Degradable material for fracture and preparation method thereof

Abstract

The application relates to the technical field of biomedical materials, in particular to a degradable material for fracture and a preparation method thereof. The silicate powder is prepared by adding calcium nitrate solution, magnesium nitrate solution and zinc nitrate solution into sodium silicate solution. The silicate powder is mixed with polyvinyl alcohol solution to prepare a mixture. The mixture is poured into a mold, and then stirring, vacuum injection, freezing, sintering and cooling to room temperature are carried out to prepare a fracture fixation object. Modified hydroxyapatite is prepared by taking L-lactic acid, toluene and nano-hydroxyapatite as raw materials. The fracture fixation object is fully immersed in the impregnating solution prepared by mixing polylactic acid, chloroform and modified hydroxyapatite to obtain the degradable material for fracture. The degradable material for fracture prepared by the application has good degradable performance and mechanical performance, can effectively promote body osteogenesis and healing, and therefore has wide application prospects in the field of biological medicine.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically a biodegradable material for fractures and its preparation method. Background Technology

[0002] Fractures are a common bone injury. Traditionally, fractures are treated with fixation devices made of metal or synthetic materials, such as metal plates and screws. Degradable materials for fractures have many advantages, such as: (1) Strong degradation ability: Degradable materials can gradually degrade in the human body, avoiding the trouble of needing a second surgery to remove traditional metal instruments, reducing the risk of secondary surgery and the patient's pain, and promoting bone healing. (2) Biocompatibility: Degradable materials usually have good biocompatibility, that is, the material can be compatible with surrounding tissues in the body and promote bone regeneration. This helps to reduce inflammatory response and tissue rejection, and promote bone healing and recovery. (3) Adjustable mechanical properties: The mechanical properties of degradable materials can be adjusted according to the location and type of fracture to provide appropriate support and stability. This helps to promote bone recovery and functional recovery. However, there are still some technical pain points to be solved for such degradable materials. For example, the degradation rate of such materials is difficult to control. If the degradation rate is too fast, it will cause the fixation device to fail prematurely; while if the degradation rate is too slow, it may delay the bone healing process. Furthermore, biodegradable materials need to possess sufficient strength to provide stable support and fixation, while also being able to gradually degrade. Therefore, researchers need to carefully balance the degradation performance and mechanical properties of materials.

[0003] To overcome the shortcomings of the prior art, the present invention provides a biodegradable material for fractures and a method for preparing the same. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable material for fractures and a method for preparing the same, in order to solve the problems in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a biodegradable material for fracture treatment includes the following steps:

[0007] Step 1: While stirring, add calcium nitrate solution, magnesium nitrate solution and zinc nitrate solution dropwise to sodium silicate solution, and adjust the pH of the solution to maintain it at 10.0-10.5. After the addition is completed, continue stirring for 20-30 hours. Then, filter, wash, dry, calcine and grind to prepare silicate powder.

[0008] Step 2: Mix silicate powder with polyvinyl alcohol solution, stir at 15-20 rpm / min for 30-50 min, then stir at 10-15 rpm / min for 60-80 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze, sinter, and cool to room temperature to prepare a fracture fixation device;

[0009] Step 3: Mix L-lactic acid and toluene, and slowly heat to 150-180℃ for 70-80 h. The reaction product is dissolved, precipitated, and vacuum dried to prepare hydroxyl-terminated polylactic acid. Disperse nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, and heat the system to 150-170℃ for 10-12 h. The reaction product is centrifuged, washed, and vacuum dried to prepare modified hydroxyapatite.

[0010] Step 4: Dissolve polylactic acid fully in chloroform, then add modified hydroxyapatite, and after stirring, standing, and degassing, prepare an impregnation solution; immerse the fracture fixation material in the impregnation solution for 10-20 minutes, and let it stand at 30-40℃ for 25-35 hours to prepare a biodegradable material for fractures.

[0011] Ideally, in step one, the molar concentrations of sodium silicate solution, calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution are all 0.6–0.8 mol / L.

[0012] In a more optimized manner, in step one, the drying temperature is 80–100℃; the calcination parameters are: calcination temperature is 950–1000℃, and calcination time is 1.5–2.5h.

[0013] Ideally, in step one, the particle size of the silicate powder is 3–5 μm.

[0014] In a more optimized manner, in step two, the mass ratio of silicate powder to polyvinyl alcohol solution is 1:1 to 2, wherein the mass concentration of polyvinyl alcohol solution is 6 to 10%.

[0015] In a more optimized manner, in step two, the freezing process parameters are: freezing temperature of -90 to -70°C and freezing time of 12 to 15 hours.

[0016] In a more optimized manner, the sintering process parameters in step two are: sintering temperature of 1150–1225℃ and sintering time of 3–4 hours.

[0017] In a more optimized manner, in step three, the vacuum drying temperature is 60–70°C and the vacuum drying time is 20–30 h.

[0018] In a more optimized manner, in step three, the mass ratio of L-lactic acid, toluene, and nano-hydroxyapatite is 10–12:13:7.

[0019] In a more optimized manner, in step four, the mass ratio of polylactic acid to chloroform is 7.4–7.8:1; wherein the mass fraction of modified hydroxyapatite in polylactic acid is 30%–40%.

[0020] The beneficial effects of this invention are:

[0021] This invention prepares silicate powder by adding calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution to sodium silicate solution. The silicate powder is then mixed with polyvinyl alcohol solution to prepare a mixture. This mixture is poured into a mold, stirred, vacuum-injected, frozen, sintered, and cooled to room temperature to prepare a fracture fixation material. Modified hydroxyapatite is then prepared using L-lactic acid, toluene, and nano-hydroxyapatite as raw materials. Polylactic acid, chloroform, and modified hydroxyapatite are mixed to obtain an impregnation solution. The fracture fixation material is then fully impregnated in the impregnation solution to obtain a biodegradable material for fracture treatment.

[0022] The present invention is characterized in that, in steps one and two, a fracture fixation device is prepared using sodium silicate solution, calcium nitrate solution, magnesium nitrate solution, zinc nitrate solution, and polyvinyl alcohol solution as raw materials. The fracture fixation device prepared by the present invention has a high degree of biodegradability, releasing calcium and phosphorus ions necessary for bone formation during degradation, thus promoting bone formation. Simultaneously, the material contains magnesium, which is non-toxic during degradation and can be excreted from the body through the circulatory system, avoiding the pain of a second surgery to remove the fixation device. Furthermore, magnesium is a cofactor for many enzymes in organisms, promoting structural stability and metabolism. The material also contains zinc, which stimulates bone formation, mineralization, and bone mass preservation. Zinc is also a highly effective inhibitor of osteoclast bone resorption, effectively promoting bone formation and maintaining good mechanical properties.

[0023] In step three, a biodegradable material for fracture treatment is prepared by impregnating the surface of the fracture fixation material with an impregnation solution made from polylactic acid and modified hydroxyapatite. On one hand, using organic polylactic acid as the main component of the impregnation solution improves the corrosion resistance and mechanical strength of the fracture fixation material. Modified hydroxyapatite possesses excellent biodegradability, osteoinductive properties, and osteoconductive properties, which can inhibit osteoclast formation, promote the formation of new cartilage during chondrogenesis, and inhibit osteoclast formation during callus remodeling, thereby improving the mechanical strength of the callus and the quality of fracture healing, and providing the mechanical support required for fracture healing. On the other hand, in step three, modifying nano-hydroxyapatite with hydroxyl-terminated polylactic acid improves the dispersibility of nanoparticles and reduces the agglomeration of nano-hydroxyapatite. Furthermore, the addition of polylactic acid as a raw material in step four, which is similarly miscible with the hydroxyl-terminated polylactic acid generated in step three, facilitates the full dispersion of nano-hydroxyapatite. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Raw material source:

[0026] Polyvinyl alcohol, provided by Hefei Tianyi New Materials Co., Ltd., model number 1788; polylactic acid, provided by Dongguan Weicai Plastic Raw Materials Co., Ltd., model number PLA3D870; nano hydroxyapatite, provided by Hubei Yamaide Biomedical Co., Ltd., specification 20nm; by mass parts, one part is 1g.

[0027] Example 1: Step 1: While stirring, calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution were added dropwise to a sodium silicate solution, with the concentration of each solution being 0.6 mol / L. The pH of the solution was adjusted to be maintained at 10.5. After the addition was completed, stirring was continued for 30 hours. Then, the solution was filtered, washed, dried at 100°C, calcined at 1000°C for 2.5 hours, and ground to prepare silicate powder with a particle size of 5 μm.

[0028] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 20 rpm / min for 50 min, then stir at 15 rpm / min for 80 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -70℃ for 15 h, sinter at 1250℃ for 4 h, and cool to room temperature to prepare a fracture fixation device;

[0029] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 180℃ for 80 hours. Dissolve, precipitate and vacuum dry at 70℃ for 30 hours to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, heat the system to 170℃ for 12 hours, and centrifuge, wash and vacuum dry at 70℃ for 30 hours to prepare modified hydroxyapatite.

[0030] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and degassing, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 20 minutes and stand at 40°C for 35 hours to prepare the biodegradable material for fractures.

[0031] Example 2: Step 1: While stirring, calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution were added dropwise to a sodium silicate solution, with the concentration of each solution being 0.6 mol / L. The pH of the solution was adjusted to be maintained at 10.4. After the addition was completed, stirring was continued for 27 hours. Then, the solution was filtered, washed, dried at 95°C, calcined at 987°C for 2.3 hours, and ground to obtain silicate powder with a particle size of 4.5 μm.

[0032] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 18 rpm / min for 45 min, then stir at 14 rpm / min for 75 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -75℃ for 14 h, sinter at 1225℃ for 3.7 h, and cool to room temperature to prepare a fracture fixation device;

[0033] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 172℃ and react at a constant temperature for 77 h. The reaction product is dissolved, precipitated, and vacuum dried at 67℃ for 27 h to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, and heat the system to 165℃ and react at a constant temperature for 11.5 h. The reaction product is centrifuged, washed, and vacuum dried at 67℃ for 27 h to prepare modified hydroxyapatite.

[0034] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and removing air bubbles, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 17 minutes and stand at 37°C for 33 hours to prepare the biodegradable material for fractures.

[0035] Example 3: Step 1: While stirring, calcium nitrate solution, magnesium nitrate solution and zinc nitrate solution were added dropwise to a sodium silicate solution, with the concentration of each solution being 0.6 mol / L. The pH of the solution was adjusted to be maintained at 10.3. After the addition was completed, stirring was continued for 25 hours. Then, the solution was filtered, washed, dried at 90℃, calcined at 975℃ for 2 hours, and ground to prepare silicate powder with a particle size of 4 μm.

[0036] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 17 rpm / min for 40 min, then stir at 13 rpm / min for 70 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -80℃ for 13 h, sinter at 1200℃ for 3.5 h, and cool to room temperature to prepare a fracture fixation device;

[0037] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 165℃ for 75 hours. Dissolve, precipitate and vacuum dry at 65℃ for 25 hours to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, heat the system to 160℃ for 11 hours, and centrifuge, wash and vacuum dry at 65℃ for 25 hours to prepare modified hydroxyapatite.

[0038] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and degassing, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 15 minutes and let it stand at 35°C for 30 hours to prepare the biodegradable material for fractures.

[0039] Example 4: Step 1: While stirring, calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution were added dropwise to a sodium silicate solution, with the concentration of each solution being 0.6 mol / L. The pH of the solution was adjusted to be maintained at 10.2. After the addition was completed, stirring was continued for 23 hours. Then, the solution was filtered, washed, dried at 85℃, calcined at 962℃ for 1.7 hours, and ground to obtain silicate powder with a particle size of 3.5 μm.

[0040] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 16 rpm / min for 35 min, then stir at 11 rpm / min for 65 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -85℃ for 12.5 h, sinter at 1175℃ for 3.2 h, and cool to room temperature to prepare a fracture fixation device;

[0041] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 157℃ for 73 hours. The reaction product is dissolved, precipitated, and vacuum dried at 63℃ for 23 hours to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, and heat the system to 155℃ for 10.5 hours. The reaction product is centrifuged, washed, and vacuum dried at 63℃ for 23 hours to prepare modified hydroxyapatite.

[0042] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and degassing, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 13 minutes and stand at 33°C for 27 hours to prepare the biodegradable material for fractures.

[0043] Example 5: Step 1: While stirring, calcium nitrate solution, magnesium nitrate solution, and zinc nitrate solution were added dropwise to a sodium silicate solution, with the concentration of each solution being 0.6 mol / L. The pH of the solution was adjusted to be maintained at 10.0 throughout. After the addition was completed, stirring was continued for 20 hours. Then, the solution was filtered, washed, dried at 80℃, calcined at 950℃ for 1.5 hours, and ground to obtain silicate powder with a particle size of 3 μm.

[0044] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 15 rpm / min for 30 min, then stir at 10 rpm / min for 60 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -90℃ for 12 h, sinter at 1150℃ for 3 h, and cool to room temperature to prepare a fracture fixation device;

[0045] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 150℃ and react at a constant temperature for 70 h. The reaction product is dissolved, precipitated, and vacuum dried at 60℃ for 20 h to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, and heat the system to 150℃ and react at a constant temperature for 10 h. The reaction product is centrifuged, washed, and vacuum dried at 60℃ for 20 h to prepare modified hydroxyapatite.

[0046] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and degassing, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 10 minutes and let it stand at 30°C for 25 hours to prepare the biodegradable material for fractures.

[0047] Comparative Example 1: The zinc nitrate solution was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Calcium nitrate solution and magnesium nitrate solution were added dropwise to sodium silicate solution while stirring. The concentration of each solution was 0.6 mol / L, and the pH of the solution was adjusted to be maintained at 10.5. After the addition was completed, stirring was continued for 30 h. Then, the solution was filtered, washed, dried at 100 °C, calcined at 1000 °C for 2.5 h, and ground to prepare silicate powder with a particle size of 5 μm.

[0048] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 20 rpm / min for 50 min, then stir at 15 rpm / min for 80 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -70℃ for 15 h, sinter at 1250℃ for 4 h, and cool to room temperature to prepare a fracture fixation device;

[0049] Step 3: Mix 10 parts L-lactic acid and 13 parts toluene, and slowly heat to 180℃ for 80 hours. Dissolve, precipitate and vacuum dry at 70℃ for 30 hours to prepare hydroxyl-terminated polylactic acid. Disperse 7 parts nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, heat the system to 170℃ for 12 hours, and centrifuge, wash and vacuum dry at 70℃ for 30 hours to prepare modified hydroxyapatite.

[0050] Step 4: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of modified hydroxyapatite. After stirring, standing, and degassing, prepare the impregnation solution. Immerse the fracture fixation material in the impregnation solution for 20 minutes and stand at 40°C for 35 hours to prepare the biodegradable material for fractures.

[0051] Comparative Example 2: The modification step of nano-hydroxyapatite was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Calcium nitrate solution, magnesium nitrate solution and zinc nitrate solution were added dropwise to sodium silicate solution while stirring. The concentration of each solution was 0.6 mol / L, and the pH of the solution was adjusted to be maintained at 10.5. After the addition was completed, stirring was continued for 30 h. Then, the solution was filtered, washed, dried at 100℃, calcined at 1000℃ for 2.5 h, and ground to prepare silicate powder with a particle size of 5 μm.

[0052] Step 2: Mix 20 parts of silicate powder with 20 parts of 6% polyvinyl alcohol solution, stir at 20 rpm / min for 50 min, then stir at 15 rpm / min for 80 min to prepare a mixture; pour the mixture into a mold, stir, vacuum inject, freeze at -70℃ for 15 h, sinter at 1250℃ for 4 h, and cool to room temperature to prepare a fracture fixation device;

[0053] Step 3: Dissolve 25 parts of polylactic acid in 3.3 parts of chloroform, then add 10 parts of nano-hydroxyapatite. After stirring, standing, and degassing, an impregnation solution is prepared. The fracture fixation material is impregnated in the impregnation solution for 20 minutes and then stood at 40°C for 35 hours to prepare a biodegradable material for fractures.

[0054] Testing and experimentation:

[0055] Bending strength test: The biodegradable material for fracture prepared in this invention is cut into specimens with a thickness of 15 mm and a width of 25 mm. The test temperature is maintained at 28℃ and the test rate is 1.2 mm / s. Bending force is slowly applied until the specified bending angle is reached, and the corresponding bending strength is tested.

[0056] In vitro degradation test: The biodegradable fracture material prepared according to this invention was used as a sample and immersed in Tris buffer solution in a shaking water bath at 37°C. The initial pH value was 7.1, and the surface area / volume ratio of the tube was 0.1 cm³. -1 The zinc ion concentration in the solution was measured in week 6.

[0057] Cell viability test: The biodegradable fracture material prepared according to this invention was cut into 4 mm thick samples and sterilized at 120°C for 20 min. Mouse pre-osteoblastic cells were then cultured in vitro at a concentration of 2 × 10⁻⁶ cells / mL. 4 Cells were seeded at the specified density in 24-well plates, and samples were placed in the plates. Cell viability was then assessed after 5 days of continuous culture. The results are shown in the table below.

[0058]

[0059]

[0060] Conclusion: The dosages in Examples 1-5 remained unchanged, with only some reaction parameters modified. Experimental data showed that the properties of the biodegradable fracture fixation material did not fluctuate significantly. Comparative Example 1: The zinc nitrate solution was removed, and everything else remained the same as in Example 1. Experimental data showed that compared to Example 1, the flexural strength decreased to 46.3 MPa, the zinc ion concentration decreased to 0 ppm, and the cell survival rate was 90%. The reason for this is that removing the zinc nitrate solution reduced the metal ion content of the fracture fixation matrix, thus decreasing the corresponding mechanical flexural strength and zinc ion concentration.

[0061] Comparative Example 2: The modification step of nano-hydroxyapatite was removed, and the rest was the same as in Example 1. The experimental data showed that compared with Example 1, the flexural strength was reduced to 47.8 MPa and the cell survival rate was 83%. The reason for this was that removing the modification step of nano-hydroxyapatite caused the nano-hydroxyapatite to agglomerate, resulting in poor performance, thus reducing the flexural strength and cell survival rate.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0063] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a degradable material for a bone fracture, characterized by: The method comprises the following steps: ​ Step 1: drop the calcium nitrate solution, the magnesium nitrate solution and the zinc nitrate solution into the sodium silicate solution while stirring, and adjust the pH of the solution to keep it at 10.0-10.5 all the time; after the dropping is completed, continue stirring for 20-30 hours; then filter, wash, dry, calcine and grind to prepare the silicate powder; Step 2: mix the silicate powder with the polyvinyl alcohol solution, stir at 15-20 rpm / min for 30-50 minutes, and then stir at 10-15 rpm / min for 60-80 minutes to prepare the mixture; pour the mixture into a mold, and then stir, vacuum inject, freeze, sinter and cool to room temperature to prepare the fracture fixation device; Step 3: mix the L-lactic acid and the toluene, slowly heat to 150-180℃ and keep the temperature constant for 70-80 hours, dissolve, sediment and vacuum dry the reaction product to prepare the hydroxyl-terminated polylactic acid; disperse the nano-hydroxyapatite into the hydroxyl-terminated polylactic acid, heat the system to 150-170℃ and keep the temperature constant for 10-12 hours, and then centrifuge, wash and vacuum dry the reaction product to prepare the modified hydroxyapatite; Step 4: dissolve the polylactic acid in the chloroform, add the modified hydroxyapatite, stir, stand still, and remove the bubbles to prepare the impregnation solution; immerse the fracture fixation device in the impregnation solution for 10-20 minutes, stand still at 30-40℃ for 25-35 hours to prepare the degradable material for fracture.

2. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 1, the substance concentration of the sodium silicate solution, the calcium nitrate solution, the magnesium nitrate solution and the zinc nitrate solution is 0.6-0.8 mol / L.

3. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 1, the drying temperature is 80-100℃; the calcination parameters are as follows: the calcination temperature is 950-1000℃, and the calcination time is 1.5-2.5 hours.

4. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 1, the particle size of the silicate powder is 3-5 μm.

5. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 2, the mass ratio of the silicate powder to the polyvinyl alcohol solution is 1:1-2, and the mass concentration of the polyvinyl alcohol solution is 6-10%.

6. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 2, the freezing process parameters are as follows: the freezing temperature is -90--70℃, and the freezing time is 12-15 hours.

7. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 2, the sintering process parameters are as follows: the sintering temperature is 1150-1225℃, and the sintering time is 3-4 hours.

8. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 3, the vacuum drying temperature is 60-70℃, and the vacuum drying time is 20-30 hours.

9. The method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 3, the mass ratio of the L-lactic acid, the toluene and the nano-hydroxyapatite is 10-12:13:

7.

10. A method for preparing a biodegradable material for fractures according to claim 1, characterized in that: In step 4, the mass ratio of the polylactic acid to the chloroform is 7.4-7.8:1; and the mass fraction of the modified hydroxyapatite in the polylactic acid is 30%-40%.

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