HK1230055B - Expansible intravertebral implant system with posterior pedicle fixation - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to an expandable intravertebral implant system with posterior pedicle fixation. More particularly, the present invention relates to a system comprising an expandable intravertebral implant that provides improved vertebral anchoring by adding a securely anchored pedicle sleeve within a vertebral pedicle.

STATE OF THE ART

Several techniques of vertebroplasty are known for performing spinal realignment to restore the original shape or morphology of a deformed vertebra following bone compression, for example caused by osteoporosis or trauma.

For example, the technique of kyphoplasty is known, which consists of introducing an inflatable balloon into a vertebra, then injecting a pressurized fluid into the balloon placed inside the vertebra in order to force the cortical shell of the vertebra, and notably the upper and lower vertebral endplates, to return to a straightened shape under the effect of pressure. Once the cortical bone shell is straightened, the balloon is deflated and removed from the vertebra, allowing the injection of bone cement into the vertebra in order to provide the straightened vertebra with a stable mechanical resistance over time.

It is also known, particularly through the international patent application WO2005/120400, an expandable implant comprising a first and a second opposed plates, capable of forming respectively a first and a second support surface within a vertebral body; these two support surfaces being intended to move away from each other along a predefined expansion plane. The expandable implant is positioned within the vertebral body, and the plates are deployed along an expansion plane corresponding to the desired bone realignment plane. Then, bone cement is injected in order to stabilize the bone realignment. The bone cement can be injected with relatively low pressure thanks to the implant which remains in place within the vertebral body.

In cases of the most severe traumas, the use of the aforementioned methods may prove insufficient. The repair of vertebral fractures, particularly compression fractures, is then preferably performed by means of screws inserted into the pedicles of the vertebrae above and below the compressed vertebra. These screws are associated with posterior rods, thereby mechanically connecting the vertebrae above and below the compressed one to allow for vertebral consolidation. Pedicle screws are well known in the state of the art. For example, screws as described in U.S. Patent 5,209,753 are known.

The disadvantage of this technique lies in the fusion of two spinal articulation levels caused by the fixation of posterior rods connecting the vertebrae above and below. Moreover, these methods do not always allow for the realignment of the compressed vertebra, but only stabilize three adjacent vertebrae, thereby locking two spinal articulation levels. The surgical procedure associated with this technique is also very invasive and requires access to at least two vertebrae.

In order to overcome these disadvantages, it appears necessary to provide a device for repairing vertebral fractures, and particularly severe compression vertebral fractures, avoiding fusion and allowing consolidation, at the level of the pedicle, of an expandable intravertebral implant located within the vertebral body.

Thus, the invention aims to associate an expandable intravertebral implant, positioned within a vertebral body, with a pedicular fixation (for example, a sleeve or sheath), intended to be anchored in the pedicle. This pedicular fixation provides high-quality bone support and anchoring. Indeed, if the vertebral body is composed of cancellous bone, having a high porosity of 30 to 90%, the pedicle is composed of cortical bone, having a porosity of 5 to 30%, thus offering a solid mechanical support for the intravertebral implant and allowing reconstruction of vertebral fractures, and notably compression fractures, even the most severe ones.

Expandable bone implant systems comprising an additional anchoring in the pedicle bone are known, such as the systems described in patent applications EP 2 074 956, US 7,291,150 and US 2009/005821. However, these systems describe an expandable member rigidly connected to the said pedicle fixation, for example by screwing the two parts together. As a result, the expansion direction of the expandable member and the positioning of the member within the vertebral body are directly dependent on the position of the pedicle fixation.

The invention has the advantage of allowing the deployment of the expandable intravertebral implant independently, according to two degrees of freedom, from the position of the pedicle fixation. The implant system also allows to rigidify (i.e., to lock all degrees of freedom) the said expandable intravertebral implant relative to the pedicle fixation, when the implant system is positioned in extension within the vertebra. Advantageously, a posterior element is associated with the pedicle fixation element, serving as a connection system, which allows attaching to the expandable intravertebral implant additional means for completing the bone realignment, for example by means of posterior rods or other systems aimed at further stabilizing the fracture site.

Thus, the present invention ensures spinal correction by means of an expandable, modular intradiscal implant system with posterior pedicle fixation.

SUMMARY

The invention therefore relates to an expandable intravertebral implant system, comprising an intravertebral implant having an anterior expandable portion within a vertebral body and a posterior portion; and a pedicle fixation having at least a hollow receiving portion for the posterior part of the intravertebral implant. according to claim 1.

According to one embodiment, the pedicle fixation includes a thread ensuring the anchoring of the said pedicle fixation in a vertebral pedicle.

According to one embodiment, the pedicle fixation comprises a hollow posterior internal portion and a hollow anterior internal portion in which the posterior part of the intradiscal implant can move according to two degrees of freedom.

According to one embodiment, the pedicle fixation comprises a main axis, and the posterior part of the intravertebral implant can translate and rotate according to the main axis of the pedicle fixation within the anterior internal portion of the pedicle fixation; thereby allowing the expansion direction of the anterior part of the intravertebral implant to be independent of the position of the pedicle fixation within the vertebral pedicle.

According to one embodiment, the anterior part of the intravertebral implant includes a first and a second platform, adapted to form respectively a first and a second support surface within a vertebral body; these two surfaces being able to move away from each other along a predefined expansion plane.

According to one embodiment, the anterior internal portion includes at least one groove on its inner surface.

According to one embodiment, a posterior portion of the posterior part of the intradiscal implant includes a cylindrical recess and at least one securing means for preventing rotational and translational relative movements between the intervertebral implant and the pedicle fixation.

According to one embodiment, the stabilization means comprises at least one through opening, passing through the posterior portion and a peripheral chamber on the surface of the posterior portion, in fluid communication with the at least one through opening.

According to one embodiment, the locking means comprises at least two slots extending axially along the posterior portion, an internal thread, and a flared rear end; which can cooperate with an expanding conical plug.

According to one embodiment, the posterior element is connected to the pedicle fixation via a threaded rod screwed into a tapped hole of the posterior internal portion.

According to one embodiment, the posterior element includes a posterior portion adapted for assembly with complementary posterior fastening elements such as bars or artificial ligaments.

BRIEF DESCRIPTION OF THE FIGURES

Other specific features and advantages will become clearly apparent from the following description, which is given by way of example and not limitation, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the implant system according to one embodiment of the present invention. Figure 2 is a side view of the intervertebral implant according to one embodiment of the present invention. Figure 3A is a side view of the pedicle fixation according to one embodiment of the present invention. Figure 3B is a cross-sectional view of the pedicle fixation according to one embodiment of the present invention. Figure 4 is a perspective view of the posterior element according to one embodiment of the present invention.Figure 5 is a side view of the implant system according to an embodiment of the present invention, mounted on an instrument adapted for inserting the implant system. Figure 6A is a side view of the implant system, according to an embodiment of the present invention, placed in a vertebra; said vertebra being represented as transparent, visible only by its outlines. Figure 6B is a top view of the implant system, according to an embodiment of the present invention, placed in a vertebra; said vertebra being represented as transparent, visible only by its outlines. Figure 7A is a cross-sectional view of the implant system according to an embodiment of the present invention,Before the expansion of the anterior part of the implant. Figure 7B is a cross-sectional view of the implant system according to an embodiment of the present invention, after expansion of the anterior part of the implant. Figure 8A is a cross-sectional view of the implant system, after expansion of the anterior part of the implant, illustrating the means for securing the pedicle fixation to the intradiscal implant according to an embodiment of the present invention. Figure 8B is a perspective view of the intervertebral implant, after expansion of the anterior part of the implant, illustrating the means for securing the pedicle fixation to the implant according to an embodiment of the present invention.Figure 8C is a perspective view of the pedicle fixation, illustrating in particular the anterior internal portion according to an embodiment of the present invention. Figure 9A is a cross-sectional view of the implant system, after expansion of the anterior part of the implant, illustrating the means for securing the pedicle fixation to the intradiscal implant according to an embodiment of the present invention. Figure 9B is a perspective view of the implant, after expansion of the anterior part, illustrating the means for securing the pedicle fixation to the intradiscal implant according to an embodiment of the present invention. Figure 10A is a lateral view of the implant system according to an embodiment of the present invention placed in a vertebra; said vertebra being represented as transparent,Visible only by its outlines. Figure 10B is a cross-sectional view of the implant system according to an embodiment of the present invention placed in a vertebra; said vertebra being represented as transparent, visible only by its outlines.

The drawings of the figures are not to scale. It goes without saying that the scope of the invention is not limited to the specific examples of realization more particularly described and represented in reference to the attached drawings; on the contrary, it encompasses all possible variations.

REFERENCES

1 Intravertebral implant, 11 Anterior part of the intravertebral implant, 12 Posterior part of the intravertebral implant, 121 Shoulder, 122 Cylindrical recess, 123 Chamber, 124 Through hole, 125 Groove, 126 Internal thread, 127 Flared posterior end, 128 Posterior portion of the posterior part of the intravertebral implant, 13 Central tensioning tube, 131 Through hole, 2 Pedicle fixation, notably pedicle sleeve, 21 Thread, 22 Posterior internal portion, 221 Tapping, 23 Anterior internal portion, 231 Groove, 24 Rotational drive means of the pedicle fixation - Notch, 25 Entry bevel, 3 Posterior element, 31 Anterior portion, 311 Thread, 32 Posterior portion, 33 Support surface, 4 Vertebra, 5 Insertion instrument, 51 Rotationally fixed cannula of the pedicle fixation, 52 Expansion tube, 6 Conical expansion plug.

DETAILED DESCRIPTION

The present invention relates to an expandable intravertebral implant system with posterior pedicle fixation.

According to a first embodiment, the implant system includes an intervertebral implant associated with a pedicle fixation that provides additional anchoring at the level of the vertebral pedicle.

According to a second embodiment, as shown in Figure 1, the implant system includes an intravertebral implant 1 associated with a pedicle fixation 2 and a posterior element 3 that allows connecting, posteriorly to the vertebra, any device intended to stabilize, reinforce, or repair a vertebral fracture, particularly a vertebral compression fracture.

Intravertebral implant

As shown in Figure 2, the intravertebral implant 1 according to the present invention includes a front portion 11 and a rear portion 12.

According to one embodiment, the anterior part 11 corresponds to a deformable and expandable intervertebral implant 1, such as the SpineJack® implant marketed by the company VEXIM, which is known to those skilled in the art and also described in patent application EP 1 778 136, incorporated herein by reference. It should be noted that those skilled in the art, upon reading the aforementioned patent application, would easily identify the necessary characteristics for implementing the present invention. In particular, the anterior part 11 of the intervertebral implant 1 of the present invention consists of an expandable portion allowing for bone realignment and comprising: a single expansion plane determined,Intrinsic to the aforementioned front portion 11, a first and a second opposed platforms, suitable for forming respectively a first and a second support surfaces in a vertebral body intended to move away from each other along said single expansion plane during implant expansion; a first and a second support for each of said first and second platforms, located underneath each of them respectively; and means for setting a determined expansion value, comprising a layer of material arranged between each support and a corresponding platform, said layer having a determined thickness that allows controlling the expansion of the implant. According to one embodiment, said front portion 11 also includes a central tensioning tube 13 for guiding the expansion of the first and second platforms.According to an alternative embodiment, the anterior portion 11 of the intradiscal implant 1 corresponds to any known intradiscal implant that is deformable, expandable, and capable of remaining within the vertebral body after expansion.

According to one embodiment, as shown in Figures 7A-B, 8A-B, 9A-B, and 10A-B, the central pull tube 13 is hollow and includes at least one through hole 131 allowing the injection of a filling material into the vertebral body 4, such as bone cement, after expansion of the first and second plates. According to one embodiment, the central pull tube 13 includes at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 through holes 131. According to one embodiment, the through hole(s) 131 extend radially through the central pull tube 13 to allow fluid communication between the internal passage and the external surface.According to one embodiment, the central tension tube 13 includes a plurality of through holes 131 regularly distributed over its surface. According to one embodiment, at least one through hole 131 is located between the two plates so as to be in fluid communication with the interior of the vertebra after implant expansion and separation of the two plates. Advantageously, injecting a filling material into the vertebra 4 allows the anterior portion 11 of the implant 1 to remain in position within the vertebral body after expansion. According to one embodiment, the filling material is a biocompatible bone cement.For example, an ionomer cement, a phosphate-calcium cement, an acrylic cement, or a compound thereof, or a resin. According to one embodiment, the filling material solidifies after injection. Advantageously, the solidification of the filling material allows to consolidate the vertebra 4 and to reinforce the stability of the implant system's insertion into the vertebra 4.

According to one embodiment, the posterior part 12 is a hollow cylindrical body connected at its front end to the rear end of the anterior part 11 by a shoulder 121. The said posterior part 12 includes a cylindrical recess 122 through which a central pull tube 13, initially located in the anterior part 11, can slide. By pulling the central pull tube 13, the central pull tube 13 slides into the cylindrical recess 122 of the posterior part 12, causing the front and rear ends of the anterior part 11 to approach each other, thereby expanding the first and second platforms of the anterior part 11 of the intervertebral implant 1. The central pull tube 13 allows controlling the deployment of the expandable deformable anterior part 11. Once the pull tube 13 has been pulled into the recess 122, the tube can no longer return to its initial position, thus maintaining the expansion of the anterior part 11 until cement or bone substitute is injected.

According to an embodiment illustrated, for example, in Figure 8B, the posterior part 12 of the intervertebral implant 1 includes a cylindrical recess 122 and at least one through hole 124. Advantageously, the at least one through hole is located in the posterior portion 128 of the posterior part 12. According to one embodiment, the posterior portion 128 corresponds to the part of the posterior section of the intervertebral implant 12 that remains permanently inside the anterior internal portion 23. According to one embodiment, the cylindrical recess 122 extends through the entire posterior part of the implant 12. According to one embodiment,The posterior part of the intervertebral implant 12, and in particular the posterior portion 128, further comprises a portion with a reduced external diameter, thereby defining a peripheral chamber 123. According to one embodiment, at least one through hole 124 extends through the posterior part of the implant 12 from the cylindrical recess 122 to the peripheral chamber 123. According to one embodiment, the posterior part 12 of the implant, and in particular its posterior portion 128, includes at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 through holes 124. According to one embodiment, the through holes 124 are regularly distributed along the posterior portion 128.

According to an embodiment illustrated in Figure 9B, the posterior part of the intradiscal implant 12 includes a cylindrical recess 122 and at least one slot 125 passing through the posterior part 12 and extending axially. Advantageously, the at least one slot 125 is located in the posterior portion 128 of the posterior part 12. According to one embodiment, the posterior portion 128 corresponds to the part of the posterior section of the intradiscal implant 12 that remains permanently inside the anterior internal portion 23. According to another embodiment, the cylindrical recess 122 extends through the entire posterior part of the implant 12.According to one embodiment, the posterior part of the intravertebral implant 12, and in particular the posterior portion 128, further comprises an internal thread 126 located on the inner surface of the cylindrical recess 122. According to one embodiment, the posterior part of the intravertebral implant 12, and in particular the posterior portion 128, further comprises a flared posterior end 127 that can cooperate with a conical expansion plug 6. According to one embodiment, the posterior part 12 comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 slots 125. According to one embodiment, the slot 125 extends over all or part of the posterior portion 128.According to one embodiment, the tapping 126 extends over all or part of the posterior portion 128.

According to one embodiment, the expansion of the intervertebral implant 1 is not caused by injecting a substance into the posterior part of the implant 1. However, injecting a filling material may help stabilize the implant once it is in its expanded position. According to one embodiment, the intervertebral implant 1 does not include a pouch intended to be filled with a substance (e.g., a filling material) in order to allow the pouch to expand. According to one embodiment, injecting a filling material through the anterior portion 11 alone does not allow the expansion of the intervertebral implant 1.

According to one embodiment, the posterior part 12 of the intervertebral implant 1 does not include an external thread intended to be screwed with the pedicle fixation 2.

Pedicle fixation

As shown in Figure 3A, the pedicle fixation 2 according to the present invention includes at least one thread 21. According to one embodiment, the pedicle fixation 2 includes a thread 21 on the external surface of the pedicle fixation 2. Said external thread 21 is suitable for providing bone anchoring in the pedicle. The anchoring of the pedicle fixation 2 in a vertebral pedicle provides additional mechanical support to the intradiscal implant 1, and particularly to the expandable anterior portion 11 of the implant 1. The insertion of the pedicle fixation 2 into the bone tissue is facilitated by a chamfer 25 located at the anterior end of the pedicle fixation 2.According to one embodiment, the external surface of the pedicle fixation 2 does not have any texture other than that induced by a thread, such as a meshed, grooved, or speckled structure. As shown in Figure 3B, the pedicle fixation 2 is a hollow cylindrical pedicle sleeve or bushing comprising a posterior internal portion 22 and an anterior internal portion 23. According to one embodiment, the pedicle fixation 2 is not a solid pedicle screw comprising a partially hollow internal portion. According to one embodiment, the pedicle fixation 2 is hollow along its entire length.According to one embodiment, the posterior internal portion 22 and the anterior internal portion 23 do not have the same surface condition.

According to one embodiment, the posterior internal portion 22 includes a threaded portion 221 or any other means within the skill of a person skilled in the art for connecting the fastening 2 to a posterior element 3.

According to one embodiment, the anterior internal portion 23 includes a bore defining a hollow receiving portion for the posterior part 12 of the intervertebral implant 1. According to one embodiment, the surface of the anterior internal portion 23 is smooth. According to one embodiment, the surface of the anterior internal portion 23 is not threaded. According to one embodiment, the intervertebral implant 1, and in particular the posterior part 12, does not pass through the entire hollow pedicle fixation 2. According to one embodiment, the posterior part 12 of the intervertebral implant 1 is intended to be inserted inside the anterior internal portion 23.According to one embodiment, the posterior part 12 serves as a guide for the pedicle fixation 2. The shoulder 121 thus acts as a guiding stop for the fixation 2. According to one embodiment, the posterior part 12 of the intervertebral implant 1 can move according to at least one degree of freedom, preferably two degrees of freedom, in the anterior internal portion 23 of the pedicle fixation 2. According to one embodiment, the posterior part 12 of the intervertebral implant 1 is slidable within the anterior internal portion 23. According to one embodiment, the mechanical connection between the posterior part 12 and the anterior internal portion 23 is a sliding pivot joint.According to one embodiment, the pedicle fixation 2, particularly the pedicle screw, defines a main axis. According to this embodiment, the posterior part 12 of the intradiscal implant 1 can rotate and translate along said main axis within the anterior internal portion 23 of the pedicle fixation 2.

Advantageously, the front portion 23 allows the intervertebral implant 1 to expand independently of the fixation pedicle 2 anchoring in the vertebral pedicle. Indeed, the translational freedom along the main axis of the pedicle fixation 2 enables the positioning (i.e., the advancement due to deployment) of the intervertebral implant 1 within the vertebral body to not be constrained. Moreover, the rotational freedom around the main axis of the pedicle fixation 2 prevents the direction of expansion of the intervertebral implant 1 from being restricted. Thus, when deployed, the intervertebral implant 1 adjusts its deployment position according to the environment in which it is deployed (i.e., the vertebral body).

According to one embodiment, the anterior internal portion 23 does not have threads. According to another embodiment, the anterior internal portion 23 and the intervertebral implant 1 are not threaded.

According to one embodiment, the front inner portion 23 further includes at least one groove 231, as shown in Figure 8C. According to one embodiment, the front inner portion 23 includes at least one axial groove (i.e., a groove parallel to the z-axis). According to one embodiment, the front inner portion 23 includes at least one transverse groove (i.e., perpendicular to the z-axis). According to one embodiment, the front inner portion 23 includes at least one inclined groove 231. According to one embodiment, the front inner portion 23 includes at least one axial and/or transverse and/or inclined groove 231.According to one embodiment, at least one groove 231 includes a non-constant section. According to one embodiment, the anterior internal portion 23 includes at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 grooves 231. According to one embodiment, the grooves are regularly distributed on the internal surface of the anterior portion 12. According to one embodiment, the pedicle fixation 2 includes at least one notch 24, or any other means within the skill of the art, for rotating the pedicle fixation 2 using an insertion instrument 5.

Back element

As shown in Figure 4, the posterior element 3 according to the present invention comprises a front portion 31 made of a rod, preferably a threaded rod 311 cooperating with the tapping 221 of the pedicle fixation 2, thereby allowing the posterior element 3 to be fixed to the pedicle fixation 2. The posterior element 3 also includes a posterior portion 32, located outside the vertebra 4, whose geometry enables assembly functions with complementary posterior fixation elements known to those skilled in the art, such as rods or artificial ligaments. Any other assembly configuration with other systems known to those skilled in the art may be considered. The posterior element 3 also includes a support surface 33 against the bone tissue or against the posterior portion of the pedicle fixation 2, depending on the choice made by the operator and/or the insertion of the pedicle fixation 2 into the pedicle bone.

Operation

After the initial creation of a pathway and the preparation of the vertebral pedicle, the implant system including the pedicle fixation 2 and the vertebral implant 1, whose posterior part 12 is inserted into the anterior internal portion 23 of the pedicle fixation 2, is inserted and screwed into the pedicle using an insertion instrument 5, as shown in Figure 5. The said insertion instrument 5 comprises a working cannula 51 rotatably connected (i.e., connected in rotation) to the pedicle fixation 2 via notches 24 that allow the pedicle fixation 2 to be screwed into the pedicle. The said insertion instrument 5 also includes an expansion tube 52 located along the main axis of the insertion instrument 5 and is configured to pass through at least the length of the posterior internal portion 22.The expansion tube 52 is fixed (i.e., connected) to the posterior part 12 of the intervertebral implant 1, and in particular is fixed to the central tensioning tube 13 of the intervertebral implant 1. The insertion depth of the implant system is controlled by the operator by screwing the pedicle fixation thread 21 into the bone tissue, in order to optimally position the intervertebral implant 1 within the vertebral body. The axial rotational positioning of the intervertebral implant 1 is independently controlled by the operator from the insertion of the pedicle fixation 2, using the tube 52 in order to maintain an expansion plane.For example, a craniocaudal expansion plan of the intravertebral implant 1, regardless of the screwing angle obtained during insertion of the pedicle fixation 2. As shown in Figures 6A, 6B, 10A and 10B, the intravertebral implant system according to the present invention is inserted through a vertebral pedicle, with the intravertebral implant 1 then located within the vertebral body and the pedicle fixation 2 being anchored in the pedicle.

According to one embodiment, after implantation of the system, the pedicle fixation 2 is firmly fixed in the pedicle, and the intravertebral implant 1 is partially secured to the pedicle fixation 2 by its posterior cylindrical portion 12. Indeed, the posterior cylindrical portion 12 is inserted into the anterior internal portion 23, thereby preventing rotational movements around the y and x axes and blocking translations along the x and y axes. As a result, these blocked degrees of freedom ensure a partial solidarity between the posterior cylindrical portion 12 inserted into the anterior internal portion 23.By "solidarization," it is meant the blocking of all degrees of freedom between the pedicle fixation 2 and the intradiscal implant 1. By "partial solidarization," it is meant the blocking of at least one degree of freedom between these two parts. The pedicle fixation 2 then abuts against the shoulder 121. Thus, the intradiscal implant 1 has an additional support point in the pedicle. According to one embodiment, the vertebral implant 1 is not solidarily connected to the pedicle fixation 2 by screwing. According to another embodiment, the posterior part 12 of the intervertebral implant 1 assembled to the pedicle fixation 2 does not pass completely through the pedicle fixation 2.According to one embodiment, the posterior part 12 of the spinal implant 1 is mounted in the anterior internal portion 23 of the pedicle fixation 2.

As shown in Figures 7A and 7B, the expansion of the intradiscal implant 1 is achieved by pulling the central pull tube 13 through the insertion instrument's tube 52 (not shown in the figures). The central pull tube 13 can slide unidirectionally within the posterior part 12 of the implant 1 to allow deployment while preventing retraction. Pulling the central pull tube 13 causes the deployment of the intervertebral implant 1 by bringing together the anterior and posterior ends of the anterior portion 11. According to one embodiment, the deployment allows the spreading apart of the endplates within the vertebral body.This expansion within the vertebral body causes the anterior displacement of the implant: the anterior part 11 of the expandable implant slides through the anterior internal portion 23 so that the anterior part 11 of the intervertebral implant adapts optimally to the environment in which it is deployed. Advantageously, the sliding connection between the posterior internal portion 23 of the pedicle fixation 2 and the posterior part 12 of the implant 1 allows the position of the deployed intervertebral implant 1 to adapt independently of the position of the pedicle fixation 2.

As shown in Figure 7B, the posterior part 12 can slide freely within the anterior internal portion 23, without exiting it, to provide a permanent additional support, thus not restricting the deployment of the intradiscal implant in a position dependent on the location of the pedicle fixation 2 within the pedicle. Indeed, the anterior internal portion 23 is designed to block the translations and rotations of the intervertebral implant 1 along the x and y axes of the pedicle fixation 2, while allowing translation and rotation along the main axis of the pedicle fixation 2 (i.e., the z-axis).

According to one embodiment, the dimensions of the posterior part 12 of the implant 1 are such that once the posterior part 12 is inserted into the anterior internal portion 23, the implant 1 cannot be removed from the pedicle fixation when it is implanted. The longitudinal dimension of the anterior internal portion 23 is sufficiently long so that the posterior part 12 remains inserted and partially connected to said anterior internal portion 23 during deployment. According to one embodiment, the length of the anterior internal portion 23 is indeed between 1 and 20 mm or between 5 and 15 mm.

According to this embodiment, the intradiscal implant 1 is free to rotate axially and translate anteriorly relative to the pedicle fixation 2. The deployment of the intradiscal implant 1 thus occurs exclusively as a function of the intradiscal bony environment, which imposes the orientation and depth of deployment of the extendable anterior portion 11 of the intervertebral implant 1. According to one embodiment, the intradiscal implant, and particularly its posterior portion 12, can move with one, two, three, four, or five degrees of freedom, preferably two degrees of freedom, even more preferably one degree of freedom in rotation and one degree of freedom in translation, within the anterior internal portion 23. According to one embodiment, the intradiscal implant 1, and particularly its posterior portion 12, can move in rotation and translation along the Z-axis within the anterior internal portion 23.

According to one embodiment, after the expansion of the intravertebral implant 1, rotation and translation along the z-axis between the intravertebral implant and the pedicle fixation are locked, thus making the expandable intravertebral implant 1 rigidly connected to the pedicle fixation 2.

According to one embodiment, the anterior part of the intradiscal implant 11 is stabilized in an expanded position by injecting a filling material into the vertebra 4 through at least one through hole 131. The filling material is injected using an injector through the pedicle fixation 2, the cylindrical opening 122 of the posterior part of the implant 12, and the hollow traction tube 13, up to the level of the anterior part 11 of the implant 1.

According to one embodiment, the posterior part of the intravertebral implant 12 is fixed to the pedicle fixation 2 by blocking the relative movements of the posterior portion 12 with respect to the pedicle fixation 2 using securing means.

According to one embodiment, as illustrated in Figure 8A, the posterior part of the intradiscal implant 12 is fixed within the pedicle fixation 2 by injecting a filling material. The filling material is injected through the posterior internal portion 22 into the cylindrical cavity 122 and into at least one through hole 124 in order to come into contact with the inner surface of the anterior internal portion 23. Advantageously, the posterior portion 128 includes a peripheral chamber 123 into which the at least one through hole 124 opens. Thus, the filling material fills the at least one through hole 124 and the peripheral chamber 123 in order to distribute the filling material at the interface between the posterior portion 128 and the anterior internal portion 23, thereby increasing the contact surface area.In order to further enhance the bonding, the front inner portion 23 includes at least one groove 231 and the injected filling material filling at least one through hole 124, the peripheral chamber 123, and at least one groove 231 of the front inner portion 23. Advantageously, the solidification of the filling material in the at least one axial groove 231 reinforces the bonding with respect to the degree of freedom of rotation around the z-axis. Advantageously, the solidification of the filling material in the at least one transverse groove 231 reinforces the bonding with respect to the degree of freedom of translation along the z-axis.Advantageously, the solidification of the filling material in the at least one inclined groove 231 reinforces the fixation according to the degrees of freedom in translation and rotation along the z-axis. Advantageously, the solidification of the filling material in the at least one groove 231 with a non-constant cross-section reinforces the fixation according to the degree of freedom in translation and rotation along the z-axis. According to one embodiment, the grooves 231 further allow injection of the filling material into the anterior internal portion 23, thereby further strengthening the fixation. According to one embodiment, the filling material injected into the cylindrical recess 122 fills the at least one through hole 124.The peripheral chamber 123 and at least one groove 231 of the anterior internal portion 23, and any part or all of the volume of the anterior internal portion 23. Advantageously, the peripheral chamber 123 allows access to the grooves 231 regardless of the orientation of the intervertebral implant 1, and in particular the orientation of the posterior portion 128, in the pedicle fixation 2.

According to one embodiment, as illustrated in Figure 9A, the posterior part of the intradiscal implant 12 is secured within the pedicle fixation 2 by means of an expanding conical plug 6. The said conical plug comprises an external thread and a flared rear end. The said plug 6 is inserted through the internal posterior portion 22, optionally after cement injection into the vertebra via the through hole 131, and screwed into the tapped hole 126 of the posterior portion 128. When the conical plug 6 is screwed into the tapped hole 126 of the posterior portion 128, the flared end of the plug comes into contact with the flared end of the posterior portion 127, causing the radial expansion of the posterior portion, made possible by the slots 125. Advantageously, the radial expansion of the posterior portion 128 into the anterior internal portion 23 secures the posterior part of the intradiscal implant 12 within the pedicle fixation 2 by means of a supporting engagement.

According to one embodiment, once the intravertebral implant 1 is deployed, secured to the pedicle fixation 2, and stabilized, if necessary by injecting a specifically adapted cement or bone substitute, it is then possible to connect (i.e., fasten) the posterior element 3 to the entire assembly of pedicle fixation 2 and intravertebral implant 1 by simply screwing and tightening the latter into the internal posterior portion 22 of the pedicle fixation 2. In this embodiment, the posterior element 3 is at least partially outside the vertebra 4 and is then able to receive posterior fixation elements such as rods or artificial ligament systems or any other means of stabilizing a vertebral fracture known to those skilled in the art.

Not being part of the invention, an example also relates to a method for treating vertebral fractures comprising: inserting a device according to the invention, wherein the posterior part 12 is already inserted into the internal anterior portion 23 within a vertebra 4, and screwing the pedicle fixation 2 into the vertebral pedicle via the external thread 21; expanding the anterior part 11 of the intravertebral implant 1, particularly by pulling the central pull tube 13; positioning the anterior part 11 of the intravertebral implant, made possible by moving the posterior part 12 of the intravertebral implant 1 in translation and rotation, along the main axis of the pedicle fixation 2, within the internal anterior portion 23 of the pedicle fixation 2; optionally injecting a filling material into the vertebral body through a through hole 131 to stabilize the anterior part 11 of the intravertebral implant; and optionally fixing the posterior part 12 within the internal anterior portion 23.

Claims (10)

1. An expandable intravertebral implant system comprising an intravertebral implant (1) comprising an anterior part (11) expandable in a vertebral body and a posterior part (12); and a pedicle fixation (2) comprising an inner posterior portion (22) and an inner anterior portion (23) defining a hollow portion receiving the posterior part (12), in which the posterior part (12) of the intravertebral implant (1) is movable according to two degrees of freedom, characterized in that the pedicle fixation (2) has a main axis and the posterior part (12) of the intravertebral implant (1) is movable in translation and in rotation, along the main axis of the pedicle fixation (2), in the inner anterior portion (23) of the pedicle fixation (2); so that the direction of expansion of the anterior part (11) of the intravertebral implant (1) is independent from the position of the pedicle fixation (2) in the vertebral pedicle.
2. The expandable intravertebral implant system according to claim 1, wherein the pedicle fixation (2) comprises a thread (21) providing anchorage of said pedicle fixation into a vertebral pedicle.
3. The expandable intravertebral implant system according to any of claims 1 to 2, wherein the anterior part (11) of the intravertebral implant (1) comprises a first plate and a second plate, able to form respectively a first bearing surface and a second bearing surface in a vertebral body; these two bearing surfaces being intended to move away from each other according to a predefined expansion plane.
4. The expandable intravertebral implant system according to any of claims 1 to 3, wherein the inner anterior portion (23) comprises at least one groove (231) on its inner surface.
5. The expandable intravertebral implant system according to any of claims 1 to 4, wherein a posterior portion (128) of the posterior part (12) of the intravertebral implant comprises a cylindrical recess (122) and at least a fastening means enabling to rotationally and translationally lock the relative movements between the intravertebral implant (1) and the pedicle fixation (2).
6. The expandable intravertebral implant system according to claim 5, wherein the fastening means comprises at least one through hole (124) through the posterior portion (128), and a peripheral chamber (123) at the surface of the posterior portion (128) in fluid communication with the at least one through hole (124).
7. The expandable intravertebral implant system according to claim 5, wherein the fastening means comprises at least two slots (125) extending axially along the posterior part (128), an internal thread (126) and a flared posterior end (127); able to cooperate with a tapered expansion cap (6).
8. The expandable intravertebral implant system according to any of claims 1 to 7, further comprising a posterior element (3), partially outside of the vertebra and integral with the pedicle fixation (2).
9. The expandable intravertebral implant system according to claim 8, wherein the posterior element (3) is integral with the pedicle fixation (2) by means of a threaded pin (311) screwed in a threaded bore (221) of the inner posterior portion (22).
10. The expandable intravertebral implant system according to claim 8 or 9, wherein the posterior element (3) comprises a posterior portion (32) enabling the assembly with complementary posterior fixation elements such as bars or artificial ligaments.