Titanium / tantalum composite porous bone defect repair stent and preparation method thereof

Abstract

The application discloses a titanium / tantalum composite porous bone defect repairing bracket and a preparation method thereof. The bracket comprises a porous titanium inner frame unit body and a porous tantalum outer unit body which is coated on the periphery of the porous titanium inner frame unit body. The bracket has the characteristics of small overall specific gravity and light weight, and has a more ideal bone affinity capacity than the porous titanium. The porous titanium inner frame unit body and the porous tantalum outer unit body have different pore structure shapes, and a bone implant with excellent mechanical properties can be obtained. The bracket has a porous structure, and the porous metal material has the advantages of light weight and large specific surface area. The interconnected pores in the bracket are more conducive to promoting cell adhesion and bone tissue healing and growth. The bracket has the two advantages of high specific strength, low elastic modulus, low density, corrosion resistance, good biocompatibility of titanium and its alloy and excellent bioactivity and osteogenesis of tantalum metal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing and medical devices, in particular to a titanium / tantalum composite porous bone defect repair scaffold and a preparation method thereof. BACKGROUND

[0002] Trauma, inflammation, bone tumor resection will cause large area bone defect, and its repair and reconstruction needs to implant bone scaffold material to restore the corresponding tissue structure at the damage site. At present, the bone scaffold material mainly includes autologous bone, allogeneic bone, biomedical metal, bioceramics and polymer materials. However, there are still few ideal bone scaffold materials in clinical practice.

[0003] Porous metal material is considered as an ideal material for medical implants, especially porous titanium and porous tantalum materials. The elastic modulus of solid metal material (about 100-120 GPa for Ti6Al4V) is usually much higher than that of human bone (10-30 GPa), and stress shielding effect will occur after implantation, causing implant loosening or fracture. However, a large number of studies have shown that such problems can be controlled by parameterizing the design of porous structure to make the elastic modulus of the implant close to that of human bone. At the same time, porous metal material has the advantages of light weight and large specific surface area, and the internal interconnected pores are more conducive to the adhesion of cells and the healing growth of bone tissue as an implant scaffold.

[0004] Titanium and its alloys are widely studied due to their high specific strength, low elastic modulus, low density, corrosion resistance and good biocompatibility, but a few prostheses of pure titanium and titanium alloys have fatigue fracture and prosthesis loosening in long-term clinical follow-up; as a new emerging biocompatible metal, tantalum has excellent bioactivity and osteogenic performance, which makes it not prone to the above problems such as prosthesis loosening, but the high melting point of tantalum metal makes it difficult to process into individualized implant shapes with complex shapes, and the high specific gravity caused by its high density makes it not suitable for implantation in human body. Therefore, the characteristics and advantages of the two can be combined to manufacture composite porous materials. The internal framework of this new type of porous material is mainly composed of porous titanium, and the outer periphery is coated with porous tantalum material to form a composite material. This not only ensures that the overall specific gravity of the material is small and the weight is light, but also has more ideal bone affinity ability than porous titanium, and obtains a bone implant with mechanical properties matching human bone and excellent biocompatibility.

[0005] However, traditional manufacturing processes are difficult to prepare porous metal implants that meet clinical needs. For example, the traditional method for preparing porous tantalum material is mainly chemical vapor deposition. The porous tantalum material prepared by chemical method has complex process, high cost and is difficult to process into complex shaped implants, which cannot meet the clinical needs. Therefore, the use of additive manufacturing technology to prepare porous metal materials is gradually becoming a mainstream trend.

[0006] As a mainstream metal additive manufacturing technology, laser selective melting has great advantages for manufacturing implant with porous structure, and the emergence of multi-material additive manufacturing technology based on laser selective melting also facilitates the manufacture of composite structures. Currently, multi-material additive manufacturing technology can realize free forming of multi-material structure in X / Y / Z direction, and laser selective melting free manufacturing multi-material equipment has been developed in laboratories of various universities and related additive manufacturing companies.

[0007] Therefore, it is feasible to obtain a titanium / tantalum composite porous bone defect repair bracket with lightweight, high specific strength and ideal bone affinity ability through multi-material additive manufacturing technology. SUMMARY

[0008] The main purpose of the present application is to overcome the shortcomings and deficiencies of single material and dense orthopedic implants, and to provide a titanium / tantalum composite porous bone defect repair bracket and a preparation method thereof. By combining the excellent mechanical properties of pure titanium / titanium alloy and the excellent bone affinity ability of pure tantalum, an orthopedic implant with mechanical properties matching human bone and excellent biocompatibility is obtained to realize the integration of diversified performance / function and meet the needs of complex application environment.

[0009] The present application is realized by the following technical solutions:

[0010] A titanium / tantalum composite porous bone defect repair bracket comprises a porous titanium internal frame unit body and an external porous tantalum unit body coated on the periphery of the porous titanium internal frame unit body. In this way, the overall specific gravity of the material is small, the weight is light, and the bone affinity ability is more ideal than that of porous titanium. The pore structure shapes of the porous titanium internal frame unit body and the external porous tantalum unit body are different, and an orthopedic implant with excellent mechanical properties can be obtained.

[0011] The thickness of the external porous tantalum unit body should be as consistent as possible, and the bone ingrowth depth is about 3mm, so the maximum thickness should be less than 3mm to reduce its weight while ensuring its excellent bone affinity ability.

[0012] When the porosity of the porous titanium internal frame unit body is P1, the volume of the titanium material model data is V1; the porosity of the external porous tantalum unit body is P2, and the volume of the tantalum material model data is V2; the equivalent porosity P of the titanium / tantalum composite porous bone defect repair bracket can be obtained by the following relationship:

[0013] ;

[0014] Wherein, V is the volume of the three-dimensional CAD model data of the defect bone; at the same time, P1, P2, V1 and V2 can be directly obtained from the three-dimensional design software.

[0015] The porous titanium inner frame unit body and the porous tantalum outer unit body adopt a nonlinear gradient density structure according to the load distribution;

[0016] The porous titanium inner frame unit body and the porous tantalum outer unit body adopt a linear gradient structure transition to optimize stress distribution;

[0017] The porous titanium inner frame unit body and the porous tantalum outer unit body have a topology optimization support and auxiliary structure designed according to the stress distribution characteristics to reasonably distribute materials and balance lightweight and load capacity;

[0018] The load distribution is established in a finite element analysis software environment, the model is given titanium and tantalum material properties, the model structure is assembled, boundary constraint conditions and stress load are set, mainly the weight and center of gravity distribution of the patient, and finite element analysis is performed after setting to obtain a Von Mises stress cloud map, i.e. the load distribution of the porous titanium and porous tantalum repair bracket.

[0019] The pore structure shape type of the porous titanium inner frame unit body and the porous tantalum outer unit body is a hexahedron, octahedron, decahedron, honeycomb structure, negative Poisson's ratio structure or gradient porous structure.

[0020] The preparation method of the titanium / tantalum composite porous bone defect repair bracket comprises the following steps:

[0021] S1, based on the CT / MRI scan of the defect bone to obtain original data, through segmentation, editing, three-dimensional calculation processing, the three-dimensional CAD model data of the defect bone is extracted;

[0022] S2, according to different material requirements, the obtained three-dimensional CAD model data of the defect bone is segmented, wherein the inner part is a titanium material model data and the outer part is a tantalum material model data;

[0023] S3, taking a biological implant as a carrier, different types of uniform porous structure unit bodies are obtained through three-dimensional modeling software forward parameterization design, the key design parameters of the porous structure unit body are changed, and different series of diversified unit body structures are obtained;

[0024] S4, combining the titanium material model data, the tantalum material model data and the different series of diversified unit body structures, the porous unit body structure is mapped to the titanium material model data and the tantalum material model data through Boolean operation to obtain a porous titanium material model and a porous tantalum material model;

[0025] S5, according to the obtained three-dimensional CAD model data of the defect bone, the porous titanium material model and the porous tantalum material model are combined to obtain a titanium / tantalum composite porous bone defect repair bracket model;

[0026] S6, the three-dimensional CAD model of the titanium / tantalum composite porous bone defect repair bracket obtained in step S5 is imported into a data processing software for processing, including placing, positioning, adding support, slicing and layering;

[0027] S7, the model data of the titanium / tantalum composite porous bone defect repair bracket processed in step S6 is imported into a multi-material laser selective melting device for SLM forming, and a titanium / tantalum composite porous bone defect repair bracket is obtained.

[0028] In step S1, the target defect bone model data is extracted, specifically the data model of the defect bone to be repaired, which is the original model of the bone, including the size and shape of the fracture gap, and the complete bone near the fracture.

[0029] In step S3, the multi-element unit structure is diversified, specifically, an implicit surface represented by an implicit function is used to construct a porous unit, and through a biomimetic design method, according to the characteristics of biological complex structures, the biological initial geometric model is reconstructed through similarity, deduction, induction and optimization methods, and a multi-element unit structure model of the biomimetic target structure is obtained.

[0030] In step S3, the key design parameters include the strut diameter, rod length and angle of the porous unit.

[0031] In step S7, in the forming process of the multi-material laser selective melting device, a layer of titanium powder material is first laid, a porous titanium internal framework is formed by laser selective forming, and after forming, the titanium powder in the same layer is removed by a vacuum suction device, then a layer of tantalum powder is laid, a porous tantalum external framework is formed by laser selective forming, and the steps are repeated until the part is completely formed. Through this way, parts of two metal materials can be quickly formed, the preparation of the tantalum-titanium porous repair bracket is realized, and the cumbersome powder changing operation is avoided.

[0032] Compared with the prior art, the present application has the following advantages and effects:

[0033] 1, the present application adopts multi-material laser selective melting 3D printing technology to integrally manufacture titanium / tantalum composite porous structure, which can more conveniently prepare porous structure, compared with traditional porous structure preparation process, shorten the manufacturing cycle, save the cost.

[0034] 2, the bone defect repair bracket manufactured by the present application has a porous structure, the porous metal material has the advantages of light weight and large specific surface area, and the internal interconnected pores are more conducive to promoting cell adhesion and bone tissue healing growth as an implant bracket.

[0035] 3, The bone defect repair bracket manufactured by the application uses titanium / tantalum composite material, which has the advantages of high specific strength, low elastic modulus, low density, corrosion resistance, good biocompatibility of titanium and its alloy, and excellent bioactivity and osteogenesis of tantalum metal. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a flow chart of the manufacturing method of the titanium / tantalum composite porous bone defect repair bracket of the application;

[0037] Figure 2 is a schematic diagram of the new titanium / tantalum composite porous bone defect repair bracket of the application which is not optimized;

[0038] Figure 3 is a schematic diagram of the porosity of the application;

[0039] Figure 4 is a schematic diagram of the titanium / tantalum composite porous bone defect repair bracket of the application which is optimized by gradient porous structure and added with support and auxiliary structure.

[0040] BRIEF DESCRIPTION OF DRAWINGS: 1 - porous titanium internal frame unit; 2 - porous tantalum; 3 - external porous tantalum unit. DETAILED DESCRIPTION

[0041] The application will be further specifically and in detail described below in combination with specific embodiments.

[0042] As shown in Figure 1 and Figure 2 , the application discloses a titanium / tantalum composite porous bone defect repair bracket and a manufacturing method thereof (as shown in Figure 1 ), and the main process steps are as follows:

[0043] Step one: based on the CT / MRI scanning of the defect bone to obtain original data, through segmentation, editing, three-dimensional calculation processing, the three-dimensional CAD model data of the patient's defect bone is extracted, and the three-dimensional CAD data is output.

[0044] Step two: according to different material requirements, the obtained three-dimensional CAD model data of the defect bone is model segmented, wherein the internal part is titanium material model data, and the outer part is tantalum material model data.

[0045] Step three: Take the biological implant as the research carrier, obtain different types of porous structure unit bodies through forward parameterization design by three-dimensional modeling software, including hexahedron, octahedron, decahedron, dodecahedron, honeycomb structure, negative Poisson's ratio structure, and gradient porous structure, change the key design parameters of the porous unit body to obtain different series of diversified unit body structures, analyze the parameter-performance mapping relationship of the pore size, porosity, and strut structure characteristics, establish a porous structure-mechanical property database, and provide diversified selection and reference for the actual different application scenarios.

[0046] Step four: Combine the titanium material model data, tantalum material model data, and different series of diversified unit body structures, map the porous unit body structure to the titanium material model data and tantalum material model data through Boolean operation, obtain the porous titanium material model and the porous tantalum material model, combine the porous titanium material model and the porous tantalum material model according to the obtained defect bone three-dimensional CAD model data, and obtain a titanium / tantalum composite porous bone defect repair bracket model, such as Figure 2 The internal framework of this porous bone defect repair bracket is mainly composed of porous titanium, and the outer periphery is coated with porous tantalum material to form a composite material.

[0047] Step five: as shown in Figure 3 , assuming that the porosity of the porous titanium structure is P1, the volume of the titanium material model data is V1; the porosity of the porous tantalum material is P2, and the volume of the tantalum material model data is V2. Then the equivalent porosity P of the titanium / tantalum composite porous bone defect repair bracket can be obtained by the following relationship:

[0048] ;

[0049] Wherein, V is the volume of the defect bone three-dimensional CAD model data.

[0050] Step six: import the obtained titanium / tantalum composite porous bone defect repair bracket three-dimensional CAD model into the data processing software for processing, including placement positioning, adding support, and slicing layering.

[0051] Step seven: import the processed titanium / tantalum composite porous bone defect repair bracket model data into the multi-material laser selective melting equipment, add titanium and tantalum powder, and set the laser power, scanning speed, scanning interval, and powder layer thickness for SLM forming to obtain the titanium / tantalum composite porous bone defect repair bracket. The optimal processing parameters of titanium and tantalum materials can be obtained through the optimization combination of process parameters.

[0052] The titanium / tantalum composite porous bone defect repair bracket obtained by the multi-material laser laser selective melting forming technology has a high degree of matching with the defect area in appearance, and the pore size, shape and porosity can be accurately controlled. Suitable materials are configured at different positions of the orthopedic implant to fully exert the characteristics of different materials, effectively reduce the elastic modulus of the implant to achieve better bone integration, and realize individual customization of the porous metal implant according to different anatomical shapes.

[0053] The embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes and shall be included in the protection scope of the present application.

Claims

1. A titanium / tantalum composite porous bone defect repair scaffold, characterized in that... It includes a porous titanium internal framework unit and an external porous tantalum unit that covers the periphery of the porous titanium internal framework unit. The porous titanium internal framework unit and the external porous tantalum unit have different pore structure shapes. When the porosity of the internal framework unit of porous titanium is P1, and the volume of the titanium material model data is V1; and the porosity of the external porous tantalum unit is P2, and the volume of the tantalum material model data is V2; then the equivalent porosity P of the titanium / tantalum composite porous bone defect repair scaffold is obtained by the following relationship: ； Where V is the volume of the 3D CAD model data of the defective bone; meanwhile, P1, P2, V1, and V2 are all obtained directly from the 3D design software; The porous titanium internal framework unit and the external porous tantalum unit adopt a nonlinear gradient density structure distributed according to the load conditions. A linear gradient structure is used to transition between the internal framework unit of porous titanium and the external porous tantalum unit to optimize stress distribution; The load distribution is achieved by creating a 3D model in the finite element analysis software environment, assigning titanium and tantalum material properties to the model, assembling the model structure, setting boundary constraints and loads, mainly the patient's weight and center of gravity distribution, and then performing finite element analysis to obtain the VonMises stress cloud diagram, which is the load distribution of the porous titanium and porous tantalum repair scaffold. The preparation of the titanium / tantalum composite porous bone defect repair scaffold includes the following steps: S1. Obtain raw data from CT / MRI scans based on the defective bone, and extract the three-dimensional CAD model data of the defective bone through segmentation, editing, and three-dimensional calculation processing; S2. Based on different material requirements, the obtained 3D CAD model data of the defective bone is segmented, with the inner part being titanium material model data and the outer periphery being tantalum material model data; S3. Using biological implants as carriers, different types of uniform porous structural units are obtained through forward parametric design using 3D modeling software. By changing the key design parameters of the porous structural units, different series of diversified unit structures can be obtained. S4. Combining titanium material model data, tantalum material model data, and diverse unit cell structures of different series, the porous unit cell structure is mapped to the titanium material model data and tantalum material model data through Boolean operations to obtain the porous titanium material model and the porous tantalum material model. S5. Based on the obtained three-dimensional CAD model data of the defective bone, the porous titanium material model and the porous tantalum material model are combined to obtain a titanium / tantalum composite porous bone defect repair scaffold model. S6. Import the three-dimensional CAD model of the titanium / tantalum composite porous bone defect repair scaffold obtained in step S5 into the data processing software for processing, including placement and positioning, adding support, and slicing and layering. S7. Import the titanium / tantalum composite porous bone defect repair scaffold model data processed in step S6 into a multi-material laser selective melting (SLM) device to obtain a titanium / tantalum composite porous bone defect repair scaffold.

2. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: The pore structure shape of the porous titanium internal framework unit and the external porous tantalum unit can be hexahedral, octahedral, decahedral, honeycomb, negative Poisson's ratio, or gradient porous structure.

3. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: In step S1, the target bone defect model data is extracted, specifically the data model of the bone defect to be repaired. This model is the original model of the bone, including the size and shape of the bone fracture gap and the intact bone near the fracture.

4. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: In step S3, the diversified unit structure is specifically constructed by using implicit surfaces represented by implicit functions to build porous units. At the same time, through biomimetic design methods, based on the characteristics of complex biological structures, the initial biological geometric model is reconstructed using similarity, deduction, induction and optimization methods to obtain the diversified unit structure model of the biomimetic target structure.

5. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: In step S3, the key design parameters include the support diameter, rod length, and angle of the porous unit.

6. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: The porous titanium internal framework unit and the external porous tantalum unit have topology-optimized support and auxiliary structures designed according to stress distribution characteristics, so as to rationally distribute the material and balance lightweight and load-bearing capacity.

7. The titanium / tantalum composite porous bone defect repair scaffold according to claim 1, characterized in that: In step S7, during the forming process of the multi-material laser selective melting equipment, a layer of titanium powder material needs to be laid first, and a porous titanium internal frame is formed by laser selective melting. After forming, the titanium powder of the same layer is removed by a vacuum adsorption device, and then a layer of tantalum powder is laid on top, and a porous tantalum external frame is formed by laser selective melting. The steps are repeated until the part is completely formed.

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