EP-4734881-A1 - 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.

Inventors

• HIRT, MARTIN

Assignees

• Aesculap AG

Dates

Publication Date

20260506

Application Date

20241119

Claims (1)

1. 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.

Description

Title: Femoral implant component or tibial implant component Description 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 and in contact therewith. Femoral and tibial implant components have mostly been made of metal alloys, particularly cobalt-chromium-molybdenum alloys. Recently, efforts have been made to manufacture these implant components from plastic, particularly PEEK (polyether ketone), which which has the advantage of an E-modulus that is more similar to that of bone. A non-metal-based implant also proves to be advantageous with regard to avoiding metal-related allergic reactions. However, with some plastics, in particular 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 parts of the type mentioned at the outset with regard to their ability to bond to the bone or cement. 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. The production of the respective implant part with an insert made of a second plastic makes it possible to select this second plastic in such a way that its bonding to bone can be optimized using typical bone cements. Therefore, when selecting the second plastic, the primary focus is not on load-bearing capacity and tribological properties, but rather on its bonding taking chemical processes into account. Therefore, the invention proposes that an insert made of another second plastic is provided, which at least partially forms the surface of the implant part that connects to the bone or cement, so that the connectability of the implant part can be optimized by the specific choice of material for the second plastic. According to one embodiment of the invention, the second plastic is EMMA. 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 or the like, is also possible. 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. In 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, which ensure a permanent anchoring of the insert in the first plastic. Through these undercut In these areas, a form-fitting integration of the insert into the first plastic of the implant component is achieved. Due to the stability of the first plastic, detachment of the insert from the second plastic is thus impossible and reliably prevented. 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 accuracy to ensure a precise fit of the implant part. 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 honeycomb-shaped, in particular with hexagonal honeycomb openings. The webs extending in the surface or plane can form a projecting connection surface towards the bone. In a further development of this idea, it proves advantageous if the webs, viewed in cross section, form undercut areas and for this purpose are designed in particular in a triangular, trapezoidal or parallelogram shape. By appropriately orienting the triangular, trapezoidal or parallelogram shape, realize the undercut areas in order to be able to anchor the insert securely in the material of the first plastic. 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. The invention also relates to an orthopaedic knee joint prosthesis having the features of claim 9. 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 impla