Manufacturing method of porous implant

Abstract

The invention discloses a manufacturing method of a porous implant, and relates to the technical field of medical instruments, and the manufacturing method comprises the following steps: obtaining a bone implant model; carrying out host bone performance adaptive uniform porous treatment on a porous structure area in contact with the host bone in the bone implant model; determining a non-uniform porous structure area in the bone implant model according to the uniform porous implant geometric model, and importing preset material performance parameters into the non-uniform porous structure area for optimization calculation; and when the stress distribution result of the non-uniform porous structure region meets a preset constraint condition, reconstructing a non-uniform porous implant geometric model according to the distribution result of the material performance parameters in the non-uniform porous structure region and the mapping relation database, and finally performing 3D printing treatment on all geometric models to obtain the porous implant. The porous implant obtained by adopting the method has relatively high bearing safety, can further promote effective stress stimulation of growth in bones, and is long in service life.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a method for manufacturing a porous implant. Background Art

[0002] According to Wolff's law, human bones are subjected to complex and changeable mechanical loads in vitro for a long time, and their macro-microstructures will produce dynamic adaptive response changes to form the best structure to meet the functional requirements of load-bearing and activity. This process makes the human bones show differences in mechanical properties in different directions, that is, anisotropy of mechanical properties. For example, the compressive elastic modulus of the femur in the axial, circumferential and radial directions are 5.8GPa, 3.4GPa and 2.1GPa, respectively, and the destructive strength is 150MPa, 111MPa and 110MPa, respectively. When faced with large bone defects in the human body caused by factors such as tumors and trauma, 3D printed porous implants are usually used for bone repair treatment. Through the optimization design of the micro-porous structure of the implant and the powerful 3D printing manufacturing capability, the development of porous implants with controllable anisotropic mechanical properties lays a solid foundation for mechanical transmission and physiological function repair in the bone defect area.

[0003] At present, the design methods of 3D printed porous implants mainly focus on: 1) Starting from the matching of macroscopic elastic modulus, under the premise of ensuring that the strength meets the safety requirements, the elastic modulus of the implant is close to that of the host bone through low modulus materials or porosity design, which can effectively reduce the stress shielding of metal prostheses and the hidden dangers of late loosening. However, this method mainly considers the mechanical properties in a single direction, such as the uniaxial tensile or compressive mechanical properties of materials or porous structures, and ignores the differences in mechanical properties in different directions, as well as the matching degree with the anisotropy of the mechanical properties of the human host bone, thus affecting the service state and service life of the implant in the body; 2) According to the concept of bionic design, the implant is designed to have a porous structure with a gradient porosity according to the hierarchical structural characteristics of the host bone anatomical morphology, but its gradient type mainly focuses on a single direction, such as axial or radial porosity changes, and lacks consideration of the anisotropy of the mechanical properties of the porous structure.

[0004] Therefore, the existing bone implant repair technology still lacks consideration of the impact of the anisotropy of the mechanical properties of the microstructure on its in vivo service performance, and has not developed an optimized design and manufacturing method that meets the mechanical function requirements of the bone defect area and considers the anisotropy of the mechanical properties of the porous structure of the implant. As a result, the existing porous implants are unable to cope with the function of mechanical transmission in the body, which will further affect the effect of the host bone growing into the porous structure of the implant and the reliability of biological fixation. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing a porous implant, which can obtain a porous implant with a porous structure having different anisotropic mechanical properties in different regions, has high load-bearing safety, can further promote effective stress stimulation of bone endophyseal growth, and has high medium- and long-term use stability and long service life.

[0006] In order to solve the above technical problems, the present invention provides a method for manufacturing a porous implant, comprising: S101, obtaining a three-dimensional bone model of a bone defect site, and constructing a finite element model of mechanical property anisotropy according to the three-dimensional bone model and simulation environment parameters to obtain a bone implant model, wherein the mechanical property anisotropy includes the elastic modulus and yield strength anisotropy of the bone; S102, performing a uniform porous treatment on the porous structure area in contact with the host bone in the bone implant model to adapt to the host bone performance, so as to obtain a mapping relationship database of the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and a uniform porous implant geometric model adapted to the mechanical properties of the host bone; S103, determining the non-uniform porous structure area in the bone implant model according to the uniform porous implant geometric model, and importing the preset material performance parameters into the non-uniform porous structure area for Optimize calculation to obtain the stress distribution result of the non-uniform porous structure area, wherein the material performance parameters include elastic modulus and yield strength anisotropy parameters; S104, determine whether the stress distribution result of the non-uniform porous structure area meets the preset constraint conditions, if it is determined to be yes, execute step S105, if it is determined to be no, filter out the distribution area that does not meet the constraint conditions and adjust its material performance parameters, and return to step S103; S105, according to the distribution results of the material performance parameters in the non-uniform porous structure area, filter out the corresponding geometric feature parameters from the mapping relationship database of the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric feature parameters, so as to reconstruct the non-uniform porous implant geometric model; S106, perform 3D printing on the bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model to obtain a porous implant.

[0007] As an improvement of the above solution, the step of obtaining a three-dimensional bone model of the bone defect site includes: obtaining bone imaging data of the bone defect site by medical imaging technology, and constructing a three-dimensional bone model.

[0008] As an improvement of the above-mentioned scheme, the step of constructing a finite element model with anisotropic mechanical properties according to the three-dimensional bone model and the simulation environment parameters to obtain a bone implant model includes: performing an initial model construction process according to the three-dimensional bone model to construct an initial bone implant model, wherein the initial model construction process includes surface smoothing processing and precise surface fitting solidification processing; adjusting the initial bone implant model through anisotropic finite element analysis and the simulation environment parameters to obtain a bone implant model.

[0009] As an improvement of the above scheme, the step S102 includes: adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and establishing a corresponding mapping relationship database; in the optimization process of the geometric characteristic parameter adjustment, judging whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone, and if the judgment is yes, obtaining a uniform porous implant geometric model that is compatible with the mechanical properties of the host bone.

[0010] As an improvement of the above scheme, the step of adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters includes: adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to output different elastic modulus and yield strength anisotropy parameters of the porous lattice unit, wherein the elastic modulus anisotropy parameter is characterized by a stiffness matrix [C], [C] = [C 11 , C 22 , C 33 , C 44 , C 55 , C 66 , C 12 , C 13 , C 23 ], the yield strength anisotropy parameter is characterized by the strength matrix [σ], [σ] = [σ 11 ,σ 22 ,σ 33 ,σ 12 ,σ 13 ,σ 23 ]; Calculate the elastic modulus anisotropy coefficient f of the porous lattice unit according to the elastic stiffness matrix [C] of the porous lattice unit e , and establish the anisotropy coefficient f of the elastic modulus of the porous lattice unit e and the geometric characteristic parameter set x iThe relationship function between: f e =F ep (x1,x2,…,x i ,…,x n ), wherein the F ep is the elastic modulus performance control function, x n is the nth geometric characteristic parameter, n is a positive integer; the yield strength anisotropy coefficient f of the porous lattice unit is calculated according to the yield strength matrix [σ] of the porous lattice unit σ , and establish the anisotropy degree coefficient f of the yield strength of the porous lattice unit σ and the geometric characteristic parameter set x i The relationship function between: f σ =F eσ (x1,x2,…,x i ,…,x n ), wherein the F eσ is the yield strength performance control function.

[0011] As an improvement of the above scheme, the elastic modulus anisotropy coefficient f of the porous lattice unit is calculated according to the elastic stiffness matrix [C] of the porous lattice unit. e The steps include: calculating the elastic modulus spatial distribution and the extreme value range of the elastic modulus spatial distribution (E min ,E max ), and the Zener coefficient is used to analyze the elastic modulus anisotropy coefficient f of the porous lattice unit e ; Calculate the yield strength anisotropy coefficient f of the porous lattice unit according to the yield strength matrix [σ] of the porous lattice unit σ The steps include: calculating the yield strength spatial distribution according to the yield strength matrix [σ] of the porous lattice unit, and calculating the yield strength anisotropy coefficient f of the porous lattice unit according to the maximum and minimum values ​​of the yield strength spatial distribution. σ .

[0012] As an improvement of the above scheme, the step of judging whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone includes: judging the difference percentage of the elastic modulus extreme value mean between the porous lattice unit and the host bone, the difference percentage of the elastic modulus extreme value variance and the elastic modulus anisotropy degree coefficient f e Whether the percentage difference of is within the preset percentage range, and the yield strength extreme value mean, yield strength extreme value variance and yield strength anisotropy degree coefficient f of the porous lattice unit σAre they all higher than the mean of the yield strength extreme value of the host bone, the variance of the yield strength extreme value and the yield strength anisotropy coefficient f σ , if it is judged as yes, it means that the two are matched successfully, otherwise it means that the two are matched unsuccessfully.

[0013] As an improvement of the above-mentioned scheme, the step of judging whether the stress distribution result of the non-uniform porous structure area meets the preset constraints includes: obtaining the stress data of each porous lattice unit through the stress distribution result of the porous structure area; judging whether there is stress in at least one direction of each porous lattice unit that is less than or equal to a preset percentage of its yield strength parameter; when the judgment is yes, it means that the stress distribution result of the non-uniform porous structure area meets the preset constraints; when the judgment is no, it means that the non-uniform porous structure area does not meet the preset constraints.

[0014] As an improvement of the above-mentioned scheme, the step of screening out the distribution area that does not meet the constraint conditions and adjusting its material performance parameters includes: screening out the porous lattice units that do not meet the constraint conditions, adding a preset elastic modulus parameter to their current elastic modulus parameters to obtain the currently adjusted elastic modulus parameters; and outputting the screened porous lattice units and their currently adjusted material performance parameters.

[0015] As an improvement of the above scheme, the structural types of the porous lattice unit in the bone implant geometric model include solid feature geometric configuration units and surface units controlled by implicit functions. The length, width and height of the porous lattice unit are 1-5 mm, the pore size range is 100-1000 μm, and the porosity is 0-90%.

[0016] The implementation of the present invention has the following beneficial effects:

[0017] The present invention reasonably designs a porous structure with different anisotropic mechanical properties distributed in different areas according to the mechanical function requirements of the porous implant to replace bone defects, effectively avoiding the problem of insufficient strength in the actual service process due to lack of consideration in different directions, and improving the overall safety of the porous implant; and based on setting a uniform porous implant geometric model that is in contact with the host bone and has similar mechanical properties, it can ensure that the stress distribution in the area where the uniform porous implant geometric model is located is consistent with the host bone during the actual load-bearing process, so as to promote effective stress stimulation of bone endophyte growth, which is beneficial to promote the growth / bone ingrowth of the host bone into the uniform porous structure area; at the same time, the non-uniform porous implant geometric model is set to ensure that the effective distribution of stress can meet the actual load-bearing strength requirements, improve the load-bearing safety of the porous implant, and thus ensure the safety and stability of the entire service process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1is a flow chart of a method for making a porous implant of the present invention;

[0019] Figure 2 is a flow chart of step S102 of the present invention;

[0020] Figure 3 It is a schematic structural diagram of the elastic stiffness matrix [C] and the elastic modulus spatial distribution of the porous lattice unit of the present invention;

[0021] Figure 4 It is a schematic structural diagram of the yield strength matrix [σ] and the spatial distribution of yield strength of the porous lattice unit hole of the present invention;

[0022] Figure 5 It is an assembly diagram of the mandibular defect and the porous implant of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention.

[0024] like Figure 1 As shown, a specific embodiment of the present invention provides a method for manufacturing a porous implant, comprising:

[0025] S101, obtaining a three-dimensional bone model of the bone defect site, and constructing a finite element model of mechanical property anisotropy according to the three-dimensional bone model and simulation environment parameters to obtain a bone implant model, wherein the mechanical property anisotropy includes the elastic modulus and yield strength anisotropy of the bone;

[0026] Specifically, the step of obtaining the three-dimensional bone model of the bone defect site includes: obtaining bone image data of the bone defect site by medical imaging technology, and constructing a three-dimensional bone model.

[0027] It should be noted that the CT or MRI bone image data of the bone defect site is imported into the Mimics three-dimensional processing software to construct a three-dimensional model of the host bone, tumor and soft tissue, and the outer surface contour of the implant and its fixation method are bionic designed according to the scope and area of ​​the bone defect and the shape of the defective bone, thereby reconstructing the bone three-dimensional model.

[0028] Furthermore, the step of constructing a finite element model with anisotropic mechanical properties according to the three-dimensional bone model and the simulation environment parameters to obtain a bone implant model comprises:

[0029] Step 1: performing an initial model construction process according to the three-dimensional bone model to construct an initial bone implant model, wherein the initial model construction process includes surface smoothing processing and precise surface fitting and solidification processing;

[0030] It should be noted that the 3D bone model was subjected to surface smoothing and precise surface fitting and solidification optimization by using Geomagic Wrap software to obtain the initial bone implant model.

[0031] Step 2: adjusting the initial bone implant model through anisotropic finite element analysis and the simulation environment parameters to obtain a bone implant model.

[0032] It should be noted that the initial bone implant model was imported into the finite element software Abaqus for finite element analysis to complete the construction of the bone implant model. Among them, the set simulation environment parameters are applied in the finite element software Abaqus. The simulation environment parameters include limiting parameters such as mechanical loads and boundary conditions applied according to the patient's daily physiological activities and stress conditions to simulate the real mechanical environment of the corresponding bone defect site (such as different occlusal load values ​​of mandibular implants, different flexion and extension, scoliosis, and axial rotation load values ​​of spinal bone implants, etc.), and also include setting the elastic modulus and yield strength anisotropic material properties of the bones (such as cortical bone and cancellous bone) of the corresponding host bone to fully consider the anisotropy of the mechanical properties of human bones and bone implants, so that the data subsequently processed and reconstructed by the bone implant model is more accurate, and the prepared bone implant is more in line with actual use requirements. It also includes setting the initial unit type parameters and mesh size parameters to mesh the assembly model for discretization, so as to facilitate the subsequent evaluation and reconstruction of the anisotropy of the mechanical properties of each porous lattice unit to ensure that the porous structure implant can meet the required different anisotropy requirements of mechanical properties.

[0033] S102, performing uniform porous processing adapted to the host bone performance on the porous structure area in contact with the host bone in the bone implant model, so as to obtain a mapping relationship database between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and a uniform porous implant geometric model adapted to the mechanical properties of the host bone;

[0034] Specifically, Figure 2 As shown, the step S102 includes:

[0035] S201, adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and establishing a corresponding mapping relationship database;

[0036] Specifically, the step of adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters includes:

[0037] Step 1: Adjust the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to output elastic modulus and yield strength anisotropic parameters of different porous lattice units, wherein the elastic modulus anisotropic parameter is characterized by a stiffness matrix [C], [C] = [C 11 , C 22 , C 33 , C 44 , C 55 , C 66 , C 12 , C 13 , C 23 ], C 11 , C 22 , C 33 They represent the stiffness coefficients of the porous lattice unit under the principal strains in the X, Y, and Z directions, respectively. 44 , C 55 , C 66 Respectively represent the stiffness coefficients of the porous lattice unit under the principal shear strain in the X, Y, and Z directions; C 12 , C 13 , C 23 They represent the stiffness coefficients of the porous lattice unit under shear strain in the XY, XZ, and YZ planes, respectively.

[0038] The yield strength anisotropy parameter is characterized by the strength matrix [σ], [σ] = [σ 11 ,σ 22 ,σ 33 ,σ 12 ,σ 13 ,σ 23 ],σ 11 ,σ 22 ,σ 33 Respectively represent the strength coefficients of the porous lattice unit in the X, Y, and Z axis directions, σ 12 ,σ 13 ,σ 23 Respectively represent the strength coefficients of the porous lattice unit in the XY, XZ, and YZ planes

[0039] It should be noted that in the finite element analysis, the geometric characteristic parameters of the porous lattice unit in the area in contact with the host bone are adjusted. Figure 5As shown, the geometric characteristic parameters include the diameter of the internal rods of the porous lattice unit, the diameter of the edge rods, and the length, width, and height of the porous lattice unit; by adjusting the above parameters, different pore diameters and porosity parameters can be obtained. In general, the length, width, and height of the porous lattice unit adopt preset fixed parameters, and the geometric characteristic parameters such as the diameter of the internal rods and the diameter of the edge rods can be changed to adjust the geometric structure of the porous lattice unit so that the anisotropy of the mechanical properties of the adjusted porous lattice unit meets the required requirements. Therefore, by adjusting the geometric characteristic parameters of each porous lattice unit, its elastic modulus and yield strength anisotropy parameters can be changed, thereby calculating the mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and establishing a corresponding mapping relationship database for subsequent use.

[0040] Step 2: Calculate the elastic modulus anisotropy coefficient f of the porous lattice unit according to the elastic stiffness matrix [C] of the porous lattice unit. e , and establish the anisotropy coefficient f of the elastic modulus of the porous lattice unit e and the geometric characteristic parameter set x i The relationship function between: f e =F ep (x1,x2,…,x i ,…,x n ), wherein the F ep is the elastic modulus performance control function, x n is the nth geometric characteristic parameter, n is a positive integer;

[0041] It should be noted that if Figure 3 As shown, according to the elastic stiffness matrix of the porous lattice unit [C] = [C 11 , C 22 , C 33 , C 44 , C 55 , C 66 , C 12 , C 13 , C 23 ] calculate the elastic modulus spatial distribution, that is, the elastic modulus data distribution of the porous lattice unit, and calculate the elastic modulus extreme value range (E min ,E max ); The elastic modulus anisotropy coefficient f of the porous lattice unit is analyzed by using the Zener coefficient (Zernike coefficient) e , f e =2×C 44 / (C 11 -C 12 );According to the elastic modulus anisotropy coefficient f of the porous lattice unit eThe anisotropy coefficient f of the elastic modulus of the porous lattice unit is constructed by combining the geometric characteristic parameters e and the geometric characteristic parameter set x i The relationship function between: f e =F ep (x1,x2,…,x i ,…,x n );

[0042] Step 3: Calculate the yield strength anisotropy coefficient f of the porous lattice unit according to the yield strength matrix [σ] of the porous lattice unit. σ , and establish the anisotropy degree coefficient f of the yield strength of the porous lattice unit σ and the geometric characteristic parameter set x i The relationship function between: f σ =F eσ (x1,x2,…,x i ,…,x n ), wherein the F eσ is the yield strength performance control function.

[0043] It should be noted that if Figure 4 As shown, according to the yield strength matrix of the porous lattice unit [σ] = [σ 11 ,σ 22 ,σ 33 ,σ 12 ,σ 13 ,σ 23 ] calculate the yield strength spatial distribution, that is, the yield strength data distribution of the porous lattice unit; according to the maximum value σ of the yield strength spatial distribution max With the minimum value σ min Calculate the yield strength anisotropy coefficient f of the porous lattice unit σ , f σ =σ max / σ min ; According to the yield strength anisotropy coefficient f of the porous lattice unit σ The anisotropy coefficient f of the yield strength of porous lattice units is constructed by combining the geometric characteristic parameters σ and the geometric characteristic parameter set x i The relationship function between: f σ =F eσ (x1,x2,…,x i ,…,x n );

[0044] The anisotropy coefficient f of the elastic modulus of the porous lattice unit e and the geometric characteristic parameter set x iThe relationship function between and the anisotropy degree coefficient f of the yield strength of porous lattice unit σ and the geometric characteristic parameter set x i The relationship function between the anisotropy coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters is jointly constructed. For example, when n = 1, that is, when there is only one geometric characteristic parameter, f e =F ep (x1)=A1x1 2 +B1x1+C1,f σ =F eσ (x1)=A2x1 2 +B2x1+C2, where A1, B1, C1, A2, B2, and C2 are all constants. For example, when n = 2, that is, when there are only two geometric characteristic parameters, f e =F ep (x1,x2)=A1x1 2 +A2x2 2 +B1x1x2+C1x1+C2x2+D1,f σ =F eσ (x1,x2)=A3x1 2 +A4x2 2 +B2x1x2+C3x1+C4x2+D2, among which A1, A2, A3, A4, B1, B2, C1, C2, C3, C4, D1, D2 are all constants.

[0045] In the process of optimizing and adjusting the geometric feature parameters, the numerical changes of the geometric feature parameters are incremented or decremented according to the preset adjustment change value to obtain new geometric feature parameters for iterative adjustment, such as X1n=X1(n-1)+N, where X1n is the specific numerical value of the first geometric feature parameter adjusted for the nth time, X1(n-1) is the specific numerical value of the first geometric feature parameter adjusted for the n-1th time, and N is the adjustment change value. A corresponding mapping relationship database is established through n groups of optimization and adjustment data for subsequent use.

[0046] S202. During the optimization process of adjusting the geometric feature parameters, determine whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone. If the result is yes, a uniform porous implant geometric model that matches the mechanical properties of the host bone is obtained.

[0047] It should be noted that when the elastic modulus and yield strength anisotropic parameters of each porous lattice unit in the porous structure region match the anisotropic parameters of the mechanical properties of the host bone, it means that the porous region in contact with the host bone has a porous structure with similar elastic modulus and yield strength anisotropic properties, and a uniform porous implant geometric model is reconstructed based on the multiple porous lattice units in the porous structure region and their geometric characteristic parameters.

[0048] Specifically, the step of judging whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone includes: judging the difference percentage of the elastic modulus extreme value mean, the difference percentage of the elastic modulus extreme value variance and the elastic modulus anisotropy degree coefficient f between the porous lattice unit and the host bone. e Whether the percentage difference of is within the preset percentage range, and the yield strength extreme value mean, yield strength extreme value variance and yield strength anisotropy degree coefficient f of the porous lattice unit σ Are they all higher than the mean of the yield strength extreme value of the host bone, the variance of the yield strength extreme value and the yield strength anisotropy coefficient f σ , if it is judged as yes, it means that the two are matched successfully, otherwise it means that the two are matched unsuccessfully.

[0049] It should be noted that the porous lattice unit and the host bone are compared and judged by a multi-parameter method to determine whether the two meet the matching requirements. When the difference percentage of the extreme value mean of the elastic modulus, the difference percentage of the extreme value variance of the elastic modulus, and the elastic modulus anisotropy coefficient f between the porous lattice unit and the host bone are e The difference percentages are all within a preset percentage range (such as 0-30%), and the yield strength extreme value mean, yield strength extreme value variance and yield strength anisotropy degree coefficient f of the porous lattice unit are σ All of them are higher than the mean of the yield strength extreme value, the variance of the yield strength extreme value and the yield strength anisotropy coefficient f of the host bone. σ When , it means that the two are matched successfully, the elastic modulus and yield strength anisotropy parameters of the current porous lattice unit are close to the anisotropy parameters of the mechanical properties of the host bone. During the actual load-bearing process, the stress distribution in the area where the uniform porous implant geometric model is located can be ensured to be consistent with that of the host bone, so as to promote effective stress stimulation for bone ingrowth, which is beneficial to promote the growth / bone ingrowth of the host bone into the uniform porous structure area.

[0050] It should be noted that the extreme value mean of elastic modulus is the mean calculated by the maximum and minimum values ​​of elastic modulus in the spatial distribution of elastic modulus, and the extreme value variance of elastic modulus is the variance calculated by the maximum and minimum values ​​of elastic modulus in the spatial distribution of elastic modulus; the extreme value mean of yield strength is the mean calculated by the maximum and minimum values ​​of yield strength in the spatial distribution, and the extreme value variance of yield strength is the variance calculated by the maximum and minimum values ​​of yield strength in the spatial distribution.

[0051] Among them, the performance similarity between the two can be accurately determined by comparing and judging multiple parameters. When each porous lattice unit in the porous structure area meets the matching requirements, it means that the porous structure has similar elastic modulus and yield strength anisotropic properties with the host bone contact area. According to the multiple porous lattice units in the porous structure area and their geometric characteristic parameters, a uniform porous implant geometric model can be reconstructed, thereby improving the load-bearing safety of the porous implant and its good mechanical repair ability in the body, and having high stability in use.

[0052] S103, determining the non-uniform porous structure region in the bone implant model according to the uniform porous implant geometric model, and importing preset material performance parameters into the non-uniform porous structure region for optimization calculation to obtain stress distribution results in the non-uniform porous structure region, wherein the material performance parameters include elastic modulus and yield strength anisotropy parameters;

[0053] It should be noted that, according to the area occupied by the uniform porous implant geometric model in the bone implant model, the remaining active space in the bone implant model is obtained, and the remaining active space is the non-uniform porous structure area that is not in contact with the host bone. The preset material performance parameters are imported into the non-uniform porous structure area for finite element optimization calculation to output the stress distribution result of the currently optimized non-uniform porous structure area, and the stress distribution result is used to determine whether the anisotropy of the mechanical properties of the currently optimized non-uniform porous structure area meets the required functional requirements, such as having reliable load-bearing safety. Among them, the preset material performance parameters are the elastic modulus and yield strength anisotropy parameters of healthy host bones, such as the elastic stiffness matrix [C] and yield strength matrix [σ] parameters of healthy host bones.

[0054] S104, judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint conditions, if it is judged to be yes, executing step S105, if it is judged to be no, screening out the distribution region that does not meet the constraint conditions and adjusting its material performance parameters, and returning to step S103;

[0055] Specifically, the step of judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint conditions includes:

[0056] Step 1: The stress data of each porous lattice unit can be obtained by the stress distribution result of the porous structure area;

[0057] It should be noted that, since the porous structure region is a grid three-dimensional model, the stress data in each direction of each porous lattice can be obtained through the stress distribution results in the porous structure region.

[0058] Step 2: Determine whether in each of the porous lattice units there is stress in at least one direction that is less than or equal to a preset percentage (e.g., 50%-80%) of its yield strength parameter. If the judgment is yes, it means that the stress distribution result of the non-uniform porous structure area meets the preset constraints. If the judgment is no, it means that the non-uniform porous structure area does not meet the preset constraints.

[0059] It should be noted that when the porous lattice unit has a stress in at least one direction that is less than or equal to a preset percentage of its yield strength parameter, it means that the porous lattice unit meets the required functional requirements and has reliable load-bearing safety. When the stress distribution result of the non-uniform porous structure area meets the preset constraint conditions, it means that the non-uniform porous structure area as a whole has met the required functional requirements. Correspondingly, when the corresponding porous lattice unit does not meet the constraint conditions, it means that the porous lattice unit has insufficient load-bearing safety and is prone to fracture or damage. At this time, the distribution area or lattice unit area that does not meet the constraint conditions is screened out for subsequent parameter optimization processing.

[0060] Furthermore, the step of screening out the distribution areas that do not meet the constraint conditions and adjusting their material performance parameters includes:

[0061] Step 1: Screen out the porous lattice units that do not meet the constraint conditions, and add a preset elastic modulus parameter to the current elastic modulus parameter to obtain the currently adjusted elastic modulus parameter;

[0062] Step 2: output the screened porous lattice unit and its currently adjusted material performance parameters.

[0063] It should be noted that, for the porous lattice unit that does not meet the constraint conditions, its current elastic modulus parameter is adjusted, that is, the various parameters of the current elastic stiffness matrix [C] are adjusted, and the preset stiffness change parameters are added to the various parameters of the current elastic stiffness matrix [C] to obtain the various parameters of the currently adjusted elastic stiffness matrix [C], that is, the currently adjusted elastic modulus parameter is obtained. Among them, the currently adjusted elastic stiffness matrix [C] corresponds to any elastic stiffness matrix [C] obtained after the above-mentioned geometric characteristic parameter optimization adjustment, that is, the adjusted elastic stiffness matrix [C] belongs to the mapping relationship database established above.

[0064] By re-inputting the screened porous lattice unit and its currently adjusted material performance parameters into the non-uniform porous structure region, finite element analysis optimization calculation processing is repeated until the overall stress distribution result of the non-uniform porous structure region meets the preset constraints, thereby ensuring that the non-uniform porous structure region as a whole meets the required functional requirements.

[0065] S105, selecting corresponding geometric characteristic parameters from a database of mapping relations between anisotropy degree coefficients of mechanical properties of porous lattice units and geometric characteristic parameters according to the distribution results of material performance parameters in the non-uniform porous structure region, so as to reconstruct a non-uniform porous implant geometric model;

[0066] It should be noted that according to the distribution results of the material performance parameters in the non-uniform porous structure region optimized under the simulated real environment (i.e., the material performance parameters of each porous lattice unit in the non-uniform porous structure region, where the corresponding elastic modulus anisotropy degree coefficient f can be calculated from the corresponding elastic stiffness matrix [C] and yield strength matrix [σ] parameters respectively e and yield strength anisotropy coefficient f σ ) The geometric characteristic parameters corresponding to the material performance parameters of each grid unit are screened out from the above-mentioned database of mapping relationships between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and the porous structure data such as the geometric characteristic parameters of each porous lattice unit are imported into the non-uniform porous structure area for model reconstruction to reconstruct the required non-uniform porous implant geometric model.

[0067] S106. Perform 3D printing on the bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model to obtain a porous implant.

[0068] It should be noted that the bone implant geometric model composed of the partition-designed uniform porous implant geometric model and the non-uniform porous implant geometric model is processed by 3D printing technology to obtain the porous implant actually required. Among them, the substrate of the porous implant is made of metal, specifically Ti6Al4V titanium alloy. The porous structure of the porous implant manufactured by the present invention has different anisotropy of mechanical properties in different regions, which effectively avoids the problem of insufficient strength in the actual service process due to lack of consideration in different directions, and improves the overall safety of the porous implant.

[0069] like Figure 5 As shown, Figure 5The assembly diagram of the defective mandible and the porous implant is shown. The peri-bone area is the uniform porous implant geometry model, which has similar mechanical property anisotropy to the host bone. In the actual load-bearing process, it can ensure that the stress distribution in the area where the uniform porous implant geometry model is located is consistent with the host bone, so as to promote effective stress stimulation of bone growth, which is conducive to promoting the growth / bone ingrowth of the host bone into the uniform porous structure area; and the non-uniform porous design area is the non-uniform porous implant geometry model, which can ensure that the effective distribution of stress can meet the actual load-bearing strength requirements, improve the load-bearing safety of the porous implant, and thus ensure the safety and stability of the entire service process.

[0070] Preferably, the structural type of the porous lattice unit in the bone implant geometric model includes a surface unit based on a solid feature geometric configuration unit and an implicit function control, the length, width and height of the porous lattice unit is 1-5 mm, the pore size range is 100-1000 μm, and the porosity is 0-90%. The specific values ​​of the length, width and height, pore size and porosity of each porous lattice unit can be determined according to the actual optimization calculation results.

[0071] In summary, the present invention reasonably designs a porous structure with different anisotropic mechanical properties distributed in different areas according to the mechanical function requirements of the porous implant to replace bone defects, effectively avoiding the problem of insufficient strength in the actual service process due to lack of consideration in different directions, and improving the overall safety of the porous implant; and based on the setting of a uniform porous implant geometric model that is in contact with the host bone and has similar mechanical properties, during the actual load-bearing process, it can ensure that the stress distribution in the area where the uniform porous implant geometric model is located is consistent with the host bone, so as to promote effective stress stimulation for bone growth, which is beneficial to promote the growth / bone ingrowth of the host bone into the uniform porous structure area; at the same time, through the setting of the non-uniform porous implant geometric model, it can ensure that the effective distribution of stress can meet the actual load-bearing strength requirements, improve the load-bearing safety of the porous implant, thereby ensuring the safety and stability of the entire service process.

[0072] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for manufacturing a porous implant, characterized in that: include: S101, obtaining a three-dimensional bone model of the bone defect site, and constructing a finite element model of mechanical property anisotropy according to the three-dimensional bone model and simulation environment parameters to obtain a bone implant model, wherein the mechanical property anisotropy includes the elastic modulus and yield strength anisotropy of the bone; S102, performing uniform porous processing adapted to the host bone performance on the porous structure area in contact with the host bone in the bone implant model, so as to obtain a mapping relationship database between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and a uniform porous implant geometric model adapted to the mechanical properties of the host bone; S103, determining the non-uniform porous structure region in the bone implant model according to the uniform porous implant geometric model, and importing preset material performance parameters into the non-uniform porous structure region for optimization calculation to obtain stress distribution results in the non-uniform porous structure region, wherein the material performance parameters include elastic modulus and yield strength anisotropy parameters; S104, judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint conditions, if it is judged to be yes, executing step S105, if it is judged to be no, screening out the distribution region that does not meet the constraint conditions and adjusting its material performance parameters, and returning to step S103; S105, selecting corresponding geometric characteristic parameters from a database of mapping relations between anisotropy degree coefficients of mechanical properties of porous lattice units and geometric characteristic parameters according to the distribution results of material performance parameters in the non-uniform porous structure region, so as to reconstruct a non-uniform porous implant geometric model; S106. Perform 3D printing on the bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model to obtain a porous implant.

2. The method for manufacturing a porous implant according to claim 1, characterized in that: The step of obtaining a three-dimensional bone model of the bone defect site comprises: Medical imaging technology is used to obtain bone imaging data of the bone defect site and construct a three-dimensional bone model.

3. The method for manufacturing a porous implant according to claim 1, characterized in that: The step of constructing a finite element model with anisotropic mechanical properties according to the three-dimensional bone model and the simulation environment parameters to obtain a bone implant model comprises: Performing an initial model building process according to the three-dimensional bone model to build an initial bone implant model, wherein the initial model building process includes surface smoothing processing and precise surface fitting and solidification processing; The initial bone implant model is adjusted through anisotropic finite element analysis and the simulation environment parameters to obtain a bone implant model.

4. The method for manufacturing a porous implant according to claim 1, characterized in that: The step S102 includes: Adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters, and establishing a corresponding mapping relationship database; In the optimization process of adjusting the geometric characteristic parameters, it is determined whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone. If so, a uniform porous implant geometric model that matches the mechanical properties of the host bone is obtained.

5. The method for manufacturing a porous implant according to claim 4, characterized in that: The step of adjusting the geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model to construct a mapping relationship between the anisotropy degree coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameters comprises: The geometric characteristic parameters of the porous lattice unit in the porous structure area in contact with the host bone in the bone implant model are adjusted to output elastic modulus and yield strength anisotropic parameters of different porous lattice units, wherein the elastic modulus anisotropic parameter is characterized by a stiffness matrix [C], [C] = [C 11 , C 22 , C 33 , C 44 , C 55 , C 66 , C 12 , C 13 , C 23 ], the yield strength anisotropy parameter is characterized by the strength matrix [σ], [σ] = [σ 11 ,σ 22 ,σ 33 ,σ 12 ,σ 13 ,σ 23 ]; The elastic modulus anisotropy coefficient f of the porous lattice unit is calculated according to the elastic stiffness matrix [C] of the porous lattice unit. e , and establish the anisotropy coefficient f of the elastic modulus of the porous lattice unit e and the geometric characteristic parameter set x i The relationship function between: f e =F ep (x1,x2,…,x i ,…,x n ), wherein the F ep is the elastic modulus performance control function, x n is the nth geometric characteristic parameter, n is a positive integer; The yield strength anisotropy coefficient f of the porous lattice unit is calculated according to the yield strength matrix [σ] of the porous lattice unit. σ , and establish the anisotropy degree coefficient f of the yield strength of the porous lattice unit σ and the geometric characteristic parameter set x i The relationship function between: f σ =F eσ (x1,x2,…,x i ,…,x n ), wherein the F eσ is the yield strength performance control function.

6. The method for manufacturing a porous implant according to claim 5, characterized in that: The elastic modulus anisotropy coefficient f of the porous lattice unit is calculated according to the elastic stiffness matrix [C] of the porous lattice unit. e The steps include: The elastic modulus spatial distribution and the extreme value range of the elastic modulus spatial distribution (E min ,E max ), and the Zener coefficient is used to analyze the elastic modulus anisotropy coefficient f of the porous lattice unit e ; The yield strength anisotropy coefficient f of the porous lattice unit is calculated according to the yield strength matrix [σ] of the porous lattice unit. σ The steps include: The yield strength spatial distribution is calculated according to the yield strength matrix [σ] of the porous lattice unit, and the yield strength anisotropy coefficient f of the porous lattice unit is calculated according to the maximum and minimum values ​​of the yield strength spatial distribution. σ .

7. The method for manufacturing a porous implant according to claim 6, characterized in that: The step of judging whether the elastic modulus and yield strength anisotropy parameters of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone comprises: Determine the difference percentage of the elastic modulus extreme value mean between the porous lattice unit and the host bone, the difference percentage of the elastic modulus extreme value variance and the elastic modulus anisotropy degree coefficient f e Whether the percentage difference of is within the preset percentage range, and the yield strength extreme value mean, yield strength extreme value variance and yield strength anisotropy degree coefficient f of the porous lattice unit σ Are they all higher than the mean of the yield strength extreme value of the host bone, the variance of the yield strength extreme value and the yield strength anisotropy coefficient f σ , if it is judged as yes, it means that the two are matched successfully, otherwise it means that the two are matched unsuccessfully.

8. The method for manufacturing a porous implant according to claim 1, characterized in that: The step of judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint conditions comprises: The stress data of each porous lattice unit can be obtained accordingly through the stress distribution result of the porous structure area; Determine whether each of the porous lattice units has stress in at least one direction that is less than or equal to a preset percentage of its yield strength parameter. If the judgment is yes, it means that the stress distribution result of the non-uniform porous structure area meets the preset constraints; if the judgment is no, it means that the non-uniform porous structure area does not meet the preset constraints.

9. The method for manufacturing a porous implant according to claim 8, characterized in that: The step of screening out the distribution area that does not meet the constraint conditions and adjusting its material performance parameters includes: Screening out the porous lattice units that do not meet the constraint conditions, and adding a preset elastic modulus parameter to the current elastic modulus parameter to obtain the currently adjusted elastic modulus parameter; The screened porous lattice unit and its currently adjusted material performance parameters are output.

10. The method for manufacturing a porous implant according to claim 1, characterized in that: The structural types of the porous lattice unit in the bone implant geometric model include solid feature geometric configuration units and surface units controlled by implicit functions. The length, width and height of the porous lattice unit are 1-5 mm, the pore size range is 100-1000 μm, and the porosity is 0-90%.

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