A method of forming a highly crosslinked ultra-high molecular weight polyethylene knee spacer

Abstract

The application discloses a kind of ultra-high molecular weight polyethylene knee joint liner and its forming method, the forming method includes the following steps: S1. raw material powder is loaded into liner mold, and knee joint liner blank is formed by moulding;Then sintering is carried out, and knee joint liner is obtained;Wherein, the raw material powder is ultra-high molecular weight polyethylene powder;Or the raw material powder is by ultra-high molecular weight polyethylene powder and antioxidant mixed;S2. under reducing atmosphere, the knee joint liner is radiated crosslinking;S3. under anaerobic condition, the knee joint liner after radiation crosslinking is annealed, and the ultra-high molecular weight polyethylene knee joint liner is obtained.The forming method of high crosslinking ultra-high molecular weight polyethylene knee joint liner disclosed in the application is controllable in crosslinking degree, and the friction surface does not need secondary mechanical processing, the surface is smooth, can be better arc surface contact with metal femoral head, reduce wear;Meanwhile, the method can significantly improve the use performance of high crosslinking ultra-high molecular weight polyethylene knee joint liner, and greatly reduce the manufacturing difficulty of the material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of orthopedic implant manufacturing, and particularly relates to a forming method of high cross-linking ultra-high molecular weight polyethylene knee joint liner. BACKGROUND

[0002] The joint composed of ultra-high molecular weight polyethylene and metal joint head has been the gold standard combination of artificial joint bearing surface. After ionizing radiation treatment, the cross-linking structure is formed between the molecular chains of ultra-high molecular weight polyethylene, which improves the wear resistance and reduces the original toughness. The impact force borne by the knee joint liner is large, and the high cross-linking ultra-high molecular weight liner needs to find a suitable balance point between wear resistance and toughness, so as to facilitate reasonable adjustment according to the weight, activity level and other factors of the patient. Since the size of the artificial knee joint is relatively small, and it needs to bear most of the body weight, the manufacturing of the high cross-linking ultra-high molecular weight polyethylene joint liner requires high.

[0003] At present, a series of standards of high cross-linking ultra-high molecular weight polyethylene implants have been established in China, such as YYT 0811-2010 standard for large-dose radiation cross-linking ultra-high molecular weight polyethylene products for surgical implants. According to these standards, a large-size ultra-high molecular weight polyethylene molding material needs to be manufactured first, and then a high cross-linking ultra-high molecular weight polyethylene material substrate is obtained through radiation cross-linking, which is usually in the form of a rod or a block. When manufacturing the knee joint liner, the substrate is mechanically processed according to the design of the joint to form the joint liner. Since the structure of the knee joint liner is complex, not only the smooth curved surface structure needs high-precision mechanical processing, but also the heterogeneous structure needs to consume a large amount of expensive substrate. SUMMARY

[0004] The purpose of the present application is to provide a forming method of high cross-linking ultra-high molecular weight polyethylene knee joint liner, which prepares the ultra-high molecular weight polyethylene into a preformed liner with a smooth curved surface and a suitable cross-linking degree. The liner does not need to be processed in the curved surface when it is finally processed into the product, which has the characteristics of improving the curved surface precision, reducing the processing difficulty, saving time and material, and easily controlling the differentiated needs of the cross-linking degree.

[0005] In the first aspect, the present application provides a forming method of high cross-linking ultra-high molecular weight polyethylene knee joint liner, which comprises the following steps:

[0006] S1. The raw material powder is loaded into the liner mold to form a knee joint liner blank by molding, and then sintering is carried out under an inert atmosphere to obtain a knee joint liner;

[0007] S2. The knee joint liner is subjected to radiation cross-linking under a reducing atmosphere;

[0008] S3. annealing the knee joint liner after radiation cross-linking under anaerobic conditions to obtain the ultra-high molecular weight polyethylene knee joint liner.

[0009] The conventional high cross-linking ultra-high molecular weight polyethylene knee joint liner needs to be molded into a powder first, i.e. processed into various forms (e.g. rectangular plate or rod) by molding or extrusion, etc. The above profile is cross-linked by radiation, and then cut and precisely machined to obtain the required specification of knee joint liner. On the one hand, the friction surface of the knee joint liner is an irregular curved surface, which requires high machining precision, and on the other hand, the processing process consumes a large amount of expensive profile.

[0010] The molding method provided by the present application first integrally molds the raw material powder, and then performs radiation cross-linking to manufacture a high cross-linking ultra-high molecular weight polyethylene knee joint liner rough member. The knee joint liner member obtained by the method only needs to be appropriately machined to obtain a smooth curved surface and a cross-linking degree controllable liner product. The method avoids the long preparation process of the conventional method, reduces the manufacturing difficulty, greatly saves the raw material, and reduces the cost.

[0011] In step S1 of the present application, the raw material powder can be an ultra-high molecular weight polyethylene powder. In some embodiments, an antioxidant is also added to the raw material powder, i.e. the raw material powder is mixed from an ultra-high molecular weight polyethylene powder and an antioxidant. The added antioxidant can reduce the oxidation of the ultra-high molecular weight polyethylene in the subsequent process.

[0012] The antioxidant in step S1 of the present application can be an antioxidant commonly used in industry, including but not limited to at least one of thiodiethylene bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, tetrakis[methylene(3,5-di-tert-butylhydroxyhydrocinnamate)]methane, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, vitamin E, benzenepropanoic 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-tris(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) monopropenoate, reaction product of benzeneamine and 2,4,4-trimethylpentene.

[0013] In the present application, the antioxidant is added to the raw material powder in an amount of 0.01 to 0.5%, for example, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., but not limited to the listed values, and other values or ranges not listed within this range are also applicable. Preferably, the antioxidant is added to the raw material powder in an amount of 0.1 to 0.3%.

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

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

[0016] In some preferred embodiments of the present application, in step S1, the knee joint liner obtained after cold pressing and sintering has a roughness Ra value of the joint surface of not more than 0.5μm.

[0017] In step S2 of the present application, the radiation crosslinking treatment needs to be carried out in a reducing atmosphere, which includes but is not limited to at least one of hydrogen, methane, and other reducing gases. Since the ultra-high molecular weight polyethylene powder contains a certain amount of dissolved oxygen and oxidizing components, when the knee joint liner is irradiated and crosslinked in a reducing atmosphere, the dissolved oxygen and oxidizing components present in the ultra-high molecular weight polyethylene are activated by the radiation particles to generate activation, and preferentially combine with hydrogen, methane, and other reducing gases, thereby neutralizing the dissolved oxygen in the material and reducing the oxidation degree of the ultra-high molecular weight polyethylene, ensuring the mechanical properties of the knee joint liner.

[0018] In step S2 of the present application, the radiation crosslinking preferably uses gamma rays, and the radiation crosslinking dose is in the range of 40-130kGy, for example, can be 40kGy, 50kGy, 60kGy, 70kGy, 80kGy, 90kGy, 100kGy, 110kGy, 120kGy, 130kGy, and the like, but is not limited to the listed values, and other values or ranges not listed in this range are also applicable.

[0019] In step S3 of the present application, the annealing treatment is carried out under oxygen-free conditions, thereby avoiding oxidation of the ultra-high molecular weight polyethylene during the annealing treatment. The oxygen-free 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, the annealing temperature is 120-135 DEG C, for example, 120 DEG C, 122 DEG C, 125 DEG C, 128 DEG C, 130 DEG C, 132 DEG C, 135 DEG C, etc., but not limited to the listed values, and other values or ranges within the range are also applicable. The annealing time is 2-120 hours, for example, 2 hours, 5 hours, 10 hours, 20 hours, 30 hours, 50 hours, 60 hours, 80 hours, 100 hours, 120 hours, etc., but not limited to the listed values, and other values or ranges within the range are also applicable.

[0021] In some preferred embodiments of the present application, in step S3, before the annealing treatment, the radiation crosslinked knee joint pad is placed in a pad mold, and then the annealing treatment is performed. In this way, the knee joint pad can maintain its original shape during the high-temperature annealing process, and deformation is avoided, thus facilitating subsequent mechanical processing.

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

[0023] By one or more of the above embodiments of the present application, the following technical effects can be achieved:

[0024] 1. The molding method of the high crosslinking ultra-high molecular weight polyethylene knee joint pad provided by the present application first integrally molds the raw material powder, and then performs radiation crosslinking, thereby manufacturing a high crosslinking ultra-high molecular weight polyethylene knee joint pad rough component. By this method, the knee joint pad component only needs to be appropriately mechanically processed, and a smooth curved surface and a controllable crosslinking degree of the pad product can be obtained. This method avoids the long preparation process of the conventional method, reduces the manufacturing difficulty, greatly saves the raw material, and reduces the cost.

[0025] 2. In the molding method of the high crosslinking ultra-high molecular weight polyethylene knee joint pad provided by the present application, the radiation crosslinking process is performed in a reducing atmosphere, so that the dissolved oxygen and oxidizing components present in the ultra-high molecular weight polyethylene are activated by the radiation particles to generate activation, and preferentially combine with hydrogen, methane and other reducing gases, thereby reducing the oxidation degree 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 high crosslinking ultra-high molecular weight polyethylene knee joint pad provided by the present application, the knee joint pad is placed in a pad mold for annealing treatment, so that the knee joint pad can maintain its original shape during the high-temperature annealing process, and deformation is avoided, thereby facilitating subsequent mechanical processing. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1A knee joint moulded UHMWPE liner according to Example 1;

[0028] Figure 2 Surface electron microscope pictures of two liners: (a) surface of the moulded liner of Example 1; (b) surface of the finished liner of Comparative Example 1;

[0029] Figure 3 Small punch test picture of the uncrosslinked UHMWPE liner of Example 1;

[0030] Figure 4 Small punch test picture of the gamma irradiation crosslinked liner of Example 1.

[0031] Figure 5 Small punch test picture of the gamma irradiation crosslinked liner of Example 2. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative work fall within the protection scope of the present application.

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

[0034] Example 1

[0035] The present embodiment provides a forming method of a high crosslinked UHMWPE knee joint liner, comprising the following steps:

[0036] S1. Put the UHMWPE powder raw material into the liner mould for moulding, with a cold pressure of 5 MPa and a pressing time of 1 h. Then put the whole mould in an oven in a moulding state, with a heating temperature of 160 ℃ and a heating time of 10 h. Carefully take the mould out of the oven, naturally cool to room temperature, and open the mould to obtain the UHMWPE knee joint liner.

[0037] S2. Perform gamma irradiation crosslinking treatment on the liner under the protection of a methane atmosphere, with a crosslinking dose of 80 kGy.

[0038] S3. Perform annealing treatment on the crosslinked liner under the protection of a nitrogen atmosphere, with an annealing temperature of 125 ℃ and an annealing time of 36 h.

[0039] Example 2

[0040] The present embodiment provides a forming method of a high crosslinking ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0041] S1. The ultra-high molecular weight polyethylene powder is mixed with antioxidant 1010(tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester) powder to obtain raw material powder, wherein the addition amount of antioxidant is 0.2% by weight. The raw material powder is placed in a liner mold for compression molding, cold pressure 8 MPa, pressing 2 h. Then the mold in the compression molding state is put into an oven as a whole, heating temperature 180°C, heating time 5 h. The mold is carefully taken out of the oven, naturally cooled to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee joint liner.

[0042] S2. The liner is subjected to gamma ray radiation crosslinking treatment under the protection of a methane atmosphere, and the crosslinking dose is 90 kGy.

[0043] S3. The crosslinked liner is subjected to annealing treatment under the protection of an argon atmosphere, annealing temperature 130°C, annealing time 24 h.

[0044] Example 3

[0045] The present embodiment provides a forming method of a high crosslinking ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0046] S1. The ultra-high molecular weight polyethylene powder is mixed with antioxidant 1010powder to obtain raw material powder, wherein the addition amount of antioxidant is 0.2% by weight. The raw material powder is placed in a liner mold for compression molding, cold pressure 10 MPa, pressing 1 h. Then the mold in the compression molding state is put into an oven as a whole, heating temperature 150°C, heating time 6 h. The mold is carefully taken out of the oven, naturally cooled to room temperature, and the mold is opened to obtain an ultra-high molecular weight polyethylene knee joint liner.

[0047] S2. The liner is subjected to gamma ray radiation crosslinking treatment under the protection of a hydrogen atmosphere, and the crosslinking dose is 60 kGy.

[0048] S3. The crosslinked liner is subjected to annealing treatment under the protection of a nitrogen atmosphere, annealing temperature 125°C, annealing time 36 h.

[0049] Example 4

[0050] The present embodiment provides a forming method of a high crosslinking ultra-high molecular weight polyethylene knee joint liner, comprising the following steps:

[0051] S1. The ultra-high molecular weight polyethylene powder is mixed with antioxidant 1010The powder is mixed thoroughly 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 liner mold to perform compression molding, with a cold pressure of 8 MPa and a compression time of 2 h. The mold is then placed as a whole in an oven to perform heating, with a heating temperature of 180°C and a heating time of 5 h. The mold is carefully taken out of the oven and naturally cooled to room temperature, and the mold is opened to obtain the ultra-high molecular weight polyethylene knee joint liner.

[0052] S2. The liner is subjected to gamma ray radiation crosslinking treatment under a methane atmosphere, with a crosslinking dose of 90 kGy.

[0053] S3. The crosslinked liner is placed in a liner mold to perform annealing treatment under a carbon dioxide atmosphere, with an annealing temperature of 130°C and an annealing time of 24 h.

[0054] Comparative Example 1

[0055] This comparative example provides a finished ultra-high molecular weight polyethylene knee joint liner, which is prepared by a traditional method, i.e., a large-size ultra-high molecular weight polyethylene block base material is prepared by irradiation crosslinking, and the ultra-high molecular weight polyethylene block base material is mechanically finished to obtain the joint liner.

[0056] Comparative Example 2

[0057] This comparative example provides a molding method of a high-crosslinking ultra-high molecular weight polyethylene knee joint liner, which comprises the following steps:

[0058] S1. The ultra-high molecular weight polyethylene powder is mixed with an antioxidant 1010The powder is mixed thoroughly 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 liner mold to perform compression molding, with a cold pressure of 8 MPa and a compression time of 2 h. The mold is then placed as a whole in an oven to perform heating, with a heating temperature of 180°C and a heating time of 5 h. The mold is carefully taken out of the oven and naturally cooled to room temperature, and the mold is opened to obtain the ultra-high molecular weight polyethylene knee joint liner.

[0059] S2. The liner is subjected to gamma ray radiation crosslinking treatment under a vacuum atmosphere, with a crosslinking dose of 60 kGy.

[0060] S3. The crosslinked liner is subjected to annealing treatment under a nitrogen atmosphere, with an annealing temperature of 125°C and an annealing time of 36 h.

[0061] Comparative Example 3

[0062] This comparative example provides a molding method of a high-crosslinking ultra-high molecular weight polyethylene knee joint liner, which comprises the following steps:

[0063] S1. Mix the UHMWPE powder with antioxidant 1010The powder is mixed thoroughly to obtain a raw material powder, with the antioxidant added in an amount of 0.2% by weight. The raw material powder is placed in a lined mold for compression molding, with a cold pressure of 10 MPa and a compression time of 1 h. The mold is then placed as a whole in an oven for heating, with a heating temperature of 150°C and a heating time of 6 h. The mold is carefully removed from the oven and allowed to cool naturally to room temperature, and the mold is opened to obtain a UHMWPE knee joint liner.

[0064] S2. The liner is subjected to gamma ray radiation crosslinking treatment under a nitrogen atmosphere, with a crosslinking dose of 60 kGy.

[0065] S3. The crosslinked liner is subjected to annealing treatment under a nitrogen atmosphere, with an annealing temperature of 125°C and an annealing time of 36 h.

[0066] Performance testing

[0067] 1. Surface morphology

[0068] Figure 1 The UHMWPE knee joint compression liner prepared in Example 1 is subjected to scanning electron microscope observation of the friction surface (curved surface), and the results are shown in Figure Figure 2 a. As can be seen from the figure, the surface of the liner is smooth.

[0069] Figure 2 b. The scanning electron microscope image of the mechanically processed knee joint friction surface in Comparative Example 1 shows that the surface of the liner is not smooth, and has obvious mechanical processing marks.

[0070] 2. Pin puncture test

[0071] The uncrosslinked liner and the crosslinked and annealed liner in Example 1 are subjected to pin puncture tests, and the test curves are shown in Figures Figure 3 and Figure 4 .

[0072] Please refer to Figures 3-4 , and Figure 3 , compared with Figure 4 , the test curve is raised, the ultimate load is increased, and the ultimate displacement is slightly decreased, which are characteristics of radiation crosslinked UHMWPE. Compared with the pin puncture test results in the literature “Study on Structure and Properties of Irradiation Crosslinked UHMWPE for Artificial Joints” (Jiang Xi, Master's Thesis, Tianjin University, 2014), it can be determined that the knee joint liner in Example 1 is successfully radiation crosslinked.

[0073] The crosslinked and annealed liner in Example 2 is subjected to a pin puncture test, and the test curve is shown in Figure Figure 5 .

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

[0075] 3. Oxidation Index Test

[0076] The samples from Example 3 and Comparative Examples 2-3 were analyzed using FTIR, with the transmission mode selected and the wavenumber range being 400-4000 cm⁻¹. -1 The number of scans was 32, and the resolution was 2cm. -1 For 1718cm -1 With 2020cm -1 Integrating the absorption peaks at each location yields the integration area A. 1718cm -1 and A 2020cm -1 The ratio of the two is the oxidation index (OI):

[0077]

[0078] The results showed that the OI value of the sample prepared in Example 3 was 0.012, while the OI values ​​of the samples prepared in Comparative Examples 2 and 3 were 0.035 and 0.037, respectively. This indicates that irradiation treatment in a reducing atmosphere can significantly reduce oxidation caused by dissolved oxygen in ultra-high molecular weight polyethylene materials, thus improving the mechanical properties of ultra-high molecular weight polyethylene gaskets.

[0079] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A method of forming a high crosslinked ultra-high molecular weight polyethylene knee spacer, characterized by, The method comprises the following steps: S1. loading raw material powder into a liner mold, and molding into a knee joint liner blank; Then sintering under inert atmosphere to obtain a knee joint liner; wherein the raw material powder is an ultra-high molecular weight polyethylene powder; or the raw material powder is a mixture of an ultra-high molecular weight polyethylene powder and an antioxidant; S2. radiation crosslinking of the knee joint liner under a reducing atmosphere; the reducing atmosphere is methane; the radiation crosslinking uses gamma rays, and the dose range of the radiation crosslinking is 40-130 kGy; S3. annealing the knee joint liner after the radiation crosslinking under an oxygen-free condition to obtain the ultra-high molecular weight polyethylene knee joint liner; the oxygen-free condition includes vacuum or inert atmosphere, and the inert atmosphere includes at least one of nitrogen, helium, argon and carbon dioxide; the annealing temperature is 120-135℃, and the annealing time is 2-120 h.

2. A method of forming a highly crosslinked ultra-high molecular weight polyethylene knee spacer as claimed in claim 1, wherein, In step S1, the antioxidant includes at least one of thiodiethylene 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, benzenepropanoic 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-tris(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) monopropenoate, and a reaction product of benzeneamine and 2,4,4-trimethylpentene; and / or, In the raw material powder, the addition amount of the antioxidant is 0.01-0.5%.

3. The molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner as described in claim 1, characterized in that, In step S1, the molding uses a cold pressing method, and the pressure of the cold pressing is 3-20 MPa; and / or, The sintering temperature is 140-200℃, and the sintering time is 2-10 h.

4. A method of forming a highly crosslinked ultra-high molecular weight polyethylene knee spacer as defined in claim 3, wherein, In step S1, the knee joint liner obtained after the cold pressing and sintering has a roughness Ra value of the joint surface of not more than 0.5 μm.

5. The molding method of a highly cross-linked ultra-high molecular weight polyethylene knee joint liner as described in claim 1, characterized in that, In step S3, the knee joint liner after the radiation crosslinking is placed in a liner mold for annealing.

6. The ultra-high molecular weight polyethylene knee spacer obtained by the molding method according to any one of claims 1 to 5.

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