is in a compressed state in this direction 50, its height defined in this direction is at most equal to the distance separating the opposite bearing faces 11, 12 and that, when it is in a relaxed state, its height is greater than this distance.

With the characteristic described above, the cage according to the invention can be introduced, for example between two vertebrae 01 and 02, by means of a tool known in this field of surgery, keeping the insert 30 in its state compressed, which makes it easier to implant the cage between these two vertebrae.

After the cage has been put in place and the tool removed, the insert is released and therefore emerges very slightly from the through cavity 20. In this relaxed state, the two end faces 31, 32 of the insert, which possibly include anchoring pins or the like, come in contact with the two bony faces and press firmly on them, preventing the cage even more safely from moving and / or migrating after its implantation.

This increased elasticity of the insert 30 as defined above can be obtained in many ways. However, the simplest and most industrial solution is obtained by making, in the insert, a slot 51 in a plane substantially parallel to the two end faces 31, 32, as illustrated in FIG. 3.

Preferably, the cage further comprises means for defining an indexing of the position of the insert 30 in the through cavity 20, in order to unequivocally define the position of the insert in this cavity, so as to facilitate the preparatory work of practitioners. These means for indexing the position of the insert in the through cavity can also be produced in different ways. For example, as illustrated in FIG. 3, they can consist of a lug 52 or the like secured to the body 10 and a groove of a determined length 53 produced in the insert 30 (or conversely: a lug secured to the insert and a groove made in the body 10). In this way, when the insert is introduced into the cavity 20, its final position is well defined when the lug 52 abuts against the end wall of the groove 53.

However, these indexing means can also be constituted, for example, by a conical fitting between the insert and the cavity. In this case, the insert 30 and the cavity 20 each have at least one conical part complementary to one another. These two conical parts unequivocally limit the insertion of the insert into the cavity obtained when the two conical surfaces come into contact in congruence with each other.

It is even possible to envisage a combination of the two embodiments described above.

It is pointed out that, in FIG. 3, the insert shown in solid lines has substantially the shape of a rectangular parallelepiped, but that it can have other shapes, for example a U shape as mentioned in dashed lines on this same figure.

Furthermore, the cross section of the insert 30 may be less than the cross section of the cavity 20 so that, as illustrated in FIGS. 1 and 2, there exists, between the insert and the wall of the cavity, at the at least one space 40 determined to be able to receive at least one of the following elements: an anchor blade 41, a bone graft, a bone substitute, a combination of at least two of these elements.

It is also specified that the anchoring blade can be mounted integrated with the insert 30 or with the body 10. FIGS. 1 and 2 represent, by way of nonlimiting example of embodiment, the case of a blade mounted to pivot by relative to the body 10. An assembly in rotation relative to the insert 30 would not pose any difficulty for the skilled person and it is for this reason that this embodiment has not been specifically illustrated.

According to a very preferred embodiment, the first material is PEEK and the second material is very advantageously chosen from the following products: titanium, mesh titanium, porous titanium, trabercular ™ titanium, a combination of at least two of these products.

It is emphasized that, although the body 10 and the through cavity 20 have both been shown in the form of rectangular parallelepipeds, they can be in any other form, in particular like those which are known from the prior art. This specifically illustrated form was taken for the simplification of the drawings and to facilitate the understanding of the present invention.

In this regard, according to a possible characteristic of the invention, the through cavity 20 is of ovoid shape or the like. This latter embodiment is interesting because it makes it possible to obtain a through cavity 20 having a larger volume than that of a cylindrical cavity, without however reducing the area of the two opposite bearing faces 11, 12 of the body 10, nor modify the two end faces 31, 32 of the insert 30. On the other hand, it makes it possible for example to accommodate a large quantity of bone substitute or the like to promote osteosynthesis.

With a cage according to the invention, the distance between the two portions of bone will be respected and maintained, even during the fusion of the PEEK with the bone medium, the insert constantly ensuring this maintenance throughout the fusion.

Claims

claims

1. Interosseous cage suitable for being inserted between two portions of bone (01, 02) with a view to joining them by osteosynthesis, comprising at least:

A body (10) delimited by two opposite bearing faces (11, 12), each bearing face being configured to be able to come into contact with a corresponding face of one of the two bone portions, said body (10) being made of a first material having a given solidity, and

^• a through-cavity (20) formed in said body (10) opening on the two bearing surfaces (11, 12),

characterized in that it further comprises an insert (30) defined between two end faces (31, 32) and having a cross section at most equal to the cross section of said through cavity (20) so that said insert is able to be slid into the cavity, this insert being further configured so that its end faces are respectively substantially in continuity with the two bearing faces (11, 12) of said body (10) when said insert (30 ) is in the through cavity (20), said insert being made of a second material more solid than the first material.

2. Cage according to claim 1, characterized in that said insert (30) has a porous structure.

3. Cage according to claim 2, characterized in that said insert is made so that it has a porous honeycomb structure.

4. Cage according to claim 3, characterized in that the honeycomb structure comprises at least one continuous channel (35) opening onto the two ends of said insert.

5. Cage according to one of the preceding claims, characterized in that the cross section of said insert (30) is less than the cross section of said cavity (20) so as to leave, between said insert and the wall of said cavity, at least one space (40) determined to be able to receive at least one of the following elements: an anchor blade (41), a bone graft, a bone substitute, a combination of at least two of these elements.

6. Cage according to one of the preceding claims, characterized in that said first material is PEEK and that the second material is chosen from the following materials: titanium, mesh titanium, porous titanium, trabercular ™ titanium, a combination of at least these products.

7. Cage according to one of the preceding claims, characterized in that said insert is configured so that its two end faces (31, 32) are respectively slightly set back from the two bearing faces (11, 12) when the insert (30) is in the through cavity (20).

8. Cage according to one of the preceding claims, characterized in that said through cavity (20) has an ovoid shape.

9. Cage according to one of the preceding claims, characterized in that said insert (30) is arranged to have increased elasticity in a direction (50) substantially perpendicular to the two said opposite bearing faces (11, 12) of so that, when said insert is in a compressed state in this direction (50), its height defined in this direction (50) is at most equal to the distance separating said opposite bearing faces (11, 12) and that, when 'it is in a relaxed state, its height is greater than this distance.

10. Cage according to claim 9, characterized in that said increased elasticity of said insert (30) is obtained by a slot (51) formed in a plane substantially parallel to the two said end faces (31, 32).

11. Cage according to one of the preceding claims, characterized in that it further comprises means (52, 53) for defining an indexing of the position of said insert in said through cavity (20).