Design method of layered porous structure of acetabular cup and acetabular cup

Abstract

The application relates to a design method of a layered porous structure of an acetabular cup and the acetabular cup, and the method comprises the following steps: modeling a plurality of rhombohedrons, so that the pore diameter is 500-1200 mu m and the porosity is 60%-90%; generating a cubic array from the rhombohedrons, introducing a simulation calculation software, and performing compression finite element simulation on the cubic array to obtain the compression strength and the elastic modulus of the cubic array; selecting a cubic array meeting the human bone performance, arraying the rhombohedron with the largest pore diameter in the cubic array to obtain an outer porous coating area capable of accommodating the acetabular cup; selecting the rhombohedron with the largest porosity to obtain an inner porous coating area capable of accommodating the acetabular cup; and then performing a Boolean operation on the two array bodies and the outer porous coating area and the inner porous coating area of the acetabular cup respectively to obtain an intersection, so that the layered porous structure of the acetabular cup is finally obtained. The acetabular cup obtained by the method can provide stability after implantation.

Description

Technical Field

[0001] The present invention relates to the field of implants, and in particular to a design method for a layered porous structure of an acetabular cup and the acetabular cup. Background Art

[0002] The human hip joint has a high rate of disease. Patients with diseases such as femoral head necrosis and osteoarthritis cannot heal on their own and require total hip replacement surgery, where a prosthesis replaces the diseased joint. The acetabular cup is one of the commonly used implants in total hip replacement surgery. Traditional acetabular cups are mostly machined from dense metal. However, the elastic modulus of dense metal is typically much higher than that of human bone, ranging from 0.02 GPa to 20 GPa. As a result, stress shielding occurs between the acetabular cup and the human bone, which can easily cause the acetabular cup to loosen after implantation, leading to surgical failure. Summary of the Invention

[0003] In response to the deficiencies of the prior art, the present invention proposes a design method for a layered porous structure of an acetabular cup and an acetabular cup. The layered porous structure can promote better growth of bone tissue into the porous coating, improve stability after implantation, and reduce material waste.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for designing a layered porous structure of an acetabular cup, the method comprising the following steps:

[0006] Step 1: Use 3D modeling software to create multiple rhombic dodecahedrons with a pore size of 500 to 1200 μm and a porosity of 60% to 90%;

[0007] Step 2: Generate a cube array from the rhombic dodecahedron; import the cube array into simulation software, perform meshing, set material properties, set boundary conditions, perform compression finite element simulation on the cube array, and obtain the compressive strength and elastic modulus of the cube array;

[0008] Step 3: Select the pore size and porosity of the rhombic dodecahedron corresponding to the cube array that meets the compressive strength of not less than 230 GPa and the elastic modulus between 0.2 and 21 GPa;

[0009] Step 4: Select the rhombic dodecahedron with the largest pore size that meets the conditions of step 3, and array it in the three-dimensional space in the length, width, and height directions in the three-dimensional modeling software so that the volume of the array can accommodate the outer porous coating area of ​​the acetabular cup; select the rhombic dodecahedron with the largest porosity that meets the conditions of step 3, and array it in the three-dimensional space in the length, width, and height directions in the three-dimensional modeling software so that the volume of the array can accommodate the inner porous coating area of ​​the acetabular cup;

[0010] Step five: performing a Boolean operation intersection of the array body in step four with the outer porous coating area and the inner porous coating area of the acetabular cup respectively, and finally obtaining the layered porous structure of the acetabular cup.

[0011] Further, in step two, when performing compression finite element simulation on the cubic array, one surface of the cubic array is selected as the upper rigid plane, the opposite surface is the lower rigid plane, and reference points are set on the edges of the upper and lower rigid planes to record the displacement and force generated during the compression process; at the same time, the cubic array and the upper and lower rigid planes are assigned corresponding material properties.

[0012] Further, in step four, the unit size of the rhombic dodecahedron with the largest pore size satisfying the conditions in step three is 1.5 mm, and the unit size of the rhombic dodecahedron with the largest porosity satisfying the conditions in step three is 1 mm.

[0013] Further, in step two, the material of the cubic array is Ti6Al4V alloy.

[0014] An acetabular cup with a layered porous structure, the acetabular cup comprising an acetabular cup base body and a layered porous structure wrapped around the acetabular cup base body; the layered porous structure is obtained by any one of the above design methods.

[0015] The beneficial effects of the present application are as follows:

[0016] 1. The present application simulates the compressive strength and elastic modulus of the porous structure by finite element simulation method, ensuring that the porous structure meets the requirements after implantation and does not break.

[0017] 2. The present application designs porous coatings with different porosities and pore diameters on the surface of the acetabular cup, which improves the pore diameter of the outer porous coating of the acetabular cup while meeting the mechanical properties of the bone, and is more conducive to the growth of bone tissue into the porous coating, thereby enhancing the combination of bone and implant and improving the stability after implantation.

[0018] 3. The inner porous coating of the acetabular cup of the present application has high porosity, which is more conducive to further reducing the weight of the acetabular cup and reducing the waste of materials. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of a rhombic dodecahedron structure.

[0020] Figure 2 is a schematic diagram of a porous structure compression model formed by a rhombic dodecahedron array and upper and lower planes.

[0021] Figure 3Schematic diagram of the porous coating area of ​​the acetabular cup.

[0022] Figure 4 Schematic diagram of the layered porous structure of the acetabular cup designed using the method of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more apparent. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Porous structures offer low bulk density and a large specific surface area. Parametric design of porous structures allows for the regulation of their mechanical properties. Applying porous structures to implants can reduce the elastic modulus of dense metals and improve stress shielding, offering benefits for patients with hip joint disorders.

[0025] Based on this, the present invention proposes a design method for a layered porous structure of an acetabular cup and an acetabular cup. First, the geometric parameters of the rhombic dodecahedron porous structure are designed, and then a compressed finite element model is established and imported into a three-dimensional simulation calculation, and planes are set at the top and bottom of the model. Then, the model is given material properties, meshing is performed, boundary conditions are set, and the upper plane displacement loading method is set. Finally, a compressed finite element simulation is performed on the model. According to the simulation results and the mechanical properties of human bones, the porosity and pore size of different layers of porous coatings are determined to obtain an acetabular cup with a layered porous structure.

[0026] The design method of the layered porous structure of the acetabular cup of this embodiment specifically includes the following steps:

[0027] Step 1: Use 3D modeling software to create multiple rhombic dodecahedrons with a pore size of 500-1200 μm and a porosity of about 60%-90%; generate a cube array from the rhombic dodecahedron. Figure 1 shown.

[0028] In this embodiment, Solidworks software is used to establish a rhombic dodecahedron porous structure model and design its geometric parameters. The pore size of the rhombic dodecahedron is the diameter of the largest inscribed sphere of the rhombic dodecahedron structure, and the porosity is the percentage of the pore volume to the maximum peripheral boundary volume. When the unit size of the rhombic dodecahedron structure is 1 mm, the porosity is in the range of 59.7% to 90.6%, and the pore diameter is in the range of 482.1 to 607.1 μm. When the unit size of the porous structure is 1.5 mm, its porosity is in the range of 64.9% to 89.9%, and the pore diameter is in the range of 810.7 to 935.7 μm. Therefore, this embodiment constructs 6 different rhombic dodecahedrons with unit sizes of 1 mm and 1.5 mm respectively. The specific dimensions of these 12 rhombic dodecahedrons are shown in Table 1. Generate a 2×2×2 cube array of the rhombic dodecahedron, and convert it into igs format after establishment.

[0029] Table 1 Dimensions of the 12 rhombic dodecahedrons

[0030]

[0031] Step 2: Generate a cube array from the rhombic dodecahedron; import the cube array into simulation calculation software, perform meshing, set material properties, set boundary conditions, perform compression finite element simulation on the cube array, and obtain the compressive strength and elastic modulus of the cube array.

[0032] The igs format exported by the rhombic dodecahedron to generate a cube array is imported into the finite element simulation software ABAQUS and used as a compression model. Planes are set at the top and bottom of the compression model to simulate the contact surface with the upper and lower pressure blocks of the compressor, and reference points are set at the edges of the upper and lower planes to record the displacement and force generated during the compression process, such as Figure 2 As shown in the figure, the compression model and the plane are assigned corresponding material properties. The compression model material is Ti6Al4V alloy, with properties of elastic modulus 113.8GPa, Poisson's ratio 0.34, density 4.43g / cm3, and yield strength 980MPa. The plane property is "rigid plane". The compression model is meshed using tetrahedral meshes for finite element division. When dividing the mesh, there are at least four units in the direction of the rod diameter, which results in more accurate simulation results.

[0033] Set the boundary conditions between the compression model and the plane, the tangential behavior between the model and the plane is "penalty contact", and the friction coefficient is 0.1.

[0034] Set the displacement loading method of the upper plane on the compression model. The lower plane is fixed, the upper plane is applied with downward displacement, and the "smooth analysis step" is used.

[0035] Compressive finite element simulations were performed on the model to obtain the mechanical properties of porous structures with different geometric parameters. The compressive strength of porous structures with a cell size of 1 mm ranged from 182.8 to 564.8 MPa, and the elastic modulus ranged from 3.42 to 6.47 GPa. The compressive strength of porous structures with a cell size of 1.5 mm ranged from 75.6 to 236.6 MPa, and the elastic modulus ranged from 1.68 to 4.14 GPa. Specific values ​​are shown in Table 2.

[0036] Table 2 Compressive strength and elastic modulus of 12 compression models

[0037]

[0038] Step 3: Select the pore size and porosity of the rhombic dodecahedron corresponding to the cube array that meets the requirements of compressive strength of not less than 230 GPa and elastic modulus between 0.2 and 21 GPa.

[0039] Step 4: Select the rhombic dodecahedron with the largest pore size that meets the conditions of step 3, and array it in the length, width, and height directions of the three-dimensional space in the 3D modeling software so that the volume of the array can accommodate the outer porous coating area of ​​the acetabular cup; select the rhombic dodecahedron with the largest porosity that meets the conditions of step 3, and array it in the length, width, and height directions of the three-dimensional space in the 3D modeling software so that the volume of the array can accommodate the inner porous coating area of ​​the acetabular cup. Among them, the inner porous coating area and the outer porous coating area are as follows: Figure 3 As shown, this area can be pre-modeled, which is a common practice in this field. The outer and inner porous coating areas were created by "rotating" in 3D software, with coating thicknesses of 1.5 mm and 1 mm, respectively.

[0040] The porosity and pore size of the different layers of porous coatings are determined based on the mechanical properties of human bone. Since the compressive strength of human bone is no less than 230 GPa and the elastic modulus is between 0.2 and 21 GPa, in this embodiment, the outer layer porous structure is ultimately selected to have a cell size of 1.5 mm, a pore size of 810.7 mm, and a porosity of 64.9%. The inner layer porous structure has a cell size of 1 mm, a pore size of 582.1 mm, and a porosity of 85.6%.

[0041] In addition, when designing rhombic dodecahedron porous structures with unit sizes other than 1mm and 1.5mm, it is also possible to simulate structures with different pore sizes and porosities and select structures with larger pore sizes and higher porosities that can meet the compressive strength and elastic modulus of human bones.

[0042] This design ensures that the compressive strength and elastic modulus of the porous structure meet the mechanical properties of bone. It also increases the pore size of the acetabular cup's outer porous coating, facilitating bone tissue ingrowth into the porous coating, thereby strengthening the bone-implant bond and improving post-implant stability. Furthermore, the high porosity of the inner porous coating further reduces the weight of the acetabular cup and minimizes material waste.

[0043] Step 5: Perform Boolean operations on the array body in step 4 and the outer porous coating area and inner porous coating area of ​​the acetabular cup to obtain the intersection, and finally obtain the hierarchical porous structure of the acetabular cup. The finally obtained hierarchical porous structure is as follows Figure 4 shown.

[0044] As another aspect of the present invention, the present invention also proposes an acetabular cup with a layered porous structure, the acetabular cup comprising an acetabular cup matrix and a layered porous structure wrapping the acetabular cup matrix; the layered porous structure is obtained by the above-mentioned design method of the layered porous structure.

[0045] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art will still be able to modify the technical solutions described in the foregoing examples or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. A method for designing a layered porous structure of an acetabular cup, characterized in that ,The method comprises the following steps: Step 1: Use 3D modeling software to create multiple rhombic dodecahedrons with a pore size of 500-1200 μm and a porosity of 60%-90%; Step 2: Generate a cube array from the rhombic dodecahedron; import the cube array into simulation software, perform meshing, set material properties, set boundary conditions, perform compression finite element simulation on the cube array, and obtain the compressive strength and elastic modulus of the cube array; Step 3: Select the pore size and porosity of the rhombic dodecahedron corresponding to the cube array that meets the compressive strength of not less than 230 MPa and the elastic modulus between 0.2 and 21 GPa; Step 4: Select the rhombic dodecahedron with the largest pore size that meets the conditions of step 3, and array it in the length, width, and height directions of the three-dimensional space in the three-dimensional modeling software so that the volume of the array can accommodate the outer porous coating area of ​​the acetabular cup; Select a rhombic dodecahedron with the largest porosity that meets the conditions of step 3, and array it in the length, width, and height directions of the three-dimensional space in a three-dimensional modeling software so that the volume of the array can accommodate the inner porous coating area of ​​the acetabular cup; Step 5: performing Boolean operations on the array body in step 4 and the outer porous coating area and the inner porous coating area of ​​the acetabular cup to obtain the intersection, and finally obtaining the layered porous structure of the acetabular cup; In the fourth step, the unit size of the rhombic dodecahedron with the largest pore size that meets the conditions of the third step is selected to be 1.5 mm, and the unit size of the rhombic dodecahedron with the largest porosity that meets the conditions of the third step is selected to be 1 mm; The outer and inner porous coating regions were obtained by rotation in 3D software.

2. The method for designing a layered porous structure of an acetabular cup according to claim 1, characterized in that In the step 2, when performing compression finite element simulation on the cube array, one of the surfaces of the cube array is selected as the upper rigid plane, the surface opposite to the upper rigid plane is selected as the lower rigid plane, and reference points are set on the edges of the upper rigid plane and the lower rigid plane to record the displacement and force generated during the compression process; at the same time, corresponding material properties are assigned to the cube array and the upper rigid plane and the lower rigid plane.

3. The method for designing a layered porous structure of an acetabular cup according to claim 2, characterized in that In the step 2, the material given to the cube array is Ti6Al4V alloy.

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