Preparation method of absorbable mineralized collagen bone repair implant

Abstract

A preparation method of an absorbable mineralized collagen bone repair implant comprises the steps that a compact layer and a plurality of protruding spiral barbs on the upper surface and the lower surface of the compact layer are prepared from a biodegradable material through an additive manufacturing process, and the barbs penetrate through a porous layer to extend outwards; preparing a porous layer by using the prepared mineralized collagen solution as a material through an additive manufacturing process or a controlled assembly process under a preset temperature condition; the porous layer at least comprises a high-porosity inner layer and a low-porosity outer layer in sequence from the direction close to the upper and lower surfaces of the compact layer to the direction far away from the upper and lower surfaces of the compact layer; and assembling the compact layer and the porous layer which are prepared and formed to form the absorbable mineralized collagen bone repair implant. According to the technical scheme, through the porous layer with the gradient porosity structure and the design of the spiral barbs, both osteoblast integration and initial mechanical support can be considered, the fixing effect can be remarkably improved, and the damage degree of bone tissue can be remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of bone repair medical device technology, and in particular to a method for preparing an absorbable mineralized collagen bone repair implant. Background Technology

[0002] Knee osteoarthritis is a disease characterized by the gradual wear and degeneration of the knee cartilage, leading to narrowing of the joint space, bone hyperplasia, and synovitis. It is more common in middle-aged and elderly people, and its early lesions are usually concentrated in the medial compartment of the knee joint. This is because the knee joint has a 5°-8° valgus angle, causing about 60%-75% of the load to pass through the medial compartment during weight-bearing, while the lateral compartment only bears 25%-40% of the load. Long-term uneven load results in the medial compartment of the knee joint bearing much greater pressure than the lateral compartment, which may eventually lead to varus deformity of the knee joint.

[0003] High tibial osteotomy (HTO) is a commonly used surgical method for treating medial compartment arthritis of the knee. Its core principle is to adjust the force distribution of the lower limb, reducing excessive load on the medial compartment, thereby relieving pain, improving knee function, and slowing disease progression. HTO surgery is mainly divided into two types: open medial wedge osteotomy and closed lateral wedge osteotomy.

[0004] However, traditional high tibial osteotomy has some limitations. For example, determining the osteotomy angle during surgery is difficult, postoperative bone healing is slow, fixation time is long, and it may restrict joint function to some extent. In addition, traditional surgical methods often cannot provide effective treatment for symptoms such as tibial plateau compression fractures or collapse.

[0005] Therefore, existing technologies often struggle to simultaneously achieve material stability, biocompatibility, and mechanical support, while also posing a risk of infection. Reportedly, an existing bone repair implant solution comprises a dense layer and porous layers on both sides, with multiple protruding triangular prism-shaped barbs on both sides of the dense layer extending outwards through the porous layer. In this solution, the dense layer effectively adjusts the weight-bearing distribution of the knee joint, correcting varus deformity, while the barbs prevent the implant from slipping out, ensuring surgical effectiveness. However, after thorough research, the inventors of this application realized that the aforementioned bone repair implant, relying solely on the dense layer to support knee joint pressure, provides insufficient support. Furthermore, the triangular prism-shaped barbs, due to their straight structure, do not bond tightly enough with bone tissue, resulting in poor fixation and a high risk of displacement and detachment. Uneven stress distribution during insertion can also damage bone tissue, hindering healing and recovery.

[0006] Therefore, developing a bone repair implant (especially suitable for high tibial osteotomy) and its preparation method that can simultaneously achieve material stability, biocompatibility, and mechanical support, more effectively support knee joint pressure, ensure fixation stability, and promote bone tissue healing and recovery, thereby effectively correcting knee joint alignment, inducing new bone growth, promoting bone healing, and providing sufficient and effective mechanical support for a long time during the healing process, is an urgent problem to be solved in this technical field. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide an absorbable mineralized collagen bone repair implant and its preparation method that can simultaneously achieve material stability, biocompatibility and sufficiently effective mechanical support, more effectively support the pressure of the knee joint, ensure fixation stability, and facilitate bone tissue healing and recovery.

[0008] To address the aforementioned problems, the present invention provides an absorbable mineralized collagen bone repair implant, comprising: a dense layer and two porous layers located on the upper and lower surfaces of the dense layer, respectively; the dense layer is made of a biodegradable material, and the porous layers are made of mineralized collagen raw materials; the upper and lower surfaces of the dense layer are provided with multiple protruding spiral barbs, which extend outward through the porous layers; the porous layers, from near the upper and lower surfaces of the dense layer to away from the upper and lower surfaces of the dense layer, sequentially include at least a high-porosity inner layer and a low-porosity outer layer; the porosity of the high-porosity inner layer is 70-90%, and the porosity of the low-porosity outer layer is 40-60%.

[0009] Optionally, continuous connecting holes are provided at the contact interface between the high-porosity inner layer and the low-porosity outer layer. The diameter of the connecting holes is 50-80% of the average diameter of the two sides, and the porosity difference is less than 20%.

[0010] Optionally, the dense layer gradually increases in thickness from the front end to the rear end of the absorbable mineralized collagen bone repair implant, forming a wedge shape.

[0011] Optionally, the absorbable mineralized collagen bone repair implant further includes bioactive coatings respectively coated on the upper and lower surfaces of the dense layer, the bioactive coatings being located between the upper and lower surfaces of the dense layer and the porous layer.

[0012] Optionally, the absorbable mineralized collagen bone repair implant further includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%.

[0013] Optionally, the absorbable mineralized collagen bone repair implant further includes multiple bone growth holes that penetrate the two porous layers and enter the dense layer.

[0014] Optionally, the bone elongation holes and the barbs are arranged alternately, with the bone elongation holes near the front end of the absorbable mineralized collagen bone repair implant arranged in a straight line, and those near the rear end of the absorbable mineralized collagen bone repair implant arranged in an arc. The line connecting the center diameters of the arc-arranged bone elongation holes has the same curvature as the rear end.

[0015] Optionally, the bone inlet holes and the barbs are arranged in an alternating ring or radial pattern.

[0016] Optionally, from the front end to the rear end of the absorbable mineralized collagen bone repair implant, the density of the barbs gradually increases, and the density of the bone growth holes gradually decreases.

[0017] Optionally, the barbs are distributed in the fixation zone and the growth zone, respectively. The length of the barbs in the fixation zone is greater than the length of the barbs in the growth zone. The friction of the barbs in the fixation zone is greater than the friction of the barbs in the growth zone. The pore size of the barbs in the growth zone is greater than the pore size of the barbs in the fixation zone. The bone growth inlets are concentrated in the growth zone. The fixation zone is close to the rear end of the absorbable mineralized collagen bone repair implant, and the growth zone is close to the front end of the absorbable mineralized collagen bone repair implant.

[0018] Optionally, the number of barbs is at least two rows, with at least three rows of bone elongation holes in the middle of the two rows of barbs, and at least one row of bone elongation holes arranged in an arc behind the second row of barbs.

[0019] Optionally, the diameter of the bone inlet hole is 0.5~2 mm, and the center distance between two adjacent bone inlets holes is 4.5~8 mm.

[0020] Optionally, the length of the barb is 2-3 mm and the bottom diameter is 3-5 mm.

[0021] To address the aforementioned problems, the present invention also provides a method for preparing the above-mentioned absorbable mineralized collagen bone repair implant, comprising: using biodegradable materials, forming the dense layer and the barbs through an additive manufacturing process; using a prepared mineralized collagen solution as a material, forming the porous layer through an additive manufacturing process under preset temperature conditions, or forming the porous layer through a controlled assembly process; assembling the prepared dense layer and the porous layer to form the absorbable mineralized collagen bone repair implant; wherein the process of forming the porous layer through additive manufacturing includes: printing the high-porosity inner layer and the low-porosity outer layer according to a preset model; precisely controlling the porosity of the high-porosity inner layer and the low-porosity outer layer through slicing parameters, wherein the slicing parameters... The parameters include linewidth, layer height, line spacing, and fill rate; the controlled assembly process for forming the porous layer includes: preparing a mineralized collagen solution comprising at least a first mineralized collagen solution and a second mineralized collagen solution; adjusting the pH of the first mineralized collagen solution to a first target pH value using an alkaline solution at a first adjustment rate; adjusting the pH of the second mineralized collagen solution to a second target pH value using a second adjustment rate; sequentially placing the first and second mineralized collagen solutions, after pH adjustment, into a mold; and forming the porous layer using a molding process; the first mineralized collagen solution is suitable for forming the high-porosity inner layer, and the second mineralized collagen solution is suitable for forming the low-porosity outer layer; the first target pH value is less than the second target pH value, and the first adjustment rate is less than the second adjustment rate.

[0022] Optionally, the porous layer and its high-porosity inner layer and low-porosity outer layer are assembled by a partitioned directional molding combined with an interface fusion control process. The partitioned directional molding combined with interface fusion control process includes: first forming the high-porosity inner layer, and while its surface is still semi-cured or contains part of a free-flowing phase, directly forming the adjacent low-porosity outer layer; controlling at least one of the temperature and solvent residue at the contact interface between the two layers during the forming of the low-porosity outer layer, so that the two materials undergo molecular chain interdiffusion and local cross-linking at the contact interface; and retaining continuous interconnecting pores at the contact interface, with a pore diameter of 50-80% of the average pore diameter on both sides and a porosity difference of less than 20%.

[0023] Optionally, the partitioned directional molding combined with interface fusion control process can be implemented by any of the following methods: 3D printing layered deposition, molding segmented molding, freeze-drying zoned temperature control, in-mold foaming local differentiation, and injection molding cavity injection.

[0024] Optionally, controlling at least one of the temperature of the two-layer contact interface and the amount of solvent residue during molding includes: controlling the temperature of the two-layer contact interface to be 5-15°C lower than the polymer curing temperature, and / or controlling the amount of solvent residue to be 1-5% of the total amount of solvent.

[0025] Optionally, before placing the first and second mineralized collagen solutions with adjusted pH values ​​into the mold, the prepared dense layer is placed in the mold in advance; the first and second mineralized collagen solutions sequentially cover the dense layer.

[0026] Optionally, the configured mineralized collagen solution further includes a third mineralized collagen solution, and the absorbable mineralized collagen bone repair implant further includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%, and the third mineralized collagen solution being suitable for forming the transition layer; the controlled assembly process for forming the porous layer further includes: adjusting the pH value of the third mineralized collagen solution to a third target pH value using an alkaline solution at a third adjustment rate; the third target pH value being between the first target pH value and the second target pH value, and the third adjustment rate being between the first adjustment rate and the second adjustment rate; after the first mineralized collagen solution is placed in the mold, the third mineralized collagen solution with pH adjusted pH value is used to cover the first mineralized collagen solution, and the third mineralized collagen solution is then covered with the second mineralized collagen solution.

[0027] Optionally, the controlled assembly process for forming the porous layer further includes: concentrating the first and second mineralized collagen solutions after pH adjustment; the concentration operation includes at least one of the following: dialysis of the first and second mineralized collagen solutions after pH adjustment into dialysis bags, filtration using a Buchner funnel, and removal of water by pressure.

[0028] Optionally, the preparation method of the absorbable mineralized collagen bone repair implant further includes: before placing the first mineralized collagen solution and the second mineralized collagen solution with pH value adjusted into the mold, allowing them to stand for a first preset time and a second preset time, respectively; or, sequentially placing the first mineralized collagen solution and the second mineralized collagen solution with pH value adjusted into the mold and allowing them to stand for a first preset time and a second preset time.

[0029] Optionally, the second preset time for the second mineralized collagen solution to stand is greater than or equal to the first preset time for the first mineralized collagen solution to stand.

[0030] Optionally, the configured mineralized collagen solution further includes a third mineralized collagen solution, and the absorbable mineralized collagen bone repair implant further includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%, and the third mineralized collagen solution being suitable for forming the transition layer; the controlled assembly process for forming the porous layer further includes: adjusting the pH value of the third mineralized collagen solution to a third target pH value using an alkaline solution at a third adjustment rate; the third target pH value being between the first target pH value and the second target pH value, the third... The adjustment rate is between the first adjustment rate and the second adjustment rate; after the first mineralized collagen solution is placed in the mold, the third mineralized collagen solution with pH adjustment is used to cover the first mineralized collagen solution, and the second mineralized collagen solution is used to cover the third mineralized collagen solution; before covering the first mineralized collagen solution or after covering the first mineralized collagen solution placed in the mold, the third mineralized collagen solution with pH adjustment is left to stand for a third preset time, the third preset time being greater than or equal to the first preset time, and the second preset time being less than or equal to the second preset time.

[0031] Optionally, the method for preparing the absorbable mineralized collagen bone repair implant further includes adding nano-silver particles to the prepared mineralized collagen solution.

[0032] Optionally, the method for preparing the absorbable mineralized collagen bone repair implant further includes adding an antioxidant to the material used to form the dense layer.

[0033] Optionally, the method for preparing the absorbable mineralized collagen bone repair implant further includes coating the upper and lower surfaces of the dense layer with a bioactive coating using surface coating technology.

[0034] Optionally, the method for preparing the absorbable mineralized collagen bone repair implant further includes forming multiple bone growth holes that penetrate the two porous layers and are drilled into the dense layer using a precision drilling technique.

[0035] Optionally, the bone insertion holes and the barbs are arranged in an alternating ring or radial pattern.

[0036] Optionally, from the front end to the rear end of the absorbable mineralized collagen bone repair implant, the density of the barbs is gradually increased, and the density of the bone growth holes is gradually decreased.

[0037] Optionally, the barbs are distributed in the fixation zone and the growth zone respectively. The length of the barbs in the fixation zone is greater than the length of the barbs in the growth zone. The friction of the barbs in the fixation zone is greater than the friction of the barbs in the growth zone. The porosity of the barbs in the growth zone is greater than the porosity of the barbs in the fixation zone. The bone growth holes are concentrated in the growth zone. The fixation zone is close to the rear end of the absorbable mineralized collagen bone repair implant, and the growth zone is close to the front end of the absorbable mineralized collagen bone repair implant.

[0038] Optionally, the porosity of the porous layer near the front end of the absorbable mineralized collagen bone repair implant is made greater than the porosity near the rear end of the absorbable mineralized collagen bone repair implant.

[0039] Compared with the prior art, the technical solution of the present invention has at least the following advantages: 1. Improved fixation and mechanical properties: From a structural optimization perspective, the high porosity of the inner layer of the multi-layered gradient porosity structure provides ample space and nutrient exchange conditions for bone cell growth, promoting new bone formation. The low porosity of the outer layer enhances overall mechanical strength, better withstands knee joint pressure, and meets the physiological needs of the human body. Compared with traditional straight barbs, the spiral barb design integrates more tightly with bone tissue, resulting in greater friction and gripping force, significantly improving fixation. It prevents the absorbable mineralized collagen bone repair implant from shifting or falling out, and the stress is evenly distributed during insertion, reducing damage to bone tissue. This ensures fixation stability and facilitates bone tissue healing and recovery.

[0040] 2. By setting continuous channels or interconnecting pores at the interface between the high-porosity inner layer and the low-porosity outer layer, and ensuring that the pore diameter of the channels or interconnecting pores is 50-80% of the average pore diameter on both sides, with a porosity difference of less than 20%, molecular-level bonding and macroscopic structural interlocking between layers are achieved, significantly enhancing the overall bonding strength and mechanical continuity of the interface. On the other hand, the connectivity of the porous structure is maintained, which is conducive to the bidirectional transfer of cell migration, nutrients and metabolites, thus taking into account both mechanical properties and biological functions, and providing a guarantee for the long-term stability and tissue repair effect of the material.

[0041] 3. By making the porosity of the porous layer near the front end of the absorbable mineralized collagen bone repair implant greater than the porosity near the rear end of the absorbable mineralized collagen bone repair implant, the transition of bone tissue from cancellous bone to dense bone is simulated, thereby improving biomechanical matching.

[0042] 4. By designing various arrangements of barbs and bone ingrowth holes, different technical effects can be achieved. For example, staggered ring or radial arrangements can increase three-dimensional fixation force, avoid force concentration in one direction, and facilitate bone tissue ingrowth in different directions, achieving multi-directional fixation force and bone tissue introduction; gradient arrangements can improve biomechanical matching by simulating the transition of bone tissue from cancellous bone to dense bone; functional zoning arrangements can divide the distribution of barbs into "fixation zone" (long barbs + high friction) and "growth zone" (short barbs + high density pores), with bone ingrowth holes concentrated in the growth zone, making the division of labor between fixation and bone integration clear and improving the bone healing speed.

[0043] Furthermore, the absorbable mineralized collagen bone repair implant provided by the technical solution of this invention has many advantages through the adoption of personalized customization and improved material performance preparation processes.

[0044] (1) 3D printing technology is based on digital models to manufacture precisely, strictly control material laying and pore structure, and ensure that the size, shape and internal structure of each absorbable mineralized collagen bone repair implant are highly consistent, which improves the stability of product quality. It can also quickly adjust the design according to clinical needs to achieve personalized customization, while improving production efficiency and reducing costs. (2) A porous layer with a multi-layered gradual porosity structure is formed through a controlled assembly process. Specifically, the pH value, adjustment rate and settling time of the mineralized collagen solution are precisely controlled to construct a porous layer with a gradual porosity structure layer by layer. This enables the mineralization process of each layer of collagen (including at least a high porosity inner layer and a low porosity outer layer) in the porous layer to be controlled by a simple and effective process. This optimizes the self-assembly of collagen fibers and the deposition of minerals, and finally obtains a bone repair material with ideal mechanical properties, mineralization degree, biocompatibility and good bone regeneration effect.

[0045] Porous layers with multi-layered gradient porosity structures formed through controlled assembly processes possess at least the following characteristics: Mineralization uniformity: In natural physiological environments, bone mineralization is a highly ordered process, with minerals being uniformly deposited on collagen fibers, giving bones excellent mechanical properties and biological functions. Mineralized collagen controlled assembly technology can simulate this natural process by precisely controlling the pH value, allowing mineral ions to be deposited on the collagen matrix in a predetermined manner and rate.

[0046] Enhanced Mechanical Properties: The technical solution of this invention achieves this through a controlled assembly method of mineralized collagen, which allows for precise control of the ratio, arrangement, and degree of bonding between minerals and collagen, thereby significantly enhancing the mechanical properties of the material. By optimizing the assembly process, minerals are evenly distributed and tightly bound between collagen fibers, effectively improving the strength and toughness of the material.

[0047] Promotes bone regeneration: Controlled assembly of mineralized collagen is structurally and compositionally closer to natural bone tissue, thus exhibiting excellent biocompatibility and bioactivity, and can better promote bone regeneration. Its biomimetic structure can provide an ideal microenvironment for cell adhesion, proliferation, and differentiation, which is conducive to the attachment and growth of osteoblasts on the material surface.

[0048] (3) By combining partitioned directional molding with interface fusion control technology, the porous layer and its high porosity inner layer and low porosity outer layer are formed and assembled, which can ensure the stable bonding and continuous stress transmission between layers with different porosities, effectively avoid interface peeling, and improve the overall mechanical properties and long-term stability of the composite material.

[0049] (4) Surface coating technology adds a bioactive coating to the surface of the dense layer, such as growth factors containing bone morphogenetic proteins, to promote bone cell adhesion, proliferation and differentiation, accelerate bone healing, and enable the absorbable mineralized collagen bone repair implant to fuse with bone tissue more quickly, helping patients to recover knee joint function more quickly.

[0050] The absorbable mineralized collagen bone repair implant provided by the technical solution of this invention can also improve the safety and effectiveness of the material: by adding nano-silver particles to the porous layer, their extremely small particle size can penetrate the bacterial cell wall, interfere with bacterial protein and nucleic acid metabolism, inhibit bacterial growth and reproduction, enhance antibacterial properties, significantly reduce the risk of infection after surgical implantation, reduce complications caused by infection, and ensure surgical safety; the dense layer introduces antioxidants to inhibit oxidation reactions, stabilize the chemical structure of the material, ensure that it maintains good mechanical properties for a long time, continuously provide reliable support for the knee joint, reduce immune reactions, reduce the risk of rejection, improve biocompatibility, facilitate long-term patient recovery, and improve the overall treatment effect. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the absorbable mineralized collagen bone repair implant structure according to Embodiment 1 of the present invention; Figure 2 This is a frontal view of the absorbable mineralized collagen bone repair implant according to Embodiment 1 of the present invention; Figure 3 This is a schematic cross-sectional view of the absorbable mineralized collagen bone repair implant according to Embodiment 1 of the present invention. Figure 4 This is an exploded schematic diagram of the absorbable mineralized collagen bone repair implant according to Embodiment 1 of the present invention; Figure 5 This is a top view schematic diagram of the arrangement of bone growth holes and barbs in the absorbable mineralized collagen bone repair implant according to Embodiment 1 of the present invention. Figure 6This is a schematic diagram of the structure of the absorbable mineralized collagen bone repair implant according to Embodiment 2 of the present invention; Figure 7 This is a top view schematic diagram of the arrangement of bone growth holes and barbs in the absorbable mineralized collagen bone repair implant of Embodiment 2 of the present invention. Figure 8 This is a schematic diagram of the structure of the absorbable mineralized collagen bone repair implant according to Embodiment 3 of the present invention; Figure 9 This is a top view schematic diagram of the arrangement of bone growth holes and barbs in the absorbable mineralized collagen bone repair implant of Embodiment 3 of the present invention. Figure 10 This is a top view schematic diagram of the arrangement of bone growth holes and barbs in the absorbable mineralized collagen bone repair implant of Embodiment 4 of the present invention. Figure 11 This is a schematic diagram illustrating the preparation method of the absorbable mineralized collagen bone repair implant according to an embodiment of the present invention; In the above figures, 1-front end; 2-rear end; 3-bone growth inlet; 4-spiral barbs; 51, 52-porous layers; 51a, 52a-high porosity inner layers; 51b, 52b-low porosity outer layers; 6-dense layer; 7-connecting pores; 8-growth zone; 9-fixation zone. Detailed Implementation

[0052] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0053] As described in the background section, existing bone repair implants for high tibial osteotomy rely solely on the dense layer to support knee joint pressure, resulting in insufficient support. Furthermore, the triangular barbs, due to their straight structure, do not integrate tightly with bone tissue, leading to poor fixation and a high risk of displacement, dislocation, or slippage. Uneven stress distribution during insertion can also damage bone tissue, hindering healing and recovery. This invention provides an absorbable mineralized collagen bone repair implant and its preparation method, addressing the aforementioned problems.

[0054] like Figures 1 to 4As shown, the absorbable mineralized collagen bone repair implant of Embodiment 1 of the present invention includes: a dense layer 6 and two porous layers (a porous layer 51 located on the upper surface of the dense layer 6 and a porous layer 52 located on the lower surface of the dense layer 6) respectively; the dense layer 6 may be made of biodegradable materials such as polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, and calcium phosphate, while the porous layers 51 and 52 are made of mineralized collagen raw materials; the upper surface of the dense layer The upper and lower surfaces are provided with multiple raised, spiral-shaped barbs 4, which extend outward through the porous layers 51 and 52. The porous layers 51 and 52, from near the upper and lower surfaces of the dense layer 6 to away from the upper and lower surfaces of the dense layer 6, sequentially include at least high-porosity inner layers 51a and 52a and low-porosity outer layers 51b and 52b. The porosity of the high-porosity inner layers 51a and 52a is 70-90%, and the porosity of the low-porosity outer layers 51b and 52b is 40-60%. In actual implementation, the dense layer 6 can gradually increase in thickness from the front end 1 to the rear end 2 of the absorbable mineralized collagen bone repair implant, forming a wedge shape to achieve tibial alignment correction. In actual implementation, the length of the wedge-shaped absorbable mineralized collagen bone repair implant is 20-45 mm, the width is 15-55 mm, the front end is 0.2-1 mm, and the rear end is 2-20 mm.

[0055] In addition to the high-porosity inner layers 51a and 52a and the low-porosity outer layers 51b and 52b, the absorbable mineralized collagen bone repair implant may also include a transition layer (not shown in the figures) located between the high-porosity inner layers 51a and 52a and the low-porosity outer layers 51b and 52b, the porosity of the transition layer being 50-70%.

[0056] Both porous layers in this embodiment of the invention employ a gradient porosity structure (or a "multi-layered gradient porosity structure"), thereby balancing osteogenic integration and initial mechanical support. This structure comprises at least two layers (or at least one transition layer between them). The inner layer is designed with high porosity, creating a highly favorable growth environment for bone cells. The outer layer is designed with low porosity, effectively enhancing the overall mechanical strength of the absorbable mineralized collagen bone repair implant. The low porosity structure allows the outer layer to better withstand various pressures from the knee joint, ensuring internal bone growth conditions while providing more stable and reliable mechanical support for the knee joint.

[0057] In the embodiments of the present invention, the two porous layers can also improve biomechanical matching by making the porosity of the porous layer near the front end of the absorbable mineralized collagen bone repair implant greater than the porosity near the rear end of the absorbable mineralized collagen bone repair implant, thereby simulating the transition of bone tissue from cancellous bone to dense bone.

[0058] It should be noted that the aforementioned technical solution, where the porosity of the front end of the absorbable mineralized collagen bone repair implant is greater than that of the rear end, represents a preferred feature of introducing a longitudinal porosity gradient along the "front end → rear end" direction on two porous layers. This solution offers clear technical benefits (simulating the transition from cancellous bone to dense bone, improving mechanical compatibility and stress transfer) and can be stably implemented with sufficient existing process support (3D printing, controlled assembly, freeze-drying / molding, etc.). This technical solution can be achieved by introducing a porosity gradient along the front end to the rear end during the fabrication process. Specifically, differentiated structures can be formed by adjusting material parameters in sections during the 3D printing or controlled assembly stages (see related descriptions below).

[0059] Compared to existing straight barbs, the spiral barbs in this invention fundamentally change the contact mode with bone tissue after implantation. The spiral structure allows for a tighter bond with the bone tissue. At the same implantation depth, the spiral barbs generate greater friction and gripping force, effectively preventing displacement or detachment of the absorbable mineralized collagen bone repair implant during use, and significantly improving fixation. Simultaneously, the unique structure of the spiral barbs allows for more even distribution of force when inserted into bone tissue, avoiding the localized stress concentration problems that may occur with straight barbs and reducing the degree of damage to bone tissue.

[0060] In this embodiment, continuous channels or connecting holes 7 can also be provided at the contact interfaces between the high-porosity inner layer 51a and the low-porosity outer layer 51b, and between the high-porosity inner layer 52a and the low-porosity outer layer 52b. The pore diameter of the channels or connecting holes 7 is 50-80% of the average pore diameter on both sides, and the porosity difference is less than 20%, so as to achieve a dual combination of mechanical interlocking and channel connectivity. In this embodiment, the contact interfaces between the high-porosity inner layer 51a and the low-porosity outer layer 51b, and between the high-porosity inner layer 52a and the low-porosity outer layer 52b, can be controlled by adjusting the temperature of the interface area (controlled at 5-15°C lower than the polymer curing temperature) and / or the amount of solvent residue (mass fraction 1-5%) during the molding process (see the relevant content of "(3) Partition-oriented molding combined with interface fusion control process" below), so that the two layers of materials maintain appropriate chain segment fluidity and diffusion ability at the interface, thereby inducing the interdiffusion and local cross-linking of molecular chains. Meanwhile, the transitional pore size and relatively similar porosity differences in the interface region promote stable physical interlocking and pore connectivity between adjacent layers. The resulting technical effects are twofold: firstly, it achieves molecular-level bonding and macroscopic structural interlocking between layers, significantly enhancing the overall bonding strength and mechanical continuity of the interface; secondly, it maintains the connectivity of the porous structure, facilitating bidirectional transport of cell migration, nutrients, and metabolites, thus balancing mechanical properties and biological functions, and ensuring the long-term stability and tissue repair effects of the material.

[0061] The absorbable mineralized collagen bone repair implant also includes multiple bone growth holes 3, which penetrate the porous layer 51 and the porous layer 52 respectively, and are inserted into (but not penetrated) the dense layer 6.

[0062] It should be noted that, in this embodiment, the connecting hole 7 is a continuous channel retained in the contact interface between the high-porosity inner layer 51a and the low-porosity outer layer 51b, and between the high-porosity inner layer 52a and the low-porosity outer layer 52b. This continuous channel is parallel to the direction of the contact interface (or can be considered perpendicular to the thickness direction of the absorbable mineralized collagen bone repair implant). The purpose is to still form a channel connection between the two layers when the molecular chains diffuse and cross-link locally through temperature control at the two-layer interface. The bone growth inlet hole 3 is a hole formed in the porous layer. The direction of the bone growth inlet hole is consistent with the thickness direction of the absorbable mineralized collagen bone repair implant, but it does not involve the channel connection between the two-layer interface.

[0063] The embodiments of the present invention provide various arrangements of the bone growth holes and barbs: The first arrangement involves an alternating arrangement of the bone elongation holes and barbs. The bone elongation holes near the front end of the absorbable mineralized collagen bone repair implant are arranged in a straight line, while those near the rear end are arranged in an arc. The line connecting the central diameters of the arc-arranged bone elongation holes has the same curvature as the rear end. There are at least two rows of barbs, with at least three rows of bone elongation holes between the two rows. At least one row of arc-shaped bone elongation holes is located behind the second row of barbs. This arrangement essentially follows the existing technology.

[0064] The second arrangement (interlaced annular or radial arrangement): the bone ingrowth holes and the barbs are arranged in an interlaced annular or radial pattern. This arrangement, based on the spiral design of the barbs, simultaneously forms annular or radial arrangements at different levels. Adjacent rows of barbs do not overlap in the projection direction. The combination of the bone ingrowth holes and barbs forms a composite network of "radial + annular," achieving the following technical effects: increased three-dimensional fixation force, avoidance of force concentration in a single direction, and facilitating bone tissue ingrowth in different directions, thereby achieving multi-directional fixation force and bone tissue introduction. Figure 5 and Figures 1-4 In combination, the arrangement of the bone entry holes 3 and barbs 4 in the absorbable mineralized collagen bone repair implant of Embodiment 1 of the present invention adopts an "interlaced ring" arrangement. For example... Figure 6 and Figure 7 As shown, the bone growth holes 3 and barbs 4 in the absorbable mineralized collagen bone repair implant of Embodiment 2 of the present invention are arranged in a "radial pattern".

[0065] The third arrangement method (gradient arrangement): See the absorbable mineralized collagen bone repair implant of Embodiment 3 of this invention. Figure 8 and Figure 9 From the front end 1 to the rear end 2 of the absorbable mineralized collagen bone repair implant, the density of the barbs 4 gradually increases, while the density of the bone elongation inlets 3 gradually decreases. The technical effect of this arrangement is to simulate the transition of bone tissue from cancellous bone to dense bone, improving biomechanical compatibility.

[0066] The fourth arrangement (functional zone arrangement): The barbs are distributed in the fixation zone and the growth zone respectively. The length of the barbs in the fixation zone is greater than that in the growth zone, the friction of the barbs in the fixation zone is greater than that in the growth zone, and the porosity of the barbs in the growth zone is greater than that in the fixation zone. The bone growth entry holes are concentrated in the growth zone. The fixation zone is close to the rear end of the absorbable mineralized collagen bone repair implant, and the growth zone is close to the front end of the absorbable mineralized collagen bone repair implant. This arrangement divides the distribution of the barbs into a "fixation zone" (long barbs + high friction) and a "growth zone" (short barbs + high-density pores), with the bone growth entry holes concentrated in the growth zone. The resulting technical effect is a clear division of labor between fixation and bone integration, improving the bone healing speed.

[0067] In the absorbable mineralized collagen bone repair implant of Embodiment 4 of the present invention, the bone elongation inlet and barbs adopt the fourth arrangement described above, such as... Figure 10 As shown, it contains two functional zones: a fixed zone 9 and a growth zone 8. The fixed zone 9 is closer to the rear end 2, and the barbs 4 are more concentrated in the fixed zone 9. The growth zone 8 is closer to the front end 1, and the bone growth foramina 3 are more densely distributed in the growth zone 8.

[0068] It should be noted that in actual implementation, the main characteristics of the above four layout methods can be combined to form layout methods with new features. In fact, it is possible to combine... Figure 1 and Figure 2 In the absorbable mineralized collagen bone repair implant of Embodiment 1 of the present invention, the bone growth holes and barbs not only adopt an "interlaced ring" arrangement, but also incorporate some features of functional zoning and gradual arrangement. The length of the barbs gradually increases from the front end to the rear end, thus forming both functional zoning and gradual distribution characteristics.

[0069] Of course, the arrangement of the bone inlet holes and the barbs is not limited to the above-mentioned methods. Other methods with specific technical effects can also be formed. For example, each row of barbs and the adjacent row of bone inlet holes can no longer be completely intersected, but can form a "misaligned diagonal" or "honeycomb" geometric distribution. This can disperse the stress concentration during implantation and improve the implantation stability.

[0070] In actual implementation, the diameter of the bone inlet hole is 0.5~2mm, and the center distance between two adjacent bone inlets is 4.5~8mm. The length of the barb is 2~3mm, and the bottom diameter is 3~5mm.

[0071] In this embodiment, the absorbable mineralized collagen bone repair implant further includes bioactive coatings respectively coated on the upper and lower surfaces of the dense layer, wherein the bioactive coatings are located between the upper and lower surfaces of the dense layer and the porous layer.

[0072] like Figure 11 As shown, to prepare the above-mentioned absorbable mineralized collagen bone repair implant, this invention also provides a corresponding preparation method, including: step S1, using biodegradable materials, a dense layer 6 and multiple protruding spiral barbs 4 are prepared by additive manufacturing process; step S21, using a prepared mineralized collagen solution as material, a high-porosity inner layer 51a and a low-porosity outer layer 51b are prepared under preset temperature conditions by additive manufacturing process or controlled assembly process to form a porous layer; step S22, using a prepared mineralized collagen solution as material, a high-porosity inner layer 52a and a low-porosity outer layer 52b are prepared under preset temperature conditions by additive manufacturing process or controlled assembly process to form a porous layer; step S3, assembling the prepared dense layer 6 and porous layer to form an absorbable mineralized collagen bone repair implant. In this embodiment of the invention, the above-mentioned absorbable mineralized collagen bone repair implant can be prepared by additive manufacturing process or by a combination of additive manufacturing process and controlled assembly process; in addition, based on the preparation achieved by the above two process methods, the porous layer and its high porosity inner layer and low porosity outer layer can be further formed and assembled by partitioned directional molding combined with interface fusion control process.

[0073] (1) Preparation by additive manufacturing (3D printing) process: The dense layer and the barbs are prepared using biodegradable materials through additive manufacturing. A porous layer is prepared using a prepared mineralized collagen solution at a preset temperature through additive manufacturing. The prepared dense layer and porous layer are assembled to form the absorbable mineralized collagen bone repair implant. The preparation of the porous layer through additive manufacturing includes: printing a high-porosity inner layer and a low-porosity outer layer according to a preset model; and precisely controlling the porosity of the high-porosity inner layer and the low-porosity outer layer using slicing parameters, including linewidth, layer height, line spacing, and fill rate.

[0074] When the porous layer is formed by additive manufacturing, the front end region of the absorbable mineralized collagen bone repair implant can be further improved by using a lower solid content or a smaller filling rate, so that the material forms larger pores and a higher porosity (about 70% to 85%) after molding and freeze-drying. Meanwhile, the rear end region of the absorbable mineralized collagen bone repair implant uses a higher solid content or a larger filling rate, so that the pore structure is more compact and the porosity is reduced to about 45% to 60%. This achieves the technical solution that "the porosity of the front end of the absorbable mineralized collagen bone repair implant is greater than that of the rear end".

[0075] 3D printing technology is based on digital models for manufacturing, resulting in a more precise process that allows for accurate control over key elements such as the placement, thickness, and pore structure of each layer of material. This highly precise manufacturing method ensures a high degree of consistency in the size, shape, and internal structure of each industrially produced absorbable mineralized collagen bone repair implant, effectively minimizing errors. Furthermore, 3D printing technology can quickly adjust design models to meet different clinical needs, enabling personalized, customized production.

[0076] (2) Preparation by combining additive manufacturing process with controlled assembly process The dense layer and the barbs are prepared by combining additive manufacturing and controlled assembly processes. The dense layer and the barbs are still prepared by additive manufacturing, while the porous layer can be prepared by controlled assembly processes.

[0077] The process of preparing the porous layer by a controlled assembly process includes: preparing a mineralized collagen solution comprising at least a first mineralized collagen solution and a second mineralized collagen solution; adjusting the pH of the first mineralized collagen solution to a first target pH value using an alkaline solution at a first adjustment rate; adjusting the pH of the second mineralized collagen solution to a second target pH value using a second adjustment rate; sequentially placing the first and second mineralized collagen solutions, after pH adjustment, into a mold; and forming the porous layer using a molding process; wherein the first mineralized collagen solution is suitable for forming the high-porosity inner layer, and the second mineralized collagen solution is suitable for forming the low-porosity outer layer; the first target pH value is less than the second target pH value, and the first adjustment rate is less than the second adjustment rate.

[0078] In this embodiment, the prepared mineralized collagen solution may further include a third mineralized collagen solution, and the absorbable mineralized collagen bone repair implant further includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%, and the third mineralized collagen solution being suitable for forming the transition layer; the controlled assembly process for preparing the porous layer further includes: adjusting the pH value of the third mineralized collagen solution to a third target pH value using an alkaline solution at a third adjustment rate; the third target pH value being between the first target pH value and the second target pH value, and the third adjustment rate being between the first adjustment rate and the second adjustment rate; after the first mineralized collagen solution is placed in the mold, the third mineralized collagen solution with the completed pH adjustment is used to cover the first mineralized collagen solution, and the third mineralized collagen solution is covered with the second mineralized collagen solution.

[0079] In actual implementation, the specific preparation process of the first mineralized collagen solution, the second mineralized collagen solution, and the third mineralized collagen solution can be achieved by various technical means. For example, they can be prepared by mixing collagen solution, mineral solution, and phosphoric acid solution, or by physically mixing collagen solution and nano-hydroxyapatite powder, or by successively adding sodium dihydrogen phosphate solution and calcium chloride solution to collagen solution. For details, please refer to the schemes given in the following embodiments.

[0080] The process of preparing the above three portions of mineralized collagen solution by mixing collagen solution, acidic solution and mineral solution may include: dissolving collagen in acidic solution to form collagen acidic solution; mixing at least two kinds of mineral powders in a predetermined ratio and stirring evenly in water to obtain mineral solution; and sequentially adding mineral solution and phosphoric acid solution to each portion of collagen acidic solution and stirring to form three portions of mineralized collagen solution.

[0081] Regarding the formation of the above three mineralized collagen solutions, they can be obtained by dividing the mineralized collagen solution prepared using the same mineralized collagen solution preparation process into N portions, or by forming each portion of the mineralized collagen solution using the same mineralized collagen solution preparation process.

[0082] In practice, the pH value of the first mineralized collagen solution is adjusted to a first target pH value using an alkaline solution at a first adjustment rate. The first target pH value is greater than or equal to 6.5, and preferably equal to 7. The alkaline solution can be one of the following: sodium hydroxide solution, potassium hydroxide solution, ammonia solution, sodium carbonate solution, sodium bicarbonate solution, etc. In practice, setting the first target pH value to be greater than or equal to 7 yields better results.

[0083] The target pH values ​​of the mineralized collagen solutions formed on each layer above the high-porosity inner layer gradually increase in magnitude. For example, the first target pH value is 7, the third target pH value is 7.5, and the second target pH value is 8.5. The increase in the third target pH value relative to the first target pH value is 0.5, and the increase in the second target pH value relative to the third target pH value is 1. Thus, the magnitude of the target pH value increase gradually increases. In addition to increasing the magnitude of the target pH value increase, the predetermined adjustment rate of the pH values ​​of the corresponding mineralized collagen solutions from the high-porosity inner layer, the transition layer, to the low-porosity outer layer can also gradually increase. For example, the adjustment rate for the first target pH value is 5 ml / min, the adjustment rate for the third target pH value is 10 ml / min, and the adjustment rate for the second target pH value is 20 ml / min. The increase in the third target pH adjustment rate relative to the first target pH adjustment rate is 5 ml / min, and the increase in the second target pH adjustment rate relative to the third target pH adjustment rate is 10 ml / min, demonstrating a gradual increase in the target pH adjustment rate. By progressively increasing the corresponding target pH values ​​of the first, third, and second mineralized collagen solutions, coupled with progressively increasing adjustment rates, the faster pH changes promote the rapid formation of a dense fibrous structure in collagen. Numerous hydroxyapatite particles are tightly packed between the collagen fibers, thus more effectively forming a progressively layered structure with varying density and porosity through precise control of the predetermined pH adjustment rate.

[0084] Before placing the first, third, and second mineralized collagen solutions (with pH adjusted) into the mold, a pre-prepared dense layer can be placed inside the mold; the first, third, and second mineralized collagen solutions sequentially cover the dense layer.

[0085] In this embodiment, the first mineralized collagen solution, the third mineralized collagen solution, and the second mineralized collagen solution, after pH adjustment, can be subjected to a standing operation and a concentration operation respectively, so that each mineralized collagen solution is solidified, and the solidified first mineralized collagen is placed at the bottom of the mold to form the high porosity inner layer.

[0086] In specific implementation, the concentration operation includes at least one of the following: dialysis of the pH-adjusted first mineralized collagen solution in a dialysis bag; filtration using a Buchner funnel; and removal of water by pressure. Concentration operations such as dialysis and filtration can remove small molecule impurities from the solution, reduce solvent content, and increase the concentration and purity of the mineralized collagen. The settling operation includes setting the pH-adjusted first mineralized collagen solution at a specific temperature (e.g., 37°C) for a first preset time. The purpose of the settling operation is to allow the particles of the suspension to precipitate. This is usually performed before the concentration operation. After both the settling and concentration operations are completed, the solidified first mineralized collagen is placed in a mold, covering the dense layer already placed in the mold. Alternatively, the settling and concentration operations can also be performed within the mold. In this case, the pH-adjusted first mineralized collagen solution can be directly placed in the mold, covering the dense layer already placed in the mold, and settling at a specific temperature (e.g., 37°C) for a first preset time, followed by concentration using pressure. Similarly, the third mineralized collagen solution, after pH adjustment, undergoes a standing and concentration process to solidify it. The solidified third mineralized collagen is then used to cover the first mineralized collagen within the mold, forming the transition layer. The standing process includes placing the pH-adjusted second mineralized collagen solution at a specific temperature (e.g., 37°C) for a third preset time, where the third preset time is not less than the first preset time. Then, the pH-adjusted second mineralized collagen solution undergoes another standing and concentration process to solidify it. The solidified second mineralized collagen is then used to cover the third mineralized collagen within the mold, forming the low-porosity inner layer. The pH-adjusted second mineralized collagen solution is then placed at a specific temperature (e.g., 37°C) for a second preset time, where the second preset time is greater than or equal to the third preset time.

[0087] After the porous layer covers the dense layer, the mold and the sample therein (the dense layer and the porous layers located on both sides) can be subjected to a molding process, which may include pressurizing and vacuum drying, or pre-freezing followed by freeze drying.

[0088] It should be noted that, during implementation, one of the two molding methods mentioned above can be selected according to the actual situation. For example, if the freeze-drying method is selected, the mold and sample need to be pre-frozen in an environment of -20℃ to -40℃ for 10-24 hours, and then placed in a freeze dryer for freeze-drying molding according to a specific program.

[0089] The principle behind the controlled assembly of mineralized collagen through pH adjustment in this invention is as follows: In neutral or slightly acidic environments, collagen molecules carry a large number of positive charges, resulting in electrostatic repulsion and weak intermolecular interactions. As the pH increases, the concentration of hydroxide ions in the solution increases, causing some acidic groups on the collagen molecules to dissociate, reducing the positive charge on the collagen molecules. This promotes the collagen molecules to approach each other and arrange themselves in an orderly manner, thereby forming collagen fibers. Simultaneously, under alkaline conditions, collagen molecules contain a suitable amount of negatively charged groups and Ca2+. 2+ Zn 2+ Mg 2+ and PO4 3- Interactions; the electrochemical properties of collagen molecules can regulate the behavior of inorganic ions in the matrix, and the carboxyl groups provide nucleation sites for hydroxyapatite, while the orderly arrangement of collagen fibers provides nucleation space for hydroxyapatite crystallization.

[0090] The embodiments of this invention prepare the porous layer through a controlled assembly process. On one hand, multiple portions of mineralized collagen solution are separately prepared to form each layer of the porous layer (high-porosity inner layer, transition layer, and low-porosity outer layer). On the other hand, for each portion of the prepared mineralized collagen solution, an alkaline solution is added at a predetermined adjustment rate to regulate and induce collagen fiber formation, stabilizing the liquid crystal tissue into a dense fibrous matrix. By controlling the adjustment of the target pH value and the adjustment rate of each portion of mineralized collagen solution, a gradual change in density is formed from the inner layer to the outer layer of the porous layer. Thus, a simple and effective process can be used to controllably assemble the mineralized collagen of the porous layer into a bone repair material with a gradually dense layered structure, enabling the bone repair material to simultaneously possess excellent properties such as uniformity, stable mechanical properties, and good bone regeneration effect.

[0091] When the porous layer is prepared by a controlled assembly process, the pH value and adjustment rate of the mineralized collagen solution can be adjusted layer by layer to form a gel structure with gradually varying density along the length direction of the collagen fibers and mineralized particles. After uniform drying, a porous layer with gradually decreasing porosity from the front end to the rear end of the absorbable mineralized collagen bone repair implant can be obtained, achieving a biomimetic mechanical and biological gradient distribution.

[0092] (3) Partitioned directional molding combined with interface fusion control process The porous layer and its high-porosity inner layer and low-porosity outer layer are assembled through a partitioned directional molding combined with an interface fusion control process. The partitioned directional molding combined with interface fusion control process includes: first forming the high-porosity inner layer, and while its surface is still semi-cured or contains part of the free-flowing phase, directly forming the adjacent low-porosity outer layer; when forming the low-porosity outer layer, controlling at least one of the temperature and solvent residue at the interface between the two layers (for example, controlling the temperature of the interface between the two layers to be 5-15°C lower than the polymer curing temperature, and / or controlling the solvent residue to be 1-5% of the total solvent mass fraction) to allow molecular chain interdiffusion and local cross-linking to occur at the interface between the two layers; the interface retains continuous channels or interconnecting pores with a pore diameter of 50-80% of the average pore diameter on both sides and a porosity difference of less than 20%.

[0093] The technical principles of the above-mentioned partitioned orientation molding combined with interface fusion control process and the expected technical effects it can achieve are analyzed below: Interface temperature control (5–15°C lower than the curing temperature): Within this temperature range, the polymer is not fully cured, and the chain segments still possess some molecular mobility (near chain relaxation / glass transition). This "semi-cured" state facilitates the interpenetration and entanglement of polymer chains in adjacent layers at the interface. Lowering the temperature prevents rapid curing of the entire system, keeping the interface in a "fusion-ready" state, while also reducing the risk of interfacial thermal degradation or bubble formation.

[0094] Solvent residue control (1–5% by mass): Retaining a small amount of solvent in the polymer can plasticize the molecular chains and improve the flowability and diffusivity of chain segments at the interface. The solvent creates a local "swelling" effect at the interface, promoting the interdiffusion of molecular chains between the two layers. Simultaneously, during subsequent drying or curing, solvent evaporation and shrinkage help to ensure a tighter adhesion between the two layers.

[0095] Analysis of expected technical effects: a) Enhance the bonding strength of the interface By using interpenetrating networks at the molecular level, interfaces are prevented from becoming "weak interfaces" or weak points for delamination. This is particularly suitable for multilayer composite materials (such as scaffolds, films, and coatings) where overall integrated performance is required.

[0096] b) Implement the interface transition area Due to interdiffusion and cross-linking, the interface is no longer a clear boundary but a continuous transition, improving stress transfer. This helps reduce crack initiation and propagation at the interface, improving fatigue and impact resistance.

[0097] c) Maintaining the overall properties of the material The temperature is lower than the complete curing temperature, which can balance flowability and molding stability and avoid macroscopic deformation. Controlling the residual solvent within a reasonable range (1–5%) can maintain the chain segment mobility without causing porosity, foaming or degradation of mechanical properties due to excessive solvent.

[0098] In specific embodiments of the present invention, the partitioned directional molding combined with interface fusion control process can be implemented by any of the following methods, including but not limited to 3D printing layered deposition, molding segmented molding, freeze-drying zoned temperature control, in-mold foaming local differentiation, and injection molding cavity injection.

[0099] a) 3D printing layered deposition In 3D printing, complex structures are achieved by depositing materials layer by layer. Controllable path planning allows for the setting of printing parameters (such as filament diameter, infill density, nozzle temperature, and deposition rate) for different regions. High-density, regularly oriented deposition is used in load-bearing areas to achieve enhanced mechanical properties; low-density, randomly oriented deposition is used in areas requiring porosity or fluid conduction to form porous structures. At the interface between these two types of regions, adjusting the nozzle temperature, deposition sequence, and transition zone infill rate ensures a smooth transition and effective physical / chemical bonding, preventing delamination and cracking.

[0100] b. Compression molding in sections The material is prefabricated into semi-finished products in different areas, and then filled and pressed in sections in the mold.

[0101] The mold is designed with partitioned cavities, and different partitions can use different formulations or different fiber / filler distributions to give the regions differentiated properties.

[0102] During the molding process, the cavity partition is removed, and temperature and pressure are applied to cause adjacent segments to melt and interpenetrate or compact and bond at the interface, thereby controlling the continuity of the interface structure and avoiding delamination.

[0103] c. Freeze-drying zone temperature control By utilizing the freeze-drying process, the material solution exhibits differentiated ice crystal growth patterns in different regions through temperature control. Near the mechanically supported region, rapid cooling induces fine, oriented ice crystals, forming dense and highly directional channels. In the central or peripheral regions, slow cooling generates large pores, enhancing permeability or bioactivity. At the interface between regions with different freezing rates, a temperature-controlled gradient facilitates a natural transition of ice crystals, avoiding sharp boundaries and thus improving interfacial continuity and overall mechanical properties.

[0104] d. Localized differentiation in in-mold foaming Material containing a foaming agent is injected into the mold, and differentiated foaming occurs in different areas through localized temperature or gas control. The load-bearing area has a low foaming ratio to maintain density and strength, while the buffer or flow-guiding area has a high foaming ratio to obtain a porous buffer structure. Under the conditions of gas diffusion and polymer melting within the mold, the interface between adjacent areas transitions through molecular chain interdiffusion, controlling the pore size gradient and interfacial bonding.

[0105] e. Injection molding with cavity injection In multi-cavity molds, different materials or different proportions of the same material are injected into different zones by controlling the injection sequence, pressure, and temperature. High-modulus materials are injected into one zone to provide rigidity, while low-modulus or porous materials are injected into another zone to enhance biocompatibility or elasticity. By controlling the temperature and pressure at the injection flow front, the injectables from different cavities can achieve mutual melting or co-solidification at the interface, avoiding cold seams or weak bonding surfaces.

[0106] (4) Other processes In this embodiment, the preparation method of the absorbable mineralized collagen bone repair implant further includes adding nano-silver particles to the prepared mineralized collagen solution. By adding nano-silver particles to the porous layer, the nano-silver, due to its extremely small particle size, possesses excellent antibacterial capabilities. Once integrated into the porous layer, it can easily penetrate the cell wall defenses of bacteria due to its tiny size advantage. After entering the bacteria, the nano-silver binds tightly to key biomolecules such as bacterial proteins and nucleic acids, interfering with the normal physiological metabolic processes of bacteria, thereby inhibiting bacterial growth and reproduction. This antibacterial mechanism is not only highly efficient but also long-lasting, exerting its effect for a considerable period after the absorbable mineralized collagen bone repair implant is implanted into the human body, enhancing antibacterial performance and reducing the risk of infection.

[0107] Furthermore, the preparation method of the absorbable mineralized collagen bone repair implant may also include adding an antioxidant to the material forming the dense layer. Adding an antioxidant to the dense layer can improve the stability and biocompatibility of the material.

[0108] The method for preparing the absorbable mineralized collagen bone repair implant further includes coating the upper and lower surfaces of the dense layer with a bioactive coating (such as growth factors containing bone morphogenetic proteins) using surface coating technology. The bioactive coating is rich in a variety of substances that can undergo specific biochemical reactions with bone tissue. These substances can provide positive signals and environmental support for the adhesion, proliferation, and differentiation of bone cells. Therefore, by adding a bioactive coating to the surface of the dense layer, bone healing can be further promoted.

[0109] The following specific examples illustrate the actual implementation of the preparation process for the above-mentioned absorbable mineralized collagen bone repair implant: Example 1 (3D Printing) Step S101, preparing collagen acid solution: Select hydrochloric acid (HCl), dissolve the collagen in it, and prepare a solution with a collagen concentration of 5.0 × 10⁻⁶. -5 An acidic solution in the mL range. In other embodiments, the acidic solution used to dissolve collagen may also be acetic acid (CH3COOH), nitric acid (HNO3), etc.

[0110] Step S102, adding calcium ion solution: While continuously stirring the above solution, slowly add a calcium ion-containing solution dropwise, strictly controlling the amount of calcium ions added per gram of collagen to be 0.01 mol. It should be noted that the calcium ion-containing solution can be calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), etc.

[0111] Step S103, Add phosphate ion solution: While stirring, slowly add the solution containing phosphate ions, ensuring that the molar ratio of phosphate ions to calcium ions is maintained at Ca / P = 1.4~1.7.

[0112] Step S104, Adjusting pH: Continuously stir the mixed solution and slowly add NaOH solution dropwise to adjust the pH of the mixed system to 6. During the adjustment process, when the pH reaches 5-6, precipitation will begin to occur in the mixed system, and the system will then present as a white suspension.

[0113] Step S105, Separation, Drying and Screening: Let the mixed system stand for 24 hours, then separate the precipitate and carefully wash away the impurity ions; then perform freeze drying treatment, first pre-freeze at -30℃ (without vacuum) for 180 min, then sublimate (with vacuum) at -10℃ for 48 hours until constant weight is reached; finally grind and sieve the dried product to screen out mineralized collagen powder with a particle size of less than 200 μm, and keep it for later use.

[0114] Step S106, Preparation of the porous layer: Accurately weigh the prepared mineralized collagen powder, disperse it in purified water, and stir continuously for 24 hours to form a mineralized collagen solution with a concentration of 0.06 g / mL. Add nano-silver particles and collagenic acid solution to the solution in a certain proportion (the specific proportion is determined according to the required antibacterial effect). After stirring evenly at 37°C, use 3D printing technology to print at a temperature of 4°C (Note: Mineralized collagen aqueous solution is difficult to 3D print at room temperature, but its temperature response characteristics can be used for 3D printing). According to the multi-layer porosity gradient structure design, when designing the 3D printing model, the dense layer and the porous layer need to be designed simultaneously and printed separately. During printing, the porous layer needs to have barbs reserved. First, a high-porosity inner layer is printed (porosity can be precisely controlled through 3D printing parameters, such as layer height and fill rate; the inner layer porosity is set at 80%, see Example 4 for details). Then, an outer low-porosity layer is printed (outer layer porosity is set at 60%-70%). After printing, the layer is pre-frozen at -30℃ (without vacuum) for 180 minutes, and then sublimated at -10℃ (with vacuum) for 48 hours to prepare a porous layer on one side. The same method is used to prepare the porous layer on the other side.

[0115] Step S107, Preparation of a dense layer: Select one or more copolymers of polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, calcium phosphate, calcium sulfate, and bioglass as the base material, add an appropriate amount of antioxidant (the amount of antioxidant added is determined according to the material characteristics and required stability), stir evenly, and then use 3D printing technology to accurately print the dense layer. The thickness of the dense layer gradually increases from the front end to the rear end, forming a wedge shape with a length of 20 mm, a width of 15 mm, a front end thickness of 0.2 mm, and a rear end thickness of 2 mm.

[0116] Step S108, Barb Processing: The barbs use the same base material and process as the dense layer, and are designed in a spiral shape using 3D printing technology. The spiral barbs are 2mm long and 3mm in diameter at the base. The barbs are distributed regularly on the upper and lower surfaces of the dense layer to ensure a secure hold.

[0117] Step S109, Bone elongation perforation processing: After the dense layer and porous layer are prepared and formed, they are assembled together, and then perforation is performed using precision perforation technology. In this embodiment, the bone elongation perforations and barbs are arranged alternately. The bone elongation perforations near the front end are arranged in a straight line, and those near the rear end are arranged in an arc. The line connecting the center diameters of the arc-arranged bone elongation perforations is the same as the arc of the rear end of the absorbable mineralized collagen bone repair implant. At least two rows of barbs are provided on both the upper and lower surfaces of the dense layer, with three rows of bone elongation perforations in the middle of the two rows of barbs. At least one row of bone elongation perforations arranged in an arc is provided behind the second row of barbs. In other embodiments, the bone elongation perforations and barbs can also adopt other arrangement methods, such as the aforementioned staggered annular or radial arrangement, gradient arrangement, functional zone arrangement, etc. The diameter of the bone elongation perforation is 0.5 mm, and the center distance between two bone elongation perforations is 4.5 mm. The absorbable mineralized collagen bone repair implant is then obtained.

[0118] Example 2 (3D printing + surface treatment) Step S201, preparing collagen acid solution: Select nitric acid, dissolve collagen in it, and prepare a solution with a collagen concentration of 5.0 × 10⁻⁶. -4 Acidic solutions in the range of mL.

[0119] Step S202, Add calcium ion solution: While continuously stirring the above solution, slowly add a calcium ion solution dropwise, strictly controlling the amount of calcium ions added per gram of collagen to be within the range of 0.1 mol.

[0120] Step S203, Add phosphate ion solution: While stirring, slowly add the solution containing phosphate ions, ensuring that the molar ratio of phosphate ions to calcium ions is maintained at Ca / P = 1.67.

[0121] Step S204, pH adjustment: Continuously stir the mixed solution and slowly add NaOH solution dropwise to adjust the pH of the mixed solution system to 7. During the pH adjustment process, when the pH reaches 5-6, precipitation will begin to occur in the mixed system; when the pH is 7, the system will present as a white suspension.

[0122] Step S205, Separation, Drying, and Screening: The mixed system was allowed to stand for 90 hours, then the precipitate was separated and impurity ions were carefully washed away. Next, freeze-drying was performed: first, pre-freezing at -25°C (without vacuum) for 180 minutes, then sublimation (with vacuum) at -5°C for 48 hours until constant weight was achieved. Finally, the dried product was ground and sieved to screen out mineralized collagen powder with a particle size less than 200 μm, which was then stored for later use.

[0123] Step S206, Preparation of the porous layer: Accurately weigh the prepared mineralized collagen powder and disperse it in purified water. Stir continuously for 48 hours to form a mineralized collagen solution with a concentration of 0.1 g / mL. Add nano-silver particles (the specific ratio is determined according to the required antibacterial effect) and collagenic acid solution to the solution in a certain proportion. After stirring evenly at 37°C, use 3D printing technology to print at a temperature of 4°C. According to the multi-layer gradient structure design, when designing the 3D printing model, the dense layer and the porous layer need to be designed simultaneously and printed separately. During printing, the porous layer needs to have barbs reserved. First, print the inner high-porosity layer (porosity can be precisely controlled through 3D printing parameters, such as layer height and fill rate; the inner layer porosity is set at 85%). Then, print the outer low-porosity layer (outer layer porosity is set at 60%-70%). After printing, pre-freeze at -25℃ (without vacuum) for 180 minutes, then sublimate at -15℃ (with vacuum) and dry for 48 hours to prepare one side of the porous layer. Use the same method to prepare the other side of the porous layer.

[0124] Step S207, Preparation of a dense layer: Select one or more copolymers of polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, calcium phosphate, calcium sulfate, and bioglass as the base material, add an appropriate amount of antioxidant (the amount of antioxidant added is determined according to the material characteristics and required stability), stir evenly, and then use 3D printing technology to accurately print the dense layer. The thickness of the dense layer gradually increases from the front end to the rear end, forming a wedge shape with a length of 30 mm, a width of 30 mm, a front end thickness of 0.5 mm, and a rear end thickness of 10 mm.

[0125] Step S208, Barb Processing: The barbs use the same base material and process as the dense layer, and are designed in a spiral shape using 3D printing technology. The spiral barbs are 2mm long and have a base diameter of 4mm. The barbs are distributed regularly on the upper and lower surfaces of the dense layer to ensure a secure hold.

[0126] Step S209, Bone Longitudinal Inlet Processing: After the dense layer and porous layer are prepared and shaped, they are assembled together, and then a precision drilling operation is performed. The bone longitudinal inlets and barbs are arranged alternately. The bone longitudinal inlets near the front end are arranged in a straight line, while those near the rear end are arranged in an arc. The line connecting the central diameters of the arc-arranged bone longitudinal inlets has the same curvature as the rear end of the absorbable mineralized collagen bone repair implant. At least two rows of barbs are provided on both the upper and lower surfaces of the dense layer, with three rows of bone longitudinal inlets between the two rows of barbs. At least one row of arc-shaped bone longitudinal inlets is provided behind the second row of barbs. The diameter of the bone longitudinal inlets is 1.5 mm, and the center-to-center distance between two bone longitudinal inlets is 6.5 mm.

[0127] In this embodiment, after step S207 or S208 and before step S209, step S210 can also be performed: surface treatment. A bioactive coating is added to the prepared dense layer surface (which is not covered by the porous layer at this time) using surface coating technology. A coating material containing bone morphogenetic proteins and other bone-healing-promoting components can be selected. This material is uniformly applied to the dense layer surface by spraying, dipping, or other methods, and then subjected to appropriate curing treatment to ensure the bioactive coating firmly adheres to the dense layer surface, further promoting bone healing.

[0128] Example 3 (Controlled Assembly Process) Step S301, Preparation of a dense layer: Select one or more copolymers of polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, calcium phosphate, calcium sulfate, and bioglass as the base material, add an appropriate amount of antioxidant (the amount of antioxidant added is determined according to the material characteristics and required stability), stir evenly, and then use 3D printing technology to accurately print the dense layer. The thickness of the dense layer gradually increases from the front end to the rear end, forming a wedge shape with a length of 45 mm, a width of 55 mm, a thickness of 1 mm at the front end, and a thickness of 20 mm at the rear end.

[0129] Step S302, Barb Processing: Using 3D printing technology, the barbs are designed in a spiral shape. The length of the spiral barb is 3mm, and the bottom diameter is 5mm. The barbs are distributed in a certain pattern on the upper and lower surfaces of the dense layer to ensure a secure hold.

[0130] Step S303, preparing collagen acid solution: Select one type of acetic acid, dissolve collagen in it, and prepare a solution with a collagen concentration of 5.0 × 10⁻⁶. -3 Acidic solutions in the g / mL range.

[0131] Step S304, Add calcium ion solution: While continuously stirring the above solution, slowly add a calcium ion solution dropwise, strictly controlling the amount of calcium ions added per gram of collagen to be within the range of 0.16 mol.

[0132] Step S305, Add phosphate ion solution: While stirring, slowly add the solution containing phosphate ions, ensuring that the molar ratio of phosphate ions to calcium ions is maintained at Ca / P = 2.

[0133] In step S306, take half of the mixed solution and pour it into the mold with the dense layer already placed. Slowly add NaOH solution to adjust the pH of the mixed system to 7.5 at a rate of 5 ml / min. During the adjustment process, when the pH reaches 5-6, the mixed system will begin to precipitate; when the pH is 7, the system will be in a white suspension state.

[0134] In step S307, the mixed system is allowed to stand for 120 hours to allow the entire sample to fully solidify. Then, the precipitate is separated and impurity ions are carefully washed away to form a high-porosity inner layer of the porous layer.

[0135] In step S308, take the remaining 1 / 2 of the mixed solution and pour it into the mold that has been prepared. Add NaOH solution dropwise to adjust the pH of the mixed system to 8.5 at a rate of 10 ml / min.

[0136] Step S309: Let the mixed system stand for 120 hours to allow the entire sample to fully solidify. Then, separate the precipitate and carefully wash away the impurity ions to form a low-porosity outer layer of the porous layer.

[0137] Step S310: Next, freeze-drying is performed. First, the product is pre-frozen (without vacuum) at -20°C for 180 minutes, and then sublimated (with vacuum) at 0°C for 48 hours until constant weight is achieved.

[0138] Step S311, Bone Longitudinal Inlet Processing: After the dense layer and porous layer are prepared, a precision drilling operation is performed. The bone longitudinal inlets and barbs are arranged alternately. The inlets near the front end are arranged in a straight line, while those near the rear end are arranged in an arc. The line connecting the central diameters of the arc-arranged bone longitudinal inlets matches the rearward curvature of the absorbable mineralized collagen bone repair implant. At least two rows of barbs are provided on both the upper and lower surfaces of the dense layer. Three rows of bone longitudinal inlets are located between the two rows of barbs, with at least one row of arc-shaped bone longitudinal inlets located behind the second row of barbs. The diameter of the bone longitudinal inlets is 2 mm, and the center-to-center distance between two bone longitudinal inlets is 8 mm.

[0139] In this embodiment, step S312 can be performed after step S301 or S302 and before step S306, for surface treatment: a bioactive coating is added to the prepared dense layer surface (which is not covered by the porous layer at this time) using surface coating technology. A coating material containing bone morphogenetic proteins and other bone-healing-promoting components can be selected. This material is uniformly applied to the dense layer surface by spraying, dipping, or other methods, and then subjected to appropriate curing treatment to ensure the bioactive coating firmly adheres to the dense layer surface, further promoting bone healing.

[0140] Example 4 (Preparation of mineralized collagen composite material with controlled porosity via 3D printing process) In this embodiment, the preparation process of the mineralized collagen composite material with porosity controlled by printing process in Example 1 or 2 will be described in detail. Other related contents involving the preparation of the absorbable mineralized collagen bone repair implant by additive manufacturing process can be referred to the relevant contents of Example 1 or 2, and will not be repeated here.

[0141] This embodiment describes a method for preparing mineralized collagen composite materials with controlled porosity using 3D printing technology, including: 1. Raw material preparation.

[0142] (1) Weigh type I collagen and dissolve it in 0.5 mol / L acetic acid solution to prepare a collagen acid solution of 1 mg / mL; (2) Add CaCl2 solution and Na2HPO4 solution sequentially according to the Ca / P molar ratio of 1.67; (3) Slowly add NaOH solution to adjust the pH to 7.0, and let it stand for 48 h; (4) Collect the precipitate, wash it with deionized water 3–5 times, freeze dry it for 24 h, grind and sieve it to obtain mineralized collagen powder with a particle size of 50–200 μm.

[0143] 2. Preparation of composite printing materials.

[0144] The obtained mineralized collagen powder was uniformly mixed with polylactic acid (PLA, molecular weight 100,000) at a ratio of PLA:MC = 3:2 (mass ratio), and 1 wt% chitosan was added as a film-forming enhancer to form a printing composite material.

[0145] 3. Principle of porosity control in 3D printing.

[0146] In this embodiment of the invention, porosity is precisely controlled through slicing parameters, mainly involving linewidth w, layer height h, line spacing p, and fill rate. The theoretical basis is as follows: Macro porosity P macro Relationship with line width w and line spacing p:

[0147] When the target total porosity is P total The proportion of micropores inside the wire material P micro hour:

[0148] Actual slicing parameters need to take into account shrinkage compensation after printing:

[0149] Recommended ceiling height:

[0150] 4. Calculation Example The printing linewidth is set to 240 μm, and the target total porosity is [missing information]. P total = 80%, micropore ratio Pmicro = 10%, drying shrinkage rate 5%. Substituting into the formula, we get:

[0151] Accordingly, in this embodiment, the line spacing is set to 2.16 mm and the layer height is set to 0.17 mm in the slicing software to achieve the target porosity of 80%.

[0152] 5. Printing and Molding (1) A high porosity inner layer structure was constructed by using a 3D printer at 4℃ and employing an alternating filament placement method of 0° / 90°. (2) The porosity of the inner layer is set to 80%, and the outer layer is controlled at 60% by adjusting the filling rate and line spacing to form a gradient porous structure; (3) After printing, the sample is pre-frozen at -20℃ for 3 hours and then freeze-dried in vacuum at -10℃ for 48 hours to obtain the final product.

[0153] 6. Results and Effects Scanning electron microscopy (SEM) observation of the printed samples showed that the pores were uniform and continuously distributed, with the pore size mainly concentrated in the range of 200–400 μm, which is consistent with the optimal window for bone tissue ingrowth. The measured porosity calculated by the weighing method was 79.2 ± 2.5%, which is basically consistent with the design value of 80%, proving the effectiveness and controllability of the method provided in this embodiment.

[0154] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] It should be noted that the technical solution of the present invention is not only applicable to high tibial osteotomy, but also to other orthopedic surgeries, such as vertebroplasty and bone defect repair. It is also customizable, such as the design of customized materials for different bone defect environments.

[0156] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing an absorbable mineralized collagen bone repair implant, characterized in that, The absorbable mineralized collagen bone repair implant comprises: a dense layer and two porous layers located on the upper and lower surfaces of the dense layer, respectively; the upper and lower surfaces of the dense layer are provided with multiple protruding barbs, which extend outward through the porous layers; the porous layers, from near the upper and lower surfaces of the dense layer to away from the upper and lower surfaces of the dense layer, sequentially include at least a high-porosity inner layer and a low-porosity outer layer; the porosity of the high-porosity inner layer is 70-90%, and the porosity of the low-porosity outer layer is 40-60%; The preparation method includes: The dense layer and the barbs are prepared using biodegradable materials through an additive manufacturing process. The porous layer is formed by additive manufacturing process using a prepared mineralized collagen solution as material under preset temperature conditions, or by controlled assembly process. The prepared dense layer and porous layer are assembled to form the absorbable mineralized collagen bone repair implant; The process of preparing the porous layer by additive manufacturing includes: printing the high-porosity inner layer and the low-porosity outer layer according to a preset model; and precisely controlling the porosity of the high-porosity inner layer and the low-porosity outer layer by slicing parameters, including linewidth, layer height, line spacing and fill rate. The controlled assembly process for forming the porous layer includes: preparing a mineralized collagen solution comprising at least a first mineralized collagen solution and a second mineralized collagen solution; adjusting the pH of the first mineralized collagen solution to a first target pH value using an alkaline solution at a first adjustment rate; adjusting the pH of the second mineralized collagen solution to a second target pH value using a second adjustment rate; sequentially placing the first and second mineralized collagen solutions, after pH adjustment, into a mold; and forming the porous layer using a molding process; wherein the first mineralized collagen solution is suitable for forming the high-porosity inner layer, and the second mineralized collagen solution is suitable for forming the low-porosity outer layer; the first target pH value is less than the second target pH value, and the first adjustment rate is less than the second adjustment rate.

2. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, The porous layer and its high-porosity inner layer and low-porosity outer layer are assembled through a partitioned directional molding combined with an interface fusion control process. This partitioned directional molding combined with interface fusion control process includes: First, the high-porosity inner layer is formed, and while its surface is still semi-cured or contains some free-flowing phase, the adjacent low-porosity outer layer is directly formed. When forming the low-porosity outer layer, at least one of the temperature at the interface between the two layers and the amount of residual solvent is controlled so that molecular chain interdiffusion and local cross-linking occur at the interface between the two layers. A continuous connecting hole is maintained at the contact interface, with a hole diameter of 50-80% of the average hole diameter on both sides and a porosity difference of less than 20%.

3. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 2, characterized in that, The partitioned directional molding combined with interface fusion control process can be implemented by any of the following methods: 3D printing layered deposition, molding segmented molding, freeze-drying zoned temperature control, in-mold foaming local differentiation, and injection molding cavity injection.

4. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 2, characterized in that, Controlling at least one of the temperature of the two-layer contact interface and the amount of solvent residue during molding includes: controlling the temperature of the two-layer contact interface to be 5-15°C lower than the polymer curing temperature, and / or controlling the amount of solvent residue to be 1-5% of the total amount of solvent.

5. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, Before placing the first and second mineralized collagen solutions, whose pH values ​​have been adjusted, into the mold, a pre-prepared dense layer is placed inside the mold; the first and second mineralized collagen solutions sequentially cover the dense layer.

6. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, The prepared mineralized collagen solution further includes a third mineralized collagen solution. The absorbable mineralized collagen bone repair implant also includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%, and the third mineralized collagen solution being suitable for forming the transition layer. The controlled assembly process for forming the porous layer further includes: adjusting the pH value of the third mineralized collagen solution to a third target pH value using an alkaline solution at a third adjustment rate; the third target pH value being between the first target pH value and the second target pH value, and the third adjustment rate being between the first adjustment rate and the second adjustment rate; after the first mineralized collagen solution is placed in the mold, the third mineralized collagen solution with the completed pH adjustment is used to cover the first mineralized collagen solution, and the third mineralized collagen solution is then covered with the second mineralized collagen solution.

7. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, The controlled assembly process for forming the porous layer further includes: concentrating the first and second mineralized collagen solutions after pH adjustment; the concentration operation includes dialysis of the first and second mineralized collagen solutions after pH adjustment in dialysis bags, removing water by Buchner funnel filtration and pressurization.

8. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, Also includes: Before placing the first and second mineralized collagen solutions, whose pH values ​​have been adjusted, into the mold, allow them to stand for a first preset time and a second preset time, respectively. Alternatively, place the first and second mineralized collagen solutions, after pH adjustment, into the mold and let them stand for a first preset time and a second preset time, respectively.

9. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 8, characterized in that, The second preset time for the second mineralized collagen solution to stand is greater than or equal to the first preset time for the first mineralized collagen solution to stand.

10. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 9, characterized in that, The prepared mineralized collagen solution further includes a third mineralized collagen solution. The absorbable mineralized collagen bone repair implant further includes a transition layer located between the high-porosity inner layer and the low-porosity outer layer, the porosity of the transition layer being 50-70%, and the third mineralized collagen solution being suitable for forming the transition layer. The controlled assembly process for forming the porous layer further includes: adjusting the pH value of the third mineralized collagen solution to a third target pH value using an alkaline solution at a third adjustment rate; the third target pH value being between the first target pH value and the second target pH value, the third adjustment... The rate is between the first adjustment rate and the second adjustment rate; after the first mineralized collagen solution is placed in the mold, the third mineralized collagen solution with completed pH adjustment is used to cover the first mineralized collagen solution, and the second mineralized collagen solution is used to cover the third mineralized collagen solution; before covering the first mineralized collagen solution or after covering the first mineralized collagen solution placed in the mold, the third mineralized collagen solution with completed pH adjustment is left to stand for a third preset time, the third preset time being greater than or equal to the first preset time, and the second preset time being less than or equal to the second preset time.

11. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, It also includes adding nano-silver particles to the prepared mineralized collagen solution.

12. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, It also includes adding antioxidants to the material used to prepare the dense layer.

13. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, It also includes coating the upper and lower surfaces of the dense layer with a bioactive coating using surface coating technology.

14. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, It also includes forming multiple bone growth holes that penetrate the two porous layers and are drilled into the dense layer using precision drilling technology.

15. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 14, characterized in that, The bone insertion holes and the barbs are arranged in an alternating ring or radial pattern.

16. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 14, characterized in that, From the front end to the rear end of the absorbable mineralized collagen bone repair implant, the density of the barbs gradually increases, while the density of the bone growth holes gradually decreases.

17. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 14, characterized in that, The barbs are distributed in the fixation zone and the growth zone, respectively. The length of the barbs in the fixation zone is greater than that in the growth zone. The friction of the barbs in the fixation zone is greater than that in the growth zone. The porosity of the barbs in the growth zone is greater than that in the fixation zone. The bone growth inlets are concentrated in the growth zone. The fixation zone is close to the rear end of the absorbable mineralized collagen bone repair implant, and the growth zone is close to the front end of the absorbable mineralized collagen bone repair implant.

18. The method for preparing the absorbable mineralized collagen bone repair implant according to claim 1, characterized in that, The porosity of the porous layer near the front end of the absorbable mineralized collagen bone repair implant is greater than the porosity near the rear end of the absorbable mineralized collagen bone repair implant.

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