Preparation method of degradable bone nail

Abstract

The invention relates to the technical field of medical orthopedic materials, and discloses a preparation method of a degradable bone nail, which comprises the following steps: preparing 28 parts of polylactic acid-glycolic acid copolymer; 20 parts of silk protein; 8 parts of polyvinyl alcohol; 3 parts of zinc alloy; 17 parts of poly (p-dioxanone); the preparation method comprises the following steps: pretreating a part of raw materials, carrying out melt blending to obtain a mixture, carrying out melt spinning molding on the mixture from an extruder through a spinneret plate of a melt spinning machine to obtain a stable composite material, and carrying out extrusion molding on the composite material through a mold to obtain a primary bone nail shape. A high-precision lathe is used for turning the formed bone nail, the surface of the bone nail is coated with a nano-silver / hydroxyapatite composite coating, the bone nail subjected to plasma treatment is subjected to radiation sterilization through gamma rays, and after sterilization, the bone nail is packaged in a sealed mode through a sterile packaging material. The obtained bone nail has the advantages of biocompatibility, degradability, high mechanical strength and high toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of medical orthopedic materials, and specifically to a preparation method of a degradable bone nail. Background Art

[0002] In modern orthopedic surgeries, bone nails, as a commonly used implant device, are mainly used to fix fracture sites to promote bone healing. However, most of the existing bone nail materials are metal-based materials, such as stainless steel and titanium alloy. Although these materials have good mechanical strength and stability, they have some significant defects. First of all, metal bone nails are not biodegradable, which means that after the fracture heals, patients need to undergo a second operation to remove them. This not only increases the pain and medical costs of patients, but also causes complications such as infections. Secondly, the biocompatibility of metal materials is relatively poor, leading to problems such as osteoporosis and stress concentration after long-term implantation in the body.

[0003] To solve these problems, in recent years, the research on degradable bone nails has gradually received attention. Degradable bone nails can be gradually absorbed by the human body after completing their fixation function, avoiding the need for a second operation. However, most of the degradable bone nail materials on the market currently are polymer materials, such as polylactic acid (PLA) and polycaprolactone (PCL). Although these materials have good biocompatibility and degradability, they still have deficiencies in mechanical strength and toughness. In addition, the production costs of these materials are relatively high, restricting their wide application in clinics.

[0004] Therefore, developing a bone nail material that not only has excellent mechanical properties but also good biocompatibility and degradability has important clinical significance and economic value. This can not only improve the treatment effect and quality of life of patients, but also reduce medical costs and promote the development of the field of orthopedic implant materials. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of a degradable bone nail, which has the advantages of biocompatibility, degradability, high mechanical strength and high toughness, and solves the problems of poor biocompatibility and difficult degradability of bone nails.

[0007] (II) Technical Solutions

[0008] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a degradable bone nail, comprising the following steps:

[0009] Step 1. Raw material preparation: Prepare poly (lactic-co-glycolic acid), silk fibroin, polyvinyl alcohol, zinc alloy, poly (p-dioxanone) and β-tricalcium phosphate in parts by weight of the formula;

[0010] Step 2. Pretreatment: Synthesize medical-grade poly(lactic-co-glycolic acid) by the method of ring-opening polymerization of lactide, and perform impurity removal pretreatment on β-tricalcium phosphate and silk protein;

[0011] Step 3. Melt blending: After uniformly mixing poly(lactic-co-glycolic acid), β-tricalcium phosphate, silk protein, and polyvinyl alcohol according to the weight ratio, put them into a twin-screw extruder. Set the temperature of the extruder to 180 - 200 °C, the screw speed to 100 - 120 r / min, and the blending duration to 5 - 10 min. During the blending process, add the pretreated poly(p-dioxanone) and zinc alloy powder, raise the temperature to 220 - 240 °C, and continue blending for 10 - 15 min;

[0012] Step 4. Melt spinning: Melt spin the mixture through the spinneret of a melt spinning machine to form a shape. The pore diameter of the spinneret is 0.5 - 1.0 mm, and the spinning speed is 10 - 20 m / min to obtain a stable composite material;

[0013] Step 5. Molding process: Extrude the composite material through a mold to obtain a preliminary bone nail shape, and control the mold temperature between 160 °C and 180 °C;

[0014] Step 6. Turning process: Use a high-precision lathe to perform turning on the formed bone nail. When turning, set the lathe speed to 800 - 1200 r / min, the lathe feed rate to 0.1 - 0.2 mm / r, and the dimensional accuracy of the processed bone nail is within ±0.03 mm;

[0015] Step 7. Coating treatment: Coat a layer of nano-silver / hydroxyapatite composite coating on the surface of the bone nail. The coating thickness is 4 - 8 microns. After coating, use plasma treatment technology to modify the surface of the coating. The parameters of plasma treatment are: power is 500 - 800 W, and the treatment duration is 10 - 20 min;

[0016] Step 8. Sterilization and packaging: Sterilize the plasma-treated bone nail by γ-ray radiation with a dose of 25 - 30 kGy, and the sterilization duration is 30 - 45 min. After sterilization, seal and package the bone nail with a sterile packaging material.

[0017] Preferably, the weight range of the raw materials of the bone nail is: 25 - 30 parts of poly(lactic-co-glycolic acid); 15 - 20 parts of silk protein; 8 - 11 parts of polyvinyl alcohol; 3 - 6 parts of zinc alloy; 17 - 22 parts of poly(p-dioxanone); 9 - 14 parts of β-tricalcium phosphate.

[0018] Preferably, the weight parts of the raw materials of the bone nail are as follows: 28 parts of poly (lactic-co-glycolic acid); 20 parts of silk protein; 8 parts of polyvinyl alcohol; 3 parts of zinc alloy; 17 parts of poly (p-dioxanone); 14 parts of β-tricalcium phosphate.

[0019] Preferably, the weight parts of the raw materials of the bone nail are as follows: 25 parts of poly (lactic-co-glycolic acid); 15 parts of silk protein; 11 parts of polyvinyl alcohol; 6 parts of zinc alloy; 22 parts of poly (p-dioxanone); 9 parts of β-tricalcium phosphate.

[0020] Preferably, the weight parts of the raw materials of the bone nail are as follows: 29 parts of poly (lactic-co-glycolic acid); 18 parts of silk protein; 9 parts of polyvinyl alcohol; 5 parts of zinc alloy; 18 parts of poly (p-dioxanone); 12 parts of β-tricalcium phosphate.

[0021] Preferably, for the zinc alloy: zinc alloy powder with a zinc content greater than 99% is selected, and the particle size is controlled within 1 - 5 microns.

[0022] Preferably, for the β-tricalcium phosphate: β-tricalcium phosphate with a purity higher than 95% is selected, and the particle size is 1 - 10 microns.

[0023] Preferably, for the synthesis of poly (lactic-co-glycolic acid) in step two:

[0024] S2.1, Selection method: The medical-grade poly (lactic-co-glycolic acid) is synthesized by the method of ring-opening polymerization of lactide.

[0025] S2.2, Proportion of raw materials: In an environment where the reaction kettle is filled with 99.9% nitrogen, lactide and glycolide with a molar ratio of 1:1 are mixed in the reaction kettle, and 0.1% - 0.5% of stannous octoate based on the total mass of lactide and glycolide is added as a catalyst.

[0026] S2.3, Mixed reaction: React at a temperature of 160 - 180 °C for 4 - 6 h, and then remove the unreacted monomers by vacuum distillation to obtain poly (lactic-co-glycolic acid) with a molecular weight between 50,000 and 150,000 and a purity greater than 99%.

[0027] Preferably, for the pretreatment of β-tricalcium phosphate in step two: The β-tricalcium phosphate powder is ultrasonically cleaned for 40 - 60 min, then placed on a tray and dried in an oven at 100 °C for 2 h.

[0028] Preferably, for the pretreatment of silk protein in step two: The silk protein is dissolved in deionized water to prepare a silk protein solution with a concentration of 10%. Acetic acid is added dropwise to the silk protein solution to adjust the pH value of the solution to 4 - 5, so that the silk protein is fully dissolved and a stable colloidal solution is formed.

[0029] Compared with the prior art, the present invention provides a preparation method of a degradable bone nail, having the following

[0030] Advantages:

[0031] 1. In the present invention, poly (lactic-co-glycolic acid) copolymer is used as the main structural material of the bone nail, and silk protein and zinc alloy in the formula weight parts are added. Among them, poly (lactic-co-glycolic acid) copolymer has good mechanical properties and biocompatibility, and the content in this range can provide stronger mechanical strength and stability, making the bone nail not easily deformed or broken when bearing external forces, and at the same time helping to improve the fatigue life of the bone nail, making it more reliable during long-term use. Silk protein has good biocompatibility and mechanical properties. The appropriate content is combined with poly (lactic-co-glycolic acid) copolymer, which not only ensures the mechanical properties of the bone nail, but also takes into account biocompatibility and degradation properties. Zinc alloy has relatively high mechanical strength and hardness, which can improve the tensile strength, bending strength and torsional strength of the bone nail, making it more stable when bearing external forces. In addition, zinc alloy with appropriate particle size also has antibacterial properties, which can reduce the infection risk after bone nail implantation, thereby improving biocompatibility.

[0032] 2. In the present invention, the bone nail is subjected to surface treatment, adding a nano-silver / hydroxyapatite composite coating treatment, and at the same time controlling the turning processing parameters, so that the dimensional accuracy of the processed bone nail is within ±0.03 mm, making its mechanical strength and biocompatibility reach the best level in the body. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Please refer to Figure 1 , a preparation method of a degradable bone nail, comprising the following steps:

[0036] Step 1. Raw material preparation: Prepare poly (lactic-co-glycolic acid) copolymer (PLGA), silk protein, polyvinyl alcohol (PVA), zinc alloy, poly (p-dioxanone) (PDO) and β-tricalcium phosphate (β-TCP) in the formula weight parts;

[0037] Step 2. Pretreatment: Synthesize medical-grade poly(lactic-co-glycolic acid) by ring-opening polymerization of lactide to ensure that its molecular weight and purity meet the requirements. Pretreat β-tricalcium phosphate and silk protein to remove impurities and enhance their compatibility with poly(lactic-co-glycolic acid).

[0038] Step 3. Melt blending: After uniformly mixing poly(lactic-co-glycolic acid), β-tricalcium phosphate, silk protein, and polyvinyl alcohol according to the weight ratio, put them into a twin-screw extruder. Set the temperature of the extruder at 180 - 200 °C, the screw speed at 100 - 120 r / min, and the blending duration at 5 - 10 min. During the blending process, add pretreated poly(p-dioxanone) and zinc alloy powder, raise the temperature to 220 - 240 °C, and continue blending for 10 - 15 min to ensure sufficient melting and mixing of the materials.

[0039] Step 4. Melt spinning: Melt-spin the mixture through the spinneret of a melt spinning machine to form a stable composite material. The aperture of the spinneret is 0.5 - 1.0 mm, and the spinning speed is 10 - 20 m / min.

[0040] Step 5. Molding process: Extrude the composite material through a mold to obtain a preliminary bone nail shape. Control the mold temperature between 160 °C and 180 °C to avoid degradation of the material during the molding process.

[0041] Step 6. Turning process: Use a high-precision lathe to turn the formed bone nail. When turning, set the lathe speed at 800 - 1200 r / min, the lathe feed rate at 0.1 - 0.2 mm / r. The dimensional accuracy of the processed bone nail is within ±0.03 mm, and ensure its surface is smooth and meets the surgical requirements.

[0042] Step 7. Coating treatment: Coat a layer of nano-silver / hydroxyapatite composite coating on the surface of the bone nail. The coating thickness is 4 - 8 microns. After coating, use plasma treatment technology to modify the surface of the coating. The parameters of plasma treatment are: power is 500 - 800 W, and the treatment duration is 10 - 20 min to further reduce the corrosion rate and improve the bioactivity.

[0043] Step 8. Sterilization and packaging: Sterilize the plasma-treated bone nail by γ-ray irradiation with a dose of 25 - 30 kGy. The sterilization duration is 30 - 45 min. When irradiating, place the bone nails in the sterilization chamber, maintaining a certain interval to ensure uniform irradiation. After sterilization, seal and package the bone nails using sterile packaging materials such as polyethylene bags or aluminum foil bags, and indicate product information, sterilization date, and expiration date on the package.

[0044] Specifically, the weight parts range of the bone nail raw materials is as follows: 25-30 parts of poly (lactic-co-glycolic acid); 15-20 parts of silk protein; 8-11 parts of polyvinyl alcohol; 3-6 parts of zinc alloy; 17-22 parts of poly-p-dioxanone; 9-14 parts of β-tricalcium phosphate.

[0045] The functions of its raw materials are as follows:

[0046]

[0047] Specifically, for the zinc alloy: Select zinc alloy powder with a zinc content greater than 99%, and control the particle size within 1-5 microns to enhance the antibacterial performance of the bone nail.

[0048] Specifically, for the β-tricalcium phosphate: Select β-tricalcium phosphate with a purity higher than 95%, and the particle size is 1-10 microns to promote bone tissue regeneration.

[0049] Specifically, the synthesis of poly (lactic-co-glycolic acid) in step two:

[0050] S2.1, Selection method: Use the method of ring-opening polymerization of lactide to synthesize medical-grade poly (lactic-co-glycolic acid);

[0051] S2.2, Raw material ratio: In an environment where the reaction kettle is filled with 99.9% nitrogen, mix lactide and glycolide with a molar ratio of 1:1 in the reaction kettle, and add 0.1%-0.5% of stannous octoate based on the total mass of lactide and glycolide as a catalyst;

[0052] S2.3, Mixing reaction: React at a temperature of 160-180 °C for 4-6 h, and then remove the unreacted monomers by vacuum distillation to obtain poly (lactic-co-glycolic acid) with a molecular weight between 50,000 and 150,000 and a purity greater than 99%.

[0053] Specifically, the pretreatment of β-tricalcium phosphate in step two: Ultrasonically clean the β-tricalcium phosphate powder for 40-60 min, remove the surface impurities and residual production reagents, place it on a tray, and dry it in an oven at 100 °C for 2 h to ensure it is dry and water-free.

[0054] Specifically, the pretreatment of silk protein in step two: Dissolve silk protein in deionized water to prepare a 10% silk protein solution, and gradually add acetic acid dropwise to the silk protein solution to adjust the pH value of the solution to 4-5, so that the silk protein is fully dissolved and a stable colloidal solution is formed.

[0055] Example 1

[0056] Specifically, the weight parts of the raw materials for the bone nail are as follows: 28 parts of poly (lactic-co-glycolic acid); 20 parts of silk protein; 8 parts of polyvinyl alcohol; 3 parts of zinc alloy; 17 parts of poly (p-dioxanone); 14 parts of β-tricalcium phosphate.

[0057] Example 2

[0058] Specifically, the weight parts of the raw materials for the bone nail are as follows: 25 parts of poly (lactic-co-glycolic acid); 15 parts of silk protein; 11 parts of polyvinyl alcohol; 6 parts of zinc alloy; 22 parts of poly (p-dioxanone); 9 parts of β-tricalcium phosphate.

[0059] Example 3

[0060] Specifically, the weight parts of the raw materials for the bone nail are as follows: 29 parts of poly (lactic-co-glycolic acid); 18 parts of silk protein; 9 parts of polyvinyl alcohol; 5 parts of zinc alloy; 18 parts of poly (p-dioxanone); 12 parts of β-tricalcium phosphate (selecting zinc alloy powder with a zinc content greater than 99.9%, and controlling the particle size within 2 microns).

[0061] Example 4

[0062] Step 6. Turning process: Use a high-precision lathe to perform turning on the formed bone nail. During the turning process, set the lathe speed to 1200 r / min and the lathe feed rate to 0.2 mm / r. The dimensional accuracy of the processed bone nail is within ±0.03 mm, and ensure that its surface is smooth and meets the surgical requirements;

[0063] Example 5

[0064] Step 7. Coating treatment: Coat a layer of silver nanowire / hydroxyapatite composite coating on the surface of the bone nail, with a coating thickness of 4 microns. After the coating is completed, use plasma treatment technology to perform surface modification on the coating. The parameters of the plasma treatment are: power of 800 W and treatment duration of 15 min to further reduce the corrosion rate and improve the bioactivity.

[0065] Comparative Example 1

[0066] Specifically, the weight parts of the raw materials for the bone nail are as follows: 20 parts of poly (lactic-co-glycolic acid); 28 parts of silk protein; 8 parts of polyvinyl alcohol; 3 parts of zinc alloy; 17 parts of poly (p-dioxanone); 14 parts of β-tricalcium phosphate (reducing the poly (lactic-co-glycolic acid) in Example 1 to 20 parts and increasing the silk protein in the example to 28 parts).

[0067] Comparative Example 2

[0068] Specifically, the weight parts of the raw materials for the bone nail are as follows: 25 parts of poly (lactic-co-glycolic acid); 15 parts of silk protein; 11 parts of polyvinyl alcohol; 22 parts of poly (p-dioxanone); 9 parts of β-tricalcium phosphate (removing the zinc alloy in Example 2).

[0069] Comparative Example 3

[0070] Specifically, the weight parts of the bone nail raw materials are as follows: 29 parts of poly (lactic-co-glycolic acid); 18 parts of silk protein; 9 parts of polyvinyl alcohol; 5 parts of zinc alloy; 18 parts of poly (p-dioxanone); 12 parts of β-tricalcium phosphate (selecting zinc alloy powder with a zinc content of 90%, and the particle size is controlled within 1 micron).

[0071] Comparative Example 4

[0072] Step Six: Turning Process: Use a high-precision lathe to perform turning on the formed bone nails. During the turning process, set the lathe speed to 1000 r / min and the lathe feed rate to 0.4 mm / r. The dimensional accuracy of the processed bone nails is within ±0.08 mm, and ensure that its surface is smooth and meets the surgical requirements;

[0073] Comparative Example 5

[0074] Step Seven: Do not perform coating treatment.

[0075] The bone nail products are made from Examples 1-3 and Comparative Examples 1-3 through the preparation method of the present invention, and their mechanical properties, biocompatibility, degradation properties, and surface properties are tested. The results are shown in Table 1 below:

[0076] Table 1

[0077]

[0078]

[0079] Comparison between Example 1 and Comparative Examples:

[0080] PLGA Content: PLGA is the main structural material of the bone nail, with good mechanical properties and biocompatibility. The higher PLGA content in Example 1 can provide stronger mechanical strength and stability, making the bone nail not easily deformed or broken when bearing external forces, so it performs better in the tensile strength, bending strength, and torsional strength tests. At the same time, the increase in PLGA also helps to improve the fatigue life of the bone nail, making it more reliable during long-term use;

[0081] Silk Protein Content: Although silk protein has good biocompatibility and certain mechanical properties, too high a content will have an adverse effect on the overall performance of the bone nail. In Comparative Example 1, the too high silk protein content will lead to a decrease in the mechanical properties of the bone nail, such as a reduction in tensile strength, bending strength, and torsional strength, and a shortening of the fatigue life. In addition, too high a silk protein content can also affect the degradation properties of the bone nail, accelerating its degradation rate, which is not conducive to the long-term stability of the bone nail in the body;

[0082] Comprehensive performance balance: In Example 1, a better balance was achieved in the ratio of PLGA and silk fibroin, which not only ensured the mechanical properties of the bone nail but also took into account biocompatibility and degradation properties, making it superior to Comparative Example 1 in all tests.

[0083] Comparison between Example 2 and Comparative Example 2:

[0084] Function of zinc alloy: Zinc alloy has relatively high mechanical strength and hardness, which can improve the tensile strength, bending strength and torsional strength of the bone nail, making it more stable when bearing external forces. In addition, zinc alloy also has antibacterial properties, which can reduce the risk of infection after bone nail implantation, thereby improving biocompatibility;

[0085] Improvement of fatigue life: The addition of zinc alloy helps to disperse stress and reduce stress concentration, making the bone nail less likely to undergo fatigue failure during long-term use, thereby prolonging its fatigue life;

[0086] Effect on degradation performance: The presence of zinc alloy in the bone nail can slow down the degradation rate of the bone nail, making it maintain stability in the body for a longer time, which is beneficial to fracture healing and bone tissue repair;

[0087] Improvement of surface properties: The addition of zinc alloy will have a certain modification effect on the surface of the bone nail, making its surface smoother, reducing surface roughness, and thus improving surface properties.

[0088] The addition of zinc alloy in Example 1 will improve the fatigue life of the bone nail, which is beneficial to fracture healing and bone tissue repair. However, zinc alloy was not added in Comparative Example 1, so it does not have the above functions.

[0089] Comparison between Example 3 and Comparative Example 3:

[0090] Zinc alloy purity: The high purity of the zinc alloy in Example 3 helps to improve the overall performance of the bone nail. High-purity zinc alloy can reduce the adverse effects of impurities on the performance of the bone nail, making the bone nail have better mechanical strength and stability. At the same time, high-purity zinc alloy also shows more excellent performance in biocompatibility, can be better compatible with bone tissue, and reduce the inflammatory reaction;

[0091] Zinc alloy particle size: The particle size of the zinc alloy powder in Example 3 is larger, which is beneficial to its uniform distribution and performance exertion in the bone nail. Larger particle size zinc alloy powder can better combine with other materials during the melt blending process to form a stable composite structure, thereby improving the mechanical properties and biocompatibility of the bone nail. However, the smaller particle size zinc alloy powder in Comparative Example 3 is prone to agglomeration during the melt blending process, affecting the performance of the bone nail;

[0092] Comprehensive performance improvement: In Example 3, the purity and particle size of the zinc alloy were optimized, making it superior to Comparative Example 3 in terms of mechanical properties, biocompatibility, degradation properties, etc., and showing more excellent comprehensive performance.

[0093] Bone nails were made from Examples 4 - 5 and Comparative Examples 4 - 5, and performance measurements were carried out. The results are shown in Table 3 below:

[0094]

[0095] It can be seen from the table that the bone nails of Example 4 and Example 5 are superior to Comparative Example 4 and Comparative Example 5 in terms of mechanical strength, biocompatibility, and degradation time. Especially for Example 5, due to the treatment with the nano - silver / hydroxyapatite composite coating, its mechanical strength and biocompatibility reach the optimal level. There are deficiencies in the turning processing parameters or coating treatment of Comparative Example 4 and Comparative Example 5, resulting in a decline in their performance.

[0096] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a degradable bone nail, characterized in that: The following steps are involved: Step 1, raw material preparation: prepare the polylactic acid-co-glycolic acid copolymer, silk protein, polyvinyl alcohol, zinc alloy, polydioxanone and β-tricalcium phosphate in parts by weight; Step 2, pretreatment: synthesizing medical-grade poly(lactic acid-co-glycolic acid) copolymer by a lactide ring-opening polymerization method, and pretreating β-tricalcium phosphate and silk protein to remove impurities; Step 3, melt blending: after uniformly mixing polylactic acid-co-glycolic acid, β-tricalcium phosphate, silk protein and polyvinyl alcohol in proportion by weight, put into a twin-screw extruder, set the temperature of the extruder to 180-200° C., the screw speed to 100-120 r / min, the blending time to 5-10 min, during the blending process, add the pretreated polydioxanone and zinc alloy powder, raise the temperature to 220-240° C., and continue blending for 10-15 min; Step 4, melt spinning: melt spinning the mixture from the extruder through the spinneret of the melt spinning machine, the aperture of the spinneret is 0.5-1.0 mm, and the spinning speed is 10-20 m / min to obtain a stable composite material; Step 5: Molding: Extruding the composite material through a mold to obtain a preliminary bone screw shape, and the mold temperature is controlled between 160°C and 180°C; Step 6, turning: Use a high-precision lathe to turn the formed bone nail. During turning, set the lathe speed to 800-1200r / min, the lathe feed rate to 0.1-0.2mm / r, and the size accuracy of the processed bone nail is within ±0.03mm; Step 7, coating treatment: a layer of nano silver / hydroxyapatite composite coating is coated on the surface of the bone screw, and the coating thickness is 4-8 microns. After the coating is completed, the coating is surface modified by plasma treatment technology. The parameters of the plasma treatment are: power is 500-800W, and the treatment time is 10-20min; Step 8, sterilization and packaging: sterilize the bone screws after plasma treatment using γ-ray radiation at a dose of 25 kilo-30 kilograys for 30-45 minutes. After sterilization, seal the bone screws with sterile packaging materials.

2. The method for preparing a degradable bone nail according to claim 1, characterized in that: The weight range of the raw materials of the bone nail is: 25-30 parts of polylactic acid-glycolic acid copolymer; 15-20 parts of silk protein; 8-11 parts of polyvinyl alcohol; 3-6 parts of zinc alloy; 17-22 parts of polydioxanone; and 9-14 parts of β-tricalcium phosphate.

3. The method for preparing a degradable bone nail according to claim 2, characterized in that: The raw materials of the bone screw are as follows: 28 parts of polylactic acid-glycolic acid copolymer; 20 parts of silk protein; 8 parts of polyvinyl alcohol; 3 parts of zinc alloy; 17 parts of polydioxanone; and 14 parts of β-tricalcium phosphate.

4. The method for preparing a degradable bone nail according to claim 2, characterized in that: The raw materials of the bone screw are as follows: 25 parts of polylactic acid-glycolic acid copolymer; 15 parts of silk protein; 11 parts of polyvinyl alcohol; 6 parts of zinc alloy; 22 parts of polydioxanone; and 9 parts of β-tricalcium phosphate.

5. The method for preparing a degradable bone nail according to claim 2, characterized in that: The raw materials of the bone screw are as follows: 29 parts of polylactic acid-glycolic acid copolymer; 18 parts of silk protein; 9 parts of polyvinyl alcohol; 5 parts of zinc alloy; 18 parts of polydioxanone; and 12 parts of β-tricalcium phosphate.

6. The method for preparing a degradable bone nail according to claim 1, characterized in that: The zinc alloy is a zinc alloy powder with a zinc content greater than 99% and a particle size controlled within 1-5 microns.

7. The method for preparing a degradable bone nail according to claim 1, characterized in that: The beta-tricalcium phosphate is selected with a purity higher than 95% and a particle size of 1-10 microns.

8. The method for preparing a degradable bone nail according to claim 1, characterized in that: Synthesis of polylactic acid-glycolic acid copolymer in step 2: S2.1, Selection method: Synthesize medical grade poly(lactic acid-co-glycolic acid) by ring-opening polymerization of lactide; S2.2, raw material ratio: in an environment where the reactor is filled with 99.9% nitrogen, lactide and glycolide are mixed in a molar ratio of 1:1 in the reactor, and 0.1% to 0.5% of the total mass of lactide and glycolide stannous octoate is added as a catalyst; S2.3, mixing reaction: react at a temperature of 160-180°C for 4-6 hours, and then remove the unreacted monomers by vacuum distillation to obtain a polylactic acid-glycolic acid copolymer with a molecular weight of 50,000-150,000 and a purity greater than 99%.

9. The method for preparing a degradable bone nail according to claim 1, characterized in that: Pretreatment of β-tricalcium phosphate in step 2: ultrasonically clean the β-tricalcium phosphate powder for 40-60 minutes, put it into a tray, and dry it in an oven at 100° C. for 2 hours.

10. The method for preparing a degradable bone nail according to claim 1, characterized in that: The pretreatment of silk protein in step 2 is as follows: dissolving silk protein in deionized water to prepare a 10% silk protein solution, adding acetic acid dropwise to the silk protein solution, adjusting the pH value of the solution to 4-5, so that the silk protein is fully dissolved and forms a stable colloidal solution.

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