Vertebral osteosynthesis equipment

Vertebral osteosynthesis equipment is disclosed, including a connection assembly with a connection piece of open type and a mating component piece positioned one with respect to the other. The connection piece includes a hole, where the mating piece is dimensioned to be engaged in the interior of the hole in a fit adjusted manner and is slidable within the hole. The connection piece is assembled to the mating component piece in separated apart position based on a force that is less than a clamping force exerted by a nut to be screwed on to a proximal threaded pin of an anchoring member that can be tightened so as to bring the connection piece and the mating component piece in a close position.

BACKGROUND

The present invention relates to a vertebral osteosynthesis equipment.

A vertebral osteosynthesis equipment includes, in a manner that is well known per se:at least one rigid rod intended to be extending along several vertebrae, and in general two rods intended to be placed on either side of the spinous processes of the vertebrae;bone anchoring members, such as screws or laminar hooks, intended for anchoring the rod or rods to the vertebrae to be treated; each bone anchoring member has a proximal threaded pin and a support surface;connection pieces to be used for connecting the rod or rods to the bone anchoring members, each connection piece having a hole for the engagement thereof on to the proximal threaded pin of a bone anchoring member and a receiving channel for the engagement of an aforementioned rod; andnuts intended to be screwed on to the proximal threaded pins of the bone anchoring members in order to tighten the connection pieces against the said support surfaces.

A known device of this type is described in particular in the published patent application No. WO 98/55038; in this device, each connection piece is of the “closed” type, that is to say it has a closed portion for delimiting the said receiving channel for receiving one aforementioned rod. Such a rod can thus only be engaged axially in this channel.

Known equipments also include, in particular as detailed in the published patent applications Nos U.S. 2013/072991 A1, U.S. 2002/169450 A1or FR 2 765 093 A1, devices comprising connection assemblies with each including a connection piece of “open” type, that is to say, having a curved portion that is adapted to only partially enclose a rod as mentioned above, and a mating component piece that, in a closer position relative to the curved portion, makes it possible to close the channel delimited by this curved portion in order to retain a rod engaged in the said channel. The connection piece and the mating component piece are provided with holes for the engagement thereof on to the proximal threaded pin of the anchoring member and comprise positioning means to ensure the positioning of one in relation to the other in a mounting position in which these holes come to be coincident with each other.

The vertebral osteosynthesis equipment according to the aforementioned prior art documents have the disadvantage of not being very easy to implement as implants due to the fact that the connection pieces and the mating component pieces are to be set in place and positioned one after another, at the bottom of the cavity, and because they have reduced dimensions, which make the risk of their escape quite high. The impact of these drawbacks are felt all the more given that the successive assembly and disassembly of the rods and connection assemblies must be carried out in order to test the curvature of the vertebral rods during the surgical intervention so as to assess whether the form and shape of the rods are such as to allow for the desired correction or adjustment to be obtained.

SUMMARY

The object of the present invention is thus to remedy these essential drawbacks.

The concerned equipment includes:at least one rigid rod intended to be extending along several vertebrae, and in general two rods intended to be placed on either side of the spinous processes of the vertebrae;bone anchoring members, such as pedicular screws or laminar hooks, intended for anchoring the said rod to the vertebrae to be treated; at least one bone anchoring member has a proximal threaded pin and a support surface;connection assemblies to be used for connecting the rod to the bone anchoring members; at least one connection assembly includes a connection piece of “open” type, that is to say, having a curved portion that delimits a receiving channel for receiving the rod and which is adapted to only partially enclose the rod, and a mating component piece that is movable relative to this said connection piece; the mating component piece is movable between a separated apart position relative to the said curved portion, in which it does not hinder the transverse engagement of the rod in the receiving channel, and a closer position relative to the said curved portion, in which the mating component piece closes the receiving channel and retains the rod in this channel; the connection piece and the mating component piece are provided with holes for engagement thereof on to the said proximal threaded pin and comprise positioning means to ensure their proper positioning in relation to one another in a mounting position in which these holes come to be coincident with each other; andat least one nut intended to be screwed on to the said proximal threaded pin so as to clamp the connection piece and the mating component piece between itself and the said support surface and to thereby bring the connection piece and the mating component piece into the said closer position;the said positioning means include:the hole in the said connection piece;a portion of the said mating component piece, dimensioned so as to be engaged in the interior of this hole in a fit adjusted manner and so as to be slidable in this hole;

andthe said connection assembly comprises:assembly means for assembling of the connection piece to the mating component piece, thereby causing the connection assembly to have a unitary structure, andmaintaining means for maintaining in place the said mating component piece in the said separated apart position, allowing for the maintaining in place of this mating component piece relative to the connection piece, this maintaining in place being brought about based on a force that is less than the clamping force exerted by the nut during the screwing of this nut on to the said proximal threaded pin.

Thanks to use of the said assembly means, the connection assembly has a unitary structure that enables the easy handling of the equipment according to the invention, without requiring the repeated installing in place and removal of separate pieces, having reduced dimensions. The maintaining means provide the ability to maintain in place the mating component piece in the said separated apart position, in order to facilitate the successive installing in place and removal of the rod or rods from the connection assemblies. When it comes to carrying out the final mounting of the equipment, the nuts are screwed on, which removes the maintained hold created by the maintaining means and makes it possible to bring the mating component pieces into the closer position relative to the curved portions, and to thereby bring about the closing of the engaging channels for engaging the rod.

The said assembly means and the said maintaining means may be constituted by means of the appropriate sizing of the hole of the connection piece and by the appropriate sizing of the said portion of the mating component piece which would be such that there would exist friction between this connection piece and this portion, thereby enabling the assembly and maintenance in place of these pieces; according to one preferred embodiment of the invention, however, the said assembling means and the said maintaining means are formed by respective engagement portions of the connection piece and of the said portion of the mating component piece brought into engagement with one another, and which are capable of being brought out of engagement when the said nut is screwed on.

According to a first possible embodiment of the invention, in this case, the said assembling means and the said maintaining means comprise a collar flange formed on to one among the connection piece and the mating component piece and by a groove provided in the other piece, the collar flange being capable of being positioned and retained in the groove in the absence of the clamping force exerted by the nut, and being capable of being extracted from this said groove during the screwing of the nut.

Preferably,the said groove is formed in the connection piece, andthe said portion of the mating component piece is formed by a series of snapping teeth disposed in a circle, forming together, externally, the said collar flange, the said teeth being resiliently movable between a radially outer position, in which the said collar flange is capable of being engaged in the said groove, and a radially inner position, in which the said teeth are deflected in a manner so as not to be an impediment to the sliding of the mating component piece in the hole that the connection piece includes.

In addition to maintaining of the mating component piece in the separated apart position, this embodiment provides for the bearing of the teeth against the connection piece along a reduced surface area, and therefore with limited friction, which allows for a relatively easy return, if necessary, of the mating component piece and of the mating component piece in the separated apart position.

According to a second possible embodiment of the invention,one among the connection piece and the mating component piece has an elongated aperture formed parallel to the direction of movement of these pieces during their passage from the said separated apart position to the said closer position; this elongated aperture is delimited by longitudinal edges and at least one of the longitudinal edges has a protuberance projecting out towards the interior of the elongated aperture; this protuberance subdivides the elongated aperture into a hold maintaining housing and a sliding portion;the other among the connection piece and the mating component piece includes a pin engaged through the elongated aperture and capable of sliding therein from the hold maintaining housing up to the sliding portion, by crossing over by force the said protuberance during this sliding.

In the separated apart position where the connection piece and the mating component piece are separated, the pin is located in the hold maintaining housing, which ensures the assembly of the connection piece and the mating component piece and maintains in place these pieces in the separated apart position. When the nut is screwed on to the said threaded pin and moves these two component pieces relative to one another, the pin crosses over the protuberance by force, in a manner such that the hold enabled by this pin and this protuberance is removed and that the two pieces can be brought in said closer position.

Preferably, the two longitudinal edges delimiting the elongated aperture each have a protuberance and the two protuberances are located so as to be facing one another.

A clear hard point is thus formed.

Preferably, the two longitudinal edges delimiting the elongated aperture each have two protuberances and each protuberance is located so as to be facing a protuberance situated on the opposite edge, the two pairs of protuberances delimiting an intermediate hold maintaining zone, thus making it possible to maintain the pin in place therein, and therefore to maintain the connection piece and the mating component piece in an intermediate position between the separated apart position and the closer position mentioned above.

Preferably, the hold maintaining housing is fit adjusted to the pin in a manner so as to keep this pin immovable within it, and therefore to keep the mating component piece immovable relative to the connection piece.

Preferably, the mating component piece and the connection piece form stop surfaces which precisely determine the said closer position of these two component pieces.

Any risk of the excessive tightening of the nut, which is likely to cause deterioration in the mating component piece, is thus eliminated, and the said stop surfaces in addition provide the ability to distribute the clamping force exerted by the nut.

Preferably, the mating component piece forms a lateral extension that makes it possible to close the receiving channel for receiving the rod and this lateral extension has a cavity in the form of a hollow cylinder formed on it.

The invention will be better understood and other characteristic features and benefits thereof will become apparent by means of the description that follows, which is provided with reference made to the accompanying diagrammatic drawing; this drawing shows, by way of non-limiting examples, two possible embodiments of relevant equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 7shows a rod1, a pedicular screw2, a connection piece3, a mating component piece4, and a nut5that are included in a vertebral osteosynthesis equipment.

In a general manner, this equipment includes:two rods1intended to be placed on either side of the spinous processes of the vertebrae to be treated;a plurality of pedicular screws2, intended to be anchored in the pedicles of these vertebrae;a plurality of connection pieces3and mating component pieces4, intended to be installed in place on the screw2; anda plurality of nuts5to be used for clamping the connection assemblies formed by the connection pieces3and the mating component pieces4on to the screws2, as is visible in thisFIG. 7.

The rods1are of the conventional type, consisting of metal rods that are to be shaped according to the correction of the vertebral column to be achieved. In the illustrated example, the said rods1have a substantially circular cross-section.

Each pedicular screw2, as represented, is of the type called “polyaxial”, that is to say comprising (seeFIG. 5) a threaded bone anchoring base6, a head7forming a surface8which constitutes a support for the said connection assembly formed by the pieces3and4, and a proximal threaded pin9connected in an articulated manner relative to the base6. In the example shown, this articulated joint is obtained in the manner described in the published patent application No. WO 98/55038, that is to say by means of a ball joint formed by a sphere (represented in broken lines inFIG. 5), that is integrally attached to the pin9. This sphere is engaged in a cavity provided in the head7and is retained in this cavity by means of crimping of the wall forming the said support surface8. This wall is shaped in a manner so as to present a peripheral surface formed as an hemisphere.

With reference toFIGS. 1 to 4, it is apparent that the connection piece3comprises a body3aand, on one side thereof, a curved portion3b.

The body3ahas:

a hole10which passes right through it from one side to the other, thereby enabling the engagement of the connection piece3on the said proximal threaded pin9,a bottom recess11that delimits a flat surface12around the bottom opening of the hole10, anda groove13that is coaxial with the hole10, arranged in a bottom area of this hole10, close to the recess11.

It will be understood that the term “bottom” is used to refer to the side of the connection piece3that is situated closest to the support surface8when the connection piece3is in place on the screw2.

The groove13is rounded and has a shallow depth, in a manner such that a snapping flange25described farther down, designed to be engaged in it as shown inFIGS. 3 and 6, may be extracted from it, as may be seen inFIGS. 4 and 7, under the effect of the clamping force exerted on the connection piece3by the nut5.

The portion3bof the connection piece3is curved in a manner so as to delimit a receiving channel15for receiving a rod1, but only partially encircles this rod, over about 180°, as can be seen inFIG. 4. The connection piece3is therefore a type of connection piece referred to as “open” type, that is to say, capable of receiving the rod1by means of transverse engagement of the rod.

The mating component piece4has a hole20passing right through it, which enables its engagement on to the said proximal threaded pin9, and includes a bottom portion4aand an top portion4b.

The bottom portion4ais in the form of a flared skirt, internally forming a hemispherical surface21for bearing against the support surface8, and forming on one side a lateral closing extension22for closing the receiving channel15. A cavity in the form of a portion of a hollow cylinder23having the same radius as the rod1, is provided on this lateral extension22.

The said bottom portion4aforms, at its top end, a planar surface24adapted to meet the surface12in the closer position shown inFIG. 4wherein the pieces3and4are locked together.

The top portion4bis formed by a series of snapping teeth disposed in a circle, each having an exterior terminal bead. The beads of the different teeth together constitute the snapping flange25mentioned above. As it is to be understood with reference toFIGS. 2 and 3, these teeth are resiliently movable between a normal position that is radially external, as may be seen inFIG. 2, and a radially internal position, as may be seen inFIG. 4, in which the teeth are resiliently deflected towards the interior of the hole20.

The top portion4bis designed to be engaged in the hole10of the connection piece3, by internal deflection of the teeth, until the latching of the collar flange25into the groove13. This latching defines the aforementioned separated apart position, in which the lateral extension22is at a distance from the free end of the curved portion3awhich is sufficient to enable a transverse engagement of the rod1, as may be seen inFIG. 6.

The internal deflection of the snapping teeth also allows for the said top portion4bto be engaged in the hole10beyond the groove13and to slide in the latter up until the closer position shown inFIG. 4. In this closer position, the lateral extension22comes to close the receiving channel15, in a manner such that the rod1engaged in this channel cannot be extracted from the channel, as can be seen inFIG. 7.

The nut5is of a known type and is thus not described in details.

In practice, the screws2(FIG. 5) are set in place in the pedicles of the vertebrae to be treated and then the assemblies of pieces3/pieces4(with each piece4in the separated apart position in relation to each piece3) are engaged on to the pins9of these different screws2, until the support surfaces21of the pieces4come up against the support surfaces8of the screws2.

The nuts5are then screwed on to the pins9up to a position of contact with the pieces3, in a manner so as to ensure the maintenance in position of the pieces4against the support surfaces8(FIG. 6); in this position, each rod1can be easily engaged in the channels15and be removed from the latter, in order to carry out the successive operations of curving and testing of the rods1.

When the rods1are completely set in the requisite shape and formed in a manner so as to make it possible to ensure the desired correction of the vertebrae, the screws5are tightened in a manner so as to move the pieces3in the direction of the pieces4and, by bringing close together the extensions22and the free ends of the curved portions3b, to close the channels15around each rod1(FIG. 7).

FIGS. 8 and 9show the second embodiment of the pieces3and4. For the purposes of simplification, the parts or elements that have already been described with reference toFIGS. 1 to 7, which happen to be found on these pieces, are denoted by the same numerical references and will not be described again.

In this case, the connection piece3has an elongated aperture30formed through its body3a, parallel to the direction of movement of the mating component piece4in relation thereto at the time of the passing of this mating component piece from the said separated apart position to the said closer position. This elongated aperture30is delimited by longitudinal edges each having two protuberances31, with each protuberance31being positioned so as to be facing another protuberance31situated on the opposite edge.

Each protuberance31is formed by inclined walls joining together so as to form a rounded top edge and is adapted to be crossed by the body of a pin40described further below.

The lower pair of protuberances31delimits, with the bottom portion of the elongated aperture30, a hold maintaining housing32having appropriate dimensions that are fit adjusted to those of the body of the pin40. The upper pair of protuberances31delimits, with the top portion of the elongated aperture30, a sliding portion33, in which the body of the pin40is capable of sliding. The two pairs of protuberances31delimit between them an intermediate hold maintaining zone34, capable of receiving the body of the pin40in a fit adjusted manner.

The mating component piece4has a circular top portion4bthat is adapted to be received in a fit adjusted manner in the hole10of the connection piece3but with the capability to slide in this hole. This top portion4bhas a threaded hole35that comes to be coincident with the elongated aperture30in the mounting position and receiving the pin40screwed into it.

This pin40has the aforementioned body, which is cylindrical and smooth, and which is intended to be received and slide in the elongated aperture30. It also has a threaded head that is intended to be screwed into the hole35.

The connection piece3in addition has a notch formed in the curved portion3b, coaxially to the hole35, and the mating component piece4has a hole formed on its side diametrically opposite to the hole35, which allows for the engagement of the pin40in these pieces3,4and the screwing of the head of this pin40into the threaded hole35.

In practice, in the space apart position of the lateral extension22and of the curved portion3b(seeFIGS. 10A and 10B), the body of the pin40is held in the hold maintaining housing32, which maintains the pieces3and4in this position. When the nut5is screwed on to the pin9, this body of the pin40comes to cross the lower pair of protuberances31and be placed in the intermediate hold maintaining zone34, which makes it possible to maintain the pieces3and4in the intermediate position shown inFIGS. 11A and 11B; this intermediate position provides the practitioner with the ability to indeed ensure the correct mounting of the rod1before the final mounting is carried out. The additional screwing of the nut5enables the body of the pin40to cross over the upper pair of protuberances31and to be placed in the sliding portion33, which makes it possible to bring the pieces3and4into the closer position shown inFIGS. 12A and 12B.

As is apparent from the foregoing, the invention provides a vertebral osteosynthesis equipment that presents the decisive advantage of making it possible to facilitate the successive operations of curving and positioning of the rods1while also obtaining a good degree of certainty of resistance over the course of time of the connection created between a rod1and a connection assembly.

The invention has been described here above with reference to the embodiments provided by way of examples. However, it goes without saying that it is not limited to these embodiments but indeed extends to all other embodiments covered by the claims appended herewith.