FR2851155A1 - Acetabular implant for prosthesis of hip, has hemispheric cup with crest where crest constitutes solid beam structure for making body of cup which forms angle of specific degrees with axis of revolution of cup - Google Patents

Abstract

The implant has a hemispheric cup (10) with a crest (15) projecting from its exterior face and screw (6) of anchorage to a bone. The crest constitutes a solid beam structure for making body of the cup which forms an angle of 25 to 45 degrees with axis of revolution of the cup and presents a length greater than ray of the cup. The cup has a cavity which is delimited by a wall in form of hollow shape portion.

Description

The present invention relates to an acetabular prosthesis implant of

hip.

  The pelvic bone can undergo significant degradations over time, at the level of the acetabular cavity, leading to deterioration and weakening of the laterally delimiting walls of this cavity, and even, in some cases, to perforation of the wall. delimiting the bottom of this cavity (see the well-known typology of Paprowsky, Perona and Lawrence).

  These degradations occur in particular after a first cotylodial implant has been put in place, making it unstable. It is then necessary to replace this implant with an implant called "recovery". This replacement involves removing the original implant, performing a bone removal to remove degraded areas, rearranging the bone site by milling, and placing the recovery implant, which has a larger diameter. to that of the original implant. Reconstitution of the bone wall by means of grafts is frequently required to reform the bearing surfaces and to position the implant correctly relative to the pelvis.

  Such a recovery implant, however, has the disadvantage of involving a reduction of bone capital, in areas already weakened and weakened. In addition, bone grafts do not offer all the guarantees of success and especially strength, and are therefore not particularly desirable in the areas of support.

  As a result, the anchoring of such an implant may not be ensured perfectly over time.

  In addition, there are cotylodial implants comprising one or more studs projecting from the outer face of the cup which they comprise, and provided with additional means of anchoring to the bone, this or these studs allowing a positioning and a fixation. cup support in the pelvic bone and said additional anchoring means for immobilizing the cup in the position determined by the or said pads.

  This or these studs, however, have a height and / or a disposition and / or an orientation that their support takes place in areas more or less deteriorated or in healthy areas underlying these areas more or less deteriorated , also likely to deteriorate.

  The anchoring of such implants can also, for this reason, not be ensured perfectly over time.

  The present invention aims to overcome this fundamental disadvantage.

  Its main objective is therefore to provide an acetabular implant, whether it is a first-line implant or a "recovery" implant, which can be perfectly immobilized with respect to the pelvic bone even in case of relatively significant deterioration of this bone at the level of the acetabulum.

  Another object of the invention is to provide an implant to achieve the above objective without inducing, compared to an existing implant, additional difficulties of implementation or significant manufacturing difficulties.

  The implant it concerns comprises, in a manner known per se, a hemispherical cup having a protrusion projecting from its outer face, and comprising means for anchoring to the bone.

  According to the invention, said projection constitutes a beam of solid and solid structure, forming a body with the cup, which forms, with the axis of revolution of the cup, an angle ranging from 250 to 450 and which has a longer length to the radius of this cup.

  The implant according to the invention thus does not comprise one or more pads of limited lengths but a true rigid beam, perfectly forming a body with the cup, this beam having a length and an orientation such that, when the cup is placed in position implantation, it is engaged deep in the thick bony part of the pelvis which forms the base of the iliac wing and which is connected to the ischium.

  This deep commitment ensures a perfect hold in position and a perfect support of the cup in healthy bone, unperceivable deterioration.

  The means for anchoring the cup to the bone may be any appropriate means, in particular an osteoinductive coating which may be porous, in particular based on calcium hydroxyapatite, and / or screws. In this second case, the cup comprises holes passing through its wall, which are advantageously arranged on either side of the plane containing the axis of said beam, these holes being suitable for receiving anchoring screws of this cup. the bone.

  The anchoring screws make it possible, once the cup is in place on the bone, to anchor this cup in lateral bony zones with respect to the plane containing the axis of the beam. This anchoring makes it possible to perfectly stabilize the cup with respect to the stresses exerted on it on either side of said plane, which tend to cause a tilting of this cup around the axis of said beam.

  Preferably, the cup comprises at least two holes on each side of said plane.

  Several screws can thus be placed in different directions, which ensures a perfect anchoring of the cup to the bone.

  Advantageously, at least one of the holes in the cup is delimited by a wall in the form of a hollow sphere portion and the screw intended to be received in this hole comprises a head whose side wall has a spherical portion shape having a diameter. slightly lower than that of said wall, so that the screw can bear against the cup while being oriented in a plurality of possible directions of insertion.

  The direction of insertion of this screw can thus be chosen according to the quality of the corresponding bone areas, to achieve an anchoring of the screw in the best conditions.

  Preferably, all the holes in the cup are delimited by a hollow sphere-shaped wall as above and receive spherical-shaped head screws as mentioned above.

  Each screw can thus be oriented according to the state of the bone, which, together with the number of holes that includes the cup, ensures a perfect anchoring of the cup to the bone.

  The beam advantageously comprises a conical portion at its free end, ending with a rounded end.

  This end facilitates the insertion of the beam into the hole in the bone to receive it, and makes a surface contact with the bone at the bottom of this hole.

  Advantageously, the beam has a cross section forming longitudinal edges, preferably sharp edges.

  This shape allows the beam to help withstand the stresses exerted laterally on the cup relative to the aforementioned plane containing the axis of the beam.

  The beam may include longitudinal recesses to reduce slightly its section and thus preserve the bone capital of the patient. These recesses are preferably contiguous so as to form on the beam sharp edges as mentioned above.

  Preferably, the implant according to the invention and an implant called "double mobility", that is to say comprises a cup, whose inner face forms, directly or not, a concave spherical surface, and an insert for receiving the femoral head, the outer face of which forms a spherical convex surface with a radius slightly less than that of the internal surface of the cup, these respective surfaces being such that the insert can have a multidirectional deflection relative to the cup when engaged in it.

  This mobility makes it possible to prevent the risk of dislocation of the femoral head in the maximum degrees of deflection of the prosthetic joint.

  The invention will be better understood, and other features and advantages thereof will become apparent, with reference to the appended schematic drawing, showing, by way of non-limiting example, a preferred embodiment of the cotylodial implant that it relates to.

  Figure 1 is a partial view of a basin whose cotylodian cavity is deteriorated; FIG. 2 is a perspective view of the cotylodial implant according to the invention; Figure 3 is a perspective view of the cup that includes this implant; FIGS. 4 to 6 are views of this cup respectively along the axis of revolution of this cup, from one side in a direction and from the side in a direction perpendicular to the view according to FIG. 5, and FIGS. 7 to 9 are Perspective views of this cup after placement on the pelvic bone, according to three different angles of view, with partial section of the bone around this cup.

  In FIG. 1, which partially represents a pelvis 1, the iliac wing 2, the ischium 3 and the cotylodial cavity 4 are recognized.

  The bone parts delimiting the cotyloldian cavity 4 have suffered significant damage over time, leading to deterioration and embrittlement of these bone parts, as well as to a perforation of the wall delimiting the bottom of this cavity (see the well-known typology of Paprowsky, Perona and Lawrence).

  The cotyloldian implant 5 shown in FIG. 2 is capable of being placed on the pelvic bone shown in FIG. 1, being able to be perfectly anchored to it by means of screws 6. This implant 5 is thus able to recreate a stable prosthetic cotylodial cavity adapted to receive the femoral head prosthetic femoral implant placed on the upper end of the femur.

  This implant 5 comprises a hollow hemispherical cup 10, an insert 11, an intermediate "jacket" 12.

  As is more particularly shown in FIGS. 2 to 6, this cup comprises a beam 15 projecting radially from the outer surface of its hemispherical portion 16.

  The beam 15 is solid, solid and perfectly integral with the hemispherical part 16, being made by casting and / or machining in one and only one piece with the latter, and being connected thereto by a flared base area. . The cup 10 may in particular be made of titanium alloy and aluminum or chromium alloy and cobalt.

  The beam 15 forms, with the axis of revolution A of the cup 10, an angle of 350, has a length of up to 80 mm, and is rectilinear, having an axis extending a diametral plane P of the cup 10 (see Figure 4). The beam 15 furthermore has a hexagonal cross section, comprises a conical end 17 with a rounded end and has six longitudinal recesses 18.

  The hemispherical portion 16 of the cup 10 internally defines a cavity 20 for receiving the liner 12 and the insert 11, and has six holes 21 arranged symmetrically with respect to the plane P. As shown in FIG. 4, two of these holes 21 have an axis contained in a plane perpendicular to this plane P, the other holes 21 having axes contained in planes forming angles of 450 with the same plane P. It appears in Figures 3 to 6 that the wall 22 of the cup 10 delimiting each hole 21 has a hollow sphere portion shape. Each screw 6 is intended to be received in one of these holes 21 and comprises a head whose side wall has a shape of sphere portion having a diameter slightly smaller than that of said wall defining each hole.

  The cup 10 further comprises a polar hole 25 allowing it to be mounted on a grasping tool used for placing this cup on the bone, by impaction, and two notches 26 in its equatorial edge 27, diametrically opposite, allowing the removing the liner 12 out of the cup if necessary during implantation.

  The insert 11 is made of a material promoting sliding, in particular of high density polyethylene. It internally delimits a spherical cavity 30 adapted to receive the abovementioned prosthetic femoral head with the possibility of multidirectional deflection, and externally has a surface 31 of spherical shape.

  The liner 12 has a hemispherical and hollow main portion, internally forming a cavity delimiting a hemispherical concave surface. This cavity has a diameter slightly greater than that of the surface 31 of the insert 11, so that this insert 11 can be received in this cavity with the possibility of multidirectional deflection.

  The main part of the liner 12 is intended to be tightly engaged in the cavity 20 formed by the cup 10, and has for this purpose an outer surface shaped so as to closely match the surface of the cup 10 delimiting the cavity 20.

  The jacket 12 also comprises an equatorial flange 32 that can be received against the equatorial edge 27 of the cup 10 when its main part is inserted into the cavity 20.

  In practice, as illustrated by FIGS. 7 to 9, two substantially perpendicular axes are marked on the pelvic bone 1, namely an axis joining the anterior superior iliac spine 35 to the ischion 3 and a axis passing at the height of the large sciatic notch 36, the practitioner locating the location of the notch 36 by inserting his finger in this notch.

  These two axes delimit four sectors in the cotyloldian cavity. An axis oblique at 450 with respect to these two axes is located, from the postero-superior sector to the antero-inferior sector, then a hole is pierced in the bone on this oblique axis, at the center of the postero-superior sector. in the direction of the thick bone portion 40 of the pelvis 1 which forms the base of the iliac wing 2 and which is connected to the ischion 3, this hole having a depth adapted to the length of the beam to be implanted.

  The beam 15 is then inserted into this hole until positioning of the hemispherical portion 16 in the cavity 4, then the screws 6 are put in place.

  The liner 12 is then inserted into the cavity 20 and the insert 11 is placed in the cavity delimited by this liner 12.

  The deep engagement of the beam 15 in said thick bone portion 40 ensures a perfect hold in position and a perfect support of the cup 10 in healthy bone, unperceivable deterioration.

  The screws 6 make it possible, once the cup 10 is in place on the bone, to anchor this cup in lateral bony zones with respect to the plane P, which makes it possible to perfectly stabilize the cup 10 with respect to the The invention thus provides a cotylodial implant 5 which can be perfectly anchored to the pelvic bone even in the event of relatively significant deteriorations of this bone at the level of the bone. cotylodian cavity, and without inducing, with respect to an existing implant, additional difficulties of implementation or significant manufacturing difficulties.

  This implant 5 may be of first intention or "recovery".

  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 forms of embodiments covered by the appended claims.

Claims (9)

  1-cotylodial implant (5) of hip prosthesis, comprising a hemispherical cup (10) provided with a projection (15) projecting from its outer face and additional means (6) for anchoring to the bone, characterized in that said projection constitutes a beam (15) of solid and solid structure, forming a body with the cup (10), which forms, with the axis of revolution (A) of the cup (10), an angle that can range from 250 to 450 and which has a length greater than the radius of this cup (10).   2 - cotyloldien implant (5) according to claim 1, characterized in that the cup (10) comprises holes (21) passing through its wall, arranged on either side of the plane (P) containing the axis of said beam (15), these holes (21) being adapted to receive anchoring screws of this cup to the bone.   3 - Cotylodial implant (5) according to claim 2, characterized in that the cup (10) comprises at least two holes (21) on each side of said plane (P).   4 - Cotylodial implant (5) according to one of claims 2 or 3, characterized in that at least one of the holes (21) of the cup (10) is delimited by a wall (22) in the form of a sphere portion hollow, the screw (6) intended to be received in this hole (21) comprising a head whose side wall has a spherical portion shape having a diameter slightly smaller than that of said wall (22), so that the screw (6) can bear against the cup (10) while being oriented in a plurality of possible insertion directions.   5 - Cotylodial implant (5) according to claim 4, characterized in that all the holes (21) that comprises the cup (10) are delimited by a wall (22) shaped hollow sphere and receive screws (6) to heads in the form of a portion of a sphere.   6- Cotylodial implant (5) according to one of claims 1 to 5, characterized in that the beam (15) comprises a conical portion (17) at its free end, ending with a rounded end.   7 - Cotylodial implant (5) according to one of claims 1 to 6, characterized in that the beam (15) has a cross section forming longitudinal edges, preferably sharp edges.   8- cotylodian implant (5) according to one of claims 1 to 7, characterized in that the beam (15) comprises longitudinal recesses (18).   9-Cotylodial implant (5) according to one of claims I to 8, characterized in that it comprises a cup (10), the inner face forms, directly or indirectly, a concave spherical surface and an insert (11) for receiving the femoral head, whose outer face (31) forms a spherical convex surface of radius slightly smaller than that of the inner surface of the cup (10), these respective surfaces being such that the insert (11) can have a multidirectional movement relative to the cup (10) when engaged in it.   - Cotylodial implant (5) according to one of claims 1 to 9, characterized in that the beam (15) forms, with the axis of revolution (A) of the cup (10), an angle of 35.