WO2013007888A1

WO2013007888A1 - Interbody cage, in particular of the tlif type

Info

Publication number: WO2013007888A1
Application number: PCT/FR2012/000263
Authority: WO
Inventors: Alain Lerch; Gilles Dubois; Jacques Flageollet; Nicolas Guena
Original assignee: Kasios
Priority date: 2011-07-08
Filing date: 2012-06-29
Publication date: 2013-01-17
Also published as: FR2977474B1; EP2729091A1; FR2977474A1

Abstract

The invention relates to an interbody cage intended to be inserted between two vertebrae, in particular using the transforaminal technique (TLIF), in order to reinforce the space between two vertebrae by means of fusion, and an insertion instrument intended to be linked to the cage for the insertion thereof. The invention also includes first means (7, 10) for rotationally connecting the insertion instrument to the cage in a first relative position of the cage in relation to the instrument. The cage is characterised in that second means (7, 9) are provided for rotationally connecting the insertion instrument to the cage in a second relative position of the cage in relation to the instrument, and, between the first relative position and the second relative position, the cage is rotated in relation to the insertion instrument by an angle of, in particular, 20 to 50° and, more particularly, by an angle of approximately 30°.

Description

Intersomatic cage, especially of the TLIF type.

The present invention relates to an interbody cage, in particular of the TLIF type (Transioraminal Lumbar Interbody Fusion). The technique of transioraminal insertion of a lumbar cage of this kind involves making an incision in the back of the patient, dissecting muscle and joints to gain access to the space between the vertebrae, removing the disc from the spine between two vertebrae, then insert the cage instead of the disc. To do this, it is necessary to circumvent the articular elements. This circumvention requires the practitioner to subject the cage during its insertion into the disc space a movement in an arc. The present invention also relates to an assembly consisting of an intersomatic cage, in particular of the TLIF genus, and a device for positioning the cage in the disc space between two vertebrae.

It is already known in the prior art assemblies of this kind comprising a cage and a rod, the cage comprising means for temporarily connecting the rod to the cage to allow the insertion thereof into space disc. In these assemblies of the prior art, the practitioner or surgeon, once the rod connected to the cage, pushes it between the vertebrae and then undergoes "- cage, always using the rod, a rotation to position it in the disc space between the vertebrae.This assembly of the prior art does not ensure the surgeon high precision of the arcuate movement and, in In particular, the axis in which the surgeon acts on the insertion rod varies during the rotation of the cage, which is not good for the accuracy of the insertion. As a result, it is also necessary to be able to insert these cages to make an incision of rather large size and to dissect a fairly large amount of muscle and / or joint in the vicinity of the disc space, even though we would like to have available an assembly that allows to minimize, on one hand, the size of the incision made and the amount of articulation and / or ^'eliminate muscle and, on the other hand, give the surgeon the maximum facility to manipulate the cage to insert it between the vertebrae.

It is already known in the prior art to provide two different positions for rotationally securing the cage relative to the instrument, which greatly facilitates the work of the surgeon. Indeed, the first position gives the surgeon great ease for a first insertion movement by the side of the cage. Then, before making an arcuate movement of the cage for its final positioning between the two vertebrae, the surgeon passes the assembly in the second relative position which gives it great ease to perform this second rotatio movement.

For example, it is known from WO 2010/075555 an assembly consisting of an intersomatic cage and an insertion instrument comprising a threaded rod intended to cooperate with the cage to insert the latter in position. The cage comprises means for mutually interconnecting the cage and the instrument in two relative positions that are rotated relative to each other. These means consist on the one hand of two lugs which are issued from the end of a sleeve surrounding the threaded rod and on the other hand of reception channels of these lugs formed at the opening of the cage by which penetrates the threaded end portion of the rod intended to cooperate with the threaded through hole formed in the ball joint. However, this assembly of the prior art is, on the one hand, complicated to manufacture, requiring the insertion instrument to be made so that it comprises a central rod carrying at its end a thread and a sleeve surrounding the rod carrying the pins, and the arrangement to be such that the rod can rotate and slide relative to the sleeve. In addition the assembly is complicated to use, in particular to move from one relative position to another.

The present invention aims to overcome the drawbacks of assemblies of the prior art by proposing an assembly of the kind mentioned above, which makes it possible to perform the insertion of the cage by having to make only one incision of very large size. small, especially in the back of the patient in the case of a TLIF technique, and to eliminate as little muscle and / or joints as possible in the vicinity of the disc space; which gives in the same time to the surgeon great facility to perform the insertion movement, including the rotation of the cage in a circular arc, for its final positioning between the two vertebrae; which is also very simple to use and whose structure is simpler, thus facilitating manufacture. According to the invention, an assembly comprising an intersomatic cage intended to be inserted between two vertebrae, in particular by the TLIF technique, in order to consolidate by fusion the space between the two vertebrae and an insertion instrument intended to be connected to the cage for insertion thereof is as defined in claim 1, improvements and advantageous embodiments being defined in the subclaims. By providing and the locking in rotation of the cage and ^'of the instrument in one of two relative positions is made on the inside of the cage, through the threaded end of the insertion rod beyond the ball joint, and no longer by means different from the rod arranged before the ball joint, the structure of the assembly is simplified, the function of the locking pins being, according to the invention, transferred to the threaded rod which more than its function of cooperation by screwing with the ball joint the relative blocking function which in the prior art was devolved to other elements, such as the pins mentioned above, complex structures. In particular, according to the invention the insertion instrument is of very simple structure, in the form of a rod which can be of cylindrical shape of revolution simple to manufacture and without moving parts such as a sleeve as in the prior art. The present invention is thus particularly useful for making disposable disposable assemblies. According to a preferred embodiment of the invention, the insertion device comprises a rod, the first and second securing means comprise respectively first and second holes formed in the cage, one end of the rod being received in the first hole when the assembly is in the first relative position, and one end of the rod, in particular said one end, being received in the second hole when the assembly is in the second relative position.

According to a preferred embodiment of the invention, the securing of the rod in the first or second position comprises a screwing, and in particular the rod comprises a threaded portion which cooperates with a threaded portion of the cage.

According to a particularly preferred embodiment of the invention, there is disposed in the cage a ball, particularly cylindrical, which is pivotable relative to the cage and which is pierced with a through hole, the through hole being able to open, depending relative rotation of the ball relative to the cage, firstly outside the cage and secondly in front of one of the holes for receiving an end of the rod respectively in the first and second positions.

Thus, the ball joint makes it possible to guide the rod for the introduction of an end into one of the holes of the two positions and, on the other hand, facilitates the passage of the rod from one of the positions to the other position.

According to a preferred embodiment of the invention, the through hole of the ball joint is threaded and the rod comprises a threaded portion intended to be screwed to the thread of the through hole of the ball joint. Thus, ^'the surgeon when inserting the rod into the cage, the screw rod in the through hole until the part end of the rod enters one of the holes to thereby reach one of the first or second positions. When he wants to go into the other position, he slightly unscrews the rod of the ball until retracting the end portion of the rod out of the first hole, then rotates the ball to bring the through hole in front of the second hole, and again screw the rod to penetrate its end in the second hole and thus be in the second position. There is thus a particularly simple system for the surgeon.

Preferably, the end portion of the rod intended to penetrate into one of the first or second holes is not threaded and is following a threaded part of the rod. According to a preferred embodiment of the invention, the cage is a TLIF cage, and in particular has a curved shape imitating the natural curvature of the vertebrae.

According to a preferred embodiment of the invention, in one of the two positions, the rod is substantially parallel to the sagittal axis of the cage.

The present invention also relates to an intersomatic cage, in particular of the TLIF type, intended to be inserted between two vertebrae, in particular by the TLIF technique, in order to consolidate by fusion the space between the two vertebrae and intended to be connected to a inserting instrument for its insertion, the first means for securing in rotation the insertion instrument to the cage in a first relative position of the cage relative to the instrument being provided, is characterized in that it is provided second means for securing in rotation the insertion instrument to the cage in a second relative position of the cage relative to the instrument, the cage between the first relative position and the second relative position having been rotated relative to the insertion instrument, in particular at an angle between 20 and 50 °, in particular about 30 °.

By way of example, an embodiment of the invention will now be described with reference to the drawings in which: FIG. 1 is a perspective view from above of a cage according to the invention; Figure 2 is a bottom view of the cage of the

Figure 1 ;

Figure 3 is a sectional view along the line A-A of Figure 1, on a larger scale; Figure 4 shows in perspective the cage of

Figures 1 to 3 and an insertion rod intended to cooperate with the cage to insert the latter between two vertebrae, a portion of the cage being torn along the line AA of Figure 1 and the opening 5 of the cage being filled with a bone substitute material; FIG. 5 is a sectional view of an assembly consisting of a cage according to FIGS.

3 and the rod of Figure 4 in the first insertion position; and Figure 6 is a view identical to Figure 5, in the second insertion position. In Figures 1 to 3, there is shown a TLIF interbody cage. This cage is meant to be inserted between two vertebrae by performing a first pushing movement by the side, then a bypass movement consisting of a rotation on a circular arc. The cage has a curved posterior wall 1 and a curved front wall 2 substantially parallel to the posterior wall 1. The two walls 1 and 2 posterior and anterior are joined by a proximal wall 3 and meet by a convex distal wall 4. The four posterior, anterior, distal and proximal walls delimit between them an open space for receiving graft or bone substitute to assist bone regrowth once the cage is inserted between the two vertebrae. The upper side of the cage is defined as the side seen from above in Figure 1 with the underside of the cage on the other side.

It is formed in the proximal wall 3 of the cage a circular cylindrical cavity 6 of vertical axis. This cavity 6 opens on the outside, on the lower side of the cage, as seen in FIG. 2. In this cylindrical cavity 6, there is inserted a ball 7 of complementary circular cylindrical shape of the cavity 6. This ball 7 is inserted into the cavity 6 by snug fit or by clipping, so as to be blocked by the dimension of the opening of the cavity 6 which is slightly smaller than the diameter of the patella while the interior of the cavity has a dimension substantially identical to that of the patella so that it can not get out of this cavity, but can however rotate along the vertical axis in the cavity 6. The ball 7 has a through hole extending perpendicularly to the vertical axis and which crosses from one side diametrically the ball 7. This through hole 16 has a thread 17 on its inner wall.

A window 8 is formed in the wall 3 between the circular cylindrical cavity 6 and the outside of the cage. Thus, this window 8 opens on the one hand into the cavity 6 and on the other hand outside the proximal side of the wall 3. In particular, this window consists of two circular cylindrical recesses 19, 20 arranged side by side. to form a cylinder having a recumbent section. On the other side of the vertical cylindrical cavity 6 with respect to the window 8, two blind cylindrical holes 9 and 10 are formed in the wall 3, between the ball and the space 5. These two blind holes 9 and 10 have a circular cylindrical shape. They are arranged to open substantially side by side in the cavity 6 having their respective blind hole cylinder axis mutually inclined relative to each other. Each of the holes 9, 10 are diametrically, with respect to the cavity 6, opposite a respective recess of the two recesses 19, 20.

In Figure 4, there is described an insertion rod for allowing the insertion of the cage of Figures 1 to 3 in the disc space between two vertebrae. The stem has a proximal portion 10 forming a handle to be taken by the surgeon. Following this proximal section, an intermediate section 11 extends to be of smaller diameter than the section 10. Finally, the rod is terminated by a distal section 12 of smaller diameter than the intermediate section 11. The intermediate section 11 has a thread 18. The distal section 12 has no threading. The threading of the intermediate section 11 corresponds to tapping 17 of the through hole 16 of the ball 7. The diameter of the distal section 12 is such that it can penetrate into the holes 9 and 10 blind). In addition, preferably, the length of the section 12 corresponds to the length of the holes 9 and 10, that is to say their dimension in the direction of their longitudinal axis. However, this feature is not a necessity and it could also be provided that the section 12 is shorter in length than the holes 9 and 10 oblong or on the contrary a slightly longer length. This will be understood later in view of the operation and the respective functions of the rod and holes.

In Figures 5 and 6, there is shown how the rod of Figure 4 cooperates with the cage of Figures 1 to 3 for its insertion between two vertebrae. In the first position shown in FIG. 5, the rod has been inserted into the recess 19 of the window 8, the intermediate section 11 being screwed into the thread 17 of the through hole and the distal section 12 of the rod emerging from the through hole to be in the blind hole. The rod-cage assembly is then in the first insertion position. The fact that the distal portion 12 is in the hole 10 causes the surgeon can no longer rotate the patella and thus the rod relative to the cage, the distal portion 12 blocking the rotation of the ball 7. In this first position , the rod and the cage are integral on the one hand in rotation by the blind hole 10-distal part 12 interaction of the rod and on the other hand in translation by the screwing of the section 11 to the tapping 17 and the fact that the part distal 12 abuts the bottom of the blind hole 10. At the same time, the screwing of the rod makes that no movement of withdrawal of the rod is possible. Thus, in this first position, the rod and the cage are secured in rotation as well as in translation. In this first position, the rod is substantially parallel to the sagittal direction. It is, in particular, perpendicular to the plane of the outer surface of the proximal wall 3.

Once the rod and the cage secured in this first position, the surgeon can insert, after making the appropriate incision, the cage between the vertebrae passing through the side. However, during this insertion, he must at one point rotate the cage to bypass joints, muscles and / or nerves to position the cage in its final position. It then passes the rod-cage assembly in a second relative position. To do this, it unscrews the shaft of the cage to cause the distal portion 12 to withdraw from the blind hole and return to the inside of the through hole of the ball joint. Once the portion 12 removed from the hole 10 and returned to the through hole of the ball 7, the latter is no longer locked in rotation and the surgeon can thus rotate the rod so that the through hole of the ball joint 7 and the distal portion 12 located therein is brought in front of the hole 9, offset from the hole 10, the rod at the same time having passed from the recess 19 to the recess 20 of the window 8. Once this rotation has been completed, the surgeon again screws the stem fully until the proximal portion 12 emerges from the through hole and now penetrates into the hole 9, thus blocking any rotation of the patella 7 and therefore any relative rotation of the rod relative to the cage. In this second position, in which the rod has been rotated by an angle to the figure of about 35 ° and which can be preferably between 25 and 50 °, the rod and the cage are secured in rotation as well as in translation. In this second position, the relative orientation of the cage and the rod is different from that in the first position. The surgeon can then rotate the assembly to bring the shaft into a position relative to the patient substantially identical to that in ^■ which it was before it has passed the rod from the first to the second position. By rotation of the rod, it is thus possible to subject the appropriate rotation to the cage for its final positioning between the two vertebrae.

Thanks to the system according to the invention, thus obtaining a very easy insertion of the cage between the two vertebrae and in particular a high accuracy in the amount of rotation that must be subjected to the cage. Once the cage is positioned, the surgeon unscrews the rod completely until it comes out of the cage.

The insertion instrument can thus have a very simple form, in particular be a simple threaded rod, without complicated moving parts. The rod, in particular its end portion, at least partly threaded, penetrates into the patella to ensure the solidarization of the instrument and the cage, and also acts, coming out of the other side of the hole crossing the ball, to block any rotation. The rod thus has, according to the invention a dual function of solidarisâtion and locking in rotation.

An embodiment has been described above with two blind holes for receiving the end of the rod after the latter has emerged from the through hole. It should be noted, however, that these two holes blind can be omitted without departing from the scope of the present invention. Indeed, by providing a relative sizing of the rod and the through hole such that the end of the rod protrudes out of the through hole when it is screwed, it is ensured that this end of the rod will be able to attack the material of the inner wall of the cage being in front of the through hole to be embedded in it and this incrustation will thus ensure the locking in the same manner as in the embodiment with the blind holes 9 and 10, the inlay digging somehow in situ the equivalent of blind holes. This embodiment without blind holes is particularly well suited to an assembly intended to be used only once (that is to say disposable).

It should be noted, moreover, that according to the invention, if it is subsequently desired to remove this cage to put a new one or simply to remove it, the surgeon only has to reintroduce the next stem the sagittal axis with respect to the patient and falls directly into the right position, which is particularly appropriate.

Preferably, the cage is made of PEEK. However, other materials, especially metallic or organic ceramics compatible conventional for interbody cages can be used.

Preferably, the ball is made of titanium. It should be noted that the patella, although an important element of the invention, is not strictly necessary to obtain the effect of the invention and, in particular, another embodiment could be envisaged. in which the holes 9 and 10 would be tapped to get the same function. However, on the one hand, the ball has the advantage of ensuring good guidance of the rod towards the blind holes 9 and 10 and, on the other hand, it also has the effect of giving the cage greater strength vertical stresses, which prevents it from breaking unexpectedly.

Claims

REVENDICA IONS

Assembly comprising an intersomatic cage, in particular of the TLIF type, intended to be inserted between two vertebrae, in particular by the TLIF technique, in order to consolidate by fusion the space between the two vertebrae and an insertion instrument for the insertion of the cage between the two vertebrae, means (7, 16, 17) for rotationally fastening the insertion instrument to the cage in at least first and second relative rotational locking positions of the instrument relative to the cage being provided, the cage of a position relative to the other having been rotated relative to the insertion instrument, the securing means comprising, on the one hand in the cage, a swivel (7) rotatable relative to the cage disposed in the cage and pierced with a threaded through hole (16) opening out of the cage, and secondly into the insertion instrument, a rod having a threaded portion intended to penetrate from outside the cage in the through hole to be screwed to the tapping (17) of the through hole, characterized in that to lock in rotation the rod relative to - the cage in each of the at least two positions, the rod is screwed into the through hole so as to emerge from this through hole on the inner side of the cage opposite the side through which the rod has penetrated into the through hole.

2. An assembly according to claim 1, characterized in that at least first and second holes (9, 10) formed in the cage are provided respectively in which the end (12) of the rod which has emerged from the through hole penetrates. depending on the desired relative locking position.

3. Assembly according to claim 1, characterized in that, when the rod leaves the ball joint, it is sinking into the wall of the cage opposite the outlet opening of the through hole to anchor and so block any relative rotation of the cage and the rod.

4. Assembly according to one of claims -1 to 3, characterized in that the insertion instrument consists only of a rod, in particular without other moving parts relative to the rod.

5. Assembly according to claim 4, characterized in that the rod is symmetrical of revolution, in particular cylindrical of revolution relative to the axis of the rod.

6. Assembly according to one of claims 1 to 5, characterized in that the rotation undergone by the cage relative to the insertion instrument between the first and second relative positions is between 20 and 50 °, in particular is equal to at 30 °.

7. Assembly according to one of the preceding claims, characterized in that the part (12) end of the rod is not threaded and is following a threaded portion (11) of the rod.

8. Assembly according to one of the preceding claims, characterized in that the cage is a cage

TLIF, and in particular has a curved shape imitating the natural curvature of the vertebrae.

9. Assembly according to one of the preceding claims, characterized in that a window is formed in the wall between the cavity (6) receiving the ball joint (7) and the outside of the cage consisting of two recesses ( 19, 20) circular cylindrical.

10. Assembly according to claim 9, characterized in that the two circular cylindrical recesses (19, 20) are arranged side by side so as to form a cylinder having a section 8 coated.