WO2014118291A1

WO2014118291A1 - Deformable interbody device

Info

Publication number: WO2014118291A1
Application number: PCT/EP2014/051827
Authority: WO
Inventors: Jérôme LEVIEUX; Guillaume AMBLARD
Original assignee: Spineart Sa
Priority date: 2013-01-31
Filing date: 2014-01-30
Publication date: 2014-08-07
Also published as: FR3001381A1

Abstract

The invention relates to a vertebral interbody fusion cage forming a tubular element comprising a circumferential wall defining an intervertebral spacing, said circumferential wall comprising at least one elongate opening (7) extending in the circumferential direction of the tubular element and creating, in same, an upper bar (11) and a lower bar (12). The circumferential wall is arranged such that a channel (13) is cut into the bar (11) at the opening (7), dividing said bar into two parts, said channel having a width (l) that renders at least one of the two parts flexible.

Description

Deformable interbody device

The present invention relates to a deformable intersomatic device and its applications.

The degeneration of the intervertebral disc tends to reduce the intradiscal space and to narrow the foramens through which the nerve roots exit the spinal canal. The surgical treatment of this type of pathology of the spine may require the fusion of one or more vertebral segments in the best possible anatomical position. The technique requires to revitalize the vertebral endplates and to use a bone graft to promote fusion of the vertebrae. In order to restore the normal space and sagittal anatomical angle of the segment (lordosis), intersomatic cages are implanted between the vertebrae, bone graft is installed in the cage and sometimes around to achieve fusion. The intersomatic cages are generally designed as a box having two lights, one on the lower face and one on the upper face, the lateral faces can also be openwork.

The Aleutian® cage from K2M (Leesburg, Virginia, USA) is designed as a box, it has two large openings, one on the underside and one on the upper face. The side faces do not have an opening. This cage is made of PEEK.

The Endoskeleton® TC cage from Titan Spine (Mequon,

Wl, USA) is designed as a box. It has two large openings, one on the underside and one on the upper face. The side faces also have large lights. This cage is made of titanium.

The Juliet®-po cage from the company SPINEART (Geneva, Switzerland) is designed as a box, it has two large openings, one on the underside and one on the upper face. The side faces have openings allowing them to slightly crash to put the graft located inside compression. This cage is made of PEEK.

These cages fulfill their role of height maintenance; also we can place graft inside. The disadvantage with these existing cages lies in the fact that the graft placed inside receives little or no mechanical load. However, the person skilled in the art knows that the graft is more likely to work and therefore to achieve the expected fusion if it receives mechanical load. This is described by Wolf's law. These cages are not sufficiently deformable to transmit a mechanical load, especially in their central area where the graft is located. This is especially true if the cage is made of a rigid material (Titanium, Peek / carbon).

WO 02/17823 A1 describes an intersomatic vertebral cage comprising a notch at a vertical bar. As a result, the corners of the cage are flexible while the side walls are not compressible.

It would therefore be desirable to have a intersomatic cage sufficiently deformable to transmit a mechanical load to a graft. It would also be desirable for this cage, although deformable, to be made of rigid material such as titanium.

But after long research the applicant has developed new intersomatic cages giving satisfaction.

This is why the present application relates to an intersomatic vertebral cage constituting a tubular element comprising a circumferential wall defining an intervertebral spacing, this circumferential wall comprising at least one opening elongated in the circumferential direction of the tubular element creating at its an upper bar and a lower bar, said wall being arranged such that at this opening, the circumferential wall comprises a bar, this bar being cut by a notch separating said bar into two parts, said notch having a width to give flexibility to at least one of the two parts.

The presence of the notch gives both sides of the bar greater flexibility than the flexibility of the same bar in one piece.

It should be noted that in the present invention, the term "tubular element" means a hollow element that is wider than long whereas a conventional tube is a hollow object, longer than wide. Also then that usually the wall thickness of a tube is small compared to the size of its lumen, the wall of a tubular member of the present invention has a large thickness.

In the present invention, the positions are indicated with respect to a standing individual seen from the front.

The flexibility of the two parts of a bar is mainly conditioned by the height of said bar. It is also conditioned by the height of the opening. Indeed a very low height of the opening may create a stop limiting flexibility. Those skilled in the art also understand that the law of limiting factors applies. Thus, if the height of the bar is not identical from one end to the other, in general the lowest height will give flexibility to the portion of bar between the point where this height is the lowest and the free end of the bar.

Thus, depending on the rigidity of the material used, the smallest height of the bar can range from 0.2 to 3.0 millimeters, preferably from 0.5 to 1.5 millimeters.

The cross section of a tubular element of the invention may have various shapes, including circular, rectangular including square, rectangular whose sides are semi circular, oval, bean or heart. According to the present invention, preferred shapes for the cross section are the rectangular shape and the bean shape.

A common feature of these tubular elements is that these, like any tube, comprise a circumferential wall, however generally provided with one or more perforations. The height of this wall determines the intervertebral spacing.

In preferred conditions of implementation of the invention, an Intersomatic vertebral cage of the invention comprises two elongate openings. Usually, a vertebral cage has an axis of symmetry. The two elongate openings are then preferably provided symmetrically. For example for a circular or oval cage, the openings will be diametrically opposed.

In the present invention, if the term "diametrically opposed aperture" is to be understood in its literal sense if the element For example, when the tubular element has a quadrilateral section, it should be understood that the openings are provided on two opposite sides.

In certain anatomical situations, it may be advantageous to provide only one elongated opening. In what follows, as is the most general case, for ease of writing and not to burden the text, we will use the term "opening" in the plural, except when the context shows that it is a question of one opening among a plurality of openings.

The openings are elongated in the circumferential direction of the tubular member. In other words, when an intersomatic vertebral cage of the invention is in place in a standing individual, said openings are elongated in a horizontal direction. Thus, at these openings, when moving in a vertical line, the wall is not continuous. We find a first bar, approximately horizontal, then a vacuum corresponding to the opening, then a second bar, approximately horizontal.

According to the invention, one of these bars is discontinuous because it is cut by a notch separating said bar into two parts.

If the top horizontal bar is cut by a notch, the bottom horizontal bar is not, and vice versa. It is preferably the upper bar, in the case of a single opening, the upper bars, in the case of two openings or more, which is notched.

The length of an opening may range from 3 millimeters to 50 millimeters, preferably from 6 millimeters to 35 millimeters and particularly from 9 millimeters to 20 millimeters. As regards the measurement of the length of an opening, the maximum length of this opening will be taken into account.

The presence of the notch gives the circumferential wall a certain elasticity over the entire length of the opening concerned. For a given bar portion, the elasticity is maximum at the end of the notch side and minimum at its opposite end where the circumferential wall is vertically continuous. Depending on the location of the notch relative to the length of a bar, one can confer different elastic properties, adapted to the anatomical situation. An intersomatic vertebral cage of the invention will preferably be made of titanium, carbon, PEEK (polyetheretherketone) or carbon reinforced PEEK.

For a posterior lumbar cage, a notch will be advantageously installed at each of the lights present on the elongated areas of the circumferential wall, either at the upper level or at the lower level. In this case, the circumferential wall consists of two elongated faces (one facing each other) and two small faces (one facing each other). The elongate faces are provided with lights, and the notch is preferably installed about the middle of each face at the upper level or the lower level.

Under preferred conditions of implementation of the invention, the intervertebral vertebral cage is a cervical cage.

In other preferred conditions of implementation of the invention, the intervertebral vertebral cage is a thoracic cage.

In other preferred conditions of implementation of the invention, the intervertebral vertebral cage is a lumbar cage. This lumbar cage may be intended for anterior or posterior installation.

In still other preferred conditions of implementation of the invention, the intervertebral vertebral cage is a lumbar cage intended for anterior installation, which comprises a circumferential wall composed of 4 faces, of which two lateral ones provided with lights and of notches according to the invention.

It should be recalled that when it is stated that the cages are for example cervical or lumbar, it is not only a question of indicating their destination or their use. These precisions imply particular technical characteristics. For example, a cervical cage will be of smaller size and of a shape, in horizontal section, close to the square (often slightly trapezoidal) while a lumbar cage intended for a posterior installation will look more like a fries, so of form lengthened, and that a lumbar cage intended for a transforaminal installation may be shaped into beans. When it is desired to make a more deformable intersomatic vertebral cage, thin walls are advantageously provided. It can also provide a wider notch. One can also choose an opening of greater height, not constituting a stop for the bar at the notch.

Those skilled in the art can with some simple experiments determine the shape, the size of the cuts and the thickness of the walls of the cage to achieve the desired deformability.

The width of a notch, measured in the direction of the length of a notched bar, may range from 0.01 to 10 mm, preferably from 0.2 to 5 mm, most preferably from 0.5 to 2 mm. In this regard it should be remembered that the function of the notch is to give some elasticity to the bar on which it is intended. The width will preferably be the same over the entire length of the cut; in other words, the walls of the notch are parallel. The term "width of the notch" means the minimum spacing between the one and the other part of the bar separated by the notch. The notch is preferably rectilinear and then comprises two walls which are opposite flat surfaces, advantageously parallel.

Still with reference to an intervertebral vertebral cage of the invention in place in an individual standing, a particularly rectilinear notch may be vertical, but will preferably be inclined. An inclined angle is preferably an angle of about 45 °.

The circumferential wall of a cervical cage may have a height of 3 to 12 mm, preferably 4 to 10 mm, most preferably 5 to 8 mm.

The circumferential wall of a cervical cage may have a thickness of 0.5 to 5 mm, preferably 1 to 5 mm, especially 2 to 4 mm, most preferably 2 to 3 mm.

Conventionally, the non-circumferential walls, that is to say the walls intended to come into contact with the vertebrae, may be provided with all kinds of reliefs helping to lock the cage in the desired position. These reliefs may be for example diamond points or sawtooth reliefs. It should be noted that in addition to the elongated openings forming a notched bar as provided in the present invention, an intersomatic vertebral cage of the invention may comprise other orifices in their circumferential wall, for example for the installation of a implement tool like a handle. These orifices may themselves be elongated, but do not constitute elongate openings within the meaning of the present invention.

The present application also relates to a method for manufacturing an intersomatic vertebral cage above, characterized in that it eliminates the material of a block or a thermoplastic resin profile unflexible, that is to say -say of rigidity comparable to that of virgin PEEK while having similar mechanical characteristics, to obtain an intersomatic vertebral cage according to the invention. One can use for this purpose a digital milling machine.

The present application also relates to a method of manufacturing an interbody vertebral cage above, characterized in that one operates by injection.

The present application also relates to a method of manufacturing an interbody vertebral cage above, characterized in that this cage is manufactured by 3D printing ("laser sintering System").

The intersomatic vertebral cages, objects of the present invention have very interesting properties and qualities. Thanks to their cut bars which thus create two half-bars, the intersomatic vertebral cages of the invention can easily be deformed under the constraints due to the movements of everyday life, which allows the graft located inside to receive constraints. mechanical. These constraints favor the taking of the graft. We thus quickly obtain the welding of two adjacent vertebrae. The present invention also allows the use of titanium which has many advantages for fusion and stability but which is relatively rigid and deforms little if the cage is not provided with suitable technical characteristics as is the case in the present invention. The intersomatic vertebral cages, objects of the present invention comprising a notch at a horizontal bar. As a result, the sidewalls are compressible.

These properties are illustrated below in the experimental part. They justify the use of vertebral interbody cages described above in a fusion method between two vertebrae.

This is why the present application also relates to a method of fusion between two adjacent vertebrae in which is implanted between two adjacent vertebrae at least one cage above (a cervical or lumbar cage for anterior route, or two lumbar cages for pathway posterior) and a bone graft is placed in the free volume of the cage delimited by the lateral walls.

The preferential conditions of implementation of the intersomatic vertebral cages described above also apply to the other objects of the invention referred to above, especially to the methods of fusion between two vertebrae.

The invention will be better understood with reference to the accompanying drawings in which

FIG. 1 represents a perspective view of an intersomatic vertebral cage of the invention,

FIG. 2 represents a perspective view of a variant of an intersomatic vertebral cage of FIG. 1,

FIG. 3 represents a side elevational view of an intersomatic vertebral cage of the invention,

FIG. 4 is a view from above of an intersomatic vertebral cage of the invention,

Figure 5 shows a side elevational view of an intersomatic vertebral cage of the invention installed between two vertebrae.

FIG. 6 represents a perspective view of an intersomatic vertebral cage of the invention, variant of that of FIG. 1,

FIG. 7 represents a perspective view of an intersomatic vertebral cage of the invention, variant of that of FIG. 1, FIG. 8 is an elevational view of a variant of the vertebral cage of FIG. 7.

Figure 9 is a top view of another variant of a spinal cage of the present invention.

As can be seen in Figure 1, the intersomatic vertebral cage shown here consists of a cage having the general shape of a rectangular parallelepiped, close to a square with rounded corners seen from above. In accordance with the above, for positions, an intersomatic vertebral cage is referred to in an upright individual.

This cage comprises four lateral walls including a front or proximal wall 1, a rear or distal wall 2 and left and right side walls 3 and 4, and an upper wall 5 and a lower wall 6 open to two adjacent vertebrae shown in FIG. Figure 5. The walls of left side 3 and right 4, slightly curved, each have an opening 7, 8 so that the walls of left side 3 and right 4 have the structure of a frame open in the middle. This frame is formed of two vertical bars 9, 10, an upper horizontal bar 1 1 and a lower horizontal bar 12. In the embodiment shown here, the upper horizontal bars are cut by a notch 13 separating said bars in two parts.

As can be seen in this FIG. 1, the rear face 2 has a height and therefore a thickness less than that of the front face 1.

The dimensions of the embodiment shown here are as follows, the cage being made of Titanium:

Length: 14mm, maximum width: 17mm, maximum height:

7mm, height at the back 2: 6mm.

Other dimensions of the cage shown: maximum length of side opening: 7mm, maximum height of side opening: 4mm, side opening area: 25mm2, length of upper horizontal bar: 7mm, height (thickness) of an upper horizontal bar: 3mm, section angle of the upper horizontal bars: approximately 45 °. Each cut comprises a first edge 14 constituting an acute bevel, which is the first to penetrate the intervertebral space during the introduction of the cage and a second edge 15. Given the inclination of the notch, it There is no risk of aggression of the bone plate during the introduction of the cage by one or other of the edges 14,15. Each notch 13 comprises two walls which are opposed flat, parallel surfaces in this embodiment.

The front wall 1 may be provided in the middle with a threaded orifice for cooperation with an insertion instrument such as a handle.

FIG. 2 represents a perspective view of a variant of an intersomatic vertebral cage of FIG. 1, in which the notch 13 is larger. Apart from this difference, the other characteristics are identical.

In FIG. 3, which represents a side elevational view of an intersomatic vertebral cage of the invention seen from the left side, there are substantially the same elements as those visible in FIG. It can further be seen that the lower wall 6 is substantially planar while the upper wall 5 is convex and curved.

It can also be observed that the orifice 7 is not provided in the middle of the cage, but is shifted towards the rear. In addition, if the orifice 7 is provided with a right front edge over most of its length, and perpendicular to the length of the bars, its rear edge has a circular arc shape connecting its upper and lower edges. Each edge is connected to its two adjacent edges by a curve. The bottom arrow of the figure represents the direction of insertion of the cage into an intervertebral space.

H represents the height of the bar, L represents the length of the bar and I represents the width of the notch.

In FIG. 4, which is a view from above of an intersomatic vertebral cage of the invention, the same technical characteristics are observed as in FIG. The cut 13 comprises a first edge 14 in a bevel blade and a second edge 15.

In Figure 5 which shows a side elevational view of an intersomatic vertebral cage of the invention installed in a functional position between two vertebrae 20, 21, one can observe substantially the same components as in Figure 3. It is better understood how the height of the circumferential wall 1, 2, 4 determines the intervertebral spacing.

FIG. 6 represents a perspective view of an intersomatic vertebral cage of the invention, variant of that of FIG. 1. Viewed from above, the cage also has a shape close to that of a square with rounded corners, but the lateral openings 7 are substantially narrower. The available space, however, largely allows the two portions of the upper bar 1 1 the possibility of vertical travel.

The intersomatic vertebral cage of the invention shown in Figure 7 differs from that of Figure 1 in that seen from above, it has a more elongated shape. Thus, if at comparable length, the surface of the lateral openings 7 is substantially identical to that of the lateral openings 7 of the cage of Figure 1, against the width of the cage is about half of that shown in Figure 1. It also differs from that shown in Figure 1 in that only one of the bars, one of the upper bars January 1 is notched.

FIG. 8 is an elevational view (side view) of a variant of the vertebral cage of FIG. 7.

Finally, in Figure 9 which is a top view of another variant of a vertebral cage of the present invention, the cage has a bean (or kidney) shape. The notch is, on the model shown, provided on a convex bar and not a concave bar of the cage.

Experimental tests

The rigidity of an intersomatic vertebral cage of the invention shown in FIG. 1 was tested as follows:

The rigidity of a PEEK cage without nicks, a non-scored titanium cage and a titanium cage according to the invention were compared using a finite element study. To do this we blocked the lower face and applied a force on the upper face. In the comparative tests it was possible to note a greater deformation (especially in the middle, where the graft is intended to be installed) of the cage according to the invention compared to the cages without incisions of the prior art.

Claims

1. An intersomatic vertebral cage constituting a tubular element comprising a circumferential wall defining an intervertebral spacing, said circumferential wall having at least one opening (7) elongated in the circumferential direction of the tubular element creating at its level an upper bar (11 ) and a lower bar (12), said wall being arranged so that at this opening (7), the circumferential wall comprises a bar (1 1), this bar (1 1) being cut by a notch ( 13) separating said bar (1 1) into two parts, said notch having a width (I), to give flexibility to at least one of the two parts.

2. A cage according to claim 1, characterized in that it comprises two openings (7) elongated.

3. A cage according to claim 2, characterized in that if an upper horizontal bar (1 1) is cut by a notch (13), the lower horizontal bar (12) is not, and vice versa.

4. A cage according to one of claims 1 to 3, characterized in that the width of a notch (13), measured in the direction of the length of a notched bar, is 0.2 to 5 mm.

5. A cage according to one of claims 1 to 4, characterized in that the notch (13) comprises two walls which are opposed flat surfaces.

6. A cage according to one of claims 1 to 5, characterized in that the upper bar (1 1) or the upper bars (1 1) comprise the notch (13).