FR2870449A1 - An rigid, hollow intervertebral implant with a rounded anterior part and convex upper and lower surfaces with areas of roughness and lateral conical openings in directions away from the vertebral plate - Google Patents

Abstract

An intervertebral implant rigid and hollow inside which has a rounded anterior part and upper and lower support surfaces against the vertebral plates which have a convex shapes when viewed in the sagittal plane, are linked in a fixed way to the rounded anterior part and present roughened areas suitable to penetrate slightly into the vertebral bones at the level of the vertebral plates. The rounded anterior part is hemispherical, domed or a pyramid with domed sides. The implant has an internal cavity opening to the exterior on the upper and lower surfaces and the areas of roughness are disposed longitudinally on either sid of the openings. The implant may also comprise lateral openings on the sides not facing the vertebral plate after implantation. These are conical with the largest aperture on the exterior. The areas of roughness are in the form of saw teeth, successive flanges or screw threads. It is disclosed that the hollow interior is intended to receive a natural or synthetic graft suitable for colonization by the bone cells after implantation.

Description

The present invention relates to an intervertebral implant.

  It is well known to insert a rigid implant, hollow internally, between two vertebrae. Such an implant has the function of restoring the distance and the anatomical position of these vertebrae, and of making a relative immobilization of these vertebrae by growth of the bone cells through the implant.

  For the placement of an implant, a suitable housing is arranged through the intervertebral disk and, where appropriate, in the vertebral trays. The vertebrae are then distracted and the implant is put in place by means of a suitable instrument to which it is connected.

  Existing implants of this type have the drawbacks of presenting insertion difficulties between the vertebrae and the risk of expulsion due to the repeated movements of the vertebrae. In addition, when the vertebral endplates have been started at the time of the development of said housing or the implants have limited support surfaces against these trays, such implants pose a risk of penetration into the bone of the vertebrae.

  The present invention aims to remedy all of these disadvantages in the best conditions.

  According to the invention, the implant concerned comprises: a rounded anterior part, and upper and lower bearing surfaces against the vertebral plates, having convex shapes seen in the sagittal plane and being continuously connected to said portion. anterior rounded, these upper and lower bearing surfaces having multiple asperities clean to penetrate slightly into the vertebrae bone at the vertebral endplates.

  The rounded anterior part and the connection of said upper and lower surfaces to this anterior part make it possible to very significantly facilitate the insertion of the implant between two vertebrae and to limit the dimensions of the housing that it is necessary to arrange to receive this implant. . This accommodation is thus easier to arrange, which is safe for the practitioner given the nearby presence of nerves and spinal cord.

  The rounded anterior portion further confers the aforementioned convex shape to said upper and lower bearing surfaces, which are then well adapted to the natural shape of the vertebral trays. The implant is thus supported against these trays by relatively large surfaces, eliminating too punctual support that can generate the risk of insertion of the implant in a tray. These forms of bearing surfaces also allow a self-retention effect of the implant between the vertebrae, preventing the risk of expulsion of the implant.

  The dimensions of said bearing surfaces also make it possible to arrange a relatively large number of asperities intended to penetrate slightly into the bone of the vertebral plates, which ensure, together with the shape of said upper and lower surfaces, a perfect retention of the implant between the vertebrae.

  The rounded anterior portion may have a substantially hemispherical, domed or "domed" pyramid shape, depending on the shape of the implant (generally parallelepipedal or cylindrical shape).

  Advantageously, the internal cavity of the implant opens on the outside of the implant at said upper and lower bearing surfaces, and said asperities are arranged longitudinally, on either side of the upper and lower openings of this cavity. .

  The cavity is intended to receive a graft, natural or synthetic, able to be colonized by bone cells during the growth of these cells after implantation. The large openings through which this cavity opens on the outside of the implant allow a large contact surface of the graft with the surrounding bone tissue; the asperities, located near the longitudinal edges of these openings, allow to slightly brighten the tissues during the placement of the implant and, in doing so, promote the bone fusion of the graft with the surrounding bone tissue.

  The implant may also include lateral openings, that is to say opening into its walls not turned towards the vertebral plates after implantation.

  These lateral openings also promote contact of the graft with the surrounding bone tissue. They may have conical shapes, with their larger diameters arranged on the outside of the implant.

  In applications other than lumbar, especially for application to cervical vertebrae, the implant according to the invention may comprise a plurality of openings arranged through its wall, distributed over its surface, to allow the arrival of the graft content in the implant in contact with surrounding bone tissue.

  The asperities can be in the form of teeth with broken line profile or sawtooth profile, or in the form of successive flanges. They can also be in the form of turns of a net, the implant then being inserted is held between the vertebrae by screwing.

  The structure of the implant according to the invention is well suited to an embodiment of this implant in polyaryletheretherketone, a material known by the abbreviation "PEEK".

  This structure is also well suited to pre-filling the implant with graft.

  The invention will be better understood, and other features and advantages thereof will appear, with reference to the appended diagrammatic drawing, representing, by way of nonlimiting example, several possible embodiments of the implant that it concerns. .

  Figures 1 to 4 are views respectively in perspective, from the side and from above, according to a first embodiment; Figures 5 to 8 are views respectively in perspective, from above and from the side, according to a second embodiment, and Figures 9 to 11 are views respectively in perspective, from above and from the side, according to a third embodiment.

  For simplicity, parts or elements of an embodiment that are identical or similar in another embodiment will be identified by the same reference numerals and will not be described again.

  Figures 1 to 4 show an intervertebral implant 1 to be inserted between two vertebrae to restore the distance and anatomical position of these vertebrae, and to achieve a relative immobilization of these vertebrae by growth of bone cells through it.

  The implant 1 according to these Figures 1 to 4 has a generally parallelepipedal shape, with an anterior portion 2 (relative to the direction of insertion of the implant between the vertebrae) shaped "pyramid with curved faces", faces upper and lower 3 (that is to say intended to come opposite the vertebral plates after implantation) of convex shapes seen in the sagittal plane (see Figure 3), the flat side walls 4 and a rear wall 5.

  The upper and lower faces 3 and the side walls 4 are connected continuously to the front part 2.

  The upper and lower faces 3 have two large oblong openings, through which an internal cavity 6 delimited by the implant 1 opens on the outside of this implant, and comprises, at the longitudinal edges of these openings, asperities 7 profile sawtooth, able to penetrate slightly into the vertebral trays bone.

  The side walls 4 comprise lateral openings 8 having conical shapes, with their larger diameters arranged on the outside of the implant 1.

  The posterior wall 5 comprises a hole 9 and two notches 10 for mounting the implant 1 on an impaction instrument.

  The cavity 6 is intended to receive a graft (not shown), natural or synthetic, able to be colonized by bone cells during the growth of these cells after placement of the implant 1.

  In practice, a suitable housing is arranged through the intervertebral disc and, where appropriate, in the vertebral endplates. The vertebrae are then distracted and the implant 1 is put in place by means of said instrument.

  The anterior part 2 and the connection of said surfaces 3 and 4 to this anterior part 2 make it possible to very significantly facilitate the insertion of the implant 1 between the two vertebrae and to limit the dimensions of the housing which it is necessary to arrange for 1. Part 2 makes it possible to confer the aforementioned convex shape on the surfaces 3, which prove to be well adapted to the natural shape of the vertebral endplates; the implant 1 thus bears against these trays by relatively large surfaces, which eliminate too punctual supports that can generate a risk of insertion of the implant 1 in a vertebral plateau. These forms of bearing surfaces 3 also allow a self-retention effect of the implant 1 between the vertebrae, preventing the risk of expulsion of the implant.

  The dimensions of said bearing surfaces 3 also make it possible to arrange a relatively large number of asperities 7 which, together with the shape of these surfaces 3, ensure perfect retention of the implant 1 between the vertebrae.

  The large openings through which the cavity 6 opens onto the outside of the implant 1 allow a large contact surface of the graft contained in the implant 1 with the surrounding bone tissue; the asperities 7, located near the longitudinal edges of these openings, allow to slightly bust the bone tissue during the establishment of the implant 1 and, in doing so, promote the fusion of the graft with the surrounding bone tissue.

  In its embodiment shown in Figures 5 to 8, the implant 1 has a generally cylindrical curved wall shape and comprises an anterior portion 2 of curved shape, more or less hemispherical. The asperities 7 are formed by the turns of a thread, the implant 1 then being put in place by screwing.

  Figures 9 to 11 show an implant 1 more particularly for the treatment of cervical vertebrae. This implant 1 comprises a thread and is also intended to be put in place by screwing. Its anterior portion 2 is in the form of a flattened dome, and it comprises a plurality of radial openings 11 arranged through its wall.

  As can be seen from the foregoing, the invention provides an intervertebral implant having, relative to homologous implants of the prior art, the decisive advantages of being relatively easy to insert between the vertebrae to be treated and to present risks of expulsion. reduced. In addition, this implant has a reduced risk of penetration into the bone of the vertebrae, and allows a fusion of the graft and vertebrae operates under the best conditions.

  It goes without saying that the invention is not limited to the embodiment described above by way of example but that it extends to all embodiments covered by the appended claims.

Claims (7)

  1 Intervertebral implant (1), rigid and internally hollow, characterized in that it comprises: - a rounded anterior part (2), and - upper and lower surfaces (3) bearing against the vertebral plates, having shapes convexes viewed in the sagittal plane and being continuously connected to said rounded anterior portion (2), said upper and lower bearing surfaces (3) having multiple asperities (7) adapted to penetrate slightly into the bone of the vertebrae at level of the vertebral trays.   2 intervertebral implant (1) according to claim 1, characterized in that the rounded front portion (2) has a substantially hemispherical shape, dome or "curved-face pyramid".   3 intervertebral implant (1) according to claim 1 or claim 2, characterized in that it defines an internal cavity (6) opening on the outside of the implant (1) at said upper and lower surfaces (3) support, and in that said asperities (7) are arranged longitudinally, on either side of the upper and lower openings of this cavity (6).   4 intervertebral implant (1) according to one of claims 1 to 3, characterized in that it comprises lateral openings (8), that is to say opening into its walls (4) not turned towards the vertebral plates after implantation .     Intervertebral implant (1) according to claim 3, characterized in that said lateral openings (8) have conical shapes, with their larger diameters arranged on the outer side of the implant (1).   6 intervertebral implant (1) according to claim 1 or claim 2, characterized in that it defines an internal cavity (6) opening on the outside of the implant (1) and in that it comprises a plurality of openings (11) arranged through its wall, distributed over its surface.   7 intervertebral implant (1) according to one of claims 1 to 6, characterized in that the asperities (7) are in the form of teeth sawtooth profile, successive flanges, or turns of a net.   8 intervertebral implant (1) according to one of claims 1 to 7, characterized in that it is made of polyaryletheretherketone material known by the abbreviation "PEEK".