HK1230055A1 - Expansible intravertebral implant system with posterior pedicle fixation - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to an expandable intradiscal implant system with posterior pedicle fixation. More particularly, the present invention relates to a system comprising an expandable intradiscal implant that provides improved spinal fixation 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 caused by bone compression, for example due to 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 bony cortical shell is straightened, the balloon is then deflated and removed from the vertebra, so that bone cement can be injected into it, intended 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 platforms, 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 platforms 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 the case of more severe traumas, the use of the aforementioned methods may prove insufficient. The repair of vertebral fractures, particularly compression fractures, is then preferably carried out 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 two adjacent vertebrae to allow for spinal 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 vertebral articulatory levels caused by the fixation of posterior rods connecting the upper and lower vertebrae. Moreover, these methods do not always allow for the realignment of the compressed vertebra, but only the stabilization of three adjacent vertebrae, thereby blocking two articulatory levels. The surgical procedure associated with this method 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 pedicle level of an expandable intravertebral implant located within the vertebral body.

Thus, the invention aims to associate with an expandable intravertebral implant, positioned within a vertebral body, a pedicular fixation (for example, a sleeve or sheath), intended to be anchored in the pedicle. This pedicular fixation provides a 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 particularly 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 as well as 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 pedicle fixation position. The implant system also allows to rigidify (i.e., to block 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 bone realignment, for example by 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 expandable anterior portion within a vertebral body and a posterior portion; and a pedicle fixation having at least one 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 posterior hollow internal portion and an anterior hollow 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 relative 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 intradiscal implant comprises a first and a second platform, adapted to form respectively a first and a second supporting surface in a vertebral body; these two surfaces being able to move away from each other along a predefined expansion plane.

According to one embodiment, the front 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 blocking rotational and translational relative movements between the intervertebral implant and the pedicle fixation.

According to one embodiment, the reinforcement means includes at least one through hole, 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 hole.

According to one embodiment, the securing means comprises at least two axial slots extending 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 secured to the pedicle fixation via a threaded rod screwed into a tapped hole in 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 provided by way of example and not limitation, in reference to the accompanying drawings, wherein: 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 outline. 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 outline. 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 portion 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 portion of the implant. Figure 8A is a cross-sectional view of the implant system, after expansion of the anterior portion 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 portion 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 intravertebral 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 intravertebral 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 Shoulders, 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 intravertebral implant associated with a pedicular fixation providing 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 for 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 part 11 and a rear part 12.

According to one embodiment, the front 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 said patent application, would easily identify the necessary characteristics for implementing the present invention. In particular, the front part 11 of the intervertebral implant 1 of the present invention consists of an expandable portion enabling bone realignment and comprising: a single expansion plane determined,Intrinsic to the aforementioned anterior part 11, a first and a second opposing platforms, adapted to form 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 beneath them respectively; and means for adjusting 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 anterior part 11 also includes a central tensioning tube 13 for controlling 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 tension tube 13 is hollow and includes at least one through hole 131 allowing the injection of a filling material into the vertebra 4, such as bone cement, after expansion of the first and second plates. According to one embodiment, the central tension 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 tension tube 13 to allow fluid communication between the internal channel and the external surface.According to one embodiment, the central tension tube 13 includes a plurality of through holes 131 regularly distributed on 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 the implant expands and the two plates spread apart. 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 the vertebral body 4 to be consolidated and strengthens the stability of the implant system's fixation in the vertebral body 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 tension tube 13, initially located in the anterior part 11, can slide. By pulling the central tension tube 13, the central tension 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 tension tube 13 allows controlling the deployment of the expandable deformable anterior part 11. Once the tension 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 intradiscal 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 portion of the posterior part of the intradiscal 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 intradiscal 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 over 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 an 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 an embodiment, the cylindrical recess 122 extends through the entire posterior part of the implant 12.According to one embodiment, the posterior part of the intradiscal 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 intradiscal 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 grooves 125. According to one embodiment, the groove 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 rear 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 pocket intended to be filled with a substance (e.g., a filling material) in order to allow the pocket to expand. According to one embodiment, simply injecting a filling material through the anterior part 11 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 have 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 said 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 including 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 section 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 intradiscal 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 intradiscal 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 intradiscal implant 1 can move according to at least one degree of freedom, preferably two degrees of freedom, within the anterior internal portion 23 of the pedicle fixation 2. According to one embodiment, the posterior part 12 of the intervertebral implant 1 is sliding 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 anterior portion 23 allows the intervertebral implant 1 to expand independently of the anchoring of the pedicle fixation 2 in the vertebral pedicle. Indeed, the translational degree of 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 without constraints. Moreover, the rotational degree of freedom around the main axis of the pedicle fixation 2 prevents any constraint on the expansion direction of the intervertebral implant 1. 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 front internal portion 23 does not have threads. According to another embodiment, the front internal portion 23 and the intervertebral implant 1 are not threaded.

According to one embodiment, the front internal portion 23 further comprises at least one groove 231, as shown in Figure 8C. According to one embodiment, the front internal portion 23 comprises at least one axial groove (i.e., a groove parallel to the z-axis). According to one embodiment, the front internal portion 23 comprises at least one transverse groove (i.e., perpendicular to the z-axis). According to one embodiment, the front internal portion 23 comprises at least one inclined groove 231. According to one embodiment, the front internal portion 23 comprises 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 a person skilled in the art, for rotating the pedicle fixation 2 using an insertion instrument 5.

Rear element

As shown in Figure 4, the posterior element 3 according to the present invention includes a front portion 31 made of a rod, preferably a threaded rod 311 cooperating with the tap 221 of the pedicle fixation 2, thus enabling the posterior element 3 to be fixed to the pedicle fixation 2. The posterior element 3 also includes a posterior portion 32, outside the vertebra 4, whose geometry allows for assembly functions with complementary and known posterior fixation elements, such as rods or artificial ligaments, as known to those skilled in the art. 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 creating the initial pathway and reaming the vertebral pedicle, the implant system comprising 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 includes a working cannula 51 rigidly 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 it is designed to pass through at least the length of the posterior internal portion 22.The expansion tube 52 is secured (i.e., connected) to the posterior part 12 of the intradiscal implant 1, and in particular is secured to the central tensioning tube 13 of the intradiscal implant 1. The insertion depth of the implant system is controlled by the operator by screwing the pedicle fixation 2's thread 21 into the bone tissue, in order to optimally position the intradiscal implant 1 within the vertebral body. The axial rotational positioning of the intradiscal 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 anchored in the pedicle.

According to one embodiment, after inserting the implant system, the pedicle fixation 2 is firmly fixed in the pedicle, and the intravertebral implant 1 is partially connected to the pedicle fixation 2 via 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 aforementioned x and y axes. As a result, these blocked degrees of freedom ensure a partial connection 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 comes into contact with 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 solidly 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 portion 12 of the implant 1 to allow deployment while preventing retraction. Pulling the central pull tube 13 enables 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 part of the implant to shift forward: the anterior portion 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 portion 12 of the implant 1 allows the deployed intervertebral implant 1 to adapt its position within the vertebral body 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, in order 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 attached 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 on the extendable anterior portion 11 of the intervertebral implant 1 the orientation and depth of deployment of said extendable portion. According to one embodiment, the intradiscal implant, and in particular its posterior portion 12, can move with one, two, three, four, or five degrees of freedom, preferably two degrees of freedom, 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 in particular 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 intradiscal implant 1, rotation and translation along the z-axis between the intradiscal implant and the pedicle fixation are locked, thus making the expandable intradiscal implant 1 integral with the pedicle fixation 2.

According to one embodiment, the anterior part of the intradiscal implant 11 is stabilized in the expanded position by injecting a filling material into the vertebral body 4 through at least one through hole 131. The filling material is injected using an injector through the pedicle fixation 2, the cylindrical recess 122 of the posterior part of the implant 12, and the hollow pull 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 recess 122 and into the 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 fills at least one through hole 124, the peripheral chamber 123, and the 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 strengthens the bonding with respect to the rotational degree of freedom around the z-axis. Advantageously, the solidification of the filling material in the at least one transverse groove 231 strengthens the bonding with respect to the translational degree of freedom along the z-axis.Advantageously, the solidification of the filling material in the at least one inclined groove 231 reinforces the bonding 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 bonding 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 bonding. 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 notably 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 fixed within the pedicle fixation 2 by means of a conical expansion plug 6. The said conical plug includes 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 threaded portion 126 of the posterior portion 128. When the conical plug 6 is screwed into the threaded portion 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 deployment of the posterior portion, made possible by the slots 125. Advantageously, the radial deployment of the posterior portion 128 into the anterior internal portion 23 fixes the posterior part of the intradiscal implant 12 within the pedicle fixation 2 by means of a support.

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 the pedicle fixation 2 and the 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 capable of receiving posterior fixation elements such as rods or artificial ligament systems or any other known means for stabilizing a vertebral fracture in the field of 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 anterior internal portion 23 of 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 intradiscal implant 1, notably by pulling the central pull tube 13; positioning the anterior part 11 of the intradiscal implant, made possible by moving the posterior part 12 of the intradiscal implant 1 in translation and rotation, along the main axis of the pedicle fixation 2, within the anterior internal 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 intradiscal implant; and optionally securing the posterior part 12 within the anterior internal 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.