Spinal stabilization device

Abstract

The invention relates to a vertebral stabilization device comprising at least two screws, each with a first portion inserted into a vertebra and a second portion separated from the first by a flange. The device further comprises at least a first connecting rod for joining the screws, and at least a first and a second fixing assembly for securing the rod to the screws. Each fixing assembly comprises at least one clip, which can be attached to the second portion of one of the screws. This clip is arranged to grip one end of the rod and includes a nut designed to thread onto the second portion and secure the clip directly or indirectly against the screw flange. Each fixing assembly is designed to create at least one ball-and-socket connection between the clip and the second portion of the screw.

Description

[0001] The present invention relates to the field of surgical implants and more particularly to spinal stabilization devices implanted in a human or animal body for the treatment of spinal pathologies.

[0002] There are many spinal stabilization devices whose general principle is to connect adjacent vertebrae with rods.

[0003] In one method, rods (sometimes called bars) are fixed on either side of the vertebrae to be connected, along a plane roughly parallel to the median sagittal plane of the spine. This method provides excellent stabilization of the vertebrae relative to one another, but its main drawback is that it significantly limits spinal mobility, hindering or even preventing certain patient movements. The rods are inserted directly into the heads of pedicle screws, which requires that the screw heads be perfectly aligned with each other, something that can sometimes be difficult to achieve.

[0004] In a second device, the subject of patent application WO 2018 / 019792, the rods are fixed in such a way that they cross on the median sagittal plane of the vertebral column. This device allows for some mobility between the two vertebrae connected by the device while reinforcing their stability. The rods have a circular ring at one end and an oblong ring at the other. During placement, the rings are engaged onto threaded sections extending from the pedicle screws, which are screwed directly into the vertebrae. The vertebrae are permanently fixed by screwing a nut onto each threaded section to tighten the rod's ring, thus fixing the rod's position relative to the pedicle screws. This fixation principle, although simple, is rather difficult to adjust precisely.Furthermore, during the tightening of the nuts, there may be a slight movement of the rod around the fixing elements, altering the initial adjustment made by the surgeon. Therefore, the placement of this device requires considerable skill and meticulousness on the part of the surgeon, which generally results in longer operating times.

[0005] Application FR 2 865 377 A1 discloses a spinal stabilization device comprising a screw in two distinct parts: a threaded proximal pin and a threaded distal screw body, the head of the pin being engaged in a proximal cavity of the body, allowing multidirectional movement between the pin and the screw body. SUBJECT OF THE INVENTION

[0006] The invention aims in particular to overcome at least in part the aforementioned disadvantages by proposing a spinal stabilization device that is compact and whose implantation is easy and quick. SUMMARY OF THE INVENTION

[0007] The present invention is defined in claim 1, while preferred embodiments are described in dependent claims.

[0008] For this purpose, a spinal stabilization device is provided, comprising at least two screws, each having a first threaded section for engagement in a vertebra and a second threaded section separated from the first by a collar. The device of the invention further comprises at least one first connecting rod having two opposite ends for connecting the second threaded sections of the screws, and at least one first fastening assembly and a second fastening assembly for attaching the ends of the rod to the screws.Each fastening assembly of the device of the invention comprises at least one clamp, which engages on the second threaded section of one of the screws, said clamp being arranged to clamp one end of the rod, and includes a nut having a lower bearing surface, said nut being arranged to be screwed onto the second threaded section by clamping the clamp directly or indirectly against an upper surface of the screw flange. Each fastening assembly is arranged to create at least one ball joint between the clamp and the second threaded section.

[0009] Thus, according to the invention, the surgeon can stabilize at least two vertebrae using at least one stabilization device according to the invention. Vertebral stabilization is easily achieved by means of rods simply fixed by the clamps of the fixation assemblies, either in a crossed configuration on the median sagittal plane of the spine or according to a conventional parallel mounting in a plane parallel to the median sagittal plane of the spine. The device according to the invention allows not only easier and more reliable fixation of the rods but also for adjustments to the setups in surgical patients, for example, by extending the setup, without having to dismantle the entire assembly as is necessarily the case with currently available instrumentation.

[0010] Preferably, the lower bearing surface of the nut and the upper bearing surface of the collar are identical spherically capped concave surfaces.

[0011] According to a first particular arrangement of the invention, the clamp of the first fastening assembly comprises a first jaw having a convex outer surface in the form of a spherical cap for bearing, here directly, on the upper surface of the collar, and a second jaw having a convex outer surface in the form of a spherical cap. The first fastening assembly comprises a first nut support sleeve, said first sleeve having a complementary concave lower frontal surface for bearing against the convex outer surface in the form of a spherical cap of the second jaw. The first support sleeve may be separate from the nut. Preferably, the first support sleeve comprises a convex upper frontal surface in the form of a spherical cap that complements the lower surface of the nut for bearing against it.

[0012] According to a second particular arrangement of the invention, the clamp of the second fastening assembly comprises a first jaw having a complementary convex spherical cap outer surface for bearing against the lower surface of the nut and a third jaw having a concave spherical cap outer surface. The second fastening assembly further comprises a second sleeve having a complementary upper frontal surface for bearing against the concave spherical cap outer surface of the third jaw. Preferably, the second sleeve has a concave lower frontal surface in the form of a spherical cap for bearing against the upper surface of the flange. Here, the nut allows the clamp to be tightened indirectly against the upper surface of the screw flange, since, according to this second arrangement, the second sleeve is positioned between the flange and the clamp.

[0013] The presence of a bushing in the first or second arrangement allows for adjusting the height of the entire fixing assembly on the second threaded section of the screw, thus enabling the rods to be positioned according to the patient's morphology and the pathology being treated. In particular, when spinal stabilization is achieved by crossing the rods along the median sagittal axis, the bushings allow for adjusting the height of the rods relative to each other without friction, or with controlled contact.

[0014] According to a third arrangement of the invention, the second fastening assembly comprises two clamps, namely a lower clamp and an upper clamp. The lower clamp comprises a first jaw having a convex outer surface in the form of a complementary spherical cap for bearing directly against the upper surface of the flange, and a second jaw having a convex outer surface in the form of a spherical cap. The upper clamp comprises a first jaw having a convex outer surface in the form of a complementary spherical cap for bearing against the lower surface of the nut, and a third jaw having a concave outer surface in the form of a complementary spherical cap to the convex outer surface of the second jaw of the first clamp, the concave outer surface of the third jaw of the second clamp bearing against the convex outer surface of the second jaw of the first clamp.

[0015] According to the invention, each clamp includes an elastically deformable portion connecting the jaws together in such a way that they are mobile relative to each other between an open position and a closed position.

[0016] According to a preferred embodiment of the invention, the first jaw is provided with a bore for engaging in the second threaded section of the screw. The bore comprises a first truncated cone section and a second cylindrical section. The first section has a large cross-section opening onto the outer surface of the first jaw and a small cross-section coinciding with a cylindrical cross-section of the second section, the second section opening onto the inner surface of the first jaw.

[0017] The second jaw also has a hole for engaging with the second threaded section of the screw. This hole comprises a first frustoconical section and a second frustoconical section. The first section has a larger cross-section opening onto the outer surface of the second jaw and a smaller cross-section coinciding with a smaller cross-section of the second section. The second section has a larger cross-section opening onto the inner surface of the second jaw. The common center of rotation of the surfaces in contact with the nut and the flange is located at the center of the smaller cross-sections of the first and second sections. Visually, the hole has a shape similar to that of a diabolo.

[0018] Optionally, the screw collar can be removable.

[0019] The unique drilling pattern of the clamps, the shape of their outer surfaces, as well as the outer surface of the collar and the lower surface of the nut, and the upper and lower front surfaces of the sockets, allow for ball-and-socket joints between the various components of the device (collar, clamp(s), socket(s), nut). This enables the surgeon to adjust the positioning of the rods with extreme precision and ease, according to the patient's anatomy and the pathology being treated. Once the optimal positioning is achieved, it is locked in place by simply tightening the nut on each screw.

[0020] According to a particular embodiment of the invention, the rod has a constant cross-section along its entire length. Preferably, the rod may be curved. The word "rod" here refers to any elongated and relatively narrow piece compared to its length, regardless of its cross-section, including rods in the common sense of the word and bars.

[0021] Preferably, the second threaded section of each screw is provided with an end portion designed to allow rotational contact with a screw-driving tool in the vertebra. It also features a breakaway point to allow the end portion of the second threaded section to be separated by breakage.

[0022] Thus, at the end of the procedure, after the screws have been screwed into the vertebrae and the device according to the invention has been put in place, the surgeon can shorten each of the screws at the point of breakage to make the device more compact and more comfortable for the patient.

[0023] Other features and advantages of the invention will become apparent from the following description of a particular and non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Reference will be made to the attached drawings, including: [ Fig. 1 ] : schematic view of three vertebrae in top view and in slight perspective, equipped with a device according to a particular embodiment of the invention; ] Fig. 2 ] : schematic longitudinal cross-sectional view of one of the screws of this device, equipped with a fastening assembly in a first configuration comprising a clamp, a socket and a nut; Fig. 3 ] : schematic longitudinal cross-sectional view of one of the screws of this device, fitted with a fastening assembly in a second configuration comprising a socket, a clamp, and a nut; Fig. 4 ] : schematic perspective view of a screw of this device, equipped with a fastening assembly in a third configuration comprising a first clamp, a second clamp and a nut; Fig. 5 ] : schematic view of this screw in longitudinal section along plane V of the figure 4 ; Fig. 6 ] : schematic view of this screw in longitudinal section along plane VI of the figure 4 of a fixing assembly inclined by ball joint connection relative to the screw; [ Fig. 7 ] : schematic exploded view of this screw and the fixing assembly; Fig. 8 ] : schematic exploded view, in longitudinal section along plane V of the figure 4 , of this screw and the fixing assembly; [ Fig. 9 ] : schematic perspective view of a pin of a clamp. DETAILED DESCRIPTION OF THE INVENTION

[0025] With reference to figures 1 à 9 The present invention relates to a spinal stabilization device comprising: at least two screws 1a; 1b; each fitted with a collar 2; at least one first connecting rod 3; at least one first fixing assembly and a second fixing assembly for fixing the ends of the rod 3 respectively to the screws 1a and 1b. Each fixing assembly comprises at least one clamp 50.1, 50.2, which engages on the second threaded section 1.2 of one of the screws and is arranged to clamp one end of the rod 3, and a nut 80.

[0026] According to an example of spinal prosthesis depicted in the figure 1 , three adjacent vertebrae Va, Vb, Vc are stabilized with a vertebral stabilization device according to the invention.

[0027] Here, the device comprises two screws, labeled 1a and 1'a, on vertebra Va; two screws, 1b and 1'b, on vertebra Vb; and two screws, 1c and 1'c, on vertebra Vc. All screws 1 and 1' are identical; the letters a, b, and c serve only to distinguish the screws according to the vertebra on which they are implanted. Each screw thus has a first threaded section, 1.1, not shown in the diagram. figure 1 but visible on the figures 2 à 7 , 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.

[0028] The vertebrae Va, Vb, and Vc to be instrumented are generally prepared beforehand before receiving the stabilization device. Typically, the articular or spinous processes of the vertebrae may have been previously reduced and the vertebrae pre-drilled to receive the screws.

[0029] As previously stated, the first threaded sections 1a.1, 1b.1, 1c.1 of screws 1a, 1b, 1c are inserted in a staggered fashion into vertebrae Va, Vb, and Vc on either side of the median sagittal plane and alternately. Thus, the first section 1a.1 of screw 1a is inserted into vertebra Va to the left of the median sagittal plane, the first section 1b.1 of screw 1b is inserted into vertebra Vb to the right of the median sagittal plane, and the first section 1c.1 of screw 1c is inserted into vertebra Vc to the left of the median sagittal plane. Symmetrically, the first section 1'a.1 of screw 1'a is inserted into vertebra Va to the right of the median sagittal plane more or less opposite screw 1a. Similarly, the first section 1'b.1 of screw 1'b is inserted into vertebra Vb to the left of the median sagittal plane more or less opposite screw 1b and the first section 1'c.1 of screw 1'c is inserted into vertebra Vc to the right of the median sagittal plane more or less opposite screw 1c.Thus, each vertebra Va, Vb, Vc is equipped with two screws respectively 1a and 1'a; 1b and 1'b; 1c and 1'c.

[0030] Since all screws are identical, the following description of a screw applies to all of them. As previously stated, each screw 1 comprises a first section 1.1 and a second section 1.2, separated by a flange 2. The first section 1.1 is fully inserted into the vertebral bone up to the flange 2. The flange 2 is thus on the surface of the vertebra, bearing against the bone, while the second section of the screw 1.2 protrudes from the vertebra.

[0031] The surgeon knows how to drill and position the screws correctly according to the patient's morphology.

[0032] A person skilled in the art will know how to shape the first section 1.1 to facilitate its insertion into the bone. For example, the first section may be self-tapping and have a pointed end. Alternatively, the first section may also be self-drilling.

[0033] The flange 2, which separates the first and second sections 1.1; 1.2 of screw 1, has a convex lower surface in the form of a spherical cap in contact with the vertebral bone and a concave upper bearing surface in the form of a spherical cap. A person skilled in the art will be able to adapt the diameter and convexity of the flange according to the patient's anatomy and the mechanical stresses involved.

[0034] The second section 1.2 of screw 1 thus protrudes from the vertebra when screw 1 is fixed. The thread of the second section 1.2 is designed to receive a fastening assembly F. Preferably, the second threaded section 1.2 is provided with an end portion arranged to allow rotational contact with a screwing tool. The end portion, shown in the figure 2 This may include a recess 1.3 with a shape complementary to that of a screwdriver tip. By way of non-limiting example, the recess may be hexagonal, cruciform, star-shaped, or triangular. Furthermore, the second threaded section 1.2 may have a breakaway feature 1.4 to allow the terminal portion of the second threaded section to be separated by breakage once the surgical procedure is complete.

[0035] The skilled craftsman will know how to manufacture the screw, here monobloc and in one piece between the first screw section, the second screw section and the collar, in biocompatible and stainless material sufficiently resistant mechanically and chemically for the intended application.

[0036] A professional will be able to determine the diameter and length of the screw best suited to the patient's age, body type, and bone quality. For example, screw lengths typically range from 65mm to 90mm.

[0037] According to this particular embodiment of the invention, the device comprises each of two pairs of connecting rods, respectively referenced 3a, 3b and 3'a, 3'b. Each rod has two opposite ends to connect to each other and in pairs the second threaded sections of two of the screws.

[0038] Thus, as illustrated in the figure 1 A first connecting rod 3a will connect the second section 1a.2 of screw 1a to the second section 1b.2 of screw 1b, and a second connecting rod 3b will connect the second section 1b.2 of screw 1b to the second section 1c.2 of screw 1c, so that screws 1a, 1b, and 1c are connected in pairs. Similarly, a third rod 3'a will connect the second section 1'a.2 of screw 1'a to the second section 1'b.2 of screw 1'b, and a fourth rod 3'b will connect the second section 1'b.2 of screw 1'b to the second section 1'c.2 of screw 1'c, so that screws 1'a, 1'b, and 1'c are connected in pairs. Rods 3a and 3'b are parallel to each other, as are rods 3'a and 3b. Rods 3a and 3'a stabilize vertebrae Va and Vb relative to each other, while rods 3b and 3'b stabilize vertebrae Vb and Vc by crossing on the median sagittal plane of the spine, respectively between vertebrae Va and Vb and between vertebrae Vb and Vc.

[0039] Each rod 3 is made of biocompatible material and has a constant cross-section along its entire length. The cross-section is circular.

[0040] The rods 3 can be made of any biocompatible material sufficiently rigid to stabilize the vertebrae relative to each other. For example, a material with a Young's modulus between 3.6 GPa and 60 GPa could be chosen. As an example, the material could be a composite material comprising a mixture of carbon fibers and polyetheretherketone (PEEK).

[0041] A skilled professional can determine the diameter of the rod cross-section based on the material used, the desired mechanical properties, and the patient's anatomy. They will also be able to determine the rod length to suit the patient's morphology and pathology, depending on whether the rods are positioned parallel to the median sagittal plane or intersect it.

[0042] 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 coupled vertebrae.

[0043] The fixing of each end of the rods 3 to one of the screws 1 is ensured by a fixing assembly F engaged on the second threaded section of the screw.

[0044] Each fastening assembly F according to the invention comprises at least one clamp 50.1, 50.2 that engages on the second threaded section 1.2 of one of the screws 1 and is arranged to clamp one end of the rod 3, and a nut 80 that has a lower bearing surface and is arranged to be screwed onto the second threaded section 1.2 by clamping the clamp 50.1, 50.2 against the upper surface of the flange 2 of the screw 1. Each fastening assembly F is arranged to create a ball joint between the clamp 50.1, 50.2 and the second threaded section 1.2. Preferably, the lower bearing surface of the nut 80 and the upper bearing surface of the flange 2, as previously described, are identical concave spherical cap surfaces.

[0045] The F fixation assembly can have several configurations depending on whether it is located on a screw implanted in one of the end vertebrae of the prosthetic segment of the spine (vertebrae Va, Vc) or on a screw implanted in an intermediate vertebra (vertebra Vb). The F fixation assembly will therefore include a socket in both configurations adapted to the end vertebrae, or a second clamp in the configuration adapted to the intermediate vertebrae.

[0046] With reference to the figure 2 The F1 fastening assembly, according to the first configuration, comprises a clamp 50.1, a socket 60, and a nut 80. The clamp 50.1 is here more or less rectangular in shape and comprises two jaws 51, 52 connected by an elastically deformable portion, here a spring-loaded metal pin 55, such that the jaws are movable relative to each other between an open and a closed position. The pin 55 is illustrated in the figure 9 It comprises a first hook-shaped leg 55.1 that elastically grips a portion of the first part 51.1 opposite the second part 51.2, and two hook-shaped legs 55.2 that elastically grip a portion of the first part 52.1 opposite the second part 52.2. Those skilled in the art will know how to make the elastically deformable portion in a different way. For example, they may make the gripper in one piece, with the two jaws connected to each other by an elastically deformable portion made of a material. The two jaws may be connected to each other by a joint, possibly with an associated spiral spring.

[0047] Each jaw 51 comprises a first part 51.1, or part connecting to the screw 1, intended to be engaged on the second section 1.2 of the screw 1, and a second part 51.2, or part connecting to the rod 3, which extends laterally relative to the first part 51.1 and which is arranged to receive one of the ends of one of the rods 3.

[0048] The first part 51.1 is roughly parallelepiped in shape with a square cross-section whose side length is approximately equal to or slightly greater than the diameter of the collar 2. The first part 51.1 comprises an inner surface 51.3 facing the jaw 52 (and thus turned inwards towards the collet 50.1) and, opposite it, an outer surface 51.4 turned outwards towards the collet 50.1. The inner surface 51.3 is a flat surface. The outer surface 51.4 is convex, forming a spherical cap complementary to that of the upper surface of the collar 2, so as to provide surface support on it.

[0049] The first part 51.1 of the first jaw 51 is provided with a bore 51.5 for engaging with the second threaded section 1.2 of the screw 1. The bore 51.5 opens on one side into the inner surface 51.3 of the first part 51.1 of the jaw perpendicular to it and on the other side into the outer surface 51.4. The bore 51.5 comprises here, along a central axis, a first frustoconical section and a second cylindrical section, the first section having a large cross-section opening onto the outer surface 51.4 and a small cross-section coinciding with a cylindrical cross-section of the second section, the second section opening onto the inner surface 51.3.

[0050] The second part 51.2 includes a semicylindrical groove 51.6 with a central axis perpendicular to the central axis of the bore 51.5 and with a radius substantially equal to or slightly less than the radius of the rod 3.

[0051] The second jaw 52 also includes a first part 52.1, or part connecting to the screw 1, intended to be engaged on the second section 1.2 of the screw 1 and a second part 52.2, or part connecting to the rod 3, which extends laterally relative to the first part and which is arranged to receive one of the ends of one of the rods.

[0052] The first part 52.1 is roughly parallelepiped in shape with a square cross-section identical to that of the first part 51.1 and comprises an inner surface 52.3 facing the jaw 51 (and therefore turned inwards towards the gripper 50.1) and, opposite it, an outer surface 52.4 turned outwards towards the gripper 50.1. The inner surface 52.3 is a flat surface. The outer surface 52.4 is convex in shape, like a spherical cap.

[0053] The first part 52.1 of the second jaw 52 is also provided with a bore 52.5 to be engaged on the second threaded section 1.2 of the screw 1. The bore 52.5 here comprises a first frustoconical section and a second frustoconical section, the first section having a large section opening onto the outer surface 52.4 and a small section coinciding with a small section of the second section, the second section having a large section opening onto the inner surface 52.3.

[0054] The second part 52.2 is identical to the second part 51.2 and faces it in such a way that the grooves 51.6 and 52.6 define a cylindrical housing to receive the end of the rod 3.

[0055] The clamp 50.1 is formed by assembling the first jaw 51 with the second jaw 52 by the pin 55. In the closed position, the grooves 51.6, 52.6 of the second parts 51.2, 52.2 of the jaws 51 and 52 form a housing with a circular cross-section smaller than that of the ends of the rod 3 allowing one end of the rod 3 to be gripped.

[0056] The F1 fastening assembly further includes a first support sleeve 60 for the nut 80. The sleeve is preferably separate from the nut 80 as shown in the figure 2 The first support sleeve 60 defines a through channel so that it can be engaged on the second section 1.2 of the screw 1. The channel is cylindrical here. The sleeve 60 comprises a convex upper front surface 60.2 in the form of a spherical cap complementary to the lower surface of the nut 80 to bear against it and a concave lower front surface 60.1 in the form of a spherical cap complementary to the outer surface 52.4 of the first part 52.1 of the second jaw 52.

[0057] Thus, a screw 1 equipped with the fastening assembly F1 according to the first configuration comprises successively engaged along the second screw section 1.2: a clamp 50.1 whose first jaw 51 is in contact with the flange 2, and whose second jaw 52 bears against the lower front surface 60.1 of the first sleeve 60, the upper front surface 60.2 of said first sleeve 60 bearing against the lower surface of the nut 80. The drilling of the first and second jaws 51, 52 and the external surfaces 51.4, 52.4 cooperating with the upper surface of the flange 2 and the lower surface of the sleeve 60 make it possible to create a ball joint around the screw.

[0058] It should be noted that the center of the spherical cap of the outer surface 51.4 and the center of the spherical cap of the outer surface 52.4 coincide and are located at the center of the small sections of the first and second segments of the bore 52.5.

[0059] On the figure 3 A second configuration of the F2 fastener assembly is shown. The F2 fastener assembly includes a second 70 socket, a 50.2 clamp, and an 80 nut.

[0060] The clamp 50.2 consists of two jaws 51, 53 connected by an elastically deformable pin 55: a first jaw 51 and a third jaw 53.

[0061] The first jaw 51 is identical to that previously described but is positioned to bear against the lower surface of the nut 80. It is recalled that the lower bearing surface of the nut 80 and the upper bearing surface of the collar 2 being of identical shapes, the outer surface 51.4 can bear indifferently against either one by forming a ball joint.

[0062] The third jaw 53 also includes a first part 53.1, or part connecting to the screw 1, intended to be engaged on the second section 1.2 of the screw 1 and a second part 53.2, or part connecting to the rod 3, which extends laterally relative to the first part 53.1 and which is arranged to receive one of the ends of one of the rods.

[0063] The first part 53.1 is roughly parallelepiped in shape with a square cross-section identical to that of the first part 51.1 and comprises an inner surface 53.3 facing the jaw 51 (and therefore turned inwards towards the gripper 50.2) and, opposite it, an outer surface 53.4 turned outwards towards the gripper 50.1. The inner surface 53.3 is a flat surface. The outer surface 53.4 is concave in shape, like a spherical cap.

[0064] The first part 53.1 of the third jaw 53 is also provided with a bore 53.5 to be engaged on the second threaded section 1.2 of the screw 1. The bore 53.5 opens at the bottom on the outer surface 53.4 and at the top on the inner surface 53.3. Taking into account the concavity of the outer surface 53.4 which fits into the first part 53.1, the bore 53.5 has a minimal length.

[0065] The second part 53.2 is identical to the second part 51.2 and faces it in such a way that the grooves 51.6 and 53.6 define a cylindrical housing to receive the end of the rod 3.

[0066] The second sleeve 70 defines a through channel so that it can be engaged on the second section 1.2 of the screw 1. The channel is cylindrical here. It may or may not be threaded. The second sleeve 70 comprises a lower front surface 70.1 in the form of a convex spherical cap complementary to the upper face of the collar 2 and an upper front surface 70.2 in the form of a concave spherical cap complementary to the concave outer surface 53.4 of the first part 53.1 of the third jaw 53.

[0067] Thus, a screw 1 equipped with the fastening assembly F2 in the second configuration comprises, successively engaged along the second section 1.2 of screw 1: a second sleeve 70 whose lower front surface 70.1 bears against the flange 2, a clamp 50.2 whose third jaw 53 has its outer surface 53.4 bearing against the upper front surface 70.2 of the second sleeve 70 and whose first jaw 51 has its outer surface 51.4 bearing against the lower bearing surface of the nut 80. The bore 51.5 of the first jaw 51, as well as the outer surfaces 51.4, 53.4 cooperating with the lower surface of the nut 80 and the upper front surface 70.2 of the second sleeve 70, make it possible to create a ball joint of the clamp 50.2 around the screw 1.

[0068] Note that the center of the spherical cap of the outer surface 51.4 and the center of the spherical cap of the outer surface 53.4 coincide.

[0069] With reference to figures 4 à 8 A third configuration of the F3 fastening assembly comprises two clamps: a lower clamp 50.1 and an upper clamp 50.2. The lower clamp 50.1 is identical to that of the F1 fastening assembly described previously, and the clamp 50.2 is identical to that of the F2 fastening assembly described previously. The outer surface 51.4 of the jaw 51 of the lower clamp 50.1 bears against the upper surface of the flange 2; the outer surface 52.4 of the jaw 52 of the lower clamp 50.1 bears against the outer surface 53.4 of the jaw 53 of the upper clamp 50.2; the outer surface 51.4 of the jaw 51 of the upper clamp 50.2 bears against the lower surface of the nut 80. This provides a ball joint connection between the clamps 50.1 and 50.2 and the screw 1.

[0070] Thus, a screw 1 equipped with the fastening assembly F3 according to the third configuration comprises successively, a lower jaw 50.1 whose first jaw 51 has its outer surface 51.4 bearing against the upper surface of the collar 2 and whose second jaw 52 has its outer surface 52.4 bearing against the outer surface 53.4 of the third jaw 53, which, together with another first jaw 51, forms the upper jaw 50.2. The outer surface 51.4 of the first jaw 51 of the upper jaw 50.2 bears against the lower surface of the nut 80. The drilling of the first jaws 51 of the first lower jaw 50.1 and of the second upper jaw 50.2, the "diabolo" drilling of the second jaw 52 of the lower jaw 50.1, and the complementary spherical cap surfaces in contact (the outer surface 51.4 of the upper jaw 50.2 with the surface lower of nut 80; outer surface 51.4 of lower clamp 50.1 with the upper surface of the collar 2; the outer surface 52.4 of the lower clamp 50.1 with the outer surface 53.4 of the upper clamp 50.2) allow to create a ball joint of the two clamps (individually and collectively) around the screw 1.

[0071] It should be noted that the center of the spherical cap of the two outer surfaces 51.4 coincide and are located at the center of the small sections of the first and second truncated conical sections of the bore 52.5.

[0072] Thus, in the layout illustrated in the figure 1 To stabilize three adjacent vertebrae Va, Vb, Vc, the surgeon will use six 1-screws, four 3-rods and six sets of fixation.

[0073] Thus, the first vertebra Va is equipped, to the left of the median sagittal plane, with a screw 1a provided with the fixing assembly F1 and to the right of the median sagittal plane with a screw 1'a provided with the fixing assembly F2.

[0074] The second vertebra Vb is equipped, to the left of the median sagittal plane, with a screw 1'b fitted with the F3 fixing assembly and to the right of the median sagittal plane with a screw 1b fitted with the F3 fixing assembly.

[0075] The third vertebra Vc is equipped, to the left of the median sagittal plane, with a screw 1c fitted with the fixing assembly F2 and to the right of the median sagittal plane with a screw 1'c fitted with the fixing assembly F1.

[0076] Once the screws are inserted into the vertebrae, the surgeon will position the rods 3a, 3'a, 3b, and 3'b, starting with those closest to the spine. Thus, rod 3'aa has one end fixed by clamp 50.1 of the F1 fixation assembly for screw 1'a, and the other end of rod 3'a is fixed by the lower clamp 50.1 of the F3 fixation assembly for screw 1'b. Rod 3b is fixed at each end, respectively, by the lower clamp 50.1 of the F3 fixation assembly for screw 1b and by clamp 50.1 of the F1 fixation assembly for screw 1c.

[0077] Rods 3a and 3'b are then fixed respectively. Rod 3a is fixed at one end to the clamp 50.2 of the fixing assembly F2 of screw 1a and at the other end to the upper clamp 50.2 of the fixing assembly F3 of screw 1b. Rod 3'b is fixed between the clamps 50.2 of screw 1'b and 50.2 of screw 1'c.

[0078] Rods 3a and 3'b are fixed so that they pass respectively over rods 3'a and 3b, the rods crossing substantially on the median sagittal plane. Rods 3'a and 3a thus stabilize vertebrae Va and Vb relative to each other, while rods 3'b and 3b stabilize vertebrae Vb and Vc relative to each other.

[0079] The surgeon will be able to adjust the positioning of the rods by rotating the clamps around each screw 1 and by using the ball joints around each screw 1, made possible by the holes in the jaws of the clamps. This allows for extremely precise adjustment in three dimensions: vertically by positioning the clamps along the second screw sections, horizontally by rotating the clamps around the screws, and horizontally by using the ball joints, while maintaining a very compact device according to the invention. Once the rods are in their optimal position, the surgeon will secure the device by tightening nut 80 on each screw and cutting the second section of each screw at the point where it will break 1.4 (shown in the diagram). figure 2 ).

[0080] For other pathologies, only two adjacent vertebrae may need to be stabilized. Here, the assembly used comprises two pairs of screws (1a, 1b and 1'a, 1'b). Screws 1'a and 1'b are fitted with the F1 fixation assembly, while screws 1a and 1b are fitted with the F2 fixation assembly. Screws 1a and 1'a are inserted on either side of the first vertebra, respectively to the left and right of the median sagittal plane, and screws 1b and 1'b are inserted on either side of the second vertebra, respectively to the right and left of the median sagittal plane. A first rod 3 is then fixed between screws 1'a and 1'b, and a second rod 3 between screws 1a and 1b.

[0081] Thus, the device according to the invention, used to stabilize the vertebrae, is easy to set up and compact. The number of screws in each device is determined by the number of vertebrae to be stabilized. Using the device according to the invention allows for optimal and precise adjustment of the rod position based on the patient's condition and anatomy. Furthermore, this adjustment can be easily modified as the condition progresses simply by changing the position of the clamps, replacing the entire fastening assembly on the screw, or changing the rods if they are no longer suitable, without requiring a lengthy operation for the patient.

[0082] This high precision in adjusting the positioning of the rods, the choice of their length and their adjustment on the jaws of the clamps makes it a tailor-made system adapted to each patient, although it includes fixing elements that are themselves of standard manufacture.

[0083] To further facilitate device implantation, each component (screws, fastening assemblies: jaws, sockets, nuts, and rods) can be marked or color-coded to allow for both rapid identification and traceability from manufacturing to implantation in the patient's body. Marking can be performed using any biocompatible method known to be such.

[0084] 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.

[0085] In particular, the instrumented vertebrae are adjacent here, but they might not be. In that case, the length of the rods will simply need to be adjusted according to the distance between the two vertebrae to be instrumented.

[0086] The rods are fixed here between the vertebrae in a crossed configuration, but the device according to the invention can also allow for the fixation of rods parallel to the median sagittal plane. Furthermore, although only one fixation method is presented here (fixation with crossed rods), depending on the patient's condition, the assemblies of devices according to the invention can be used to instrument some vertebrae in a crossed configuration and other vertebrae in a parallel configuration.

[0087] The stem here has a circular cross-section, but it could have an oval, triangular, rectangular, polygonal, etc. cross-section.

[0088] The stem here has a constant cross-section, but it could have a narrower cross-section at the ends than in the center, or conversely, a wider cross-section at the ends than in the center.

[0089] The stems here have a predefined length but they could be cut to the desired length.

[0090] The stems could be straight instead of curved.

[0091] The screws here are solid, but they could be hollow to allow for fixation or the passage of a pin to facilitate percutaneous surgery.

[0092] The jaws here have a roughly parallelepiped shape but can take any shape, for example cylindrical, polyhedral, or ovoid... The groove of the second part can have an angular or polygonal section so that once the two jaws of the clamp are closed, the second parts of the jaws form a channel with a square or polygonal section.

[0093] The device could include nuts incorporating 60 sockets in one piece, and / or screws incorporating 70 sockets in one piece and / or screws and nuts as described here.

[0094] The F1 and F2 fixation assemblies here include a socket, but this could be replaced by one or more stackable washers depending on the desired height, the first and last washers taking the shape of the lower and upper front surfaces of the socket, or the socket could be completely absent from the fixation assembly if the patient's anatomy allows it.

[0095] In particular, the device of the invention is applied here to humans, but it can be adapted to any vertebrate, especially domestic animals such as equines or dogs. Naturally, a person skilled in the art will be able to adapt the dimensions of the device's components accordingly, especially the length and diameter of the screws and rods, and consequently the dimensions of the clamps, sockets, and nut.

Claims

1. Vertebral stabilization device, comprising: - at least two screws (1a; 1b), each having a first threaded portion (1a.1; 1b.1) to be engaged in a vertebra and a second threaded portion (1a.2; 1b.2) separated from the first threaded portion by a flange (2); - at least one first connection rod having two opposite ends to connect the two threaded portions of the screws to one another; and - at least one first securing assembly and one second securing assembly to secure the ends of the rod to the screws, each securing assembly comprising at least one clip (50), which is able to be engaged on the second threaded portion (1.2) of one of the screws and arranged to clamp an end of the rod, and a nut (80) which has a lower bearing surface and which is designed to be screwed on the second threaded portion (1.2) by clamping the clip against an upper surface of the flange of the screw, each securing assembly being arranged to create a ball-and-socket joint connection between the clip and the second threaded portion.

2. Device according to claim 1, wherein the lower bearing surface of the nut (80) and the upper bearing surface of the flange (2) are spherical cap-shaped concave surfaces which are identical to one another.

3. Device according to claim 1 or 2, wherein the clip (50) at least of the first securing assembly (F1) comprises a first jaw (51) having a complementary spherical cap-shaped convex outer surface (51.4) to bear on the upper surface of the flange (2), and a second jaw (52) having a spherical cap-shaped convex outer surface (52.4), the first securing assembly (F1) comprising a first support sleeve (60) of the nut (80) having a complementary lower front surface to bear against the spherical cap-shaped convex outer surface of the second jaw.

4. Device according to claim 3, wherein the first support sleeve (60) is distinct from the nut (80).

5. Device according to claim 4, wherein the first support sleeve (60) comprises a spherical cap-shaped convex upper front surface complementary of the lower surface of the nut to bear against it.

6. Device according to claim 1 or 2, wherein the clip (50.2) at least of the first securing assembly (F2) comprises a first jaw (51) having a complementary spherical cap-shaped convex outer surface to bear against the lower surface of the nut (80) and a third jaw (53) having a spherical cap-shaped concave outer surface, the first securing assembly comprising a second support sleeve (70) having a complementary upper front surface (70.2) to bear on the spherical cap-shaped concave outer surface of the third jaw.

7. Device according to claim 6, wherein the second support sleeve (70) has a complementary spherical cap-shaped concave lower front surface (70.1) to bear on the upper surface of the flange (2).

8. Device according to any one of the preceding claims, wherein the second assembly (F3) comprises two clips, namely a lower clip (50.1) and an upper clip (50.2), the lower clip (50.1) comprising a first jaw (51) having a complementary spherical cap-shaped convex outer surface (51.4) to bear on the upper surface of the flange (2), and a second jaw (52) having a spherical cap-shaped convex outer surface, the upper clip (50.2) comprising a first jaw (51) having a complementary spherical cap-shaped convex outer surface (51.4) to bear against the lower surface of the nut (80) and a third jaw (53) having a spherical cap-shaped concave outer surface (53.4) complementary of the spherical cap-shaped convex outer surface (52.4) of the second jaw (52) to bear on it.

9. Device according to any one of claims 3 to 8, wherein each clip comprises an elastically deformable portion (55) connecting the jaws (51, 52; 51, 53), such that these are movable against one another between an open position and a closed position.

10. Device according to any one of claims 3 to 9, wherein the first jaw (51) is provided with a bore to be engaged on the second threaded portion (1.2) of the screw (1), the bore comprising a first truncated cone-shaped portion and a second cylindrical portion, the first portion having a large cross-section opening onto the outer surface (51.4) of the first jaw (51) and a small cross-section combined with a cylindrical cross-section of the second portion, the second portion opening onto the inner surface (51.3) of the first jaw (51).

11. Device according to claims 3 to 10, wherein the second jaw (52) is provided with a bore to be engaged on the second threaded portion (1.2) of the screw (1), the bore comprising a first truncated cone-shaped portion and a second truncated cone-shaped portion, the first portion having a large cross-section opening onto the outer surface (52.4) of the second jaw (52) and a small cross-section combined with a small cross-section of the second portion, the second portion having a large cross-section opening onto the inner surface (52.3) of the second jaw (52), the common centre of rotation being disposed against the small cross-sections of the first and second portions.

12. Device according to any one of the preceding claims, wherein the flange (2) is removable.

13. Device according to any one of the preceding claims, wherein the rod (3) has a constant cross-section over its entire length.

14. Device according to any one of the preceding claims, wherein the rod (3) is curved.

15. Device according to any one of the preceding claims, wherein the second threaded portion (1.2) of each screw (1) is provided with an end portion designed to enable a rotating connection with a tool for screwing the screw into the vertebra, and a breaking piece to be able to separate the end portion from the second threaded portion by breaking.

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