HIP JOINT IMPLANT WITH RESHAPEABLE FASTENING BRACKETS

Abstract

Hip joint implant for fastening to a pelvic bone (9), with a support body which has a socket (6) and whose convex outer face is designed to bear on the pelvic bone (9) and which, on its concave inner face, has a receiving seat for a pelvis-side bearing that is designed to receive a joint head of a femoral component of a hip prosthesis, and with outwardly directed flat fastening brackets (2, 3) which are arranged at the edge region of the socket (6) and are each provided with at least one receiving seat for a fastening means. The fastening brackets (2, 3) are made of a reshapeable biocompatible material and are connected to the socket (6) via a non-releasable cohesive bond (7), wherein the socket (6) is made of another, stiffer biocompatible material. A high degree of robustness of the socket (6) is thus combined with what is, by virtue of the reshapeability, an improved adaptation to the anatomical conditions of the respective pelvic bone. This improves reliability of fastening, stability and long-term behavior.

Claims

1-15. (canceled)

16. A hip joint implant for fastening to a pelvic bone comprising: a support body comprising a socket with a convex outer face designed to bear on the pelvic bone; a concave inner face with a receiving seat to receive a joint head of a femoral component of a hip prosthesis; and at least two outwardly directed flat fastening brackets arranged at the edge of the socket and providing at least one receiving fastening seat.

17. The hip implant joint of claim 16, wherein the fastening brackets are made of a reshapeable biocompatible material.

18. The hip implant joint of claim 16, wherein the fastening brackets are connected to the socket via a non-releasable cohesive bond, and the socket is made from a more stiff biocompatible material.

19. The hip joint implant of claim 18, wherein the cohesive bond is a welded connection.

20. The hip joint implant of claim 19, wherein the welded connection is an electron beam welded connection.

21. The hip joint implant of claim 20, wherein the cohesive bond has a welded-through weld seam.

22. The hip joint implant of claim 16, wherein the fastening brackets are made in one piece with a fastening ring, said fastening ring engaging around the support body and connected to the support body by a cohesive bond.

23. The hip joint implant of claim 22, wherein the fastening brackets are prefabricated with openings for fastening, and the fastening ring is prefabricated with an opening for receiving the support body.

24. The hip joint implant of claim 16, wherein the receiving seat is prefabricated to be dimensionally accurate to the external dimension of the support body, and to an external diameter of the support body to enable an interference fit.

25. The hip joint implant of claim 16, wherein the support body is made of a non-cold-formable material.

26. The hip joint implant of claim 16, wherein the support body is made of a titanium alloy which is less formable than pure titanium with tensile strength of at least 800 MPa.

27. The hip joint implant of claim 16, wherein the fastening brackets are made of pure titanium of grade 2, 3, or 4, and the support body is made of a titanium alloy.

28. The hip joint implant of claim 16, wherein the support body has a circumferential support shoulder and a centering ring in which a fastening ring can be received.

29. The hip joint implant of claim 16, wherein the support has a transition region between the support body and fastening brackets comprising a milled surface.

30. A modular hip joint system comprising: the hip joint implant of claim 16, further comprising a plurality of sockets which are differently configured but have a uniform external diameter.

31. The modular hip joint system of claim 30, wherein a plurality of uniform external diameters are provided graduated in different sizes.

32. A method for producing a hip joint implant for fastening to a pelvic bone, with a support body which has a socket and whose convex outer face is designed to bear on the pelvic bone and which, on its concave inner face, together with a bearing component, forms the seat for receiving a joint head of a femoral component of a hip prosthesis, and with outwardly directed flat fastening brackets which are arranged at the edge region of the socket and are each provided with at least one receiving seat for a fastening means, comprising: prefabricating the support body and the socket from a first material, prefabricating the fastening brackets from a reshapeable, biocompatible second material, pre-assembly of the fastening brackets on the support body, and welding of the fastening brackets to the support body.

33. The method of claim 32, wherein the welding is electron beam welding.

Description

[0025] The invention is explained in more detail below on the basis of an illustrative embodiment and with reference to the accompanying drawing, in which:

[0026] FIG. 1 shows an illustrative embodiment of the hip joint implant in the state when fitted on a pelvic bone;

[0027] FIG. 2 shows a view of a prefabricated fastening ring with fastening brackets;

[0028] FIG. 3 shows a perspective view of a socket-like support body;

[0029] FIG. 4 shows a perspective view of a pre-assembled state;

[0030] FIG. 5 shows a cross-sectional view of a weld seam as a connection between fastening ring/brackets and support body;

[0031] FIG. 6 shows a perspective view of a completed hip joint implant, with bent fastening brackets and with a bearing component that is ready for assembly; and

[0032] FIGS. 7a, b show an embodiment of the socket-like support body in a modular construction.

[0033] An illustrative embodiment of a hip joint implant according to the invention is shown in FIG. 1 in a state when fitted on a pelvic bone 9 (acetabulum).

[0034] The hip joint implant is designated as a whole by reference number 1 and comprises a socket-like support body 6 on which two flat and elongate fastening brackets 2 are arranged pointing upward (cranially). A shorter fastening bracket 3, extending downward (caudally), is provided on the opposite side of the socket-like support body 6 (in the following also called socket for short).

[0035] In the illustrative embodiment shown, the implant 1 is composed of two components, namely the socket 6 and a fastening component, which comprises the fastening brackets 2, 3 and a fastening ring 4, on which the fastening brackets 2, 3 are arranged. The fastening brackets 2 are each elongate, flat elements which are provided with a multiplicity of bores 21 for receiving fastening means. The fastening bracket 3 is likewise a flat element, but, in the illustrative embodiment shown, it is shorter and wider than the fastening brackets 2.

[0036] This embodiment is only an example; the invention is not limited thereto. The fastening bracket 3 is likewise provided with a plurality of bores 31 for receiving fastening means. The bores 21, 31 are designed as through-openings for receiving a fastening means (not shown). Screws known per se, in particular bone screws, function as fastening means.

[0037] Reference is now made to FIG. 2. The fastening brackets 2, 3 are arranged protruding radially outward on a ring 4, which is designated as a fastening ring. In the illustrative embodiment shown, the fastening brackets 2, 3 and the fastening ring 4 are made in one piece. They are made of a titanium material, namely pure titanium of grade 2 or grade 4. This material has extremely good biocompatibility and moreover has the advantage that it can also be easily deformed manually. It is therefore possible for the operator to reshape the fastening brackets 2, 3 even during the implantation, i.e. during the operation, if necessary, and thus better adapt them to the particular anatomical features of the pelvic bone 9 of the respective patient. The one-piece design of the fastening ring 4 ensures a high degree of strength and good handling.

[0038] The fastening ring 4 delimits an inner region 40 which is designed to receive the socket-like support body 6.

[0039] In the illustrative embodiment shown, the fastening ring 4 is designed fully circumferentially, although this is not absolutely necessary; the ring does not need to be completely closed.

[0040] The socket-like support body 6 shown in FIG. 3 has a substantially hemispherical shape. Its main part is curved in a dome shape and provided with a multiplicity of fastening bores 61. On its convex outer face, the socket-like support body 6 is designed to bear against the bone surfaces of the pelvic bone 9 and for this purpose is expediently provided with a surface or coating that promotes the incorporation of bone substance. On its inner face, the socket-like support body is correspondingly concave and, together with a bearing component, forms the receiving seat for a joint head (not shown) of a femoral component of a hip joint prosthesis. As bearing component, a bearing shell 8 (see FIGS. 6 and 7) made of material that promotes sliding can be inserted in the socket 6. In a variant, the bearing shell 8 can optionally also be designed for dual mobility. In this case, the bearing shell basically consists of two bearing shells nested one inside the other, namely an outer shell 81 and an inner shell 82. A further bearing surface 83 is thus obtained between them (shown in FIG. 6 by a dashed line). The additional degree of freedom achieved reduces wear and tear between the bearing shell 8 and the socket 6; moreover, greater mobility can thus be achieved, and therefore improved protection against dislocation.

[0041] The socket-like support body 6 is made of a biocompatible titanium alloy, which has quite a high degree of strength in order to take up the bearing forces of the hip joint. TiAl6V4 in particular has proven useful as a titanium alloy. It has a high degree of strength and robustness. It is typically too stiff to be bent by hand. It is therefore particularly suitable for taking up the considerable bearing forces of the hip joint, which are exerted by the joint head, and leading them into the pelvic bone 9.

[0042] During production, the socket-like support body 6 is pre-assembled by being inserted into the opening 40 of the fastening ring 4. It is inserted until the fastening ring 4, in the region of the upper end on the socket edge 60, engages with an exact fit around the socket-like support body 6, preferably with an interference fit. Thus, in a pre-assembled state, the socket-like support body 6 is retained on the fastening ring 4 with fastening brackets 2, 3, as is shown in FIG. 4. In this state, a cohesive bond 7 between the socket 6 and the fastening ring 4 with the fastening brackets 2, 3 can then be produced by electron beam welding. The cohesive bond 7 is preferably designed with a welded-through weld seam, in particular what is called a square butt weld, as is shown in FIG. 5. The welded connection 7 ensures a firm connection even between different materials, namely in the present case between the titanium alloy TiAl6V4 for the socket 6 and pure titanium (grade 2 or grade 4) for the fastening brackets 2, 3 with their fastening ring 4.

[0043] FIG. 5 also reveals a support shoulder 62 which ensures that the fastening ring 4, with the fastening brackets 2, 3 arranged thereon, is positioned and supported on the socket 6. In particular, a flat and level arrangement is obtained such that a surface that is as continuous as possible is formed at the top. Provision can preferably also be made that, after the production of a welded connection 7, it is possible, by overmilling, to create a smooth transition of the top between the socket 6, with its socket edge 60, the welded connection 7 and the top of the fastening ring 4. This final state is shown in FIG. 6.

[0044] Finally, the fastening brackets can already be at least partially pre-formed. This is also shown in FIG. 6. Here, the fastening brackets 2 are already pre-formed to a contour of the pelvic bone 9, as is typically to be expected. Fine adaptation to the respective individual anatomy of the pelvic bone can then be carried out intraoperatively by the surgeon, simply by bending the fastening brackets 2, 3 by hand.

[0045] The invention can be used in the context of a modular hip joint system. Here, differently configured sockets 6, 6′ are provided, which differ in particular in terms of their size (dimensioning). Thus, sockets 6 of different sizes can be provided, although they are connectable in the same way, by means of the welded connection 7, to the fastening ring 4 with the fastening brackets 2, 3.

[0046] However, the modular sockets can also differ in terms of their further configuration, in particular in terms of the configuration of the inner face. A modularly configured socket 6′ of this kind is shown in FIG. 7a. It has positioning grooves 66 for precision-angle positioning of modular bearing inserts (not shown). A bearing shell 8 can be inserted into the socket 6, as has already been explained above for FIG. 6.

[0047] Optionally, a centering ring 64, as shown in FIG. 7b, can be formed on the socket 6. In terms of its external diameter, it is precisely matched to the width of the opening 40 and thus permits precise fitting and centering of the socket 6 in relation to the fastening ring 4 with the fastening brackets 2, 3. Particularly when using a modular socket 6′, a centering ring 64 can be used to achieve secure positioning and centering even of sockets of different sizes. The centering ring 64 can be designed as a separate element or, particularly in the case of sockets having relatively large dimensions, can also be designed as a recess and thus be made in one piece with the socket 6.