Femur implant part or tibia implant part

Abstract

The invention relates to a femur implant part (2) or tibia implant part made of a first plastic (10), in particular PEEK, for an orthopaedic knee joint prosthesis, wherein when implanted, the femur implant part (2) or the tibia implant part has surface regions (4) facing, respectively, the femur bone or the tibia bone and is in contact with same. According to the invention, the femur implant part (2) or the tibia implant part comprises at least one insert part (12) made of a second plastic (18), which forms parts of the surface regions (4) in contact with bones and / or cement.

Description

[0001] Title: Femoral implant component or tibial implant component

[0002] Description

[0003] The invention relates to a femur implant part or tibia implant part, each made of a first plastic, in particular of PEEK, for an orthopaedic knee joint prosthesis, wherein the femur implant part or the tibia implant part, in the implanted state, has surface areas facing the femur bone or the tibia bone, respectively, and in contact therewith.

[0004] Femoral and tibial implant components have mostly been made of metal alloys, particularly cobalt-chromium-molybdenum alloys. For some time now, efforts have been made to produce these implant components from plastic, particularly PEEK (polyether ketone), which has the advantage of a modulus of elasticity more similar to that of bone. A non-metal-based implant has also proven advantageous in terms of avoiding metal-related allergic reactions. However, with some plastics, particularly load-bearing, resilient and wear-resistant plastics such as PEEK, there is the problem of a cement or bone bond that still needs to be improved. The present invention is therefore based on the object of improving implant components of the type mentioned at the outset with regard to their ability to bond to the bone or cement.

[0005] This object is achieved according to the invention in an implant part of the type mentioned in that the femur implant part or the tibia implant part comprises at least one insert part made of a second plastic, which partially forms the surface areas in contact with bone and / or cement.

[0006] The production of the implant part in question with an insert made of a second plastic makes it possible to select this second plastic in such a way that its ability to bond to bone can be optimized using typical bone cements. When selecting the second plastic, the focus is therefore not primarily on load-bearing capacity and tribological properties, but rather on its ability to bond taking chemical processes into account. The invention therefore proposes that an insert made of a different second plastic be provided, which at least partially forms the surface of the implant part that bonds to the bone or cement, so that the ability of the implant part to bond can be optimized through the specific choice of material for the second plastic.

[0007] According to one embodiment of the invention, the second plastic is EMMA.

[0008] Plastics of the type in question here can be processed in a variety of ways. As thermoplastics, they can be injection molded or extruded. 3D printing or filling with tribologically active components or with reinforcing materials, such as carbon fibers, is also possible.

[0009] According to one embodiment of the invention, it proves to be advantageous that the femur implant part or the tibia implant part is produced as a plastic injection-molded part, wherein the at least one insert part is overmolded with the first plastic.

[0010] In a further development of this idea, it has proven advantageous that, when overmolding the insert, undercut areas are formed in a direction orthogonal to the adjacent surface area in contact with bone or cement. These undercut areas ensure permanent anchoring of the insert in the first plastic. These undercut areas achieve, to a certain extent, a form-fitting integration of the insert into the first plastic of the implant component. Due to the stability of the first plastic, detachment of the insert from the second plastic is thus impossible and reliably prevented.

[0011] Furthermore, it proves advantageous if the insert is formed from the first plastic material so that it is flush with the surface areas in contact with the bone and / or cement. With such a flush and preferably at least partially flat design of the surface areas, the contact areas to be prepared on the bone can also be formed with the required precision to ensure a precise fit of the implant component.

[0012] According to one embodiment of the invention, it is proposed that the insert is a lattice part with webs and through-openings. The lattice part can be designed as a cross lattice or also honeycomb-shaped, in particular with hexagonal honeycomb openings. The webs extending in the surface or plane allow a projecting connection surface to the bone to be formed. In a further development of this idea, it proves advantageous if the webs, viewed in cross-section, form undercut regions and for this purpose are particularly triangular, trapezoidal or parallelogram-shaped. The undercut regions can be realized by appropriate orientation of the triangular shape, trapezoidal shape or parallelogram shape in order to be able to anchor the insert securely in the material of the first plastic.

[0013] Notwithstanding this, it proves to be advantageous if the insert is extended in a plane, and a thickness of the insert in the direction orthogonal to the plane is 1-4 mm.

[0014] The invention also relates to an orthopaedic knee joint prosthesis having the features of claim 9.

[0015] Further features, details and advantages of the invention emerge from the patent claims and the drawing and subsequent description of a preferred embodiment of an implant part according to the invention.

[0016] The drawing shows:

[0017] Figure 1 is a perspective view (although schematic) of a femur implant part according to the invention; and

[0018] Figure 2 is a sectional view of a grid-shaped insert (schematic representation, not to scale) which is overmolded with the plastic of the implant part; Figure 3 is a perspective view of the grid-shaped insert before being overmolded with plastic.

[0019] Figures 1 and 2 show schematically the design of an implant part, here by way of example in the form of a femur implant part 2 according to the present invention. The perspective view in Figure 1 shows the femur implant part 2 obliquely from above, i.e. with a view of surface regions 4 which face inwards and are in contact with the bone (not shown). Furthermore, one can see a centrally arranged connection region 6 for attaching further connecting elements, such as shaft elements, in order to attach the implant part to the prepared femur bone, typically using bone cement. Also visible are the condylar surface regions 8 which run obliquely upwards from bottom to top and by means of which the femur implant part 2 can be brought into sliding surface contact against the meniscus or a meniscus replacement part (not shown) of a total knee endoprosthesis during operation.

[0020] The femoral implant part 2 is formed on the basis of a first load-bearing plastic 10, in particular PEEK, and comprises, in surface regions 4 in contact with bone, one or more structured inserts 12, shown in light in Figure 1, each in the form of a lattice part 14 with a lattice structure of webs 16 made of a second plastic 18, in particular and preferably PMMA, which cross one another, for example, at an acute angle α. The insert 12 is shown in Figure 3 before being embedded in the first plastic 10. The crossing webs 16 of the lattice structure of the insert 12 form, for example, a diamond-shaped honeycomb shape. Figure 2 shows a schematic section through a portion of the insert 12 embedded in the first plastic 10; it extends, for example, in a plane 11 orthogonal to the drawing plane of Figure 2.It can be seen that the insert part 12 and its lattice structure and webs 16 have bevelled flanks 20 which form undercut areas 22 orthogonal to the plane 11 with material of the first plastic 10, so that the insert part 12 is held in a form-fitting manner in the supporting plastic 10 of the femur implant part 2.

Claims

Patent claims 1. Femur implant part (2) or tibia implant part, each made of a first plastic (10), in particular of PEEK, for an orthopedic knee joint prosthesis, wherein the femur implant part (2) or the tibia implant part, in the implanted state, has surface regions (4) facing the femur bone or the tibia bone and in contact therewith, characterized in that the femur implant part (2) or the tibia implant part comprises at least one insert part (12) made of a second plastic (18), which partially forms the surface regions (4) in contact with bone and / or cement.

2. Femoral implant part (2) or tibial implant part, characterized in that the second plastic is PMMA.

3. Femur implant part (2) or tibia implant part, characterized in that it is produced as a plastic injection-molded part, wherein the at least one insert part (12) is overmolded with the first plastic (10).

4. Femur implant part (2) or tibial implant part, characterized in that when the insert part (12) is overmolded in the direction orthogonal to the undercut areas (22) are formed adjacent to the surface area (4) in contact with bone or cement, which ensure a permanent anchoring of the insert part (12) in the first plastic (10).

5. Femur implant part (2) or tibia implant part, characterized in that the insert part (12) is formed from the first plastic (10) so as to be flush with the surface areas (4) in contact with bone and / or cement.

6. Femoral implant part (2) or tibial implant part, characterized in that the insert part (12) is a grid part (14) with webs (16) and through openings.

7. Femur implant part (2) or tibial implant part according to claim 6, characterized in that the webs (16) form undercut areas when viewed in cross-section and are in particular triangular, trapezoidal or parallelogram-shaped.

8. Femoral implant part (2) or tibial implant part, characterized in that the insert part (12) extends in a plane (11), and a thickness of the insert part (12) in the direction orthogonal to the plane (11) is 1.0 - 4.0 mm.

9. Orthopaedic knee joint prosthesis with a femoral implant part (2), with a tibial implant part and with a meniscus replacement part which forms a sliding partner for the femoral implant part (2) and is held on the tibia implant part, characterized in that the femoral implant part (2) and / or the tibia implant part is designed according to one or more of the preceding claims.

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