Molding method of high-crosslinking ultra-high molecular weight polyethylene knee joint pad

Abstract

The invention discloses an ultra-high molecular weight polyethylene knee joint pad and a forming method thereof, and the forming method comprises the following steps: S1, filling raw material powder into a pad mold, and carrying out mold pressing to form a knee joint pad blank; and sintering to obtain the knee joint pad. Wherein the raw material powder is ultra-high molecular weight polyethylene powder; or the raw material powder is formed by mixing ultra-high molecular weight polyethylene powder and an antioxidant; s2, performing radiation crosslinking on the knee joint pad in a reducing atmosphere; and S3, under an anaerobic condition, carrying out annealing treatment on the knee joint pad after radiation crosslinking to obtain the ultra-high molecular weight polyethylene knee joint pad. According to the forming method of the high-crosslinking ultra-high molecular weight polyethylene knee joint pad, the crosslinking degree is controllable, a friction surface does not need secondary machining, the surface is smooth, good cambered surface contact with a metal femoral head can be achieved, and abrasion is reduced; meanwhile, the method can remarkably improve the use performance of the high-crosslinking ultra-high molecular weight polyethylene knee joint pad, and the manufacturing difficulty of the material is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of orthopedic implant manufacturing, and in particular to a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner. Background Art

[0002] The joint composed of ultra-high molecular weight polyethylene and metal joint head has always been the gold standard combination of artificial joint load-bearing surfaces. After ultra-high molecular weight polyethylene is treated with ionizing radiation, a cross-linked structure is formed between the molecular chains, which improves the wear resistance while reducing the original toughness. The impact force that the knee joint pad needs to bear is large, and the highly cross-linked ultra-high molecular weight pad needs to find a suitable balance between wear resistance and toughness to facilitate reasonable adjustment according to factors such as the patient's weight and activity level. Since the artificial knee joint is relatively small in size and needs to bear most of the body's weight, the manufacturing requirements of the highly cross-linked ultra-high molecular weight polyethylene joint pad are high.

[0003] At present, a series of standards for highly cross-linked ultra-high molecular weight polyethylene implants have been established in China, such as the standard requirements for high-dose radiation cross-linked ultra-high molecular weight polyethylene products for surgical implants, YYT 0811-2010. According to these standards, it is necessary to first manufacture large-sized ultra-high molecular weight polyethylene molding compounds, and then obtain highly cross-linked ultra-high molecular weight polyethylene material substrates through radiation cross-linking, which are usually in the shape of rods or blocks. When manufacturing knee pads, the substrate is machined according to the design of the joint to make joint pads. Since the structure of knee pads is relatively complex, not only does the smooth curved surface structure require high-precision machining, but the heterogeneous structure also requires a large amount of expensive substrates. Summary of the invention

[0004] The object of the present invention is to provide a molding method for a highly cross-linked ultra-high molecular weight polyethylene knee joint pad, by making ultra-high molecular weight polyethylene into a prefabricated pad with a smooth curved surface and an appropriate degree of cross-linking. The pad does not need to be processed on the curved surface when it is finely processed into a product in the later stage. It has the characteristics of improving the curved surface accuracy, reducing the processing difficulty, saving time and materials, and it is easy to control the differentiated needs of the degree of cross-linking.

[0005] In a first aspect, the present invention provides a method for molding a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0006] S1. The raw material powder is loaded into a liner mold and molded into a knee liner green body; and then sintered under an inert atmosphere to obtain a knee liner;

[0007] S2. Radiation cross-linking the knee pad under a reducing atmosphere;

[0008] S3. Under anaerobic conditions, annealing the radiation-crosslinked knee liner to obtain the ultra-high molecular weight polyethylene knee liner.

[0009] At present, conventional high-crosslinked ultra-high molecular weight polyethylene knee pads require first molding ultra-high molecular weight polyethylene powder, that is, processing it into various forms (for example, rectangular plates or rods, etc.) through molding or extrusion, radiation crosslinking the above-mentioned profiles, and then cutting and precision machining to obtain knee pads of the required specifications. On the one hand, the friction surface of the knee pad is an irregular arc surface, which requires high processing accuracy, and on the other hand, the processing process consumes a large amount of expensive profiles.

[0010] In the molding method provided by the present invention, the raw material powder is first molded into an integral part, and then radiation cross-linked, so as to produce a high-cross-linked ultra-high molecular weight polyethylene knee joint pad rough component. The knee joint pad component obtained by this method only needs appropriate mechanical processing to obtain a pad product with a smooth curved surface and controllable cross-linking degree. This method avoids the lengthy preparation process of the conventional method, reduces the manufacturing difficulty, and greatly saves raw materials and reduces costs.

[0011] In step S1 of the present invention, the raw material powder may be ultra-high molecular weight polyethylene powder. In some embodiments, an antioxidant is added to the raw material powder, that is, the raw material powder is a mixture of ultra-high molecular weight polyethylene powder and an antioxidant. The added antioxidant can reduce the oxidation of ultra-high molecular weight polyethylene in subsequent processes.

[0012] In step S1 of the present invention, the antioxidant can be an antioxidant commonly used in industry, including but not limited to thiodimethylene bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, tetra[methylene(3,5-di-tert-butylhydroxyhydrocinnamate)]methane, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, vitamin E, phenylpropionic acid 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-C7-C9 branched alkyl ester, N,N'-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), 2,4-bis(dodecylthiomethyl)-6-methylphenol, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, 1,3,5-tri(3, at least one of 1,3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 2,4-bis(octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, tris(2,4-di-tert-butylphenyl)phosphite, or pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol) monoacrylate, and the reaction product of benzylamine and 2,4,4-trimethylpentene.

[0013] In the present invention, the amount of antioxidant added to the raw material powder is 0.01-0.5%, for example, it can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable. Preferably, the amount of antioxidant added to the raw material powder is 0.1-0.3%.

[0014] In step S1 of the present invention, the compression molding is preferably performed by cold pressing, and the pressure of the cold pressing is 3 to 20 MPa, for example, 3 MPa, 5 MPa, 8 MPa, 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa, etc., but is not limited to the listed values, and other values ​​or ranges not listed in the numerical range are also applicable. Preferably, the pressure of the cold pressing is 10 to 15 MPa.

[0015] In step S1 of the present invention, sintering needs to be carried out in an inert atmosphere, and the inert atmosphere includes but is not limited to at least one of nitrogen, argon and helium, preferably nitrogen. The sintering temperature is 140 to 200°C, for example, it can be 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable. The sintering time is 2 to 10h, for example, it can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc., but it is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable. Preferably, the sintering temperature is 160 to 180°C, and the sintering time is 5 to 8h.

[0016] In some preferred embodiments of the present invention, in step S1, the knee joint liner obtained after cold pressing and sintering has a joint surface roughness Ra value of no more than 0.5 μm.

[0017] In step S2 of the present invention, the radiation cross-linking treatment needs to be carried out in a reducing atmosphere, and the reducing atmosphere includes but is not limited to at least one of reducing gases such as hydrogen and methane. Since the ultra-high molecular weight polyethylene powder contains a certain amount of dissolved oxygen and oxidizing components, when the knee joint pad is irradiated and cross-linked in a reducing atmosphere, the dissolved oxygen and oxidizing components in the ultra-high molecular weight polyethylene will be activated by the radiation particles and preferentially combined with reducing gases such as hydrogen and methane, thereby neutralizing the dissolved oxygen in the material, reducing the degree of oxidation of the ultra-high molecular weight polyethylene, and ensuring the mechanical properties of the knee joint pad.

[0018] In step S2 of the present invention, the radiation cross-linking preferably adopts gamma rays, and the dosage range of radiation cross-linking is 40-130 kGy, for example, it can be 40 kGy, 50 kGy, 60 kGy, 70 kGy, 80 kGy, 90 kGy, 100 kGy, 110 kGy, 120 kGy, 130 kGy, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0019] In step S3 of the present invention, the annealing treatment is carried out under anaerobic conditions, thereby preventing the ultra-high molecular weight polyethylene from being oxidized during the annealing treatment. The anaerobic conditions include vacuum or an inert atmosphere, and the inert atmosphere includes but is not limited to at least one of nitrogen, helium, argon, and carbon dioxide.

[0020] In step S3 of the present invention, the annealing temperature is 120-135°C, for example, it can be 120°C, 122°C, 125°C, 128°C, 130°C, 132°C, 135°C, etc., but it is not limited to the listed values, and other values ​​or ranges not listed in the numerical range are also applicable. The annealing time is 2-120h, for example, it can be 2h, 5h, 10h, 20h, 30h, 50h, 60h, 80h, 100h, 120h, etc., but it is not limited to the listed values, and other values ​​or ranges not listed in the numerical range are also applicable.

[0021] In some preferred embodiments of the present invention, in step S3, before annealing, the radiation cross-linked knee pad is placed in a pad mold and then annealed. This allows the knee pad to maintain its original shape during high temperature annealing to avoid deformation, thereby reducing subsequent mechanical processing.

[0022] The second aspect of the present invention provides an ultra-high molecular weight polyethylene knee joint liner obtained by the above molding method.

[0023] Through one or more of the above embodiments of the present invention, at least the following technical effects can be achieved:

[0024] 1. In the molding method of the highly cross-linked ultra-high molecular weight polyethylene knee pad provided by the present invention, the raw material powder is first molded into an integral part, and then radiation cross-linked, so as to manufacture a high-cross-linked ultra-high molecular weight polyethylene knee pad rough component. The knee pad component obtained by this method only needs appropriate mechanical processing to obtain a pad product with a smooth curved surface and controllable cross-linking degree. This method avoids the lengthy preparation process of the conventional method, reduces the manufacturing difficulty, and greatly saves raw materials and reduces costs.

[0025] 2. In the molding method of the highly cross-linked ultra-high molecular weight polyethylene knee joint pad provided by the present invention, the radiation cross-linking process is carried out under a reducing atmosphere, so that the dissolved oxygen and oxidizing components present in the ultra-high molecular weight polyethylene will be activated by the radiation particles and preferentially combine with reducing gases such as hydrogen and methane, thereby reducing the degree of oxidation of the ultra-high molecular weight polyethylene and ensuring the mechanical properties of the knee joint pad.

[0026] 3. In the molding method of the highly cross-linked ultra-high molecular weight polyethylene knee joint pad provided by the present invention, the knee joint pad is placed in a pad mold for annealing treatment, which can enable the knee joint pad to maintain its original shape during the high-temperature annealing process and avoid deformation, thereby helping to reduce subsequent mechanical processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1The ultra-high molecular weight polyethylene knee joint molded liner in Example 1;

[0028] Figure 2 The electron microscope images of the surfaces of the two gaskets are as follows: (a) the surface of the molded gasket in Example 1; (b) the surface of the finely processed gasket in Comparative Example 1;

[0029] Figure 3 This is a small punching test diagram of the uncrosslinked ultra-high molecular weight polyethylene liner in Example 1;

[0030] Figure 4 This is a small punching test diagram of the gamma ray radiation cross-linked liner in Example 1;

[0031] Figure 5 This is a small punching test diagram of the gamma ray radiation cross-linked liner in Example 2. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] In the following embodiments and comparative examples, various raw materials, equipment, etc. can be obtained by purchase unless otherwise specified.

[0034] Example 1

[0035] This embodiment provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0036] S1. Place the ultra-high molecular weight polyethylene powder into the pad mold for compression molding, with a cold pressure of 5MPa and compression for 1h. Then place the mold in the compression state into an oven for heating at 160℃ for 10h. Carefully take the mold out of the oven, cool it naturally to room temperature, open the mold, and obtain the ultra-high molecular weight polyethylene knee pad.

[0037] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under the protection of methane atmosphere, and the cross-linking dose is 80 kGy.

[0038] S3. The cross-linked liner is annealed under nitrogen atmosphere protection at a temperature of 125° C. for 36 hours.

[0039] Example 2

[0040] This embodiment provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0041] S1. Ultra-high molecular weight polyethylene powder and antioxidant The 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) powder is fully mixed to obtain a raw material powder, wherein the amount of antioxidant added is 0.2 wt %. The raw material powder is placed in a pad mold for compression molding, with a cold pressure of 8 MPa and compression for 2 h. Then the mold in the compression state is placed in an oven for heating at a temperature of 180°C for a heating time of 5 h. The mold is carefully taken out of the oven, cooled naturally to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee pad.

[0042] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under the protection of methane atmosphere, and the cross-linking dose is 90 kGy.

[0043] S3. The cross-linked liner is annealed under argon atmosphere protection, with an annealing temperature of 130° C. and an annealing time of 24 h.

[0044] Example 3

[0045] This embodiment provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0046] S1. Ultra-high molecular weight polyethylene powder and antioxidant The 1010 powder is fully mixed to obtain a raw material powder, wherein the antioxidant is added in an amount of 0.2 wt %. The raw material powder is placed in a pad mold for compression molding, with a cold pressure of 10 MPa and compression for 1 hour. Then the mold is placed in an oven for heating at a temperature of 150° C. for 6 hours. The mold is carefully taken out of the oven, cooled naturally to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee pad.

[0047] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under the protection of hydrogen atmosphere, and the cross-linking dose is 60 kGy.

[0048] S3. The cross-linked liner is annealed under nitrogen atmosphere protection at a temperature of 125° C. for 36 hours.

[0049] Example 4

[0050] This embodiment provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0051] S1. Ultra-high molecular weight polyethylene powder and antioxidant The 1010 powder is fully mixed to obtain a raw material powder, wherein the antioxidant is added in an amount of 0.3% by weight. The raw material powder is placed in a pad mold for compression molding, with a cold pressure of 8 MPa and compression for 2 hours. Then the mold is placed in an oven for heating at a temperature of 180°C for 5 hours. The mold is carefully taken out of the oven, cooled naturally to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee pad.

[0052] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under the protection of methane atmosphere, and the cross-linking dose is 90 kGy.

[0053] S3. Place the cross-linked liner into a liner mold and perform annealing treatment under the protection of a carbon dioxide atmosphere at a temperature of 130° C. for 24 hours.

[0054] Comparative Example 1

[0055] This comparative example provides a finely processed ultra-high molecular weight polyethylene knee joint pad, which is prepared by a traditional method, that is, a large-sized ultra-high molecular weight polyethylene block substrate is first prepared by radiation cross-linking, and then the ultra-high molecular weight polyethylene block substrate is mechanically finely processed to make a joint pad.

[0056] Comparative Example 2

[0057] This comparative example provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0058] S1. Ultra-high molecular weight polyethylene powder and antioxidant The 1010 powder is fully mixed to obtain a raw material powder, wherein the antioxidant is added in an amount of 0.2 wt %. The raw material powder is placed in a pad mold for compression molding, with a cold pressure of 10 MPa and compression for 1 hour. Then the mold is placed in an oven for heating at a temperature of 150° C. for 6 hours. The mold is carefully taken out of the oven, cooled naturally to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee pad.

[0059] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under vacuum atmosphere protection, with a cross-linking dose of 60 kGy.

[0060] S3. The cross-linked liner is annealed under nitrogen atmosphere protection at a temperature of 125° C. for 36 hours.

[0061] Comparative Example 3

[0062] This comparative example provides a molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0063] S1. Ultra-high molecular weight polyethylene powder and antioxidant The 1010 powder is fully mixed to obtain a raw material powder, wherein the antioxidant is added in an amount of 0.2 wt %. The raw material powder is placed in a pad mold for compression molding, with a cold pressure of 10 MPa and compression for 1 hour. Then the mold is placed in an oven for heating at a temperature of 150° C. for 6 hours. The mold is carefully taken out of the oven, cooled naturally to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee pad.

[0064] S2. The above-mentioned liner is subjected to gamma ray radiation cross-linking treatment under the protection of nitrogen atmosphere, and the cross-linking dose is 60 kGy.

[0065] S3. The cross-linked liner is annealed under nitrogen atmosphere protection at a temperature of 125° C. for 36 hours.

[0066] Performance Testing

[0067] 1. Surface morphology

[0068] Figure 1 The ultra-high molecular weight polyethylene knee joint molded liner prepared in Example 1. The friction surface (curved surface) of the liner was observed by scanning electron microscopy. The results are as follows Figure 2 As shown in a. It can be seen from the figure that the surface of the liner is smooth.

[0069] Figure 2 b is a scanning electron microscope image of the machined knee joint friction surface in Comparative Example 1. It can be seen from the figure that the surface of the liner is not smooth and has obvious traces of machining.

[0070] 2. Small punching test

[0071] The uncrosslinked liner and the liner after crosslinking annealing in Example 1 were subjected to small punching tests respectively, and the test curves are shown in FIG. Figure 3 and Figure 4 .

[0072] See also Figure 3-4 ,and Figure 3 compared to, Figure 4 The test curve is upturned, the limit load increases, and the limit displacement decreases slightly. These characteristics are consistent with the characteristics of radiation cross-linked ultra-high molecular weight polyethylene. Compared with the small punching test results in the literature "Research on the Structure and Properties of Radiation Cross-linked Ultra-High Molecular Weight Polyethylene for Artificial Joints" (Jiang Xi, Master's thesis of Tianjin University, 2014), it can be judged that the radiation cross-linking of the knee joint liner in Example 1 is successful.

[0073] The liner after cross-linking annealing in Example 2 was subjected to a small punching test, and the test curve is as follows: Figure 5 shown.

[0074] like Figure 5 As shown in , the test curve is upward, the ultimate load increases, and the ultimate displacement decreases slightly. These characteristics are consistent with the characteristics of radiation-crosslinked ultra-high molecular weight polyethylene. Therefore, it can be judged that the radiation crosslinking of the knee joint liner in Example 2 is successful.

[0075] 3. Oxidation index test

[0076] The samples of Example 3 and Comparative Examples 2-3 were analyzed using FTIR in the transmission mode with a wave number range of 400-4000 cm -1 , the number of scans is 32 times, and the resolution is 2cm -1 . 1718cm -1 With 2020cm -1 The integral area A is obtained by integrating the absorption peaks at 1718cm -1 and A 2020cm -1 , the ratio of the two is the oxidation index (OI):

[0077]

[0078] The results show that the OI value of the sample prepared in Example 3 is 0.012, while the OI values ​​of the samples prepared in Comparative Examples 2-3 are 0.035 and 0.037, respectively. This indicates that when irradiated in a reducing atmosphere, the oxidation caused by dissolved oxygen in the ultra-high molecular weight polyethylene material can be significantly reduced, thus being beneficial to improving the mechanical properties of the ultra-high molecular weight polyethylene liner.

[0079] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for molding a highly cross-linked ultra-high molecular weight polyethylene knee joint liner, characterized in that: The following steps are involved: S1. The raw material powder is loaded into a pad mold and molded into a knee pad blank; Then, sintering is performed under an inert atmosphere to obtain a knee joint pad; wherein the raw material powder is ultra-high molecular weight polyethylene powder; or the raw material powder is a mixture of ultra-high molecular weight polyethylene powder and an antioxidant; S2. Radiation cross-linking the knee pad under a reducing atmosphere; S3. Under anaerobic conditions, annealing the radiation-crosslinked knee liner to obtain the ultra-high molecular weight polyethylene knee liner.

2. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S1, the antioxidant includes thiodimethylene bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, tetra[methylene (3,5-di-tert-butyl hydroxyhydrocinnamate)] methane, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, vitamin E, phenylpropionic acid 3,5-bis (1,1-dimethyl-ethyl) -4-hydroxy-C7-C9 branched alkyl ester, N,N'-hexane-1,6-diyl bis (3-(3,5-di-tert-butyl-4-hydroxyphenyl propionamide)), 2,4-bis (dodecylthiomethyl) -6-methylphenol, triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) at least one of 1,3,5-triazine-2,4,6(1H,3H,5H)-trione, tris(2,4-di-tert-butylphenyl)phosphite, or pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol) monoacrylate, and the reaction product of benzylamine and 2,4,4-trimethylpentene; and / or, The added amount of the antioxidant in the raw material powder is 0.01-0.5%.

3. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S1, the compression molding is performed by cold pressing, and the pressure of the cold pressing is 3-20 MPa; and / or, The sintering temperature is 140-200° C., and the sintering time is 2-10 hours.

4. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 3, characterized in that: In step S1, the knee joint pad obtained after cold pressing and sintering has a joint surface roughness Ra value of no more than 0.5 μm.

5. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S2, the reducing atmosphere includes at least one of hydrogen and methane.

6. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S2, the radiation cross-linking uses gamma rays, and the radiation cross-linking dose range is 40 to 130 kGy.

7. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S3, the oxygen-free condition includes vacuum or an inert atmosphere, and the inert atmosphere includes at least one of nitrogen, helium, argon, and carbon dioxide.

8. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S3, the annealing temperature is 120-135° C., and the annealing time is 2-120 hours.

9. The method for forming a highly cross-linked ultra-high molecular weight polyethylene knee joint liner according to claim 1, characterized in that: In step S3, the radiation cross-linked knee joint liner is placed in a liner mold for annealing.

10. An ultra-high molecular weight polyethylene knee joint pad obtained by the molding method according to any one of claims 1 to 9.

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