Self-adaptive orthopedic external fixation composite material and preparation method thereof

Abstract

The invention discloses a self-adaptive orthopedic external fixation composite material and a preparation method thereof. Comprising a gradient modulus layer, a dynamic buffer layer and a high-expansion layer, according to the self-adaptive orthopaedic external fixation composite material disclosed by the embodiment of the invention, the composite material can be quickly attached to limbs and form mechanical support in gradient transition from outside to inside by utilizing the initial soft state of the material, so that the rigidity required by fracture reduction is ensured, and the stress shielding effect caused by too hard material is effectively reduced, thereby promoting bone healing and improving the bone fracture reduction rate. In the whole rehabilitation period, the limb rehabilitation device can adapt to swelling and regression changes of limbs, tight attachment is always maintained, compression on the skin in the swelling peak period is avoided, instability caused by fixing looseness after detumescence is also prevented, when rehabilitation angle adjustment needs to be conducted, materials can be safely softened through simple cold compress, painless adjustment is achieved, and the rehabilitation effect is good. In the adjusting process, all the layers have a synergistic effect, stress is effectively dispersed, and traction damage to the skin is completely eradicated.

Description

Technical Field

[0001] This application relates to the technical field of medical materials, and more particularly to an adaptive orthopedic external fixation composite material and its preparation method. Background Technology

[0002] Traditional orthopedic external fixation materials mainly include plaster casts and thermoplastic polymer sheets. Although plaster casts are inexpensive and easy to use, they have significant drawbacks such as being heavy, having poor breathability, not being able to be reshaped, and being unable to adapt to changes in limb swelling. They can easily lead to pressure sores, impaired blood circulation, and loosening of fixation, thus affecting the fracture healing process.

[0003] While existing thermoplastic external fixation materials (such as polylactic acid, polycaprolactone, or TPU-based sheets) have certain advantages in terms of plasticity and lightweight, they generally suffer from problems such as a single modulus and excessive rigidity. While providing sufficient fixation strength, they often cause a significant stress shielding effect, inhibiting the physiological mechanical stimulation of bone tissue and delaying callus formation. Especially when facing the inevitable swelling-reduction dynamic process of the limb after surgery, existing materials lack adaptive deformation capabilities, often leading to complications or reduction failure due to excessive pressure or loose fixation. In addition, once these materials have solidified, they are difficult to adjust again. If the fixation angle needs to be adjusted, it usually requires reheating and softening, which is complicated and carries the risk of burns. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, one objective of this application is to provide an adaptive orthopedic external fixation composite material and its preparation method, which is initially soft and conformable, and forms gradient mechanical support after curing, effectively reducing stress shielding; it can adapt to changes in swelling and swelling reduction, and the angle can be adjusted painlessly with cold compresses; the layers work together to disperse stress, and with modular splicing design, it takes into account fixation reliability, comfort and clinical adaptability.

[0006] To achieve the above objectives, the first aspect of this application proposes an adaptive orthopedic external fixation composite material, comprising a gradient modulus layer, a dynamic buffer layer, and a high-stretch layer, wherein the gradient modulus layer, the dynamic buffer layer, and the high-stretch layer are distributed sequentially from the outside to the inside; the gradient modulus layer is a quaternary blend shape memory polymer of polylactic acid, polyhydroxyalkanoate, thermoplastic polyurethane, and nano-hydroxyapatite; the dynamic buffer layer is made of polylactic acid microcapsules and a silicone rubber matrix; and the high-stretch layer is a ternary blend elastomer of quaternized chitosan, polycaprolactone, and polyethylene glycol.

[0007] In addition, the adaptive orthopedic external fixation composite material and its preparation method proposed in this application may also have the following additional technical features: In one embodiment of this application, the mass ratio of polylactic acid, polyhydroxyalkanoate, thermoplastic polyurethane and nano-hydroxyapatite in the gradient modulus layer is 45-55 parts: 20-28 parts: 15-22 parts: 3-8 parts, and the particle size of nano-hydroxyapatite is 20-50 nm.

[0008] In one embodiment of this application, the thickness of the dynamic buffer layer is 0.5-1 mm, and the mass ratio of polylactic acid microcapsules to silicone rubber matrix in the dynamic buffer layer is 75-85 parts: 15-25 parts, with polylactic acid microcapsules having a particle size of 50-100 μm and a wall thickness of 5-10 μm.

[0009] In one embodiment of this application, the thickness of the high-stretch layer is 0.3-0.8 mm, and the mass ratio of quaternized chitosan, polycaprolactone and polyethylene glycol in the high-stretch layer is 30-40 parts: 50-60 parts: 5-10 parts, and the polyethylene glycol has a molecular weight of 600-1000.

[0010] In one embodiment of this application, the gradient modulus layer, the dynamic buffer layer, and the high stretch layer are bonded together with an adhesive. The adhesive is a mixture of polylactic acid and glycolic acid copolymers, with a polylactic acid to glycolic acid molar ratio of 50 parts:50 parts to 75 parts:25 parts.

[0011] In one embodiment of this application, the gradient modulus layer adopts a "modular unit and elastic hinge" design, which can be flexibly spliced ​​according to the fracture site, and the gradient modulus layer is provided with multiple air pores, the pore diameter of which is 200-400μm and the density is 25-35 pores / cm³. 2 .

[0012] In one embodiment of this application, a protective mechanism is provided on the gradient modulus layer; the protective mechanism includes an elastic tube installed in the gradient modulus layer; a plurality of separation tubes are fixedly installed on the elastic tube; and a filling bladder is fixedly installed at one end of the separation tube.

[0013] In one embodiment of this application, the top and bottom of the module unit of the gradient modulus layer are respectively provided with pluggable connection seals.

[0014] In one embodiment of this application, a control valve is fixedly installed on the bottom end of the elastic tube, and an inflatable bladder is connected to the bottom of the control valve.

[0015] A method for preparing an adaptive orthopedic external fixation composite material includes the following steps: 1. Preparation of gradient modulus layers 1. Dry polylactic acid, polyhydroxyalkanoate and thermoplastic polyurethane at 80 degrees Celsius for four hours according to the specified ratio; 2. The dried mixture and modified nano-hydroxyapatite are simultaneously added to a twin-screw extruder and extruded at a temperature of 110–120℃ and a pressure of 5–8 kg / cm². 2 Under certain conditions, the materials are melt-blended and extruded into sheets with a thickness of 2–3 mm. 3. Use laser drilling equipment to create breathable micropores on the sheet, with a pore size of 200–400 μm and a pore density of 25–35 pores / cm². 2 ; 4. The sheet material is processed into modular units through molding process, and the elastic hinge structure is formed simultaneously. The edge of the module is reserved with assembly grooves for connecting the elastic hinge. 2. Preparation of dynamic buffer layer a. Polyethylene glycol is used as the core material and polylactic acid is used as the wall material, and they are dissolved in an appropriate amount of organic solvent at a mass ratio of 3:1; b. Emulsify the above solution by adding it dropwise to a solution containing 1% polyvinyl alcohol; c. Stir continuously at 40℃ to evaporate the organic solvent and solidify the microcapsules; d. Collect the product and process it to obtain microcapsules with a particle size of 50–100 μm; e. Mix the silicone rubber matrix with the above microcapsules in a predetermined ratio, add 0.5–1 parts by weight of dicumyl peroxide as a crosslinking agent, and stir thoroughly until homogeneous; f. Place the mixture in a mold and heat it at 60°C and a pressure of 3 kg / cm². 2 Under certain conditions, a dynamic buffer layer with a thickness of 0.5–1 mm is obtained by compression molding. 3. Preparation of high-strength layer 1. Prepare 1% acetic acid aqueous solution of quaternized chitosan, dichloromethane solution of polycaprolactone, and aqueous solution of polyethylene glycol respectively; 2. Mix the three solutions according to the set ratio and stir at room temperature until a homogeneous and transparent blend solution is formed; 3. The blending solution is cast into a polytetrafluoroethylene mold and dried in a vacuum drying oven at 60°C for 24 hours. After the solvent evaporates, a flexible film with a thickness of 0.3–0.8 mm is obtained, which is the high stretch layer. 4. Three-layer composite and modular assembly 1. Apply a polyadhesive solution evenly to the contact surfaces between the outer and middle layers, and between the middle and inner layers; 2. After stacking the three layers in sequence, place them in a hot press at 70–80℃ and a pressure of 5–6 kg / cm². 2Under the specified conditions, hot press for 10–15 minutes, then allow to cool naturally to room temperature and demold to complete the three-layer integrated composite. 3. Cut the composite board to the preset size, and assemble the aforementioned modular units and elastic hinges through the reserved slots to finally obtain a modular product.

[0016] The adaptive orthopedic external fixation composite material of this application utilizes the material's initial softness to quickly conform to the limb and form a gradient mechanical support from the surface inwards. This ensures the rigidity required for fracture reduction while effectively reducing the stress shielding effect caused by excessive material hardness, thereby promoting bone healing. Throughout the rehabilitation cycle, it adapts to changes in limb swelling and regression, maintaining a close fit at all times. This avoids pressure on the skin during peak swelling and prevents instability caused by loosening of the fixation after swelling subsides. When adjustments to the rehabilitation angle are needed, simple cold compresses can safely soften the material, enabling painless adjustment. During the adjustment process, the layers work synergistically to effectively disperse stress and prevent traction damage to the skin. While providing reliable fixation, this material greatly improves patient comfort, treatment safety, and rehabilitation flexibility. Furthermore, its splicable design allows it to adapt to different positions, increasing its adaptability during use.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of an adaptive orthopedic external fixation composite material according to Embodiment 1 of this application; Figure 2 This is a schematic diagram of the structure of an adaptive orthopedic external fixation composite material according to Embodiment 2 of this application; Figure 3 for Figure 2 An enlarged structural diagram of the central protective mechanism.

[0019] As shown in the figure: 10, gradient modulus layer; 20, dynamic buffer layer; 30, high elasticity layer; 40, protective mechanism; 401, elastic tube; 402, separation tube; 403, filling bladder. Detailed Implementation

[0020] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0021] The adaptive orthopedic external fixation composite material and its preparation method according to embodiments of this application are described below with reference to the accompanying drawings.

[0022] Example 1 like Figure 1 As shown, the adaptive orthopedic external fixation composite material of this application embodiment includes a gradient modulus layer 10, a dynamic buffer layer 20, and a high stretchable layer 30, wherein the gradient modulus layer 10, the dynamic buffer layer 20, and the high stretchable layer 30 are distributed sequentially from the outside to the inside; the gradient modulus layer 10 is a quaternary blend shape memory polymer of polylactic acid, polyhydroxyalkanoate, thermoplastic polyurethane, and nano-hydroxyapatite; the dynamic buffer layer 20 is made of polylactic acid microcapsules and a silicone rubber matrix; and the high stretchable layer 30 is a ternary blend elastomer of quaternized chitosan, polycaprolactone, and polyethylene glycol.

[0023] In one embodiment of this application, such as Figure 1 As shown, the mass ratio of polylactic acid, polyhydroxyalkanoate, thermoplastic polyurethane and nano-hydroxyapatite in the gradient modulus layer 10 is 45-55 parts: 20-28 parts: 15-22 parts: 3-8 parts, and the particle size of nano-hydroxyapatite is 20-50 nm.

[0024] It should be noted that in the gradient modulus layer 10, polylactic acid can provide a rigid foundation to ensure fixed strength; polyhydroxyalkanoates can optimize the shape memory effect and improve the phase change response speed; thermoplastic polyurethane can enhance the material's toughness and reversible deformation ability, ensuring secondary adjustment performance; nano-hydroxyapatite: modified with silane coupling agent (KH550), with a particle size of 20-50nm and good dispersion uniformity, achieves modulus gradient distribution through gradient dispersion (high content in the surface layer and low content in the inner layer), while improving biocompatibility. Modulus gradient: after curing, the surface modulus is 5-8GPa (to ensure fixed strength), and the inner layer interface modulus is 2-3GPa (to reduce stress shielding).

[0025] In one embodiment of this application, such as Figure 1 As shown, the thickness of the dynamic buffer layer 20 is 0.5-1mm, and the mass ratio of polylactic acid microcapsules to silicone rubber matrix in the dynamic buffer layer 20 is 75-85 parts: 15-25 parts. The polylactic acid microcapsules have a particle size of 50-100μm and a wall thickness of 5-10μm.

[0026] It should be noted that in the dynamic buffer layer 20, the silicone rubber matrix is ​​made of medical-grade methyl vinyl silicone rubber, which provides basic elastic buffering capacity and good compression rebound rate. The polylactic acid microcapsules contain polyethylene glycol phase change media (molecular weight 1500-2000, phase change temperature 32-35℃), which absorbs local stress through the release of latent heat of phase change and micro-expansion of volume, and neither of them is cytotoxic or skin irritating.

[0027] In one embodiment of this application, such as Figure 1 As shown, the thickness of the high stretchable layer 30 is 0.3-0.8 mm, and the mass ratio of quaternized chitosan, polycaprolactone and polyethylene glycol in the high stretchable layer 30 is 30-40 parts: 50-60 parts: 5-10 parts, and the polyethylene glycol has a molecular weight of 600-1000.

[0028] It should be noted that the quaternized chitosan in the high-stretch layer 30 can enhance antibacterial properties and biocompatibility, and has an antibacterial effect against Staphylococcus aureus and Escherichia coli. Polycaprolactone can provide a highly elastic base to ensure that the material can stretch significantly with swelling. Polyethylene glycol can enhance the material's skin affinity and reversible stretch, thus improving the fit after swelling subsides.

[0029] In one embodiment of this application, such as Figure 1 As shown, the gradient modulus layer 10, the dynamic buffer layer 20 and the high stretch layer 30 are bonded together with an adhesive. The adhesive is a mixture of polylactic acid and glycolic acid copolymer, with a molar ratio of polylactic acid to glycolic acid of 50 parts: 50 parts to 75 parts: 25 parts.

[0030] It should be noted that the adhesive has a bonding strength of ≥2.5MPa, and its degradation products are lactic acid and glycolic acid, which are non-irritating and meet safety standards.

[0031] In one embodiment of this application, such as Figure 1 As shown, the gradient modulus layer 10 adopts a "modular unit and elastic hinge" design, which can be flexibly spliced ​​according to the fracture site. Furthermore, the gradient modulus layer 10 has multiple ventilation holes with a pore size of 200-400 μm and a density of 25-35 holes / cm³. 2 .

[0032] It should be noted that the elastic hinge is made of a blend of TPU and polycaprolactone, which can improve its elongation at break.

[0033] Specifically, when it needs to be used, the outer layer of the material is in a soft state at room temperature (≤25℃). At this time, it can be directly wrapped or attached to the fracture site for shaping to closely match the limb contour. After the material comes into contact with the skin, the material is heated through the skin. The material begins to solidify within 1-2.5 minutes. The solidification process forms a gradient modulus from the surface to the inside, which quickly provides stable support. The middle and inner layers respond synchronously, buffering pressure and closely adhering to the skin to complete the fixation. During the fixation period, the high elasticity of the inner layer material allows it to stretch, while the middle layer elastically deforms, together releasing pressure and avoiding compression of the skin. The inner layer material elastically recovers and automatically contracts, while the middle layer rebounds, maintaining a continuous fit and fixation to prevent loosening. It can automatically adapt to changes in swelling and swelling of the limb. When an angle adjustment is needed, apply a cold source (such as an ice pack) at 0-8℃ to the outer layer for about 5 minutes to soften it to an adjustable state. While it is softened, gently apply external force and adjust it to the desired new angle using the modular hinge structure of the outer layer. After adjustment, remove the cold source. The material will re-solidify within about 30 seconds at room temperature, locking in the new angle. The middle and inner layers absorb stress and expand and contract accordingly during the adjustment process, effectively protecting the skin from stretching.

[0034] By utilizing the material's initial softness, it can quickly conform to the limb and form a gradient of mechanical support from the surface inwards. This ensures the rigidity required for fracture reduction while effectively reducing the stress shielding effect caused by excessively hard material, thereby promoting bone healing. Throughout the rehabilitation cycle, it adapts to changes in limb swelling and regression, maintaining a close fit at all times. This avoids pressure on the skin during peak swelling and prevents instability caused by loosening of fixation after swelling subsides. When adjustments to the rehabilitation angle are needed, simple cold compresses can safely soften the material, enabling painless adjustments. During the adjustment process, the layers work synergistically to effectively disperse stress and prevent traction damage to the skin. While providing reliable fixation, this material greatly improves patient comfort, treatment safety, and rehabilitation flexibility. Furthermore, its modular design allows it to adapt to different positions, increasing its adaptability during use.

[0035] Example 2 In one embodiment of this application, such as Figure 2 and Figure 3 As shown, a protective mechanism 40 is provided on the gradient modulus layer 10; the protective mechanism 40 includes an elastic tube 401 installed in the gradient modulus layer 10; a plurality of separation tubes 402 are fixedly installed on the elastic tube 401; a filling bladder 403 is fixedly installed at one end of the separation tube 402.

[0036] In one embodiment of this application, such as Figure 2 and Figure 3The top and bottom of the module unit of the gradient modulus layer 10 shown are respectively provided with pluggable connecting seals.

[0037] It should be noted that the connecting seal is used to connect two module units, and after connection, it can ensure that the two elastic tubes 401 can have normal air circulation.

[0038] In one embodiment of this application, such as Figure 2 and Figure 3 A control valve is fixedly installed on the bottom end of the elastic tube 401 shown, and an air bladder is connected to the bottom of the control valve.

[0039] It should be noted that the airbag can be repeatedly pressed. When the airbag is reset, the air in the elastic tube 401 will not be released. The control valve is a one-way valve. When the airbag is inflated, the air that has entered the elastic tube 401 will not flow out. The air can be discharged by manually adjusting the control valve. Furthermore, the size of the filling bladder 403 can be controlled by controlling the amount of air discharged, thereby controlling the air permeability.

[0040] Specifically, in actual use, when it is necessary to block the vent, the external inflation bladder is connected to the control valve, the control valve is opened, and then the inflation bladder is pressed to allow the gas inside the inflation bladder to enter the elastic tube 401, then through the elastic tube 401 into the separation tube 402, and finally through the separation tube 402 into the filling bladder 403. The gas increases the air pressure inside the filling bladder 403, causing the filling bladder 403 to inflate and block the vent.

[0041] Gas is injected into the filling bladder via an external inflatable bladder, causing it to inflate and precisely seal the corresponding vents. The operation is simple, responsive, and requires no power source or complex equipment. After sealing, local airflow is effectively reduced, minimizing heat loss and the intrusion of external pollutants, thus improving patient comfort and safety. When sealing is not required, the filling bladder naturally contracts without affecting its original breathability, expanding the material's adaptability to different rehabilitation stages and environmental conditions. At the same time, it maintains a simple structure and good biocompatibility, significantly enhancing the product's clinical usability and personalized fit.

[0042] A method for preparing an adaptive orthopedic external fixation composite material includes the following steps: 1. Preparation of gradient modulus layer 10 (1) Dry polylactic acid, polyhydroxyalkanoate and thermoplastic polyurethane at 80 degrees Celsius for four hours according to the formula; (2) The dried mixture and modified nano-hydroxyapatite were simultaneously added to a twin-screw extruder and extruded at a temperature of 110–120℃ and a pressure of 5–8 kg / cm². 2Under certain conditions, the materials are melt-blended and extruded into sheets with a thickness of 2–3 mm. (3) Use laser drilling equipment to create breathable micropores on the sheet, with a pore size of 200–400 μm and a pore density of 25–35 pores / cm. 2 ; (4) The sheet material is processed into modular units by molding process, and the elastic hinge structure is formed simultaneously. The edge of the module is reserved for assembly grooves for connecting the elastic hinge. 2. Preparation of dynamic buffer layer a. Polyethylene glycol is used as the core material and polylactic acid is used as the wall material, and they are dissolved in an appropriate amount of organic solvent at a mass ratio of 3:1; b. Emulsify the above solution by adding it dropwise to a solution containing 1% polyvinyl alcohol; c. Stir continuously at 40℃ to evaporate the organic solvent and solidify the microcapsules; d. Collect the product and process it to obtain microcapsules with a particle size of 50–100 μm; e. Mix the silicone rubber matrix with the above microcapsules in a predetermined ratio, add 0.5–1 parts by weight of dicumyl peroxide as a crosslinking agent, and stir thoroughly until homogeneous; f. Place the mixture in a mold and heat it at 60°C and a pressure of 3 kg / cm². 2 Under certain conditions, a dynamic buffer layer with a thickness of 0.5–1 mm is obtained by compression molding. 3. Preparation of high-strength layer (1) Prepare 1% acetic acid aqueous solution of quaternized chitosan, dichloromethane solution of polycaprolactone and aqueous solution of polyethylene glycol respectively; (2) Mix the three solutions according to the set ratio and stir at room temperature until a uniform and transparent blend solution is formed; (3) The blending solution is cast into a polytetrafluoroethylene mold and dried in a vacuum drying oven at 60°C for 24 hours. After the solvent evaporates, a flexible film with a thickness of 0.3–0.8 mm is obtained, which is the high stretch layer. 4. Three-layer composite and modular assembly (1) Apply a polyadhesive solution evenly to the contact surfaces between the outer layer and the middle layer, and between the middle layer and the inner layer; (2) After stacking the three layers in sequence, place them in a hot press at 70–80℃ and a pressure of 5–6 kg / cm². 2 Under the specified conditions, hot press for 10–15 minutes, then allow to cool naturally to room temperature and demold to complete the three-layer integrated composite. (3) Cut the composite board into preset dimensions and assemble the aforementioned modular units and elastic hinges through the reserved slots to finally obtain a modular product.

[0043] In summary, the adaptive orthopedic external fixation composite material of this application, by utilizing the initial soft state of the material, can quickly conform to the limb and form a mechanical support with a gradient transition from the surface to the interior. This ensures the rigidity required for fracture reduction while effectively reducing the stress shielding effect caused by excessive material hardness, thereby promoting bone healing. Throughout the rehabilitation cycle, it can adapt to changes in limb swelling and regression, maintaining a close fit at all times. This avoids pressure on the skin during peak swelling and prevents instability caused by loosening of fixation after swelling subsides. When adjustments to the rehabilitation angle are needed, simple cold compresses can safely soften the material, enabling painless adjustment. During the adjustment process, the layers work synergistically to effectively disperse stress and prevent traction damage to the skin. While providing reliable fixation, this material greatly improves patient comfort, treatment safety, and rehabilitation flexibility. Furthermore, its splicable design allows it to adapt to different positions, increasing its adaptability during use.

[0044] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0046] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An adaptive orthopedic external fixation composite material, characterized in that, It includes a gradient modulus layer (10), a dynamic buffer layer (20), and a highly scalable layer (30), wherein, The gradient modulus layer (10), dynamic buffer layer (20), and high-stretch layer (30) are distributed from the outside to the inside. The gradient modulus layer (10) is a quaternary blend shape memory polymer of polylactic acid, polyhydroxy fatty acid ester, thermoplastic polyurethane and nano-hydroxyapatite. The dynamic buffer layer (20) is made of polylactic acid microcapsules and silicone rubber matrix; The high-strength layer (30) is a terpolymer blend of quaternized chitosan, polycaprolactone and polyethylene glycol.

2. The adaptive orthopedic external fixation composite material according to claim 1, characterized in that, The mass ratio of polylactic acid, polyhydroxy fatty acid ester, thermoplastic polyurethane and nano-hydroxyapatite in the gradient modulus layer (10) is 45-55 parts: 20-28 parts: 15-22 parts: 3-8 parts, and the particle size of nano-hydroxyapatite is 20-50 nm.

3. The adaptive orthopedic external fixation composite material according to claim 1, characterized in that, The thickness of the dynamic buffer layer (20) is 0.5-1mm. The mass ratio of polylactic acid microcapsules and silicone rubber matrix in the dynamic buffer layer (20) is 75-85 parts: 15-25 parts. The polylactic acid microcapsules have a particle size of 50-100μm and a wall thickness of 5-10μm.

4. The adaptive orthopedic external fixation composite material according to claim 1, characterized in that, The thickness of the high stretchable layer (30) is 0.3-0.8 mm, and the mass ratio of quaternized chitosan, polycaprolactone and polyethylene glycol in the high stretchable layer (30) is 30-40 parts: 50-60 parts: 5-10 parts, and the polyethylene glycol has a molecular weight of 600-1000.

5. The adaptive orthopedic external fixation composite material according to claim 1, characterized in that, The gradient modulus layer (10), dynamic buffer layer (20) and high stretchable layer (30) are bonded together with an adhesive. The adhesive is a mixture of polylactic acid and glycolic acid copolymer, with a polylactic acid to glycolic acid molar ratio of 50 parts: 50 parts to 75 parts: 25 parts.

6. The adaptive orthopedic external fixation composite material according to claim 1, characterized in that, The gradient modulus layer (10) adopts a "modular unit and elastic hinge" design, which can be flexibly spliced ​​according to the fracture site. The gradient modulus layer 10 is provided with multiple air pores, the pore diameter of which is 200-400μm and the density is 25-35 pores / cm. 2 .

7. The adaptive orthopedic external fixation composite material according to claim 6, characterized in that, A protective mechanism (40) is provided on the gradient modulus layer (10). The protective mechanism (40) includes an elastic tube (401) installed within the gradient modulus layer (10). Multiple separation tubes (402) are fixedly installed on the elastic tube (401); A filling bladder (403) is fixedly installed at one end of the separation tube (402).

8. The adaptive orthopedic external fixation composite material according to claim 7, characterized in that, The top and bottom of the module unit of the gradient modulus layer (10) are respectively provided with pluggable connection seals.

9. The adaptive orthopedic external fixation composite material according to claim 7, characterized in that, A control valve is fixedly installed on the bottom end of the elastic tube (401), and an inflatable bladder is connected to the bottom of the control valve.

10. The method for preparing the adaptive orthopedic external fixation composite material as described in any one of claims 1-6, characterized in that, Includes the following steps: 1). Preparation of the gradient modulus layer (10): (1) Dry polylactic acid, polyhydroxyalkanoate and thermoplastic polyurethane at 80 degrees Celsius for four hours according to the formula; (2) The dried mixture and modified nano-hydroxyapatite are simultaneously added to a twin-screw extruder and extruded at a temperature of 110–120℃ and a pressure of 5–8 kg / cm². 2 Under certain conditions, the materials are melt-blended and extruded into sheets with a thickness of 2–3 mm. (3) Use laser drilling equipment to create breathable micropores on the sheet, with a pore size of 200–400 μm and a pore density of 25–35 pores / cm. 2 ; (4) The sheet material is processed into modular units by molding process, and the elastic hinge structure is formed simultaneously. The edge of the module is reserved with an assembly groove for connecting the elastic hinge. 2) Preparation of the dynamic buffer layer: a. Polyethylene glycol is used as the core material and polylactic acid is used as the wall material, and they are dissolved in an appropriate amount of organic solvent at a mass ratio of 3:1; b. Emulsify the above solution by adding it dropwise to a solution containing 1% polyvinyl alcohol; c. Stir continuously at 40℃ to evaporate the organic solvent and solidify the microcapsules; d. Collect the product and process it to obtain microcapsules with a particle size of 50–100 μm; e. Mix the silicone rubber matrix with the above microcapsules in a predetermined ratio, add 0.5–1 parts by weight of dicumyl peroxide as a crosslinking agent, and stir thoroughly until homogeneous; f. Place the mixture in a mold and heat it at 60°C and a pressure of 3 kg / cm². 2 Under certain conditions, a dynamic buffer layer with a thickness of 0.5–1 mm is obtained by compression molding. 3) Preparation of the high-strength layer: (1) Prepare 1% acetic acid aqueous solution of quaternized chitosan, dichloromethane solution of polycaprolactone and aqueous solution of polyethylene glycol respectively; (2) Mix the three solutions according to the set ratio and stir at room temperature until a uniform and transparent blend solution is formed; (3) The blending solution is cast into a polytetrafluoroethylene mold and dried in a vacuum drying oven at 60°C for 24 hours. After the solvent evaporates, a flexible film with a thickness of 0.3–0.8 mm is obtained, which is the high stretching layer. 4). Three-layer composite and modular assembly: (1) Apply a polyadhesive solution evenly to the contact surfaces between the outer layer and the middle layer, and between the middle layer and the inner layer; (2) After stacking the three layers in sequence, place them in a hot press at 70–80℃ and a pressure of 5–6 kg / cm². 2 Under the specified conditions, hot press for 10–15 minutes, then allow to cool naturally to room temperature and demold to complete the three-layer integrated composite. (3) Cut the composite board into preset dimensions and assemble the aforementioned modular units and elastic hinges through the reserved slots to finally obtain a modular product.

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