Pedicle fixation device, its method and installation tools

Abstract

The invention relates to a pedicle fixation device (D) comprising a connector (100) for connecting at least one connecting rod (200) to a pedicle screw (300). The device includes an elastic spacer (500) such that, during assembly of the connector (100) onto the pedicle screw (300), the spacer deforms. This device is notable in that the connector (100) has a deformable portion (150) which, under the action of a tool, is deformed to protrude internally into the connector and cooperate with a vertical concave volume (523) of the spacer (500) positioned therein to constitute a rotational stop allowing the translation of the elastic spacer (500) within the hollow core of the connector (100). Said vertical concave volume (523) has been previously positioned in front of the deformable portion (150). The invention also relates to a method for installing said device. Abbreviated drawing: Fig. 1.

Description

Title of the invention: Pedicle fixation device, its method and its installation tools

[0001] FIELD OF APPLICATION OF THE INVENTION

[0002] The invention relates to the field of pedicle fixation devices of the type associating a spherical head screw with a connector and in particular to adaptations making it possible to optimize and make modular the connection between the head and the connector.

[0003] DESCRIPTION OF THE STATE OF THE ART

[0004] Known in the prior art are clamping screws inside a U-shaped, double U-shaped or C-shaped connecting connector of a polyaxial or monoaxial pedicle screw for the immobilization in rotation and translation of a connecting rod of an osteosynthesis device known per se.

[0005] The connection between the connector, in particular a U-shaped connector sometimes called a tulip, and the spherical head of the screw is the subject of studies in order to make it modular.

[0006] For example, US2016206357 discloses a modular head pedicle screw assembly comprising a bone screw, a tulip, a locking split ring, and a cradle. The locking split ring is positioned within the tulip in a recess in an interior surface of the tulip. The cradle has a proximal end for engaging the connecting rod and a distal end for receiving the bone screw. The cradle has an outer surface positioned between the ends. The outer surface is sized to move axially within the tulip.The cradle expands the locking split ring to a preloaded initial position and upon insertion of the tulip onto the bone screw, the cradle moves proximally disengaging the locking split ring, simultaneously causing the locking split ring to relax into an unexpanded state while providing tactile and audible feedback to the surgeon and locking the bone screw into the tulip. The inner surface of the tulip and the split ring are preformed for this purpose.

[0007] The disadvantages of this solution are as follows:

[0008] - it requires two parts,

[0009] - it does not provide braking of the connection until the connecting rod is locked rusty in the connector,

[0010] - it does not ensure rotational locking in particular until the connecting rod is not locked in the connector,

[0011] - impacting, i.e. installing the connector on the head requires effort important for split ring deformation purposes,

[0012] - it does not allow easy dismantling, that is to say disassembly.

[0013] Document US2017224386 describes orthopedic fixation devices that include a connecting member or tulip and a bone fastener, wherein the bone fastener can be loaded into the connecting member through the bottom of a bore in the connecting member. The described orthopedic fixation devices may include modular locking clamp assemblies that can be attached to fasteners or screws already implanted in the bone. The modular locking clamp assemblies may include polyaxial locking clamp assemblies, as well as monoaxial locking clamp assemblies.

[0014] For this, the device comprises two parts which fit into the tulip:

[0015] - a first part or cradle cooperating at one end with the connecting rod and at another end with an elastic spherical bearing,

[0016] - a second elastic spherical part or bearing opening and closing to allow the spherical head of the screw to be inserted into the tulip, retain it and guide the ball joint formed.

[0017] The disadvantages of this solution are as follows:

[0018] - it requires two parts: a corner element and a clamping element,

[0019] - it does not brake the ball joint but creates notches corresponding to as many different angular positions,

[0020] - it does not ensure rotational locking in particular until the connecting rod is not locked in the connector,

[0021] - it does not allow easy disimpaction.

[0022] Ease of assembly and disassembly is all the more important in this area when the screws are cemented, that is to say when they are not only screwed in but also sealed, making them very difficult to unscrew.

[0023] Document US2015032162 discloses a coupling assembly for coupling a rod to a bone anchor, the coupling assembly comprising a receiving portion having a first end, a second end and a central axis extending through the first end and the second end, a recess for receiving a rod, and a housing space for housing a head of a bone anchor, the housing space having an opening at the second end for inserting the head; a pressure member configured to be positioned at least partially in the housing space, the pressure member having a first end including a first end surface and a second end facing the second end of the receiving portion, a central axis coaxial with the central axis of the receiving portion, and a flexible portion for clamping an inserted head, a rod receiving member which is a separate part comprising a first end comprising a first end surface and a channel for insertion of a rod adjacent the first end and a second end having a second end surface facing the second end of the receiving portion, wherein the first end surface projects over an upper surface of an inserted rod; wherein the first end surface of the pressure member is configured to extend into the channel of the rod receiving member; and wherein the pressure member comprises a portion that is configured to cooperate with a portion of the rod receiving member under an axial load such that either the portion of the pressure member or the portion of the rod receiving member is deformed so as to move the first end surface of the pressure member further into the channel of the rod receiving member in an axial direction.

[0024] This solution offers a rotation lock but it has the following disadvantages:

[0025] - it requires two parts for locking on the screw,

[0026] - it requires additional parts for rotational locking,

[0027] - it does not envisage de-impacting.

[0028] Document US20160262803 describes a spinal fixation system connector comprising spring cage members. In some embodiments, an engaging member, such as a bone screw, may be configured to be coupled with and received within a connector body. A spring cage structure may also be configured to be coupled to the connector body. The spring cage structure may include a spring configured to be positioned in a relaxed configuration and a flexed configuration, such that the spring defines an opening having a first size in the relaxed configuration and a second, larger size in the flexed configuration to allow the opening to receive and engage a head of the engaging member within the connector body.

[0029] This solution is implemented by a single part but has the following drawbacks:

[0030] - it does not control the tightening between the spring cage and the screw head,

[0031] - it does not control the position of the spring cage when inserting the head,

[0032] - it does not envisage de-impacting.

[0033] BRIEF DESCRIPTION OF THE INVENTION

[0034] The applicant has carried out research aimed at solving the drawbacks of the devices of the prior art.

[0035] This research led to the observation that the mobility of the flexible element or spring cage could in certain situations pose problems for the practitioner when installing the device.

[0036] However, this change of position is necessary to change the behavior of the flexible element which must accommodate the spherical head of the screw once the screw is screwed in, allow controlled polyaxial, monoplanar or monoaxial mobility of the tulip during its positioning and guarantee fixation once the spinal rod is installed.

[0037] The pedicle fixation device of the invention comprises a connector for connecting at least one connecting rod to a pedicle screw;

[0038] said pedicle screw comprising at one end a spherical head,

[0039] said connector comprising an upper part adopting the shape of an open U and a lower part,

[0040] the lower part being provided with a hollow through core opening into the upper part allowing it to be threaded onto the spherical head of the pedicle screw and

[0041] the open upper part receiving the at least one connecting rod and being provided with a threaded hollow portion receiving a clamping screw for the purpose of holding the at least one connecting rod in position in the connector once mounted.

[0042] The device further comprises an elastic spacer provided with a hollow spacer core and received in the hollow core of the connector, said elastic spacer comprising a first end called the upper end on which the at least one connecting rod exerts pressure once mounted and a second end called the lower end cooperating with the spherical head of the screw,

[0043] the two ends of the spacer being connected by an elastic intermediate portion allowing the widening of the lower end subjected to axial stress,

[0044] said upper end of the elastic spacer being preformed with a cradle in which a portion of said connecting rod is housed once mounted.

[0045] Said elastic spacer is made in one piece with the elastic intermediate portion perforated so that the remaining material can accept elastic deformation, the lower end of the spacer being constituted by a stop ring provided with at least one slot which allows a change in diameter between a reduced diameter less than the diameter of the spherical head and an enlarged diameter greater than the diameter of the spherical head,

[0046] The hollow core of the connector is preformed with an end opening into the upper part of the connector, a widened intermediate portion and a lower portion of reduced diameter, so that, when assembling the connector on the pedicle screw, the elastic spacer subjected to axial compression deforms, so that the lower end of the spacer then positioned in the widened intermediate portion of the hollow core of the connector, enlarges its diameter and allows the introduction of the spherical head into the hollow core of the elastic spacer, then inducing the disappearance of the axial compression and the return to reduced diameter of the lower end of the elastic spacer.

[0047] According to the invention, this device is remarkable in that the hollow through core of the connector and the external dimensions of the spacer allow it to be inserted from above,

[0048] the upper end of the spacer is equipped with a radial projection which cooperates with the thread of the threaded portion so as to constitute a first axial stop positioning the lower end of the elastic spacer in the enlarged portion of the hollow core of the connector,

[0049] the outer surface of the spacer is provided with a vertical concave volume,

[0050] the connector is provided with a deformable portion which, under the action of a tool, is deformed to project internally into the hollow core of the connector and cooperate with the vertical concave volume of the spacer which is positioned there so as to constitute a rotation stop allowing the translation of the elastic spacer in the hollow core of the connector,

[0051] said vertical concave volume having been previously positioned in front of the deformable portion.

[0052] The qualifiers lower or low and upper or high used above or in the present description must be interpreted according to the position of the qualified element relative to the axis of the screw, the terms lower and low relating to the elements positioned closer to the bone or the center of the body and the terms upper and high relating to the elements positioned further from the bone or the center of the body.

[0053] This device is advantageous in that a single element, i.e. the elastic spacer, ensures continuity between the spherical head and the connecting rod. In fact, the spacer cooperates with the spherical head and the connecting rod also exerts pressure on it. In fact, the lower end ensures the function of an axial stop but remains linked to the upper end which, itself, stops in the hollow core of the connector and receives the stress from the connecting rod received by the connector. Thus, a single action is necessary for impacting.

[0054] The elasticity will facilitate the introduction of the spacer into the connector.

[0055] The hollow core of the connector accommodates with axial play said spacer which has this axial play to change axial position inside the hollow core of the connector. The hollow core of the connector is therefore sized relative to the dimensions of the spacer to leave this axial play.

[0056] Nevertheless, the characteristic of the invention makes it possible to partially fix (in one direction only) the axial position of the spacer in the position where it can engage on the screw head, that is to say in the position where the spacer can expand. It is not the elasticity of the spacer which will allow its lower end to pass from a portion where it is retained to a portion where it can expand but it is its capacity to to stop so as to position the lower end in the widened portion. The elasticity mainly allows the expansion and return to position to accommodate and retain the head.

[0057] This point fixation of the axial position is further supplemented by a rotation stop which allows the elastic spacer to be oriented in the desired position. This rotation stop allows the cradle to be oriented relative to the branches of the U of the connector while allowing translation in one direction.

[0058] It also ensures the correct positioning of the radial projection of the elastic spacer, correct positioning which will be used for the following position linked to securing the connector on the screw.

[0059] Indeed, in this first position, the connector and elastic spacer assembly can be threaded or clipped onto the head and the assembly can be subject, if possible, to an adjustment of the angular position. Similarly, in this first position, it is possible to easily disengage or unclip said assembly from said head.

[0060] According to another particularly advantageous characteristic of the invention, the hollow core of the connector is preformed under the threaded portion of a hollow forming a second axial stop for said radial projection in a position where the lower end of the elastic spacer is located in the reduced diameter portion of the hollow core of the connector, for the purpose of holding in position on the screw head the elastic spacer and the associated connector. This characteristic proposes to fix the securing position, that is to say to hold in position the connector assembly and associated spacer on the screw head. It is understood that the rotational locking makes it possible to keep the radial projection on the same trajectory to come and cooperate after translation with said hollow.This second axial stop allows the spacer to be held in position and therefore its lower end in the reduced diameter portion of the hollow connector core, which guarantees retention on the screw head.

[0061] The device thus makes it possible to fix a high position and a low position for securing the screw by controlling the axial play in two stages.

[0062] According to another particularly advantageous characteristic of the invention, said deformable portion is constituted by a portion of thinned wall whose partial punching ensures its projection into the hollow core. The partial punching has the advantage of maintaining a link between the punched part and the wall of the connector while causing said punched part to project into the hollow core of the connector. This has the effect of maintaining the axial orientation of the spacer in order to keep the cradle of the spacer aligned with the U-shaped housing of the screw head.

[0063] According to another particularly advantageous characteristic of the invention, said radial projection is preformed at the end of a tongue whose elasticity allows it to change position in a translational movement of the spacer in the core. hollow of the connector from the first axial stop to the second axial stop. The elasticity of the tab allows the projection to retract towards the hollow core of the spacer temporarily when the latter is subjected to a thrust stress and to return in radial projection to cooperate with said hollow.

[0064] To prevent a return backward, according to another particularly advantageous characteristic of the invention, the connecting rod once received in the cradle prevents the bending of the tongue and keeps it in position with the associated projection for the purpose of securing the second axial stop.

[0065] The dimensions of the cradle and the rod are defined in such a way that the presence of the rod in the cradle prevents the tongue spacer from being retracted towards the hollow core.

[0066] Other characteristics of the device are associated or not to complete all or part of the characteristics above:

[0067] - the connector is preformed with external notches for gripping purposes;

[0068] - the hollow core of the elastic spacer is open at its two ends and is provided with a groove for gripping purposes;

[0069] - the elastic intermediate portion of the spacer is provided with a plurality of oblong holes which join as many slots made in the stop ring constituting the lower end, said oblong holes following a helical path in the wall of the elastic intermediate portion;

[0070] - the external cylindrical portions of the stop ring forming the edges of the slots are provided with a flat surface;

[0071] - the elastic spacer and the connector are sized such that the elastic spacer is projecting and visible in the open part of the connector when the radial projection is in the first axial stop position;

[0072] - said hollow is open so as to allow the presence to be seen from the outside or the absence of the radial projection in said hollow.

[0073] The device also has characteristics linked to the reduction of the number of possible rotation axes at the level of the screw head.

[0074] Thus, according to another particularly advantageous characteristic of the invention, the device comprises a rotation locking pin comprising a head and a rod, the rod of the pin being inserted into an imprint made in the screw head and taking up the profile of said imprint, the head of the pin being cylindrical to cooperate with a cylindrical surface formed in the hollow core of the elastic spacer to make the connection between the screw and the connector monoaxial.

[0075] To ensure the same function, according to another characteristic, the spherical head is preformed with an axial cylindrical projection to cooperate with a cylindrical surface provided in the hollow core of the elastic spacer to make the screw mo- axial connection between the screw and the connector.

[0076] In addition, specific tool characteristics are associated with the device in order to ensure the various operations necessary for its implementation.

[0077] According to these characteristics, the device comprises:

[0078] - a pre-assembly tool comprising a gripping module and a tool punching of the deformable part of the connector;

[0079] - a fitting / impaction tool comprising a connector gripping module and a relative displacement module between the elastic spacer and the connector,

[0080] the gripping module comprising two ends

[0081] one end forming a handle for its user and one preformed end of two branches positioned for gripping purposes on either side of the two branches of the U formed by the connector,

[0082] The gripping module further comprises a hollow core into which the movement module is temporarily inserted.

[0083] The relative displacement module comprising two ends:

[0084] one end forming a handle for its user and a support end coming to bear on the upper end of the elastic spacer opening into the hollow core of the connector, the pushing movement of the displacement module relative to the gripping module exerted by the user ensuring the descent of the elastic spacer into the hollow core of the connector;

[0085] - a disassembly / disimpaction tool comprising a gripping module of the connector and an elastic spacer gripping module,

[0086] the gripping module comprising two ends

[0087] one end forming a handle for its user and one preformed end of two branches positioned for gripping purposes on either side of the two branches of the U formed by the connector,

[0088] the gripping module further comprising a hollow core into which the gripping module is temporarily inserted,

[0089] the input module comprising two ends:

[0090] an end forming a handle for its user and an expandable gripping end passing from a retracted position for insertion into the hollow core of the elastic spacer to a deployed gripping position, the traction movement of the gripping module relative to the gripping module exerted by the user ensuring the raising of the elastic spacer.

[0091] Finally, another object of the invention concerns the method of installing and uninstalling the device described above, using or not the tools also described above.

[0092] According to the invention, the method of installing the device is remarkable in that it includes a pre-assembly operation, which consists of

[0093] mount the elastic spacer in the hollow core of the connector

[0094] by introducing by translation the elastic spacer into said hollow core from the top of the connector,

[0095] to rotate said inserted spacer 90 degrees in order to

[0096] - that the cradle is aligned with the U-shaped opening of the connector,

[0097] - that the projection cooperates with the thread, and

[0098] - that the vertical concave volume is positioned facing the deformable portion of the connector,

[0099] - that the lower end of the elastic spacer is positioned in the inter part enlarged medial part of the hollow core of the connector,

[0100] and

[0101] To deform the deformable portion equipping the connector in order to make it protrude into the vertical concave volume.

[0102] According to another particularly advantageous characteristic of the invention, the method comprises a mounting / impaction operation, which consists of threading the pre-mounted assembly onto the spherical head of the pedicle screw, the screw head being positioned in the hollow core of the elastic spacer. The position of the spacer also allows easy disassembly.

[0103] According to another particularly advantageous characteristic of the invention, the method comprises a securing operation which consists of moving the connector in translation relative to the elastic spacer, in order to:

[0104] that the lower end of the latter is positioned in the hollow core portion with reduced diameter so as to prevent the elastic ring from opening and the connector from being held in position on the spherical head,

[0105] that the projection cooperates with the second axial stop and forms a stop notch,

[0106] Once the rod is installed in the cradle, it is no longer possible to de-impact it due to the radial projection being locked in position.

[0107] According to another particularly advantageous characteristic of the invention, the method also comprises a disassembly / disimpaction operation which consists of raising the elastic spacer inside the hollow core and thus allowing its deployment in the widened portion by a traction movement by retracting the projection of the hollow volume forming the second axial stop. To allow this disimpaction, the connecting rod is previously removed from the cradle. This withdrawal movement leads to the deformation of the radial projection. Then, either the spacer is forced back to deform the projection and release it, or a tool cooperating in the drilling is inserted to push back the projection and release it.

[0108] Assembly and disassembly will therefore be possible without having to unscrew or unseal the screw already installed. The use of fenestrated screws (with grooves for the passage of the sealing cement) will be made easier.

[0109] The fundamental concepts of the invention having just been set out above in their most elementary form, other details and characteristics will emerge more clearly on reading the description which follows and with reference to the appended drawings, of several non-limiting embodiments of a device in accordance with the invention. Brief description of the drawings

[0110] [Fig-1] is a schematic drawing of an exterior front view of an embodiment of a device according to the invention receiving a connecting rod;

[0111] [Fig.2] is a schematic drawing of a front sectional detail view of the device of [Fig.l] at the connector level;

[0112] [Fig.3] is a schematic drawing of a front sectional detail view of the connector alone;

[0113] [Fig.4a] is a schematic drawing of an exterior front view of a mode of rea lization of an elastic spacer;

[0114] [Fig.4b] is a schematic drawing of an exterior perspective view from below of the elastic spacer of [Fig.4a];

[0115] [Fig.4c] is a schematic drawing of an exterior side perspective view of the elastic spacer of [Fig.4a];

[0116] [Fig.4d] is a schematic drawing of a three-quarter perspective exterior view of the elastic spacer of [Fig.4a];

[0117] [Fig.5a] illustrates by a detailed sectional view the installation from above of the elastic spacer in the connector;

[0118] [Fig.5b] illustrates by a detailed sectional view the start of insertion of the elastic spacer into the connector;

[0119] [Fig.5c] illustrates by a detailed sectional view the position of the elastic spacer in the connector after continuation of the insertion;

[0120] [Fig.5d] illustrates by a detailed perspective view the ninety degree rotation of the elastic spacer;

[0121] [Fig.5e] illustrates by a detailed sectional view of the punching of the deformable portion;

[0122] [Fig.6] is a schematic drawing of a front sectional detail view of the impact;

[0123] [Fig.7] illustrates in detail in section an angular possibility offered by the phase impact;

[0124] [Fig.8] is a schematic drawing in exterior front view of the connector and spacer assembly;

[0125] [Fig.9] and [Fig. 10] illustrate in front view in section the phase of securing the connector on the screw head;

[0126] [Fig. 11] is a schematic drawing in exterior side view of the assembly after securing;

[0127] [Fig. 12] is a schematic front view drawing in section of the impact of a monoaxial screw;

[0128] [Fig. 13] is a schematic drawing of an exterior view of an embodiment of a gripping tool of the device,

[0129] [Fig. 14] is a schematic drawing of an exterior view of an embodiment of a thrust module cooperating with the gripping tool for impacting and securing purposes;

[0130] [Fig. 15a] to [Fig. 15e] illustrate by complete and partial external views the behavior of the action of the tool for impacting and securing purposes;

[0131] [Fig.16] is a schematic drawing of an exterior view of an embodiment of a traction module cooperating with the gripping tool for de-impacting purposes;

[0132] [Fig. 17a] to [Fig. 17c] illustrate by complete and partial external views the behavior of the tool action for impact removal purposes.

[0133] DESCRIPTION OF A PREFERRED EMBODIMENT

[0134] As illustrated by Figures 1 and 2, the pedicle fixation device referenced D as a whole comprises a connector 100 here adopting the shape of a U intended to connect a connecting rod 200 to a pedicle screw 300 comprising a spherical head 310. Although illustrated here with a circular section, it should be noted that the connecting rod(s) may have another section. In addition, although illustrated here with a U shape, it should be noted that the connector 100 may have another but equivalent shape such as a double U.

[0135] Said U-shaped connector 100 comprises an upper part and a lower part.

[0136] The lower part is the central lower part of the U and is provided with a hollow through core 110 which, defined around a first axis, allows the connector 100 to be threaded onto the spherical head 310 of the pedicle screw 300 and to accommodate said head 310. The upper part comprises the branches 130 and 140 of the U between which the connecting rod 200 is accommodated. They are provided with a threaded portion 120 accommodating a clamping screw 400 for the purpose of holding the connecting rod 200 in position between the branches 130 and 140.

[0137] Said hollow core 110 accommodates between the screw head 310 and the rod 200 an elastic spacer 500 formed with a hollow core 510 and accommodated coaxially. This hollow spacer core 510 is preformed in a spherical shape to accommodate and cooperate with the spherical head 310. It is dimensioned so that the rotation on the received spherical head is braked.

[0138] As illustrated in more detail by figures 4a to 4d, this elastic spacer 500 comprises a first upper end 520 with which the connecting rod 200 comes into contact and a second lower end 530 cooperating with the spherical head 310 of the screw 300.

[0139] As illustrated, the two ends 520 and 530 are connected by an elastic intermediate portion 540 allowing the two ends 520 and 530 subjected to an axial compressive stress to be mobilized in particular by widening the lower zone.

[0140] The lower end 530 forms an axial stop ring provided with two slots 531 and whose connection with the elastic portion 540 allows a change in diameter between a reduced diameter less than the diameter of the spherical head 310 and an enlarged diameter greater than the diameter of the spherical head 310.

[0141] Externally, the elastic spacer 500 adopts the general shape of a cylinder. This cylinder is the subject of a plurality of preformations and is composed from top to bottom:

[0142] -a first upper end defining the upper end 520,

[0143] - an intermediate portion defining the elastic intermediate portion 540, and

[0144] - a second split lower end defining the lower end 530 constituting the axial stop ring.

[0145] The wall of the elastic intermediate portion 540 is provided with two oblong holes 541 which join as many slots 531 provided in the ring constituting the lower end 530, thus forming two tabs of material. According to the non-limiting embodiment illustrated, the ring constituting the lower end 530 comprises an external peripheral edge provided with a chamfer 532.

[0146] These oblong holes 541 follow a helical path in the wall of the elastic truncated cone-shaped intermediate portion 540. This helical path makes it possible to reproduce with the material between said holes, the shape of a coil spring and its elasticity.

[0147] It is understood that the slots 531 and the oblong holes 541 make it possible to obtain an elastic spacer 500 which accepts axial deformations tending to vary its length and radial deformations tending to vary its diameter. To facilitate radial deformation, the external cylindrical portions of the stop ring formed by the end 530 forming the edges of the slots 531 are provided with a flat 533.

[0148] The upper end 520 of the spacer 500 is equipped with a radial projection 521 whose function is described below. This radial projection 521 is preformed at the end of a tab 522 whose elasticity allows it to change position.

[0149] The outer surface of the spacer 500 is further provided with a vertical concave volume constituted here by a vertical notch 523 preformed in the body of the spacer 500 in opposition to the tab relative to the axis of the spacer. Its function is described below.

[0150] Said upper end 520 of the elastic spacer 500 is also preformed with a cradle 524 in which a portion of said connecting rod 200 is housed once mounted (see figures 1 and 2). The axis of the cradle 524 is arranged in a vertical plane perpendicular to the common median vertical plane of the tongue 522 and the notch 523.

[0151] As illustrated by figures 5a to 5e, the hollow core 110 of the connector 100 accommodates from above said spacer 500 which slides inside to the position illustrated by [Fig.5c].

[0152] As illustrated by [Fig. 3], the hollow core 110 of the connector 100 is preformed with a succession of portions adopting different profiles and diameters, the main ones of which are described below from the lower end to the upper end:

[0153] - a portion 111 of narrow diameter but greater than the diameter of the spherical head 310 to allow its passage but less than the diameter of the lower end 530 of the elastic spacer 500,

[0154] - an enlarged portion 112 of larger diameter so that the difference in diameter with the portion of diameter 111 located below define a support collar and corresponding substantially to the external diameter of the lower end 530 of the elastic spacer 500 to retain the expansion of this lower end 530,

[0155] - an upper portion 113 of diameter enlarged relative to the portion 112 and defined to allow expansion of the lower end 530 of the elastic spacer 500 when positioned therein,

[0156] - a guide portion 114 of diameter smaller than that of the widened portion 113 located below and opening into the upper part.

[0157] As illustrated, the receiving recess 115 of the connecting rod 200 is deeper than the position of this portion 114 so that the connecting rod 200 can exert a stress on the spacer.

[0158] The connector 100 is further provided:

[0159] - of a portion of thinned wall 150 which under the action of a tool is punched for protrude internally into the hollow core of the connector 100,

[0160] - under the threaded portion 120, of a hollow 160 opening outwards arranged in opposition of the punchable wall portion 150.

[0161] - external notches 170 for gripping purposes (see figures 1 and 5a).

[0162] As illustrated by Figures 5a to 5e, the pre-assembly provides that the spacer elastic 500 is positioned in the connector 100 before impact. For this, the elastic parts of the spacer 500 are radially constrained to reduce their diameter according to the arrows Fl until reaching a smaller diameter and thus allowing the passage and reception of the lower end 530 of the spacer 500 in the widened portion 113 as illustrated by [Fig.5c].

[0163] In this first insertion phase, the radial projection 521 is arranged in the recess separating the branches 130 and 140 of the connector. The spacer is then rotated ninety degrees so that said projection 521 cooperates with the threaded portion as illustrated by [Fig.5d] to reach the position illustrated by [Fig.5e]. The projection 521 then constitutes a first axial stop in a position where the lower end 530 of the elastic spacer 500 is arranged in the widened portion 113 of the hollow core 110 of the connector 100. Indeed; the cooperation of the projection 521 with the thread 120 prevents the translation of the spacer in a direction opposite to its direction of insertion.

[0164] The notch 523 is then facing the thinned portion 150 which at this stage is the subject of a partial punching operation so that, as illustrated, the thinned portion 150 projects internally into said notch 523 so as to constitute a rotation stop nevertheless allowing the translation of the elastic spacer 500 in the hollow core 110 of the connector 100 in the insertion direction while controlling the position of the projection 521. This portion 150 deformed under the action of the punching will also serve as an emergency non-return stop to prevent the spacer 500 from rising in the hollow core of the connector 500 in the event that the projection 521 is defective.

[0165] This first abutment allows non-final mounting of the connector assembly 100 and associated elastic spacer 500 on the screw head 310 as illustrated by [Fig. 6]. This pre-assembly can be carried out by means of a tool 600 comprising at a first end a gripping module 610 such as that illustrated by [Fig. 13]. The assembly formed by the elastic spacer 500 and by the connector 100 can be mounted on the head 310 and detached from the latter easily.

[0166] The braking exerted by the hollow core of the spacer 500 on the head 310 allows the angular position of said assembly to be adjusted. [Fig.7] illustrates a possible inclined position. This adjustment and / or this non-definitive assembly are thus carried out without the risk of the spacer 500 rotating in the connector 100.

[0167] [Fig.8] illustrates the visual reference constituted by the bottom of the cradle 524 which remains arranged above the bottom of the receiving recess 115. The practitioner thus knows that the assembly formed by the elastic spacer 500 and by the connector 100 is in a non-final mounting position.

[0168] The transition to a definitive fixing is illustrated by figures 9 and 10. In these figures, the spacer 500 under the action of the relative displacement module 700 associated with the tool 600 as illustrated by figures 14 and 15a to 15e, moves in the hollow core 110 downwards. Its lower end 530 passes from a portion 113 where its thickness knotting was authorized to a portion 112 of smaller diameter where once the head 310 is received, the end 530 can no longer expand so that the assembly formed by the elastic spacer 500 and by the connector 100 cannot separate from the head 310.

[0169] For this, the support end 710 of the relative displacement module 700 comes to bear on the upper end of the elastic spacer 500 by coming to match the cradle 524, the pushing movement of the displacement module relative to the gripping module 610 exerted by the user ensures the descent of the elastic spacer 500 into the hollow core 110 of the connector 100.

[0170] This relative movement of the spacer 500 in the hollow core is permitted by the elasticity of the tab 522 which allows the projection 521 to retract inwards and then return to position once positioned opposite the hollow 160. This is a second axial stop which prevents the spacer from coming out of the reduced diameter portion 112 in order to guarantee fixing. This movement of the spacer 500 is also permitted by the relationship of the deformed portion 150 forming a projection in the notch 523 which only ensures anti-rotation and does not prevent translation.

[0171] Thus, the radial projection of the elastic spacer cooperates in the high position with the threaded zone of the connector in order to maintain a high position, then with a through hole in the connector in order to maintain a low position.

[0172] The fact that the hollow 160 is constituted by a through hole allows the practitioner to see that the projection 521 is present and that therefore the assembly is definitive as illustrated by [Fig. 11].

[0173] The fixing is finalized by the presence of the rod 200 received between the branches 130 and 140 of the connector 100 and in the cradle 525. As illustrated by [Fig.2], the physical presence of the rod 200 in the cradle 525 prevents the tab 522 from returning towards the inside of the spacer 500 and therefore maintains the radial projection in position.

[0174] [Fig. 12] illustrates in the pre-assembly position a situation where the connection with the screw 300' is monoaxial. To implement it, the spherical head 310' is preformed with an axial cylindrical projection 311' which cooperates with a cylindrical surface 525 formed in the hollow core of the elastic spacer coaxially with the latter. This cylindrical surface 525 has a diameter allowing the penetration of the axial cylindrical projection during assembly while limiting its rotational movements to make the connection monoaxial, that is to say in this situation which only allows rotation along the axis of the screw.

[0175] Figures 13 to 17c illustrate the tooling of the device which makes it possible to implement the assembly and disassembly processes.

[0176] This tooling is based on the gripping tool or module 600 illustrated by the drawing of [Fig. 13] which can be used for the non-final assembly of the assembly formed by the connector 100 and the elastic spacer 500 on the head of the screw 300. This tool or gripping module 600 has two ends:

[0177] an end 620 forming a handle for its user and an end 610 preformed with two branches positioned for gripping purposes on either side of the two branches 130 and 140 of the U formed by the connector 100,

[0178] This gripping module 600 further comprises a hollow core into which other modules are temporarily inserted depending on the operation to be implemented.

[0179] Thus, as illustrated by figures 14 and 15a, in order to carry out a definitive assembly or impacting, this gripping module 600 is associated with a relative displacement module 700 which controls the displacement between the elastic spacer 500 and the connector 100 ensuring the securing of the assembly.

[0180] This relative displacement module 700 comprises two ends.

[0181] The first end 720 forms a control button for its user above the handle 620 of the gripping module as illustrated in [Fig. 15b].

[0182] The second support end 710 comes to bear on the cradle 524 preformed in the upper end of the elastic spacer 500 opening into the hollow core of the connector 100 as illustrated by [Fig.l5d].

[0183] Pressing the control button 720 ([Fig.15c]) by the user ensures the raising of the gripping module 600 and therefore the relative lowering of the elastic spacer 500 into the hollow core of the connector 100 ([Fig. 15e]).

[0184] As illustrated by figures 16 to 17c, in order to implement a disassembly or de-impacting operation, said gripping module 600 is associated with a module for gripping the elastic spacer 800 which is inserted into the hollow core. This gripping is carried out on the elastic spacer 500 by means of a groove 526 formed in the hollow core of the spacer and accessible because the latter opens out at both ends of the spacer 500.

[0185] The input module 800 has two ends.

[0186] A first end 820 forming a handle for its user which is arranged above the end 620 of the gripping module 600 as illustrated by figures 17a and 17b.

[0187] A second expandable gripping end 810 passing from a retracted position of insertion into the hollow core of the elastic spacer 500 to a deployed gripping position coming to be introduced into the groove 526, as illustrated by [Fig.17c].

[0188] The expansion is controlled by the rotation of a wheel 821 fitted to the handle 820.

[0189] The traction movement of the gripping module 800 relative to the gripping module 600 exerted by the user ensures the relative raising of the spacer. elastic 500, the deformation of the various projecting elements. The rise of the spacer 500 in the hollow core of the connector 100 allows the lower end 530 of the spacer 500 to return into the enlarged portion 113 of the hollow core of the connector 100 and therefore to expand to free itself from the head of the screw 300.

[0190] It is understood that the device which has just been described and represented above has been done so with a view to disclosure rather than limitation. Of course, various arrangements, modifications and improvements may be made to the above examples, without departing from the scope of the invention.

Claims

1. Claims Pedicle fixation device (D) comprising a connector (100) for connecting at least one connecting rod (200) to a pedicle screw (300); said pedicle screw comprising at one end a spherical head (310), said connector comprising an upper part adopting the shape of an open U and a lower part, the lower part being provided with a hollow core (110) passing through, opening into the upper part, allowing it to be threaded onto the spherical head of the pedicle screw and the open upper part receiving the at least one connecting rod and being provided with a threaded hollow portion (120) receiving a clamping screw (400) for the purpose of holding in position in the connector the at least one connecting rod (200) once mounted, the device further comprising an elastic spacer (500) provided with a hollow spacer core and received in the hollow core of the connector (100), said elastic spacer (500) comprising a first end called the upper end on which the at least one connecting rod (200) exerts pressure once mounted and a second end called the lower end cooperating with the spherical head (310) of the screw (300), the two ends of the spacer being connected by an elastic intermediate portion (540) allowing the widening of the lower end subjected to axial stress, said upper end (520) of the elastic spacer being preformed with a cradle in which a portion of said connecting rod (200) is housed once mounted, said elastic spacer (500) being made in one piece with the openwork elastic intermediate portion so that the remaining material can accept elastic deformation, the lower end (530) of the spacer being constituted by a stop ring provided with at least one slot which allows a change in diameter between a reduced diameter less than the diameter of the spherical head and an enlarged diameter greater than the diameter of the spherical head, the hollow core of the connector (100) being preformed of an end opening into the upper part of the connector of an enlarged intermediate portion (113) and of a lower portion of reduced diameter (112), so that, during assembly of the connector (100) on the pedicle screw (300), the elastic spacer subjected to axial compression deforms, so that the lower end of the spacer then positioned in the enlarged intermediate portion (113) of the hollow core of the connector, enlarges its diameter and allows the introduction of the spherical head (310) into the hollow core of the elastic spacer (500), then inducing the disappearance of the axial compression and the return to reduced diameter of the lower end of the elastic spacer (500), CHARACTERIZED BY THE FACT THAT the hollow core (110) passing through the connector and the external dimensions of the spacer (500) allows its insertion from above,the upper end (520) of the spacer is equipped with a radial projection (521) which cooperates with the thread of the threaded portion (120) so as to constitute a first axial stop positioning the lower end (530) of the elastic spacer in the widened portion (113) of the hollow core (110) of the connector (100), the outer surface of the spacer is provided with a vertical concave volume (523), the connector (100) is provided with a deformable portion (150) which under the action of a tool is deformed to project internally into the hollow core of the connector and cooperate with the vertical concave volume (523) of the spacer (500) which is positioned there so as to constitute a rotation stop authorizing the translation of the elastic spacer (500) in the hollow core of the connector (100), said vertical concave volume (523) having been previously positioned in front of the deformable portion (150).,

2. Device (D) according to claim 1, CHARACTERIZED BY THE FACT THAT the hollow core (110) of the connector (100) is preformed under the threaded portion (120) of a hollow (160) forming a second axial stop for said radial projection (521) in a position where the lower end (530) of the elastic spacer (500) is located in the portion of reduced diameter (112) of the hollow core of the connector (100), for the purpose of holding in position on the screw head (310) the elastic spacer (500) and the associated connector (100).

3. Device (D) according to claim 1, CHARACTERIZED BY THE FACT THAT said deformable portion (150) of the connector is constituted by a portion of thinned wall whose partial punching ensures its projection into the hollow core of the connector (100).

4. Device (D) according to claim 1, CHARACTERIZED BY THE FACT THAT said radial projection (521) is preformed at the end of a tab (522) whose elasticity allows it to change position in a translational movement of the spacer (500) in the hollow core (110) of the connector (100) from the first axial stop to the second axial stop.

5. Device (D) according to claim 4, CHARACTERIZED BY THE FACT THAT the connecting rod (200) once received in the cradle (524) prevents the bending of the tongue (522) and keeps it in position with the associated projection for the purpose of securing the second axial stop.

6. Device (D) according to any one of claims 1 to 5, CHARACTERIZED BY THE FACT THAT the connector (100) is preformed with external notches (170) for gripping purposes.

7. Device (D) according to any one of claims 1 to 6, CHARACTERIZED BY THE FACT THAT the hollow core of the elastic spacer (500) opens out at its two ends and is provided with a groove (526) for gripping purposes.

8. Device (D) according to the claim according to any one of claims 1 to 7, CHARACTERIZED BY THE FACT THAT the elastic spacer (500) and the connector (100) are dimensioned such that the elastic spacer (500) projects and is visible in the open part of the connector (100) when the radial projection (521) is in the first axial stop position.

9. Device (D) according to claim 2, CHARACTERIZED BY THE FACT THAT said hollow (160) opens out so as to allow the presence or absence of the radial projection (521) in said hollow (160) to be seen from the outside.

10. Device (D) according to any one of claims 1 to 9, CHARACTERIZED BY THE FACT THAT the elastic intermediate portion (540) of the spacer is provided with a plurality of oblong holes (541) which join as many slots (531) provided in the stop ring constituting the lower end (530), said oblong holes (541) following a helical path in the wall of the elastic intermediate portion (540).

11. Device (D) according to claim 10, CHARACTERIZED BY THE FACT THAT the external cylindrical portions of the stop ring forming the edges of the slots (531) are provided with a flat (533).

12. Device (D) according to any one of claims 1 to 11, CHARACTERIZED BY THE FACT THAT it comprises a rotation locking pin comprising a head and a rod, the rod of the pin being inserted into an imprint made in the screw head and taking up the profile of said imprint, the head of the pin being cylindrical to cooperate with a cylindrical surface formed in the hollow core of the elastic spacer to make the screw monoaxial.

13. Device (D) according to any one of claims 1 to 11, CHARACTERIZED BY THE FACT THAT the spherical head (310') is preformed with an axial cylindrical projection (311') to cooperate with a cylindrical surface (525) formed in the hollow core of the elastic spacer (500) to make the screw monoaxial (300').

14. Device (D) according to any one of claims 1 to 13, CHARACTERIZED BY THE FACT THAT it comprises a pre-assembly tool comprising a gripping module and a punching tool for the deformable part of the connector.

15. Device (D) according to any one of claims 1 to 13, CHARACTERIZED BY THE FACT THAT it comprises a fitting / impaction tool comprising a gripping module (600) for the connector and a module for relative movement between the elastic spacer and the connector, the gripping module (600) comprising two ends, one end (620) forming a handle for its user and one end (610) preformed with two branches positioned for gripping purposes on either side of the two branches of the U formed by the connector (100), the gripping module comprising a hollow core into which the relative movement module (700) is temporarily inserted, the relative movement module (700) comprising two ends: one end (720) forming a control button for its user and a support end (721) coming to bear on the upper end of the elastic spacer (500) opening into the hollow core of the connector (100),the pushing movement of the displacement module relative to the gripping module exerted by the user ensuring the descent of the elastic spacer (500) into the hollow core of the connector (100).,

16. Device (D) according to any one of claims 1 to 13, CHARACTERIZED BY THE FACT THAT it comprises a disassembly tool comprising a gripping module (600) for the connector and a gripping module (800) for the elastic T spacer (500), the gripping module (600) comprising two ends, one end (620) forming a handle for its user and one end (610) preformed with two branches positioned for gripping purposes on either side of the two branches of the U formed by the connector (100), the gripping module (600) further comprising a hollow core into which the gripping module (800) is temporarily inserted, the gripping module (800) comprising two ends: one end (820) forming a handle for its user and an expansible gripping end (810) passing from a retracted insertion position into the hollow core of the T spacer elastic (500) in a deployed gripping position,the traction movement of the gripping module (800) relative to the gripping module (600) exerted by the user ensuring the raising of the elastic spacer (500).,

17. Method for installing a fixing device (D) according to any one of claims 1 to 16, CHARACTERIZED BY THE FACT THAT it comprises a pre-assembly operation, which consists of mounting the elastic spacer (500) in the hollow core of the connector (100) by introducing by translation the elastic spacer (500) into said hollow core from the top of the connector (100), rotating said spacer (500) introduced 90 degrees so that the cradle is aligned with the U-shaped opening of the connector (100), the projection (521) cooperates with the thread (120), the vertical concave volume (523) is positioned facing the deformable portion (150) of the connector, and the lower end (530) of the elastic spacer is positioned in the widened intermediate part (113) of the hollow core of the connector, and deforming the portion deformable (150) equipping the connector in order to make it protrude into the vertical concave volume (523).

18. Installation method according to claim 17, CHARACTERIZED BY THE FACT THAT it comprises a mounting operation, which consists of threading the pre-mounted assembly onto the spherical head (310) of the screw- dicular (300), screw head (310) being positioned in the hollow core of the elastic spacer (500).

19. Installation method according to claim 18, CHARACTERIZED BY THE FACT THAT it comprises a securing operation which consists of moving the connector (100) in translation relative to the elastic spacer (500), so that the lower end (530) of the latter is positioned in the hollow core portion with reduced diameter (112) so as to prevent the elastic ring from opening and the connector (100) from being held in position on the spherical head (310), so that the projection (521) cooperates with the second axial stop.

20. Installation method according to claim 19, CHARACTERIZED BY THE FACT THAT it comprises a disassembly operation which consists of raising the elastic spacer (500) inside the hollow core of the connector (100) and thus allowing its deployment in the widened portion by a traction movement by deforming the different projections.

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