Spinal stabilization device

Abstract

The invention relates to a vertebral stabilization device comprising at least two screws with a first section engageable in a vertebra and a second threaded section separated by a collar, at least one first connecting rod for connecting the second sections of the screws and at least one first fixing assembly and one second fixing assembly for fixing the rod to the screws. Each fixing assembly comprises at least one clamp arranged to tighten the first rod, and a nut. The clamp comprises a first jaw and a second jaw that are identical and held together by an elastic member. According to a variant of the invention, the device may comprise a third fixing assembly with at least one clamp with a first jaw and a third jaw, having an inner surface identical to that of the first jaw and an outer surface complementary to that of a second jaw. FIGURE OF THE ABSTRACT: [Fig. 1]

Description

Title of the invention: Spinal stabilization device

[0001] BACKGROUND OF THE INVENTION

[0002] The present invention relates to the field of surgical implants and more particularly to vertebral stabilization devices implanted in a human or animal body for the treatment of spinal pathologies.

[0003] There are many spinal stabilization devices whose general principle is to connect adjacent vertebrae by rods.

[0004] In a first type of device, the rods (sometimes also called bars) are fixed on either side of the vertebrae to be connected in a plane substantially parallel to the median sagittal plane of the spine. This device makes it possible to obtain very good stabilization of the vertebrae relative to each other but significantly limits the mobility of the column, hindering or even preventing certain movements of the patient. According to this first device, the rods are directly inserted into the pedicle screw heads, which requires that the screw heads be perfectly aligned with each other, which is sometimes difficult to achieve.

[0005] In a second type of device described in document WO-A-2018 / 019792, the rods are fixed to the vertebrae in such a way that the rods cross on the median sagittal plane of the spine. This latter device makes it possible to maintain a certain mobility between the two vertebrae connected by the device while reinforcing their stability. The rods have a first end in the form of a circular ring and a second end in the form of an oblong ring. During installation, the rings are engaged respectively on threaded sections extending the pedicle screws screwed directly into the vertebrae. The vertebrae are definitively fixed by screwing a nut onto each threaded section to tighten the ring of the rod, thus fixing the position of the rod relative to the pedicle screws. This fixing principle, although simple, is quite difficult to adjust precisely.Additionally, when tightening the nuts, there may be slight movement of the rod around the fasteners altering the initial fit made by the surgeon.

[0006] It is therefore understood that vertebral stabilization devices must allow the stabilization / fixation of the vertebrae while attempting to maintain the maximum possible mobility for the patient. These devices must also allow the surgeon to adjust said devices as finely as possible. Documents FR-A-2 865 377, WO-A-98 / 55038, EP-A-1 665 994 thus present devices comprising a pedicle screw screwed into a vertebra, the head of this screw is shaped in such a way that it can accommodate a pin on which is engaged a clamp which tightens one end of the rod. The adjustment is made possible by the movement relative to the pin in relation to the screw.

[0007] The main disadvantage of these different systems is that they involve numerous parts to be assembled, which increases the cost of said devices and lengthens the duration of interventions.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular to overcome at least in part the aforementioned drawbacks by proposing a spinal stabilization device which is compact, made up of few parts and which is easy and quick to install. Summary of the invention

[0010] For this purpose, a vertebral stabilization device is provided which comprises:

[0011] - at least two screws each having a first threaded section to be engaged in a vertebra and a second threaded section separated from the first threaded section by a collar;

[0012] - at least one first connecting rod having two opposite ends for connecting the second threaded sections of the screws to each other; and

[0013] - at least a first fixing assembly and a second fixing assembly for securing the ends of the rod to the screws, each fastening assembly comprising at least one clamp, engageable on the second threaded section of one of the screws and arranged to clamp one end of the first rod, and a nut which has a lower bearing surface and which is arranged to be screwed onto the second threaded section by tightening the clamp against an upper surface of the collar of the screw.

[0014] According to the invention, said at least one clamp here comprises a first jaw and a second jaw identical to each other, held together by an elastic holding member. The first jaw comprises an inner surface facing an inner surface of the second jaw. The inner surface comprises, at a first connecting part of each jaw, a hollow and a projection of complementary shapes, the first connecting parts being engaged in each other to form a hinge.

[0015] Thus, the vertebral stabilization device according to the invention comprises only four different parts: a screw, a rod, a jaw in two copies and a nut. The surgeon will thus be able to carry out the stabilization of at least two vertebrae using at least one stabilization device according to the invention. The stabilization of the vertebrae is easily carried out by means of rods simply fixed by the clamps of each fixation assembly, said clamps being composed of two identical jaws whose first associated parts form a hinge. The stabilization of the vertebrae is carried out indifferently in a crossed manner on a median sagittal plane of the spinal column or according to a conventional assembly of the rods on a plane parallel to the midsagittal plane of the spine. The device according to the invention not only allows easier and more reliable fixation of the rods but also allows for assembly revisions in operated patients, for example with an extension of the assembly, without having to disassemble the assembly as is necessarily the case with currently available instrumentation. In addition, due to the few different parts it consists of, it is more economical to manufacture and easier and faster to assemble during the surgical procedure.

[0016] Preferably, the first part of each jaw comprises two semi-cylindrical surfaces, of the same diameter and the same length, in the extension of one another and located in the width of the jaw, the first semi-cylindrical surface forming the projection, the second semi-cylindrical surface forming the hollow. Thus, when assembling two jaws facing one another, the first projecting semi-cylindrical surface of the first jaw is housed in the second hollow semi-cylindrical surface of the second jaw while the second hollow semi-cylindrical surface of the first jaw fits the first projecting semi-cylindrical surface of the second jaw to form a hinge.

[0017] Each jaw comprises, opposite the first part, a second part for connection to the rod, which comprises a hollow receiving surface, preferably semi-cylindrical, which is arranged to receive a portion of the rod and which has a depth less than a radius of the rod.

[0018] Preferably, the hollow semi-cylindrical receiving surface of the second connecting part to the rod has an axis parallel to an articulation axis of the hinge formed by the first part of the jaw.

[0019] Each jaw further comprises, beside the first part, a third part for connection to the screw which comprises a cylindrical-truncated hole opening right through. The cylindrical-truncated hole has a larger diameter adjacent to an outer surface of the jaw, opposite the inner surface, and has a smaller diameter adjacent to the inner surface of said jaw.

[0020] Each jaw preferably has an outer surface which is convex in the shape of a spherical cap and which is complementary to that of the upper surface of the collar or the nut.

[0021] The cylindrical-truncated drilling of the jaws as well as the convex spherical cap shape of their respective external surface makes it possible to create a ball joint connection between the clamp and the second screw section on the one hand between the collar and the clamp and on the other hand between the clamp and the nut, which allows the surgeon to adjust the stabilization device extremely precisely to the patient being operated on.

[0022] When the stabilization device is used to stabilize a vertebra not to another vertebra but to at least two other vertebrae, the stabilization device vertebral according to the invention comprises at least a second connecting rod and a third fixing assembly. Said third fixing assembly comprises at least one clamp, engageable on the second threaded section of one of the screws and arranged to tighten one end of the second rod. The clamp comprises a first jaw and a third jaw. The third jaw has an inner surface identical to the inner surface of the first jaw and an outer surface of concave shape in a spherical cap complementary to a convex outer surface of a second jaw.

[0023] The device according to the invention thus makes it possible to stabilize at least two vertebrae in a plane parallel to the median sagittal plane or in a crossed manner with the same device with great precision of adjustment. The device according to the invention also makes it possible to easily resume the adjustment of said device, for example following changes in the patient's condition. In addition, the small number of parts making up the device allows for faster installation, while reducing its manufacturing cost.

[0024] Other characteristics and advantages of the invention will emerge from reading the following description of particular and non-limiting embodiments of the invention. Brief description of the drawings

[0025] Reference will be made to the accompanying drawings, among which:

[0026] [Fig.l] [Fig.l] is a slightly perspective schematic view of a spine of which two vertebrae are fitted with the device according to the invention;

[0027] [Fig.2] [Fig.2] is a slightly perspective schematic view of a clamp of a first or second fixing assembly composed of two identical jaws;

[0028] [Fig.3] [Fig.3] is a slightly perspective schematic view of a bit;

[0029] [Fig.4] [Fig.4] is an exploded schematic perspective view of two jaws identical to form a clamp of a first or second fixing assembly;

[0030] [Fig.5a] [Fig.5a] is a schematic view in longitudinal section of a screw of a fixing device during assembly, without a nut;

[0031] [Fig.5b] [Fig.5b] is a schematic view in longitudinal section of a screw of a fixing device during assembly, with nut;

[0032] [Fig.6] [Fig.6] is a schematic view in slight perspective of a spacer;

[0033] [Fig.7] [Fig.7] is a slightly perspective schematic view of a spine of which three vertebrae are fitted with the device according to the invention;

[0034] [Fig.8] [Fig.8] is a slightly perspective schematic view of a clamp of a third fixing assembly;

[0035] [Fig.9] [Fig.9] is an exploded perspective view of a screw comprising a third fixing assembly composed of two clamps, the first clamp bearing against the collar being composed of two identical jaws, the second clamp located between the first clamp and the nut is composed of a first and a third jaw;

[0036] [Fig. 10] [Fig. 10] is a schematic perspective view of a screw comprising a third fixing assembly composed of two clamps, the first clamp bearing against the collar being composed of two identical jaws, the second clamp located between the first clamp and the nut is composed of a first and a third jaw. DETAILED DESCRIPTION OF THE INVENTION

[0037] With reference to Figures 1 to 6, according to a first embodiment, the invention relates to a vertebral stabilization device, here illustrated for the stabilization of two adjacent vertebrae Va and Vb, comprising: - at least two screws 1a; 1b; each fitted with a collar 2; - at least one first connecting rod 3; - at least a first set of fixings Fa and a second set of fixing Fb for fixing the ends of the rod 3 respectively to the screws 1a and 1b. Each fixing assembly comprises at least one clamp 5a, 5b, engageable on the second threaded section 1.2 of one of the screws and arranged to tighten one end of the rod 3, and a nut 8.

[0038] According to the example of a spinal column device shown in [Fig.l], two adjacent or non-adjacent vertebrae Va, Vb are stabilized with a vertebral stabilization device according to the invention, the rods of which cross along the median sagittal plane.

[0039] Here, the device comprises two screws referenced 1a, 1a on vertebra Va, two screws 1b, 1'b on vertebra Vb. All screws 1, 1' are identical, the letters a, b only serving to distinguish the screws according to the vertebra on which they are implanted, the apostrophe making it possible to distinguish the screw implanted on the right (without apostrophe) from the screw implanted on the left (with apostrophe) of the median sagittal plane.

[0040] Each screw, here in one piece and in one piece, comprises a first threaded section 1.1, not shown in [Fig.l] and visible in figures 5a or 5b, to be engaged in the vertebra and a second threaded section 1.2 separated from the first threaded section 1.1 by a collar 2.

[0041] The vertebrae Va, Vb to be instrumented are generally previously prepared before receiving the stabilization device. Conventionally, the articular or spinous processes of the vertebrae may have been previously reduced or resected in whole or in part and the vertebrae previously drilled to receive the screws 1. The first section 1.1 is completely inserted into the bone of the vertebra up to the collar 2. The collar 2 is thus on the surface of the vertebra, resting on the bone, the second section of the screw 1.2 being projecting from the vertebra. The surgeon knows how to drill and correctly position the screws 1 according to the morphology of the patient.

[0042] A person skilled in the art will know how to shape the first section 1.1 so as to facilitate its engagement in the bone. For example, the first section may be self-tapping and have an end cut into a point shape. Alternatively, the first section may also be self-drilling.

[0043] The collar 2 which separates the first and second sections 1.1; 1.2 of the screw 1 has a convex lower surface, in the form of a spherical cap, in contact with the bone of the vertebra and a concave upper surface, in the form of a spherical cap, for bearing against the clamp. A person skilled in the art will be able to adapt the diameter, height and convexity of the collar according to the anatomy of the patient and the screwing force undergone when the collar is brought into contact with the bone.

[0044] The second section 1.2 of the screw 1 thus projects from the vertebra when the screw 1 is fixed. The thread of the second section 1.2 is made so as to receive a fixing assembly F. The second threaded section 1.2 is provided with an end portion arranged to allow a rotational connection with a screwing tool. The end portion, shown in [Fig.l] only, may thus comprise an imprint 1.3 of a shape complementary to that of the tip of a screwdriver. By way of non-limiting examples, the imprint may be hexagonal, cruciform, star-shaped or triangular. In addition, the second threaded section 1.2 may comprise a break initiation 1.4 visible in [Fig.6] to be able to separate by breakage the end portion of the second threaded section when the surgical intervention is finished.

[0045] The screw is here in one piece and in one piece between the first screw section 1.1, the collar 2 and the second screw section 1.2. It is made of biocompatible and stainless material which is sufficiently mechanically and chemically resistant for the intended application.

[0046] A person skilled in the art will be able to determine the diameter and length of the screw to be best suited to the age, morphology and bone quality of the patient. By way of illustration, the length of the screws can typically be between 30mm and 90mm.

[0047] According to the embodiment illustrated in [Fig.l], the device comprises two rods 3a, 3b. Each rod has two opposite ends for connecting the second threaded sections of two of the screws to each other. Thus, when the stabilization of the vertebrae is carried out by crossing the rods on the median sagittal plane, a first connecting rod 3a will connect the second section 1.2a of the screw 1a implanted in the vertebra Va to the right of the median sagittal plane to the second section 1'.2b of the screw 1b implanted in the vertebra Vb to the left of the median sagittal plane and a second connecting rod 3b will connect the second section 1'.2a of the screw 1a implanted in the vertebra Va to the left of the median sagittal plane to the second section 1.2b of the screw 1b implanted in the vertebra Vb to the right of the median sagittal plane.

[0048] Alternatively, when the stabilization is done parallel to the median sagittal plane, the rod 3a will connect the second threaded section 1.2a of the screw 1a to the second threaded section 1.2b of the screw 1b, the screws 1a, 1b being implanted respectively in the vertebrae Va, Vb both to the right of the median sagittal plane. The rod 3b will connect the second threaded section of screw 1'.2a of the screw 1a to the second section of screw 1'.2b of the screw 1'b, respectively implanted in the vertebrae Va, Vb to the left of the median sagittal plane.

[0049] Each rod 3a, 3b is made of a biocompatible material that is sufficiently rigid to achieve stabilization of the vertebrae between them. For example, a material with a Young's modulus of between 3.6 GPa and 60 GPa will be chosen. For example, the material may be a composite material comprising a mixture of carbon fibers and polyetheretherketone (PEEK). Each rod 3 has a constant section, here circular over its entire length.

[0050] A person skilled in the art is able to determine the diameter of the section of the rod according to the material used, the desired mechanical characteristics and the anatomy of the patient. He will also be able to determine the length of the rods to adapt it to the morphology and pathology of the patient and according to whether the rods are placed parallel to the median sagittal plane or whether they cross on it.

[0051] Preferably and according to the particular embodiment of the invention, the rods are curved, thus facilitating their placement and limiting interference with the central part of the stabilized vertebrae.

[0052] The fixing of each end of the rods 3 to one of the screws 1a, 1b is ensured by a fixing assembly F engaged on the second threaded section 1.2a; 1.2b of the screw 1a; 1b.

[0053] The fixing assembly comprises at least one clamp 5. The clamp 5 is composed of two jaws identical to each other 5c and 5d held by an elastic holding member. The letters c and d make it possible to distinguish the first jaw from the second as well as the elements relating thereto. It is recalled that the two jaws 5c and 5d are strictly identical. Each jaw 5c, 5d comprises an inner surface 5c. 1; 5d. 1 and an outer surface 5c. 2; 5d. 2 extending parallel to each other and three parts: a first part for connection to the other jaw 5c. 3, 5d. 3; a second part for connection to the rod 5c. 4, 5d. 4 opposite the first; and, between the first and the second part, a third part 5c. 5, 5d. 5 for connection to the screw 1.

[0054] More precisely and as particularly illustrated by Figures 2 to 6, the inner surface 5.1 of each jaw 5 comprises at a first connecting part 5.3 to the other jaw, a hollow 5.31 and a projection 5.32 of complementary shapes. Preferably, the hollow and the projection are of semi-cylindrical shape of identical diameter and length, and extend in the extension of one another in the width of the jaw 5. Thus, when the jaws 5c, 5d are assembled, the inner surfaces 5c.1, 5d.1 are opposite each other and the hollow 5c.31 and the projection 5c.32 of the first jaw 5c cooperate in a complementary manner respectively with the projection 5d.32 and the hollow 5d.31 of the second jaw 5d. The first connecting parts of each jaw 5c.3, 5d.3 are thus engaged in each other so as to form a hinge making it possible to articulate, along an axis of rotation corresponding to the central axis of the projections and hollows of the first parts 5.3c, 5.3d, the jaws 5c, 5d relative to each other. Here, by way of illustration, the diameter of the projection (and therefore of the hollow) is approximately 2 mm.

[0055] Opposite the first part 5.3, each jaw comprises a second connecting part 5.4 to the rod 3. This second part 5.4 comprises a hollow receiving surface 5.41, arranged to receive a portion of the rod 3, which has a depth identical to or less than half the section of the rod 3. The receiving surface 5.41 is preferably arranged so as to have an axis parallel to the articulation axis of the hinge formed by the first part 5.3. Thus, when the rod portion 3 is placed between the receiving surfaces 5c.4, 5d.4 of the two jaws 5c, 5d, said rod portion 3 is perfectly held since it is pinched (or even slightly crushed) between the two jaws 5c, 5d, thus preventing the rod portion 3 from coming out of the clamp 5 once the device according to the invention is installed on the patient's vertebrae. Here, the rod 3 having a circular section between 4 and 6 mm, the hollow receiving surface 5.41 is semi-cylindrical with a radius identical to that of rod 3. .

[0056] Each jaw further comprises, next to the first part 5.3, a third connecting part 5.5 to the screw 1. This third part 5.5 is more or less parallelepipedal and comprises a cylindrical-truncated hole 5.51 opening right through. The cylindrical-truncated hole is made in such a way that the largest diameter is adjacent to the outer surface 5.2 of the jaw 5 and that, on the other hand, the smallest diameter of the hole is adjacent to the inner surface 5.1. The inner surface 5c. 1, 5d.1 of the third connecting part is flat while the outer surface 5c.2, 5d.2 is shaped as a convex spherical cap 5.52 complementary to the upper surface of the collar 2 or the nut 8.

[0057] The clamp is formed by assembling the two jaws 5c, 5d, their respective inner surface 5c. 1, 5d.1 being placed opposite each other. The two jaws thus assembled, the three parts 5c.3, 5c.5, 5c.4 of the first jaw 5c are opposite the three parts 5d.3, 5d.5 and 5d.4 of the second jaw 5d. the first part 5c.3 of the first jaw 5c complements the first part 5d.3 of the second jaw 5d to form the hinge of the clamp, the truncated conical drilling 5c.51, 5d.51 of each jaw of the third part 5c, 5d makes it possible to obtain a drilling right through the clamp 5 to be engaged on the second screw section 1.2. Figuratively, the drilling of the clamp has a diabolo shape. The common center of rotation of the clamp in contact with the nut and the collar is arranged in the center of the clamp. Finally, the second parts 5c.4 and 5d.4 of the jaws 5c, 5d form a housing for a rod end 3 in which the rod end is fixed.

[0058] The two assembled jaws are secured by the elastic holding member, here a clip 6, made of spring metal, fixed in such a way that the jaws are movable relative to each other between an open position and a closed position, positions permitted by the hinge formed by the complementarity of the first parts 5.3 of each jaw. The clip 6 is in the form of a plate having two opposite edges each provided with a pair of tabs 6.1 which will respectively enclose, for the first pair of tabs, a portion of the outer surface 5c.2 of the first part 5c.3 of the first jaw 5c and, on the other hand, for the second pair of tabs 6.2 a portion of the outer surface 5d.2 of the first part 5d.3 of the second jaw 5d. The clip 6 aligns and puts pressure on the assembly of the jaws 5c, 5d, thus constituting the clamp 5. The opening of the clamp facilitates the insertion of the rod 3 into the housing formed by the second parts 5c, 4c, 5d.4 of the jaws 5c, 5d of the clamp 5 thus assembled. The person skilled in the art can use any type of clip to secure the first parts of each of the jaws.

[0059] The nut 8 is arranged to be engaged on the second screw section 1.2 and to tighten the clamp 5 against the collar 2 once said clamp 5 is engaged on the second screw section 1.2 and the rod 3 positioned by the surgeon. The nut 8 comprises an inner surface 8.1 facing the outer surface 5d.2 shaped as a concave spherical cap of the clamp 5.

[0060] Thanks to the ball joint connection obtained by the diabolo shape of the drilling of the two jaws 5.c, 5d,, the concave shapes of the surfaces of the collar 2 and the nut 8.1 facing the outer surfaces of the two jaws respectively, and of the outer surface 5c.2 in contact with the collar 2 and the outer surface 5d.2 facing the inner surface 8.1 of the nut, the surgeon can very finely adjust the angular positioning of the clamp relative to the screw to obtain a positioning of the rod perfectly adapted to the patient. Indeed, the clamp 5 forms a partial sphere with the outer surfaces 5c.2, 5d.2 of the jaws 5c, 5d whose center is located equidistant from the jaws 5c, 5d.

[0061] The fixing assembly F may, if the person skilled in the art deems it necessary and depending on the morphology of the patient, comprise a spacer 11 which may be placed either between the collar 2 and the clamp 5, or between the clamp 5 and the nut 8. The spacer 11 has its ends shaped in such a way as to maintain the ball joint connection between the clamp and the screw. For example, a first end of the spacer 11 may be shaped as a concave spherical cap 11.1 to be in contact with the clamp and the second The end of this same spacer can be shaped into a convex spherical cap 11.2 to be in contact with the collar or the nut. The person skilled in the art will be able to determine the height of the spacer and its position (between the collar 2 and the clamp 5 or between the clamp 5 and the nut 8). The presence of a spacer thus makes it possible to adjust the height of the fixing assembly on the second threaded section of the screw, thus allowing positioning of the rods adapted to the morphology of the patient and the pathology to be treated. In particular, when vertebral stabilization is done by crossing the rods in the median sagittal plane, the spacers make it possible to adjust the height of the rods relative to each other without friction, or with controlled contact.

[0062] According to a second embodiment of the invention, the surgeon may be required to stabilize more than two vertebrae, here three vertebrae Va, Vx, Vb as illustrated by figures 7 to 10. In this situation, some of the stabilized vertebrae will be stabilized simultaneously by two rods 3ax, 3'xb, 3'ax, 3xb as illustrated by [Fig.8]. It is therefore necessary to have a third fixation assembly comprising at least two clamps 10 engageable on the second threaded section lx.2, l'x.2 of one of the screws and arranged to tighten one end of the second rod 3xb, 3'xb. Like the clamp 5, the clamp 10 comprises two jaws, a first jaw 5e strictly identical to the jaws 5c, 5d of the clamp 5, and a jaw 9 having an inner surface 9.1 identical to the inner surface 5e. 1 of the first jaw and an outer surface 9.2 different from the outer surface 5 e.2 of the first jaw. Thus, as for the clamp 5, the first parts 5e.3 and 9.3 of each jaw 5e and 9 comprise a hollow 5.31, 9.31 and a projection 5.32, 9.32 of complementary shapes. Preferably, the hollow and the projection are of semi-cylindrical shape of identical diameter and length and extend in the extension of one another in the width of the jaw 5, 9. The first parts complement one another, the hollow 5.31 in complement of the projection 9.32 and the projection 5.32 in complement of the hollow 9.31 to form the hinge, the third parts 5e.5 and 9.5 are pierced in a cylindro-truncated manner to obtain a drilling of the clamp 10 from one side to the other in the shape of a diabolo. As for the clamp 5, the second parts 5e.4 and 9.4 form a housing for one end of the rod 3xb, 3'xb. The outer surface 9.2 of the jaw 9 is shaped as a concave spherical cap, complementary to the outer surface 5d.2 of the second jaw 5d of the first clamp 5.According to this arrangement, the screw Ix comprises, bearing against the collar 2x, a first clamp 5 comprising two jaws 5c, 5d. The outer surface 5c.2 of the first jaw 5c bears against the collar 2x, the outer surface 5d.2 of the second jaw 5d is in contact with the outer surface 9.2 of the first jaw 9 of the second clamp 10. The outer surface 5e.2 of the second jaw 5e of the second clamp 10 then bears with the inner surface 8x.l of the nut 8x. .

[0063] When the surgeon has to fit three vertebrae, he will thus be able to implant the device according to the invention comprising the fixation assembly F with a single clamp 5 in the vertebrae which only accommodate one rod 3, here the vertebrae Va, Vb and the device according to the invention comprising the fixation assembly F' with two clamps 5, 10 in the vertebrae or vertebrae which accommodate two rods, here Vx.

[0064] The device according to the invention thus allows the surgeon to stabilize as many vertebrae as the patient's condition requires, to finely adjust the orientation and position of the rods thanks to the ball joint connection between the clamp and the screw, all with ease and speed of installation linked to the small number of different elements: a screw, two different jaws, one with an outer surface shaped as a convex spherical cap, and the other with an outer surface shaped as a convex spherical cap capable of being combined to form a clamp with two convex outer surfaces or with one convex outer surface and the other concave outer surface, a nut, and optionally a spacer.

[0065] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0066] In particular, the person skilled in the art is able to adapt the device according to the invention according to the number of vertebrae to be fitted and the number of rods necessary for the stabilization of each vertebra, whether the stabilization is crossed or parallel to the median sagittal plane, or whether it comprises both types of stabilization (crossed and parallel). The person skilled in the art can thus use a clamp 5 and two clamps 10 engaged one after the other on the second screw section if the vertebra requires stabilization with three rods, each additional rod being held by an additional clamp 10.

[0067] Here, the rod 3 is of circular section but it could be of a different section, for example prismatic or ovoid. The person skilled in the art will then know how to adapt the hollow receiving surface of the second connecting part of the clamp to the section of the rod so that the latter is perfectly held by the clamp.

[0068] The jaws are configured so as to be associated. It is thus possible to produce a clamp with two jaws 9, the two outer surfaces of which are concave.

[0069] The clip 6 can be removed once the nut 8 is tightened, the clip only serving to hold the jaws temporarily for assembly.

Claims

Claims

1. Vertebral stabilization device, comprising: - at least two screws (1a, 1b) each having a first threaded section (1.1a, 1.1b) for being engaged in a vertebra (Va, Vb) and a second threaded section (1.2a, 1.2b) separated from the first threaded section by a collar (2); - at least one first connecting rod (3) having two opposite ends for connecting the second threaded sections of the screws to each other; and - at least a first fixing assembly (F) and a second fixing assembly (F') for fixing the ends of the rod (3) to the screws (1a, 1b), each fixing assembly comprising at least one clamp (5), engageable on the second threaded section (1.2a, 1.2b) of one of the screws (1, 2) and arranged to tighten one end of the first rod (3), and a nut (8) which has a lower bearing surface and which is arranged to be screwed onto the second threaded section (1.2a, 1.2b) by clamping the clamp (5) against an upper surface of the collar (2a, 2b) of the screw (la, 1b), said at least one clamp (5) comprising a first jaw (5c) and a second jaw (5d) identical to each other and held together by an elastic holding member (6), the first jaw comprising an inner surface (5c. 1) facing an inner surface (5d. 1) of the second jaw (5d), the inner surface comprising, at a first connecting part (5.3) of each jaw, a hollow (5.31) and a projection (5.32) of complementary shapes, the first connecting parts (5c. 3, 5d. 3) being engaged one in the other to form a hinge.

2. A spinal stabilization device according to claim 1, wherein the first part of each jaw comprises two semi-cylindrical surfaces of the same diameter and length extending in line with each other across the width of the jaw, the first cylindrical surface forming the projection (5.32), the second cylindrical surface forming the hollow (5.31).

3. A vertebral stabilization device according to claim 1 or 2, wherein each jaw comprises, opposite the first part (5.3), a second connecting part (5.4) to the rod (3), which comprises a hollow receiving surface (5.41) which is arranged to receive a portion of the rod (3) and which has a depth less than a radius of the stem.

4. A spinal stabilization device according to claim 3, wherein the recessed receiving surface (5.41) of the second part (5.4) has an axis parallel to an articulation axis of the hinge formed by the first part (5.3).

5. Vertebral stabilization device according to claims 1 to 4, in which each jaw (5c, 5d) comprises, next to the first part (5.3), a third part (5.5) for connection to the screw (1), comprises a cylindro-truncated conical bore (5.51) opening right through, the cylindro-truncated conical bore having a larger diameter adjacent to an outer surface (5c.2, 5d.2) of the jaw (5c; 5d) opposite the inner surface (5c.1, 5d.l), and a smaller diameter adjacent to the inner surface (5c.1, 5d.l).

6. A vertebral stabilization device according to any one of claims 1 to 5, wherein the third part (5c.5, 5d.5) of each jaw (5c, 5d) comprises a convex outer surface (5c.2, 5d.2) shaped as a spherical cap complementary to that of the upper surface of the collar (2) or the nut (8).

7. A vertebral stabilization device according to any one of claims 1 to 6, comprising at least one second connecting rod (3') and a third fixing assembly comprising at least one clamp (10), engageable on the second threaded section (la”.2, 1 ”b.2) of one of the screws (la”, 1b”) and arranged to tighten one end of the second rod (3'), the clamp comprising a first jaw (5e) and a third jaw (9) having an internal surface (9.1) identical to the internal surface (5e.1) of the first jaw 5e and an external surface (9.2) of concave spherical cap shape complementary to an external surface (5c.2, 5d.2) of a second jaw (5c, 5d).

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