WO2007010410A1

WO2007010410A1 - Osteosynthetic implant

Info

Publication number: WO2007010410A1
Application number: PCT/IB2006/002824
Authority: WO
Inventors: Jérôme LEVIEUX
Original assignee: Spineart Sa
Priority date: 2005-06-30
Filing date: 2006-06-26
Publication date: 2007-01-25
Also published as: FR2887755B1; FR2887755A1

Abstract

The invention concerns an implant (1) for an osteosynthetic device comprising a bone anchoring device provided with a bone anchoring system (2) and a head (3) for fixing a coupling element (4), the head (3) including two lateral branches (5, 5v) delimiting a channel (6) for receiving the coupling element (4), and a component (7) for locking the coupling element (4), one of the lateral branches (5v) including internally a lining for guiding the locking component (7), the width of the locking component (7), the spacing of the lateral branches (5, 5v) and the width of the coupling element (4) being adapted such that the coupling element (4) is enclosed between the other lateral branch (5) and the locking component (7).

Description

The present invention relates to an osteosynthesis implant including the spine and a device for fixing several vertebrae together and support the spine.

For various pathologies, spine surgeons are made to fix two or more vertebrae together. They use for this purpose different osteosynthesis systems. All have at least one anchoring element and a connecting element which are secured to one another. These systems can be classified into two major families: systems whose connecting element is a plate and systems whose connecting element is a generally cylindrical bar and often provided with roughness on the surface.

The systems comprising a connecting element which is a bar are themselves classifiable in several families: those whose anchor element has a U-shaped slot or a bore in which the bar is housed, and those which have an intermediate element similar to a clamp which is fixed on the anchoring element and pinches the connecting element.

Among the systems whose anchor element has a slot there are so-called "monoaxial" systems and so-called "polyaxial" systems. Monoaxial systems imply that the connecting element is locked at a fixed angle with respect to the anchoring element, while the polyaxial systems have a ball joint allowing the elements to be locked in almost any relative position.

For simplicity of use by surgeons, polyaxial systems are now preferred.

While these systems allow surgeons some tolerance in the placement of anchoring implants, they have several disadvantages that complicate the surgical procedure and therefore increase the risk of operative fault.

Indeed polyaxial systems currently available have an anchor element having an articulated head and movable on a ball joint, and a element of ocage to come ixer es i éren es parties. The articulated head remains mobile until the surgeon has fixed the assembly. It can then move freely, which makes perilous the establishment of the connecting element, especially in cases of long fixtures (more than three anchors in which we just insert the connecting element).

Moreover, the blocking element must be installed during the operation by the surgeon and this operation is more or less delicate depending on the case.

In addition, the anchoring elements are made of several parts, which increases their manufacturing price. Conventionally, as described for example in FR-A-2 658 414 or 2 680 461 or EP-A-0 283 373 or 0 348 272, the fixing body of the cylindrical connecting element comprises a thread which guides a locking screw of said connecting element in a radial direction relative to this connecting element, collinear with the point of contact of the connecting element on which the locking pressure is exerted, so that the connecting element is pressed against The bottom of the U-shaped slot or bore. In FR-A-2 802 796, the locking screw is offset, but again, thanks to a flange or a conical end, presses the connecting element against the bottom of the U-slot.

However, the Applicant has designed a new type of osteosynthesis implant that preserves the placement tolerance of the anchoring elements and overcomes the aforementioned drawbacks.

Unlike the prior art, according to the invention, the axis of movement of the locking screw follows a direction offset from the point of contact of the connecting element on which is exerted the blocking pressure and n encloses and does not block the connecting element against the bottom of the U-slot or the bore, but encloses it and locks it laterally. The locking forces are therefore exerted perpendicularly to the branches of the U and not towards the bottom of the slot. Also contrary to the prior art, according to the invention, the locking screw does not rest on a threaded cylinder or on the two opposite U-shaped branches, but on a single branch and on the connecting element itself. in support against the other branch.

This is why the present application relates to an implant for an osteosynthesis device comprising: an anchor for bone anchoring provided with a bone anchoring system and a fixing head for a connecting element, in which the head comprises two lateral branches delimiting between them a receiving channel of the connecting element, and also comprising: - an elongate locking member of the connecting element, characterized in that one of the lateral branches has internally a bowl (or casing) for guiding the locking piece, the width of the locking piece, the spacing of the lateral branches and the width of the connecting element being adapted so that the connecting element is clamped between the other lateral branch and the locking piece.

The implant for osteosynthesis device according to the invention is advantageously monobloc.

The bone anchoring system may in particular comprise a hook to attach for example behind a pedicle. It preferably comprises a screw, and the implant according to the invention is then in particular a pedicle screw.

The fixation head is installed at the end of the bone anchoring system. It advantageously has a generally spherical or cylindrical configuration. Preferably one or advantageously several flats reduce the dimensions. The head comprises a receiving channel of the connecting element which is an elongated slot in which a segment of the connecting element is placed. This slot delimits two branches installed laterally on the head. The connecting element is supported on one of the branches, and the locking piece of the connecting element is supported on the other branches. The bottom of the elongated slot, located on the side of the anchoring system, may be flat, concave or preferably convex.

Under preferred conditions of implementation of the invention the branch on which the connecting element is supported and therefore forming a stop may be full, or provided with any means (s), preferably holes or recesses allowing the connecting element to rest on the wall in several distinct areas.

The connecting element is advantageously a preferably cylindrical rod, in particular of homogeneous section. Its surface can be smooth but uomμreπα avan ageusemen es aspérés, for example, diamond points, streaks or ribs.

The elongate locking piece of the connecting element may be a lug, but preferably a bolt or a threaded screw (e). This screw or bolt advantageously comprises one or more slots for screwing with the aid of a suitable screwdriver, or in particular a profiled hole, in particular with hexagon bolts for screwing with the aid of an Allen key. The elongated blocking piece is generally rectilinear, without collar or other embossed.

One of the lateral branches is internally cascaded to guide the locking piece in the locking position of the connecting element.

The branches are preferably of the same length, in particular to provide a wide range of angulations between the connecting element and the body of the implant (that is to say to the axis of the anchor screw in the case of a pedicle screw) but one of them may be shorter than the other of 5, 10, 15, 20, 25, 30, 35 or 40%, the length being measured along the axis general of the implant for osteosynthesis device including a pedicle screw.

The elongated locking piece of the connecting element can be guided parallel to the inner wall of the receiving channel against which the connecting element is clamped. But the guide axis of the elongate locking piece may form an open or closed angle, for example from 1 to 10 °, preferably from 2 to 8 °, in particular from 4 to 8 °. If the angle is open relative to the clamping direction of the locking piece, the connecting element is even better blocked in the receiving channel since the output of the latter is narrower.

This is why the rectilinear side of the elongated blocking member acting on the connecting element is therefore generally parallel to the inner wall of the receiving channel against which is enclosed the connecting element.

Under preferred conditions of implementation of the invention, the inner bowl that has one of the side branches is threaded and the locking piece of the connecting element is a threaded screw. For the sake of simplification of the presentation, below we will deal with the case of a tapered inner bowl with arcuate cross-section, cooperating with a screw.

The inner cup provided on one of the branches for guiding the locking screw of the connecting element does not fully incorporate said screw. This . . . _. ,,. ,. Inner casing can be very flush. An arcuate casing of 20 or less is sufficient for effective guidance. However, in other preferred conditions of implementation of the invention, the casing in a circular arc is advantageously greater than 60 °, preferably greater than 90 °, especially greater than 180 °, particularly greater than 200 ° more particularly greater than 250 °. An inner casing in an arc of greater than 180 ° circle, thus surrounding the screw on more than half of its circumference allows the natural maintenance of the screw. Thus, the implant can be manipulated with the screw partially engaged without risk of falling thereof. The bowl may partially close to form a tube. But as the cooperation between the locking screw and the connecting element is on the side of said locking screw, the latter must be free over most of its length to allow this cooperation.

The arc angle values given above do not mean that the arc is continuous, but relate to the end values of the theoretical arc. For example, two diametrically opposed 10 ° arcs allow the natural retention of the screw as a continuous arc of more than 180 °.

The channel provided between the two lateral branches for the installation of the connecting element may be central vis-à-vis the head. In still other preferred conditions of implementation of the invention, this channel is offset laterally with respect to the axis of the head of the implant, as shown in the figures. This configuration assists the surgeon in aligning the channels of several anchors implanted on a plurality of vertebrae, for example by screwing one pedicle screw adjacent to another another half a turn more or less to shift one relative to the other. other the reception channels of two adjacent spinal screws. In particular, in the case of a pedicle screw where the axis of the head of the implant and the axis of the screw are generally collinear, the channel is offset laterally with respect to the axis of the screw.

The various elements are normally manufactured in the materials conventionally used in spinal implantology (in particular titanium alloy TA6V4 or medical Inox).

The implant according to the invention is used for example, and preferably, as follows: The following is a discussion of the case of an implant with a threaded inner cup cooperating with a screw, the connecting element being a rod.

When two pedicle screws have been screwed into the pedicles of two adjacent vertebrae, oriented so that the receiving channels of the connecting element are aligned, the rod is installed in these channels, if the locking screws are not previously installed against the internal threaded bowl, they are installed, screwed, the screw comes to a stop about tangential to the rod, then screws more firmly and the screw continues its progression and then presses the rod placed in a good position against the opposite branch to that of the screw. The rod is thus pinched between the side of the screw and the opposite branch to that guiding the screw

As understood from the above, the tightening of the rod tends to spread the branches. Therefore, in yet other preferred conditions of implementation of the invention, a ring or a perforated lid to allow access to the clamping instrument, for example a screwdriver, is installed on the upper part of the head. of fixation. For this purpose, the outer portion of the upper part of the fixing head is advantageously hollowed out or comprises a groove. Such strapping techniques to avoid spacing are part of the general knowledge of the mechanic and are conventionally used in the same arrangement in various fields, as varied as for example the cooperage, or the field of electrical connections as described for example in FR-A -938 922, GB-A-447 323 or US-A-4 526437. The use of a ring of small width leaves the greatest freedom of installation of the rod at various angles. A strapping also makes it possible to reduce the section of the fixing head.

The present application also relates to a kit for osteosynthesis above, characterized in that it comprises at least two implants above for osteosynthesis device and a connecting element of suitable size.

The implants for osteosynthesis device object of the present invention have very interesting properties and qualities. They allow in particular a non-perpendicular position between the anchoring element and the connecting element. Their design allows one-piece manufacturing, which solved pro ects e mo i es es ar cu ed on ro ueee e manufacturing linked to the multiplication of the parts constituting the implants.

In addition, the implants which are the subject of the present invention have, if desired, their own blocking element which is not to be added by the surgeon, a gesture that can be delicate.

Another advantage of the present invention is that the implants above allow to fix the connecting element in position not necessarily perpendicular to the body of the implant (that is to say to the axis of the screw anchoring in the case of a pedicle screw). By non-perpendicular position within the meaning of the present invention is meant that the connecting element can form an angle of greater than 90 ° to less than 170 °, preferably 95 to 160 °, very preferably 100 to 140 °.

In addition, it is not necessary, as in the prior art to screw a stop screw to lock the connecting rod against the bottom of the channel. Partial screwing is enough, which shortens the duration of the intervention.

These qualities justify the use of the kits described above, to fix between them at least two vertebrae.

This is why the present application also relates to the use of a kit according to the invention for fixing between them at least two vertebrae.

The preferred conditions of implementation of implants described above also apply to the other objects of the invention referred to above, including kits and their uses.

The invention will be better understood if one refers to the appended drawings in which:

FIGS. 1, 2 and 3 are side views of an implant according to the invention, in the configuration of a spinal screw,

- Figures 4 and 5 are top views of an implant according to the invention, respectively corresponding to Figures 2 and 3.

FIG. 1 represents an implant according to the invention, in the form of a spinal screw. imp an comprises on a king e sys th anchoring bone, in this case a screw 2 (whose threads are not shown) and on the left a head 3 for fixing a connecting element (not shown).

The fixing head 3 comprises two lateral branches 5, 5v which provide the head, seen laterally along the axis of a connecting element, a generally U-shaped.

Thus, the two lateral branches 5, 5v delimit between them a channel 6 for receiving a connecting element. In the illustrated embodiment, the branch 5v shown at the top of the figure is, seen from this angle, wider than the other branch 5. The two branches have the same length.

The bottom 8 of the receiving channel 6 has a convex shape. Thus, it is possible to have a connecting element in many angulations relative to the axis of the screw 2. In Figure 2, we can observe the same elements as in Figure 1, but can be observed in addition to connecting blocking piece 7, which in this embodiment is a bolt 7.

As seen above, the branch 5v shown at the top of the figure is wider than the opposite branch 5. It includes a threaded bowl parallel to the axis of the screw 2 and shifted upwardly from the diagram and can thus gird the bolt 7. As it continuously surrounds the latter over more than 180 degrees, here about 270 degrees, the bolt 7 naturally fits in his dwelling.

The bolt 7 has straight sides, shown horizontally in the figure, from one end to the other.

As seen in the figure, a portion of the bolt 7 forms a protuberance beyond the branch 5v, protuberance directed inwardly of the receiving channel 6.

In the version shown here, the bolt 7 is guided parallel to the axis of the screw 2. It has been realized a version where the bolt 7 is not guided parallel to the axis of the screw 2 but forms an open angle of 6 ° with respect to the tightening direction of the locking piece. The bolt 7 is not horizontal as shown in this figure 2, but goes from the left to the right of the diagram. In Figure 1, the same elements are used as in Figure 2 and in Figure 1, but in addition an element 4 has been installed for connecting several spinal screws of this type.

Here, the connecting element 4 is a cylindrical rod 4 ribbed surface.

Two connecting rods 4 are shown here to illustrate the angular and lateral installation tolerance of the connecting rods 4, authorized by the implants according to the invention.

As is still observed in the figure, the spacing between the lateral branches 5 and 5v, the diameter of the bolt 7 and the diameter of the rod 4 are adapted so that the rod is clamped between the branch 5 shown at the bottom of the Figure, and the bolt 7, more precisely the side of this bolt 7. The rod 4 is not pressed against the bottom of the U-shaped head, but wedged between the side branches 5, 5v, directly pressed against the branch 5 , and indirectly through the bolt 7, against the branch 5v.

All the different dimensions can be adapted to give all the desired tightening.

It is of course necessary to take into consideration the threads of the bolt 7 and the surface texture of the connecting rod 4. In Figures 1, 2 and 3, it may be noted that the receiving channel 6 is offset laterally with respect to the axis of the head and the screw of the implant. This configuration helps the surgeon to align the channels 6 of several anchors implanted on several vertebrae.

FIG. 4 is a view from above of FIG. 2, that is to say an axial view of the spinal screw 1.

It can be observed that the upper branch 5v surrounds on three quarters of its circumference, the bolt 7.

A hexagonal recess 9 is machined in the latter, to receive, in this version, an Allen key to proceed to tighten the bolt 7 blocking.

FIG. 5 is a view similar to that of FIG. 4, but corresponding to FIG. As mentioned in FIG. 4, it is possible to observe the installation of the rod 4 allowing the connection between several implants of the same general type.

It can be seen that the connecting rod 4 is pressed by the side of the locking bolt 7 against the lower branch 5 with which it comes into contact along two surfaces to the left and to the right of the figure.

The side of the locking bolt 7 guided by the branch 5v is parallel to the contact surface of the opposite branch 5 against which it is pressed. The locking of a rod 4 is therefore here at three points (more precisely three surfaces, namely the outer ends of the branch 5 does not include the bolt 7, and the portion of the bolt 7 located in the center of the implant.

In this diagram, it is better understood that it is not necessary that the bolt 7 is almost completely surrounded by the branch to act effectively.

The connecting element 4 can interconnect different types of implants, for example spinal screw and spinal hook type implants. When it is desired to minimize the dimensions of the head 3 of an implant according to the invention, it is possible to provide, towards the ends of branches 5, 5v situated to the left of FIGS. 1, 2 and 3, a cap, a ring or a ring which can be installed (e), including soft friction, around the ends of the branches 5, 5v, to prevent them from deviating from each other during tightening.

In such a case, instead of being curved as shown in Figures 1, 2 and 3, the ends of the branches 5 and 5v are not rounded, but straight. In fact, the head then has a generally cylindrical shape.

In the case of an implant such as that shown here, the ring will not be circular, but will include two parallel straight portions and two rounded portions interconnecting the opposite ends of the parallel straight portions.

Claims

1. An implant (1) for an osteosynthesis device comprising: - a device for bone anchoring provided with a system (2) for bone anchoring and a head (3) for fixing a connecting element (4), wherein the head (3) comprises two lateral branches (5, 5v) delimiting between them a channel (6) for receiving the connecting element (4), and also comprising:

- an elongated piece (7) for blocking the connecting element (4), characterized in that one of the lateral branches (5v) internally comprises a bowl for guiding the piece (7) blocking, the width of the piece (7) blocking, the spacing of the lateral branches (5, 5v) and the width of the connecting element (4) being adapted so that the connecting element (4) is sandwiched between the other lateral branch (5) and the blocking piece (7).

2. An implant (1) according to claim 1, characterized in that it is monobloc.

3. An implant (1) according to claim 1 or 2, characterized in that the bottom of the channel (6) for receiving the connecting element (4) is convex.

4. An implant (1) according to one of claims 1 to 3, characterized in that the leg (5) on which the connecting element (4) comes to bear is provided with orifices or recesses allowing the connecting element (4) to rest on its wall in several distinct areas.

5. An implant (1) according to one of claims 1 to 4, characterized in that the piece (7) for locking the connecting element (4) is a bolt or a screw (e) (7) .

6. An implant (1) according to one of claims 1 to 5, characterized in that one of the lateral branches (5v) is internally cascaded to guide the locking piece (7) in the locking position of the element link (4).

7. An implant (1) according to one of claims 1 to 6, characterized in that the guide axis of the locking piece (7) forms an open or closed angle of 1 to 10 °, relative to the internal wall of the lateral branch (5) against which the connecting element (4) is clamped.

. It is also possible to provide an interior cup having one of the lateral branches (5v) and the locking piece (7) of the connecting element (4) is a screw. threaded.

9. An implant (1) according to one of claims 1 to 8, characterized in that the bowl is arcuate greater than 180 °.

10. An implant (1) according to one of claims 1 to 9, characterized in that the channel (6) provided between the two lateral branches (5, 5v) for the installation of the connecting element (4) is offset laterally with respect to the axis of the head (3) of the implant (1).

11. A kit for osteosynthesis characterized in that it comprises at least two implants for osteosynthesis device as defined in one of claims 1 to 10 and a connecting element (4) of suitable size.