The present invention relates to a piece of vertebral osteosynthesis equipment.

The immobilization of two consecutive vertebrae by placing between these vertebrae, an implant intended to be colonized by growing bone cells so as to achieve what should be called "bone fusion" of the vertebrae, is well known. This intervertebral implant may notably be in the form of a cage in stiff material, against which the vertebrae bear, the cavity(ies) of which receive(s) a porous, bone or synthetic graft.

Associating with the intervertebral implant, a member for connecting two vertebrae externally to the intervertebral space, notably as a clamp, is also known, the respective branches of which are inserted into the bodies of both vertebrae. With this connecting member, both vertebrae may be immobilized for the time during which bone fusion is performed and the risk of expelling this implant out of this space may be prevented. It is preferable that this connecting member be connected to the intervertebral implant so that it may further be an obstacle to movements of the implant in the intervertebral space.

Such a piece of equipment is currently implanted via an anterior approach, in order to have sufficient space for being able to place the connecting member in the vertebral bodies and for achieving the assembly of this connecting member to the intervertebral implant.

This anterior approach however has the significant drawback of being strongly invasive and of making the surgical operation complicated.

Therefore there exists the need of a piece of vertebral osteosynthesis equipment as mentioned earlier, which may be placed via an approach other than a purely anterior approach, and in particular via a side approach.

The object of the present invention is to provide such a piece of equipment. This piece of equipment comprises in a way known perse,

- an intervertebral implant;

- a member for connecting vertebral bodies of both treated vertebrae intended to be assembled to the intervertebral implant; - a member for assembling the connecting member to the intervertebral implant, and

- instruments for placing this implant, this connecting member and this assembling member. According to the invention,

- the intervertebral implant comprises on its proximal side relatively to the direction of its introduction into the intervertebral space, a hole comprising two coaxial portions, i.e. a proximal portion of larger section and a distal portion of smaller section, these proximal and distal portions comprising respective connecting means; - the connecting member comprises a hole which allows it to be engaged onto a guiding rod intended to be inserted into said distal portion of the hole of the implant;

- the assembling member comprises a conduit which allows it to be engaged and closely fitted on this same guiding rod, and connecting means able to cooperate with the connecting means of the proximal portion of the hole of the implant. By "close-fitting engagement", it should be understood that the assembling member may be engaged by sliding it on the guiding rod, but without any substantial play perpendicularly to the axis of this guiding rod.

The vertebral osteosynthesis piece of equipment according to the invention thus comprises a guiding rod intended to be connected to the implant as soon as before this implant is placed in the intervertebral space, and intended to remain in place on this implant until the end of the placement procedure, this guiding rod not being an obstacle for placing said assembling member by means of both portions of the hole which the implant comprises.

The guiding rod thus allows the assembling member to be perfectly guided and aligned with the axis of the hole of the implant.

The result is that with the piece of equipment according to the invention, the assembling of the connecting member with the implant may be carried out under the best conditions, and the placement of the assembling member is easy, which allows the use of a narrow and not very invasive approach, in particular a purely side approach.

The setting-up instruments in addition to said guiding rod, which includes connecting means able to cooperate with the connecting means of the distal portion of the hole of the implant, in order to achieve the assembling of this rod to the implant, may comprise: an instrument for introducing and/or impacting the implant in the intervertebral space, which comprises a conduit allowing it to be fittingly engaged onto said guiding rod when this rod is connected to the implant, and which comprises a distal end capable of bearing against the implant in this engagement condition; an instrument for creating holes in the vertebral bodies of both vertebrae, comprising a conduit which allows it to be fittingly engaged on said guiding rod when this rod is connected to the implant; - an instrument for introducing and/or impacting the connecting member, comprising a conduit which allows it to be fittingly engaged onto said guiding rod when this rod is connected to the implant, and which comprises a distal end capable, in this engagement condition, of bearing against the connecting member engaged on the guiding rod; - an instrument for introducing and placing the assembling member, which comprises a conduit allowing it to be fittingly engaged on said guiding rod when this rod is connected to the implant.

Here also, by "fittingly engaged" it should be understood that the setting-up instruments may be slidably engaged onto the guiding rod but without any substantial play perpendicularly to the axis of this guiding rod.

The procedure for placing the piece of equipment comprises the following steps:

- connecting the guiding rod to the implant;

- engaging onto the guiding rod the introduction and/or impaction instrument and then introducing and/or impacting the implant into the intervertebral space; - withdrawing the introduction and/or impaction instrument;

- engaging onto the guiding rod the instrument for creating holes in the vertebral bodies and creating these holes by means of this instrument;

- withdrawing the instrument for creating holes in the vertebral bodies;

- engaging onto the guiding rod the connecting member and the instrument for introducing and/or impacting this connecting member and placing the connecting member on the vertebral bodies; - withdrawing the instrument for introducing and/or impacting the connecting member;

- engaging onto the guiding rod the assembling member and the instrument for introducing and placing this assembling member and placing the assembling member in the proximal portion of the hole of the implant by means of this instrument;

- withdrawing the instrument for introducing and placing the assembling member;

- withdrawing the guiding rod.

With the piece of equipment according to the invention, it is thereby possible to obtain, in addition to perfect coaxiality of the assembling member with the hole of the implant, perfect parallelism of the holes made in the vertebral bodies with this same hole of the implant, and coaxiality of the hole of the connecting member with this hole of the implant.

The means for connecting the guiding rod to the distal portion of the hole of the implant may comprise slightly conical forms of the distal end portion of the guiding rod and of this distal portion of the hole, preferably however, these connecting means comprise a tapped thread of said distal portion of the hole and a threading on the distal end portion of the guiding rod.

Preferably, the means for connecting the assembling member and the proximal portion of the hole of the implant comprise a tapped thread of said proximal portion of the hole and a threading of the assembling member.

Advantageously, in this case, the connecting member comprises, at its hole, allowing this connecting member to be engaged onto the guiding rod, a tapped portion through which the assembling member should be screwed in order to be able to be then screwed into said proximal portion of the hole of the implant.

In the case when the assembling member would unscrew from the hole of the implant until it emerges from this hole, said tapped portion of the connecting member would allow this assembling member to be retained on the connecting member.

The implant advantageously comprises at least one cavity for receiving a porous graft intended to be invaded by growing bone cells. Preferably, in this case, the implant comprises a wall parallel to the direction of its introduction into the intervertebral space, in which the aforementioned hole of this implant is made. This wall creates an area of sufficient thickness for creating this hole and allows longitudinal reinforcement of the implant, making the latter able to support without any risk of deterioration the stresses generated by its introduction and/or its impaction into the intervertebral space. According to a preferred embodiment of the piece of equipment, in this case, said wall is extended on the distal side, with two walls diverging from each other, these divergent walls being connected to two opposite peripheral walls of the implant.

With this shape, the impaction forces may be perfectly distributed over the whole of the structure of the implant. The two divergent walls further allow delimitation with the peripheral walls of the implant of a distal cavity of large size, able to receive a graft having an extending contact surface with the bone tissues of the vertebrae.

Preferably, the connecting member and the instrument for introduction and/or impacting this connecting member comprise connecting means allowing this connecting member and this instrument to be bound with each other in rotation about the axis of the hole which the connecting member comprises and of the conduit which the instrument comprises.

The latter when it is engaged onto the guiding rod, enables the connecting member to be angularly oriented for the case when this would prove to be necessary in order to bring this connecting member opposite to the pierced holes in the vertebral bodies.

These connecting means may notably comprise protrusions laid out on the distal end of the instrument and corresponding cavities laid out on the connecting member. The invention will be understood and other features and advantages thereof will become apparent with reference to the appended schematic drawing, illustrating as a non-limiting example, a preferred embodiment of the piece of equipment to which it relates.

Fig. 1 is a perspective view of an intervertebral implant and of a connecting member as a clamp which this piece of equipment comprises;

Fig. 2 is a side view, at an enlarged scale, of a screw for assembling the connecting member to the implant; Fig. 3 is a partial view of the connecting member, similar to Fig. 1 at an enlarged scale;

Fig. 4 is a partial view of the connecting member, at an enlarged scale, as a sectional view along the line IV-IV of Fig. 3; Fig. 5 is a top view of the implant, as a partial sectional view at a proximal hole which this implant comprises; and

Figs. 6-11 are front views, with a partial sectional view of different elements being part of the piece of equipment, during successive steps for placing this piece of equipment on two consecutive vertebrae of a vertebral column. The figures represent a piece of vertebral osteosynthesis equipment including an intervertebral implant 1 , a member 2 for connecting the vertebral bodies 100 of two treated vertebrae, a member 3 for assembling the connecting member 2 to the intervertebral implant, and instruments 50-54 for placing this implant 1 , this connecting member 2 and this assembling member 3. By more particularly referring to Figs. 1 and 5, it appears that the intervertebral implant 1 is in the form of a cage delimiting cavities 6 for receiving porous, bone or synthetic grafts. These grafts are intended to be colonized by growing bone cells, so as to achieve what should be called "bone fusion" of the vertebrae.

The implant 1 is intended to be introduced into the intervertebral space to be treated via a side approach. It comprises peripheral walls, including an anterior wall

7, a posterior wall 8 and side walls 9. It also comprises internal walls, including a proximal wall 10, parallel to the direction of the direction of its introduction into the intervertebral space and positioned in a middle position relatively to the anterior wall

7 and to the posterior wall 8, and two distal walls 1 1 diverging from each other, connected to the distal end of the wall 10 on the one hand, and to the walls 8 and 9, on the distal side, on the other hand.

The implant 1 also comprises, on its proximal side, relatively to its direction of introduction into the intervertebral space, a hole comprising two coaxial portions 12, 13, i.e. a proximal portion 12 with a larger diameter and a distal portion 13 of smaller diameter, both of these proximal and distal portions 12, 13 being tapped.

The proximal portion 12 is intended to receive the assembling member 3, screwed into it, as this appears in Fig. 1 1 , and the distal portion 13 is intended to receive, also screwed into it, the distal end portion of a guiding rod 50, cf. Figs. 6-10. The respective diameters of these proximal and distal portions 12, 13 are such that the assembling member 3 may be screwed into the proximal portion 12 while the guiding rod 50 is screwed into the distal portion 13. The connecting member 2 is in the form of a clamp, comprising a central branch and two jagged side branches intended to be inserted into holes 101 (cf. Fig. 9) created in the vertebral bodies 100.

The central branch comprises a middle hole 15 which crosses it, forming as this is shown in Figs. 3 and 4, a proximal cup 15a and a distal tapped portion 15b. It also comprises two diametrically opposite cavities 16 created from its proximal face.

The assembling member 3 is in the form of a cannulated screw comprising a milled head and a distal threaded portion extending on only one portion of its body. This distal threaded portion is able to be screwed through the portion 15b of the member 2 and into the proximal portion 12 of the hole of the implant 1. As this appears in Figs. 10 and 1 1 , the internal conduit of this assembling member 3 is such that the member 3 is able to be fittingly engaged onto the guiding rod 50, with however the possibility of sliding and of rotating; the assembling member 3 may thus be screwed through the distal tapped portion 15b of the connecting member 2 and then into the proximal portion 12 of the hole of the implant 1 , allowing the assembling of this member 2 and of the implant 1 to be achieved. In this position, the milled head of the assembling member 3 takes a place in the proximal cup 15a of the hole 15.

The instruments 50-54 comprise said guiding rod 50, an instrument 51 for introducing and impacting the implant 1 into the intervertebral space, an instrument 52 for creating holes in the vertebral bodies 100, an instrument 53 for introducing and impacting the connecting member 2 and an instrument 54 for introducing and placing the assembling member 3.

As shown in Fig. 6, the instrument 51 for introducing and impacting the implant

1 into the intervertebral space 102 comprises a tubular sleeve 60 delimiting a conduit which allows it to be fittingly engaged onto the guiding rod 50 while this rod is connected to the implant 1. This instrument 51 also comprises a flared distal end 61 capable of bearing against the implant 1 in this engagement condition in order to allow the introduction and impaction of the implant 1 into the intervertebral space 102.

In Fig. 7, it appears that the instrument 52 for creating holes in the vertebral bodies 100 comprises a head 62 for creating holes, having a shape similar to that of the connecting member 2, and a tubular sleeve 63 delimiting a conduit which allows it to be fittingly engaged onto the guiding rod 50 while this rod is connected to the implant 1. This instrument 52 may be slid on this rod 50 until it achieves piercing of the vertebral bodies 100 or enlargement and forming of holes created beforehand in these vertebral bodies 100 (cf. Fig. 8). The instrument 53 for introducing and impacting the connecting member as for it comprises (cf. Fig. 9) a tubular sleeve 64 delimiting a conduit which allows it to be fittingly engaged onto the guiding rod 50 while this rod is connected to the implant 1. This instrument 53 also includes a flared distal end 65 capable of bearing against the implant 1 in this engagement condition and two protrusions capable of engaging with the cavities 16 of the member 2 in order to achieve a rotary connection of this instrument 53 and of this member 2 about the axis of the rod 50. The instrument 53 thus in addition to introduction and impaction of the member 2, allows this member 2 to be angularly oriented for the case when this would prove to be necessary in order to bring the side branches of the latter to facing the holes 101 pierced in the vertebral bodies 100.

The instrument 54 for introducing and placing the assembling member 3, visible in Fig. 10, comprises a tubular sleeve 66 delimiting a conduit which allows it to be fittingly engaged onto the guiding rod 50 when this rod is connected to the implant 1 and has a distal conformation which allows it to be rotationally engaged with a corresponding proximal conformation of the head of the assembling member 3.

In practice, the procedure for placing the piece of equipment comprises the following steps:

- connecting the guiding rod 50 to the implant 1 ;

- engaging onto the guiding rod 50 the introduction and impaction instrument 51 and then introducing and impacting the implant 1 into the intervertebral space 102

(cf. Fig. 6);

- withdrawing the instrument 51 ; - engaging onto the guiding rod 50 the instrument 52 for creating holes in the vertebral bodies (cf. fig. 7) and creating these holes by means of this instrument (cf. Fig. 8);

- withdrawing the instrument 52; - engaging onto the guiding rod 50 the connecting member 2 and the instrument

53 for introducing and impacting this connecting member 2 (cf. fig. 9) and placing the connecting member 2 on the vertebral bodies 100;

- withdrawing the instrument 53;

- engaging onto the guiding rod 50 the assembling member 3 and the instrument 54 for introducing and placing this assembling member 3 (cf. fig. 10) and placing the assembling member 3 in the proximal portion 12 of the hole of the implant 1 by means of this instrument;

- withdrawing of the instrument 54;

- withdrawing the guiding rod 50 (cf. fig. 11 ). The invention thus provides a piece of vertebral osteosynthesis equipment comprising a guiding rod 50 intended to be connected to the implant 1 as soon as before this implant is placed in the intervertebral space 102 and intended to remain in place on this implant 1 until the end of the placement procedure, this guiding rod 50 not being an obstacle to the placement of the assembling member 3 by means of the two portions 12, 13 of the hole which the implant 1 comprises.

The guiding rod 50 allows the different instruments to be perfectly guided throughout the procedure and to be aligned with the axis of the hole of the implant 1 ; therefore with it, it is possible to obtain (i) perfect parallelism of the hole 101 created in the vertical bodies 100 with this hole of the implant 1 ; (ii) perfect coaxiality of the hole 15 of the connecting member 2 with this hole of the implant 1 and (iii) perfect coaxiality of the assembling member 3 with this same hole.

The result is that with the piece of equipment, the assembling of the connecting member 2 with the implant 1 may be achieved under best conditions, and the placement of the assembling member 3 is easy, which allows the use of a narrow and not very invasive approach, in particular a purely lateral approach. The invention has been described above with reference to an embodiment provided as an example. It is obvious that it is not limited to this embodiment, but that it extends to all the other embodiments covered by the appended claims.