Preparation method of low-wear knee joint replacement prosthesis

Abstract

The invention relates to the technical field of knee joint replacement prostheses, in particular to a preparation method of a low-abrasion knee joint replacement prosthesis. According to the technical scheme, the joint replacement prosthesis comprises a tibia liner, a thighbone prosthesis, a tibia support and a neodymium magnet; the tibia liner, the thighbone prosthesis and the tibia support are subjected to injection molding by adopting the same type of mold structure; the preparation method of the replacement prosthesis comprises the following steps: step 1, preparing raw materials required for forming the prosthesis; step 2, preparing a tibia liner, a thighbone prosthesis and a tibia support by combining an injection mold, and preparing a neodymium magnet block by combining alloy smelting in a smelting furnace, mold forming, vacuum sintering and tempering treatment; and step 3, splicing the replacement prosthesis. Metal abrasion is avoided from the aspect of materials, then inflammatory mediators are prevented from being released, the long-term stability of the replacement prosthesis is ensured, the magnetic suspension state between the prosthesis structures is achieved according to the homopolar repulsion principle between magnets, then contact abrasion is avoided, and the service life of the prosthesis is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of knee joint replacement prostheses, and particularly to a preparation method of a low-wear knee joint replacement prosthesis. Background Art

[0002] The prosthesis material system mostly adopts a "metal - polyethylene" composite structure: the femoral component is mainly made of cobalt-chromium-molybdenum alloy, and some high-end products adopt surface treatment technologies such as ceramicized zirconia or titanium nitride; the tibial tray mostly selects titanium alloy; the polyethylene liner generally adopts ultra-high molecular weight polyethylene, and in recent years, it has gradually been upgraded to highly cross-linked polyethylene with antioxidant treatment and vitamin E-doped polyethylene. The current clinical service life of prostheses shows significant differentiation: the 10-year survival rate of prostheses with ordinary polyethylene liners is 85% - 90%, and it drops to 75% - 80% after 15 years; while the 15-year survival rate of prostheses using highly cross-linked polyethylene can reach 92% - 95%. However, the annual failure rate of prostheses in obese (BMI > 30) patients is 2.3 times that of normal weight patients. The wear problem remains the core challenge restricting the service life of prostheses, and 67% of the cases in joint replacement revision surgeries are related to prosthesis wear. Although many current studies attempt to reduce prosthesis wear by means of material improvement or prosthesis structure design, for example, using polyetheretherketone reinforced with carbon fiber (CFR-PEEK) material can reduce the wear rate by 40% - 60%. In terms of prosthesis design, the new generation of prostheses reduces the contact stress from 35 MPa to 22 MPa by optimizing the tibiofemoral joint surface matching degree (the contact area is increased by 30% - 50%) and restrictive design, but these measures still cannot avoid the generation of wear particles. Polymer materials, especially ultra-high molecular weight polyethylene, are widely used as the liner material for the joint surface due to their good biocompatibility and moderate flexibility. It can buffer the impact force during joint movement and reduce the hard friction between joints. However, during long-term reciprocating joint movement, ultra-high molecular weight polyethylene will gradually generate tiny wear particles when rubbing against metal or ceramic. Once these particles break off and enter the surrounding tissues, they will trigger macrophage phagocytosis reactions, release inflammatory mediators, and then lead to osteolysis, causing the fixation between the prosthesis and bone tissue to become loose, which is one of the core problems affecting the long-term stability of knee joint replacement prostheses. For the above reasons, this application proposes a preparation method of a low-wear knee joint replacement prosthesis that utilizes the principle of like poles repelling each other in a magnetic field to form a magnetic suspension micro-gap between the femoral prosthesis and the tibial spacer, thereby extending the service life of the prosthesis. Summary of the Invention

[0003] The object of the present invention is to address the problems in the background art and propose a preparation method of a low-wear knee joint replacement prosthesis that utilizes the principle of like poles repelling each other in a magnetic field to form a magnetic suspension micro-gap between the femoral prosthesis and the tibial spacer, thereby extending the service life of the prosthesis.

[0004] Technical solution of the present invention: A method for preparing a low-wear knee joint replacement prosthesis, the joint replacement prosthesis comprising a tibial insert, a femoral prosthesis, a tibial tray and a neodymium magnet;

[0005] The preparation method of the replacement prosthesis comprises the following steps:

[0006] Step 1, preparing the raw materials required to form the prosthesis:

[0007] The tibial insert comprises the following raw materials in parts by mass: 99.5-99.8 parts of highly crosslinked ultra-high molecular weight polyethylene and 0.2-0.5 parts of antioxidant; the femoral prosthesis comprises the following raw materials in parts by mass: 80-88 parts of polyetheretherketone and 0.5-1.2 parts of reinforcing composite material; the tibial tray comprises the following raw materials in parts by mass: 98-99.8 parts of polyurethane and 0.2-0.5 parts of catalyst; the neodymium magnet comprises the following raw materials in parts by mass: 29-32 parts of neodymium, 63-67 parts of iron, 1-1.2 parts of boron, and 1-5 parts of dysprosium;

[0008] Step 2, preparing the tibial insert, femoral prosthesis, and tibial tray by combining injection molds, and preparing the neodymium magnet block by combining a melting furnace to melt the alloy, mold forming, vacuum sintering, and tempering treatment;

[0009] Step 3, assembling the replacement prosthesis: multiple groups of neodymium magnet blocks are respectively encapsulated in the tibial insert and the femoral prosthesis, and the neodymium magnet blocks on the contact surface between the tibial insert and the femoral prosthesis have the same magnetism.

[0010] Optionally, the tibial insert, femoral prosthesis, and tibial tray are injection molded using the same type of mold structure.

[0011] Optionally, the antioxidant used for the tibial insert is one or a combination of vitamin E and phenolic antioxidants;

[0012] The reinforcing composite material used for the femoral prosthesis is carbon fiber, and the carbon fiber accounts for 0.5%-3% of the raw materials required for the femoral prosthesis, and the length of the carbon fiber is in the range of 0.1 mm-5 mm;

[0013] The catalyst used for the tibial tray is dibutyltin dilaurate, and the proportion in the total mass of the tibial tray raw materials is 0.05%-0.2%.

[0014] Optionally, the molecular weight range of the highly crosslinked ultra-high molecular weight polyethylene is 1 million-6 million, and the crosslinking degree range is 60%-90%;

[0015] The polyurethane is prepared by reacting a polyol with an isocyanate, and the molar ratio range of the polyol to the isocyanate is 1:1.1-1:1.5.

[0016] Optionally, the polyol is any one of polyether polyol and polyester polyol, and the number average molecular weight ranges from 500 to 3000;

[0017] The isocyanate is any one of toluene diisocyanate and diphenylmethane diisocyanate.

[0018] Optionally, the molding die includes a sprue, a sprue cavity, a heating plate 1, an upper molding cavity, a lower molding cavity, and a heating plate 2;

[0019] Among them, the upper molding cavity and the lower molding cavity are combined to replace the shapes of the tibial insert, femoral prosthesis, and tibial tray.

[0020] Optionally, after the upper molding cavity and the lower molding cavity are closed, the shape of the molding cavity matches the designed tibial insert, femoral prosthesis, and tibial tray model 1:1;

[0021] The molding cavity is made of S136 die steel material, and the inner wall of the molding cavity is coated with polytetrafluoroethylene.

[0022] Optionally, the tibial insert is divided into an upper tibial insert and a lower tibial insert. Oval installation grooves are provided in both the upper tibial insert and the lower tibial insert. The upper and lower groups of oval installation grooves form a magnet block installation cavity, and a neodymium magnet block is encapsulated in the installation cavity;

[0023] The upper tibial insert and the lower tibial insert are sealed and installed through a snap structure.

[0024] Optionally, the femoral prosthesis includes upper and lower parts, and the two parts are closed and installed through a snap structure to achieve the sealed installation of the neodymium magnet block and prevent body fluid from seeping in.

[0025] Optionally, the tibial insert includes the following raw materials in parts by mass: 99.6 parts of highly crosslinked ultra-high molecular weight polyethylene and 0.35 parts of antioxidant;

[0026] The femoral prosthesis includes the following raw materials in parts by mass: 84 parts of polyetheretherketone and 0.9 parts of reinforcing composite material;

[0027] The tibial tray includes the following raw materials in parts by mass: 99 parts of polyurethane and 0.35 parts of catalyst;

[0028] The neodymium magnet includes the following raw materials in parts by mass: 30 parts of neodymium, 65 parts of iron, 1.1 parts of boron, and 3 parts of dysprosium.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] 1. The present invention realizes the magnetic suspension state of the joint prosthesis by setting the neodymium magnet block and combining the principle that the same poles repel each other between magnets, thereby making the tibial pad and the femoral prosthesis in a gap state, thereby minimizing the wear of the prosthesis and extending the service life of the prosthesis. The replacement joint is highly safe to use, the probability of inflammation is low, and the replacement joint is safer to use;

[0031] 2. In order to maximize the conduction of magnetic field and reduce the generation of metal wear particles, the femoral prosthesis, tibial liner and tibial tray are injection molded with polymer materials, which avoids the metal particles generated by the wear of traditional metal materials, thereby reducing the risk of postoperative osteolysis. In addition, the hardness of polymer materials is closer to that of natural articular cartilage, which is more in line with the concept of bionics.

[0032] 3. The femoral prosthesis of the present invention is similar to the design of the current posterior stabilized knee prosthesis. The tibial pad is located between the femoral prosthesis and the tibial tray, and assumes the function of the natural meniscus, and can be used as a mechanical buffer structure. In addition, the inner and outer sides of the pad are connected with the inner and outer condyles of the femoral prosthesis in an arc-shaped concave surface. Because the inner and outer condyle structures of the femoral prosthesis are convex structures, the arc-shaped concave surface of the pad can match the convex surface of the condyle structure of the femoral prosthesis. This structure is designed based on the matching of the femoral condyle and the meniscus structure in the normal knee joint, so it is more ergonomic and the joint is smoother to use.

[0033] In summary, the present invention avoids the appearance of wear metal from the material point of view, thereby avoiding the release of inflammatory mediators, ensuring the long-term stability of the replacement prosthesis, and utilizing the principle of like poles repelling each other between magnets to achieve a magnetic suspension state between the various prosthetic structures, thereby avoiding contact wear and extending the service life of the prosthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the buckle structure in the present invention is given;

[0035] Figure 2 It is a schematic diagram of the magnetic suspension principle when the tibial liner and the femoral prosthesis are bent at different angles;

[0036] Figure 3 It is a structural diagram of the molding die in the present invention.

[0037] Reference numerals:

[0038] 1. Storage head;

[0039] 2. Storage chamber;

[0040] 3. Heating plate 1;

[0041] 4. Forming the upper cavity;

[0042] 5. Forming the lower cavity;

[0043] 6. Heating Plate 2 Detailed Implementation Manner

[0044] The technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments.

[0045] The components of the embodiments of the present disclosure generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the claimed present disclosure, but merely represents selected embodiments of the present disclosure.

[0046] All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0047] In the description of the present disclosure, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present disclosure.

[0048] In the description of the present disclosure, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations.

[0049] Embodiment

[0050] As Figure 1 - Figure 2 shown, a method for preparing a low-wear knee joint replacement prosthesis proposed by the present invention, the joint replacement prosthesis includes a tibial insert, a femoral prosthesis, a tibial tray, and a neodymium magnet;

[0051] The tibial insert, femoral prosthesis, and tibial tray are injection molded using the same type of mold structure;

[0052] The method for preparing the replacement prosthesis includes the following steps:

[0053] Step 1. Prepare the raw materials required to form the prosthesis:

[0054] The tibial liner comprises the following raw materials in parts by mass: 99.6 parts of highly crosslinked ultra-high molecular weight polyethylene and 0.35 part of vitamin E; the molecular weight range of the highly crosslinked ultra-high molecular weight polyethylene is 1 million - 6 million, and the crosslinking degree range is 88%;

[0055] The femoral prosthesis comprises the following raw materials in parts by mass: 84 parts of polyetheretherketone and 0.9 part of carbon fiber;

[0056] The tibial tray comprises the following raw materials in parts by mass: 99 parts of polyurethane and 0.35 part of dibutyltin dilaurate; the polyurethane is prepared by reacting polyol with isocyanate. The polyol is polyether polyol, and the isocyanate is toluene diisocyanate. The specific preparation process is as follows: in a reaction kettle, polyether polyol and toluene diisocyanate are mixed at a molar ratio of 1:1.5, and 0.12% by mass of dibutyltin dilaurate is added as a catalyst. The reaction temperature is controlled at 90 °C, and the reaction time is 4 h to obtain a polyurethane material;

[0057] The neodymium magnet comprises the following raw materials in parts by mass: 30 parts of neodymium, 65 parts of iron, 1.1 parts of boron, and 3 parts of dysprosium;

[0058] Step 2, as Figure 3 shown, the tibial liner, femoral prosthesis, and tibial tray are prepared by combining with an injection molding die; the molding die comprises a sprue bush 1, a storage cavity 2, a heating plate 1 3, an upper molding cavity 4, a lower molding cavity 5, and a heating plate 2 6;

[0059] The upper molding cavity and the lower molding cavity are combined to replace the shapes of the tibial liner, femoral prosthesis, and tibial tray;

[0060] After the upper molding cavity and the lower molding cavity are closed, the shape of the molding cavity matches the designed models of the tibial liner, femoral prosthesis, and tibial tray 1:1;

[0061] The molding cavity is made of S136 die steel, and the inner wall of the molding cavity is coated with polytetrafluoroethylene;

[0062] The preparation of the neodymium magnet block is realized by combining alloy melting in a melting furnace, die molding, vacuum sintering, and tempering treatment; the specific preparation process is as follows:

[0063] 1. Raw material preparation: Prepare neodymium, iron, boron, and dysprosium auxiliary addition elements according to mass percentages. All raw materials need to ensure high purity to reduce the influence of impurities on magnetic properties;

[0064] 2. Alloy melting: The prepared raw materials are put into a vacuum induction melting furnace. In a high-vacuum environment, the raw materials are melted and fully mixed by induction heating. The melting temperature is usually controlled at 1550 °C, and it is maintained at this temperature for 0.5 h to ensure uniform alloy composition. Subsequently, the melted alloy liquid is poured into a specific die, and after cooling and solidifying, an ingot is obtained;

[0065] 3. Powder production: The ingot is crushed. First, it is crushed into smaller particles by coarse crushing equipment, and then fine powder production equipment such as a jet mill is used to further crush the particles into micron-sized alloy powder. During the powder production process, the operation is carried out under the protection of argon gas;

[0066] 4. Molding: The alloy powder is fully and evenly mixed with epoxy resin, put into a mold, and the powder is formed into a neodymium magnet block blank of the required shape under a pressure of 100 MPa by means of compression molding or injection molding;

[0067] 5. Sintering: The blank is put into a vacuum sintering furnace and sintered at a high temperature of 1100 °C. The sintering process can eliminate the pores inside the blank, increase the density, and enhance the magnetic properties of the magnet. The sintering time is 2.5 hours, and then it is cooled to room temperature with the furnace;

[0068] 6. Tempering treatment: To further optimize the magnetic properties, the sintered magnet is subjected to tempering treatment. The magnet is heated to 700 °C, held for 2 hours and then slowly cooled. Tempering can adjust the internal tissue structure of the magnet, improving the stability and remanence intensity of the magnet.

[0069] 7. Surface treatment: The magnet is subjected to surface treatment such as electroplating or coating with protective paint to enhance its corrosion resistance and extend its service life;

[0070] Step 3. Assembly of the replacement prosthesis: Multiple groups of neodymium magnet blocks are respectively encapsulated in the tibial liner and the femoral prosthesis. The neodymium magnet blocks on the contact surface between the tibial liner and the femoral prosthesis have the same magnetic properties; specifically, the tibial liner is divided into an upper tibial liner and a lower tibial liner. Oval installation grooves are provided in both the upper tibial liner and the lower tibial liner, and the upper and lower groups of oval installation grooves form a magnet block installation cavity, and the neodymium magnet blocks are encapsulated in the installation cavity;

[0071] The upper tibial liner and the lower tibial liner are hermetically installed through a buckle structure. The femoral prosthesis includes upper and lower parts, and the two parts are hermetically installed through a buckle structure to realize the hermetic installation of the neodymium magnet blocks and prevent body fluids from seeping in. The buckle structure is divided into two parts. The upper parts of multiple groups of buckles are fixedly connected to the upper liner of the tibial liner and the upper part of the femoral prosthesis, and the lower parts of the buckles are fixedly connected to the lower liner of the tibial liner and the lower part of the femoral prosthesis, thereby realizing hermetic encapsulation.

[0072] Prosthesis performance test:

[0073] Magnetic positioning effect: In the simulated joint movement experiment, through the monitoring of the magnetic field detection equipment, the repulsive force generated by the neodymium magnet blocks on the contact surface between the tibial liner and the femoral prosthesis is stable, and the positioning accuracy error during joint movement is controlled within ±0.2 mm, effectively improving the stability of joint movement.

[0074] Overall mechanical properties: The assembled joint replacement prosthesis was tested for mechanical properties. In the loading tests under simulated human walking, running, jumping and other motion states, the prosthesis could withstand a pressure of up to 2000 N without deformation, damage or other situations, meeting the needs of daily human movements.

[0075] Specifically, it is shown in the following table:

[0076]

[0077] Combined with Figure 2 As shown, the performance tests of the prosthesis under different bending states are as follows:

[0078] Specifically, it is shown in the following table:

[0079]

[0080]

[0081] Combined with the above data table, it can be known that the prosthesis of this embodiment has more excellent mechanical properties and higher durability in meeting the complex movement needs of the human body, and can provide a more reliable joint replacement effect for patients.

[0082] The above specific embodiments are only an optional embodiment of the present invention. Based on the technical solution of the present invention and the relevant revelations of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A method for preparing a low-wear knee replacement prosthesis, characterized in that: The joint replacement prosthesis includes a tibial liner, a femoral prosthesis, a tibial tray and a neodymium magnet; The method for preparing a joint replacement prosthesis comprises the following steps: Step 1: Prepare the raw materials needed to make the prosthesis: The tibial liner comprises the following raw materials in parts by weight: 99.5-99.8 parts of highly cross-linked ultra-high molecular weight polyethylene and 0.2-0.5 parts of an antioxidant; The femoral prosthesis comprises the following raw materials in parts by weight: 80-88 parts of polyetheretherketone and 0.5-1.2 parts of reinforced composite raw materials; The tibial tray comprises the following raw materials in parts by weight: 98-99.8 parts of polyurethane and 0.2-0.5 parts of catalyst; The neodymium magnet comprises the following raw materials by weight: 29-32 parts of neodymium, 63-67 parts of iron, 1-1.2 parts of boron, and 1-5 parts of dysprosium; Step 2: Combine the injection mold to prepare the tibial pad, femoral prosthesis and tibial tray, and combine the smelting furnace to smelt the alloy, mold forming, vacuum sintering and tempering treatment to prepare the neodymium magnet block; Step 3: Assembly of replacement prostheses: Multiple groups of neodymium magnet blocks are respectively encapsulated in the tibial liner and the femoral prosthesis. The neodymium magnet blocks on the contact surface of the tibial liner and the femoral prosthesis have the same magnetic properties.

2. A method for preparing a low-wear knee replacement prosthesis according to claim 1, characterized in that: The tibial pad, femoral prosthesis and tibial tray are injection molded using the same type of mold structure.

3. The method for preparing a low-wear knee replacement prosthesis according to claim 1, characterized in that: The antioxidant used in the tibial pad is one or more combinations of vitamin E and hindered phenol antioxidants; The reinforced composite material used in the femoral prosthesis is carbon fiber, which accounts for 0.5%-3% of the raw materials required for the femoral prosthesis, and the length of the carbon fiber is 0.1mm-5mm; The catalyst used in the tibial tray is dibutyltin dilaurate, which accounts for 0.05%-0.2% of the total mass of the tibial tray raw materials.

4. The method for preparing a low-wear knee replacement prosthesis according to claim 1, characterized in that: The molecular weight of the highly cross-linked ultra-high molecular weight polyethylene is in the range of 1 million to 6 million, and the degree of cross-linking is in the range of 60% to 90%; The polyurethane is prepared by reacting polyol and isocyanate, and the molar ratio of the polyol to the isocyanate is in the range of 1:1.1-1:1.

5.

5. The method for preparing a low-wear knee replacement prosthesis according to claim 4, characterized in that: The polyol is any one of polyether polyol and polyester polyol, and the number average molecular weight ranges from 500 to 3000; The isocyanate is any one of toluene diisocyanate and diphenylmethane diisocyanate.

6. The method for preparing a low-wear knee replacement prosthesis according to claim 1, characterized in that: The molding die comprises a material storage head (1), a material storage cavity (2), a first heating plate (3), an upper molding cavity (4), a lower molding cavity (5), and a second heating plate (6); The upper molded cavity and the lower molded cavity are combined with the shape change of the tibial liner, the femoral prosthesis and the tibial tray.

7. A method for preparing a low-wear knee replacement prosthesis according to claim 6, characterized in that: After the upper molding cavity and the lower molding cavity are molded together, the shape of the molding cavity matches the designed tibial liner, femoral prosthesis and tibial tray model in a 1:1 ratio; The molding cavity is made of S136 mold steel, and the inner wall of the molding cavity is coated with polytetrafluoroethylene.

8. The method for preparing a low-wear knee replacement prosthesis according to claim 6, characterized in that: The tibial pad is divided into an upper tibial pad and a lower tibial pad. The upper tibial pad and the lower tibial pad are both provided with an elliptical mounting groove. The upper and lower groups of elliptical mounting grooves form a magnet block mounting cavity. The neodymium magnet block is encapsulated in the mounting cavity. The upper tibial pad liner and the lower tibial pad liner are sealed and installed via a buckle structure.

9. The method for preparing a low-wear knee replacement prosthesis according to claim 8, characterized in that: The femoral prosthesis consists of an upper part and a lower part, and the two parts are closed and installed with a snap-fit ​​structure to achieve a sealed installation of the neodymium magnet block to prevent the infiltration of body fluids.

10. The method for preparing a low-wear knee replacement prosthesis according to claim 1, characterized in that: The tibial liner comprises the following raw materials in parts by weight: 99.6 parts of highly cross-linked ultra-high molecular weight polyethylene and 0.35 parts of an antioxidant; The femoral prosthesis comprises the following raw materials in parts by weight: 84 parts of polyetheretherketone and 0.9 parts of reinforced composite raw materials; The tibial tray comprises the following raw materials by weight: 99 parts of polyurethane and 0.35 parts of catalyst; The neodymium magnet comprises the following raw materials in parts by weight: 30 parts of neodymium, 65 parts of iron, 1.1 parts of boron, and 3 parts of dysprosium.

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