A method of manufacturing a porous implant

Abstract

The application discloses a manufacturing method of a porous implant, and relates to the technical field of medical devices, and comprises the following steps: obtaining a bone implant model; performing uniform porous treatment on a porous structure region in the bone implant model which is in contact with host bone and is adapted to the performance of the host bone; determining a non-uniform porous structure region in the bone implant model according to a uniform porous implant geometric model, and importing preset material performance parameters into the non-uniform porous structure region to perform optimization calculation; when stress distribution results of the non-uniform porous structure region meet preset constraint conditions, reconstructing a non-uniform porous implant geometric model according to distribution results of the material performance parameters in the non-uniform porous structure region and a mapping relationship database, and finally performing 3D printing processing on all geometric models to obtain the porous implant. The porous implant obtained by the application has high bearing safety, can further promote effective stress stimulation of bone ingrowth, and has a long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, and in particular to a manufacturing method of a porous implant. BACKGROUND

[0002] According to the Woolf's law, the human bone is subjected to complex and variable mechanical load for a long time, and the macro and micro structures thereof will produce dynamic adaptive response changes to form an optimal structure to meet the functional requirements of bearing and activity. This process makes the human bone exhibit mechanical performance difference in different directions, i.e. mechanical performance anisotropy. For example, the compression elastic modulus of the femur in the axial, circumferential and radial directions is 5.8 GPa, 3.4 GPa and 2.1 GPa respectively, and the breaking strength is 150 MPa, 111 MPa and 110 MPa respectively. When a large bone defect is caused by factors such as tumor and trauma, a 3D-printed porous implant is 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, a porous implant with controllable mechanical performance anisotropy is developed to lay a solid foundation for the mechanical transmission and physiological function repair of the bone defect area.

[0003] At present, the design method of the 3D-printed porous implant mainly focuses on: 1) starting from the macro elastic modulus matching, under the premise that the strength meets the safety requirements, the elastic modulus of the implant is made close to that of the host bone through the low modulus material or porosity design, which can effectively reduce the stress shielding of the metal prosthesis and the hidden trouble of its later loosening. However, this method mainly considers the mechanical performance in a single direction, such as the uniaxial tensile or compressive mechanical performance of the material or the porous structure, ignores the difference in mechanical performance in different directions, and the matching degree with the mechanical performance anisotropy of the human host bone, thereby affecting the service state and service life of the implant in the body; 2) according to the bionic design concept, the porous structure with porosity gradient is designed according to the layered structure characteristics of the host bone anatomical morphology, but the gradient gradient type mainly focuses on a single direction, such as the axial or radial porosity change, and lacks consideration of the mechanical performance anisotropy of the porous structure.

[0004] Therefore, the existing bone implant repair technology still lacks consideration of the influence of the mechanical performance anisotropy of the microstructure on the in-body service performance, and has not developed an optimization design and manufacturing method considering the mechanical function requirements of the bone defect area and the mechanical performance anisotropy of the porous structure of the implant, thereby causing the existing porous implant to be difficult to well cope with the mechanical transmission function in the body, which will further affect the effect of the host bone growth into the porous structure of the implant and the reliability of the biological fixation. SUMMARY

[0005] The technical problem solved by the present application is to provide a manufacturing method of a porous implant, which can obtain a porous implant with different mechanical property anisotropy in different regions, has higher bearing safety, can further promote the effective stress stimulation of bone ingrowth, has high long-term use stability of the porous implant, and has a long service life.

[0006] To solve the above technical problems, the present application provides a manufacturing method of a porous implant, comprising: S101, obtaining a bone three-dimensional model of a bone defect site, and performing finite element model construction processing of mechanical property anisotropy according to the bone three-dimensional model and simulation environment parameters to obtain a bone implant model, wherein the mechanical property anisotropy includes elastic modulus and yield strength anisotropy of the bone; S102, performing uniform porous processing of host bone performance adaptation on a porous structure region in the bone implant model that contacts the host bone to obtain a mapping relationship database of mechanical property anisotropy degree coefficients and geometric characteristic parameters of a porous lattice unit, and a uniform porous implant geometric model that is adapted to the mechanical property of the host bone; S103, determining a 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 of 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 results of the non-uniform porous structure region meet preset constraint conditions, if yes, performing step S105, and if no, screening out distribution regions that do not meet the constraint conditions and adjusting the material performance parameters thereof, and returning to step S103; S105, screening out corresponding geometric characteristic parameters from the mapping relationship database of mechanical property anisotropy degree coefficients and geometric characteristic parameters of the porous lattice unit according to the distribution results of the material performance parameters in the non-uniform porous structure region to reconstruct a non-uniform porous implant geometric model; S106, performing 3D printing processing 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 scheme, the step of obtaining the bone three-dimensional model of the bone defect site comprises: obtaining bone image data of the bone defect site through medical imaging technology, and constructing a bone three-dimensional model.

[0008] As an improvement of the above scheme, the step of constructing the finite element model of mechanical property anisotropy according to the three-dimensional model of the bone and the simulation environment parameters to obtain the bone implant model comprises: constructing an initial bone implant model according to the three-dimensional model of the bone, wherein the initial model construction process comprises surface smoothing processing and accurate curved surface fitting solidification processing; and adjusting the initial bone implant model through anisotropic finite element analysis and the simulation environment parameters to obtain the bone implant model.

[0009] As an improvement of the above scheme, the step S102 comprises: adjusting the geometric feature parameters of the porous lattice unit in the porous structure region of the bone implant model in contact with the host bone, constructing a mapping relationship between the anisotropy degree coefficient of the mechanical property of the porous lattice unit and the geometric feature parameters, and establishing a corresponding mapping relationship database; and in the optimization process of the geometric feature parameter adjustment, judging whether the output elastic modulus and yield strength anisotropy parameters of the porous lattice unit match the mechanical property anisotropy parameters of the host bone, and if yes, obtaining a uniform porous implant geometric model that matches the mechanical property of the host bone.

[0010] As an improvement of the above scheme, the step of adjusting the geometric feature parameters of the porous lattice unit in the porous structure region of the bone implant model in contact with the host bone to construct a mapping relationship between the anisotropy degree coefficient of the mechanical property of the porous lattice unit and the geometric feature parameters comprises: adjusting the geometric feature parameters of the porous lattice unit in the porous structure region of the bone implant model in contact with the host bone to output different elastic modulus and yield strength anisotropy parameters of the porous lattice unit, wherein the elastic modulus anisotropy parameters are represented by a stiffness matrix [C], [C] = [C 11 , C 22 , C 33 , C 44 , C 55 , C 66 , C 12 , C 13 , C 23 ], and the yield strength anisotropy parameters are represented by a strength matrix [σ], [σ] = [σ 11 , σ 22 , σ 33 , σ 12 , σ 13 , σ 23 ]; calculating the elastic modulus anisotropy degree coefficient f e of the porous lattice unit according to the elastic stiffness matrix [C] of the porous lattice unit, and establishing a mapping relationship between the elastic modulus anisotropy degree coefficient f e of the porous lattice unit and the geometric feature parameter group x iRelationship function: f e =F ep (x1,x2,…,x i ,…,x n ), wherein, the F ep Let x be the control function for the elastic modulus performance. n Let f be the nth geometric characteristic parameter, where n is a positive integer; calculate the anisotropy coefficient f of the yield strength of the porous lattice unit based on the yield strength matrix [σ]. σ And establish the anisotropy coefficient f of the yield strength of porous lattice unit. σ With geometric characteristic parameter set x i Relationship function: f σ =F eσ (x1,x2,…,x i ,…,x n ), wherein, the F eσ This is the control function for yield strength performance.

[0011] As an improvement to the above scheme, the elastic modulus anisotropy coefficient f of the porous lattice unit is calculated based on the elastic stiffness matrix [C] of the porous lattice unit. e The steps include: calculating the spatial distribution of the elastic modulus and the extreme range of the spatial distribution of the elastic modulus (E) based on the elastic stiffness matrix [C] of the porous lattice unit. min E max The anisotropy coefficient f of the elastic modulus of the porous lattice unit was analyzed using Zener coefficients. e The yield strength anisotropy coefficient f of the porous lattice unit is calculated based on the yield strength matrix [σ] of the porous lattice unit. σ The steps include: calculating the spatial distribution of yield strength based on the yield strength matrix [σ] of the porous lattice unit, and calculating the anisotropy coefficient f of the yield strength of the porous lattice unit based on the maxima and minima of the spatial distribution of yield strength. σ .

[0012] As an improvement to the above scheme, the step of determining whether the anisotropy parameters of the elastic modulus and yield strength of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone includes: determining the percentage difference between the mean extreme values ​​of the elastic modulus of the porous lattice unit and the host bone, the percentage difference between the variances of the extreme values ​​of the elastic modulus, and the anisotropy coefficient f of the elastic modulus. e Whether the percentage difference is within the preset percentage range, and whether the mean extreme value of yield strength, the variance of extreme value of yield strength, and the anisotropy coefficient of yield strength of the porous lattice unit are all within the preset percentage range. σWhether the maximum yield strength, the yield strength variance and the yield strength anisotropy degree coefficient f of the host bone are all higher than the maximum yield strength, the yield strength variance and the yield strength anisotropy degree coefficient f of the porous implant σ If yes, it is indicated that the two match successfully, otherwise, it is indicated that the two match unsuccessfully.

[0013] As an improvement of the above scheme, the step of judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint condition comprises: obtaining stress data of each porous lattice unit through the stress distribution result of the porous structure region; judging whether the stress of each porous lattice unit in at least one direction is less than or equal to a preset percentage of the yield strength parameter thereof, if yes, it is indicated that the stress distribution result of the non-uniform porous structure region meets the preset constraint condition, otherwise, it is indicated that the non-uniform porous structure region does not meet the preset constraint condition.

[0014] As an improvement of the above scheme, the step of screening out the distribution region not meeting the constraint condition and adjusting the material performance parameter thereof comprises: screening out the porous lattice unit not meeting the constraint condition, increasing a preset elastic modulus parameter on the current elastic modulus parameter thereof to obtain a current adjusted elastic modulus parameter; and outputting the screened porous lattice unit and the current adjusted material performance parameter thereof.

[0015] As an improvement of the above scheme, the structure type of the porous lattice unit in the bone implant geometric model comprises a solid feature geometry unit and a curved surface unit controlled by an implicit function, the length, width and height of the porous lattice unit are 1-5 mm, the pore size range is 100-1000 mu m, and the porosity is 0-90%.

[0016] The present application has the following beneficial effects:

[0017] According to the mechanical function requirement of the porous implant for replacing the bone defect, the present application rationally designs the porous structure with different mechanical performance anisotropy in different regions, effectively avoids the problem of insufficient strength in the actual service process due to the lack of consideration in different directions, and improves the overall safety of the porous implant; moreover, based on the setting of the uniform porous implant geometric model in contact with the host bone and having similar mechanical properties, the stress distribution of the region where the uniform porous implant geometric model is located can be ensured to be consistent with the host bone in the actual bearing process, so as to promote the effective stress stimulation of the bone growth and be beneficial to promoting the host bone growth / long into the uniform porous structure region; at the same time, the non-uniform porous implant geometric model can ensure that the effective stress distribution can meet the actual bearing strength requirement, improve the bearing safety of the porous implant, and thus ensure the safety and stability in the entire use and service process. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1is a flow chart of a manufacturing method of a porous implant of the present application;

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

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

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

[0022] Figure 5 is an assembly diagram of a defective mandible and a porous implant of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. It is hereby declared that the up, down, left, right, front, back, inner and outer directions appearing or about to appear in the present application are based on the drawings of the present application, and are not specific limitations on the present application.

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

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

[0026] Specifically, the step of obtaining the three-dimensional 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 model of the bone.

[0027] It should be noted that the obtained 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 to design the outer surface profile of the implant and its fixation side according to the bone defect range and area and the shape of the defective bone, so as to reconstruct the three-dimensional model of the bone.

[0028] Further, the step of performing a finite element model construction process of mechanical property anisotropy according to the three-dimensional model of the bone and simulation environment parameters to obtain a bone implant model includes:

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

[0030] It should be noted that the surface smoothing processing and accurate curved surface fitting solidification and other optimization processing are performed on the bone three-dimensional model by the Geomagic Wrap software to obtain the initial bone implant model.

[0031] Step 2, adjusting the initial bone implant model by 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 is imported into the finite element software Abaqus for finite element analysis to complete the construction of the bone implant model. The simulation environment parameters set in the finite element software Abaqus include limitation parameters such as mechanical load and boundary conditions applied according to the daily physiological activities and stress conditions of the patient to simulate the real mechanical environment of the corresponding bone defect site (such as different occlusal load values of the mandibular implant, different flexion, lateral bending, and axial rotation load values of the spinal bone implant, etc.), and the elastic modulus and yield strength anisotropic material properties of the corresponding host bone (such as cortical bone and cancellous bone) are set to fully consider the anisotropy of the mechanical properties of the human body bone and the bone implant, so that the data processed and reconstructed by the bone implant model subsequently is more accurate, and the bone implant prepared is more in line with the actual use requirements. The initial element type parameter and the grid size parameter are set to discretize the assembled model by grid, so as to evaluate and reconstruct the mechanical performance anisotropy of each porous lattice unit in the subsequent process, so as to ensure that the porous structure implant can meet the required different mechanical performance anisotropy requirements.

[0033] S102, performing a uniform porous processing of the host bone performance adaptation on the porous structure region in contact with the host bone in the bone implant model to obtain a mapping relationship database of the mechanical performance anisotropy degree coefficient and the geometric feature parameter of the porous lattice unit, and a uniform porous implant geometric model adapted to the mechanical performance of the host bone;

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

[0035] S201, adjusting the geometric feature parameter of the porous lattice unit on the porous structure region in contact with the host bone in the bone implant model to construct a mapping relationship of the mechanical performance anisotropy degree coefficient and the geometric feature parameter of the porous lattice unit, and establish a corresponding mapping relationship database;

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

[0037] Step 1, adjusting the geometric characteristic parameters of the porous lattice units in the porous structure region of the bone implant model in contact with the host bone to output different elastic modulus and yield strength anisotropy parameters of the porous lattice units, wherein the elastic modulus anisotropy parameters are represented by the 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 respectively represent the stiffness coefficients of the porous lattice units under the action of the X, Y, Z axial principal strain, C 44 , C 55 , C 66 respectively represent the stiffness coefficients of the porous lattice units under the action of the X, Y, Z axial principal shear strain; C 12 , C 13 , C 23 respectively represent the stiffness coefficients of the porous lattice units under the action of the shear strain in the XY, XZ, YZ planes.

[0038] The yield strength anisotropy parameters are represented 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 units in the X, Y, Z axial directions, σ 12 ,σ 13 ,σ 23 respectively represent the strength coefficients of the porous lattice units in the XY, XZ, YZ planes

[0039] It should be noted that in the finite element analysis, the geometric characteristic parameters of the porous lattice units in the region in contact with the host bone are adjusted. For example, Figure 5As shown, the geometric characteristic parameters include the diameters of the internal members and edge members of the porous lattice unit, as well as the length, width, and height of the porous lattice unit. By adjusting these parameters, different pore sizes and porosity parameters can be obtained. Generally, the length, width, and height of the porous lattice unit are preset fixed parameters. By changing the geometric characteristic parameters such as the diameters of the internal members and edge members, the geometry of the porous lattice unit can be adjusted to ensure that the anisotropy of its mechanical properties meets the required standards. Therefore, by adjusting the geometric characteristic parameters of each porous lattice unit, its elastic modulus and yield strength anisotropy parameters can be changed. This allows for the calculation of the mapping relationship between the anisotropy coefficient of the porous lattice unit's mechanical properties and the geometric characteristic parameters, and the establishment of a corresponding mapping relationship database for subsequent use.

[0040] Step 2: Calculate the elastic modulus anisotropy coefficient f of the porous lattice unit based on the elastic stiffness matrix [C] of the porous lattice unit. e And establish the anisotropy coefficient f of the elastic modulus of porous lattice unit. e With geometric characteristic parameter set x i Relationship function: f e =F ep (x1,x2,…,x i ,…,x n ), wherein, the F ep Let x be the control function for the elastic modulus performance. n Let n be the nth geometric feature parameter, where n is a positive integer;

[0041] It should be noted that, as Figure 3 As shown, according to the elastic stiffness matrix [C]=[C] of the porous lattice unit 11 C 22 C 33 C 44 C 55 C 66 C 12 C 13 C 23 The spatial distribution of the elastic modulus, i.e., the distribution of elastic modulus data of porous lattice units, was calculated, and the range of extreme values ​​of the elastic modulus (E) in the spatial distribution of the elastic modulus was calculated. min E max The anisotropy coefficient f of the elastic modulus of the porous lattice unit was analyzed using the Zener coefficient. e f e =2×C 44 / (C 11 -C 12 According to the anisotropy coefficient f of the elastic modulus of the porous lattice unit... eThe elastic modulus and anisotropy coefficient f of the porous lattice unit constructed with geometric characteristic parameters e With geometric characteristic parameter set x i Relationship function: 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 based on the yield strength matrix [σ]. σ And establish the anisotropy coefficient f of the yield strength of porous lattice unit. σ With geometric characteristic parameter set x i Relationship function: f σ =F eσ (x1,x2,…,x i ,…,x n ), wherein, the F eσ This is the control function for yield strength performance.

[0043] It should be noted that, as Figure 4 As shown, according to the yield strength matrix [σ]=[σ] of the porous lattice unit 11 ,σ 22 ,σ 33 ,σ 12 ,σ 13 ,σ 23 The spatial distribution of yield strength, i.e., the yield strength data distribution of porous lattice units, is calculated; based on the maximum value σ of the spatial distribution of yield strength... max With the minimum value σ min The yield strength anisotropy coefficient f of the porous lattice unit was calculated. σ f σ =σ max / σ min According to the anisotropy coefficient f of the yield strength of the porous lattice unit σ The yield strength anisotropy coefficient f of porous lattice unit constructed with geometric characteristic parameters σ With geometric characteristic parameter set x i Relationship function: 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 With geometric characteristic parameter set x ia relationship function between the relationship function and the degree of anisotropy coefficient f of the yield strength of the porous lattice unit σ and the geometric characteristic parameter group x i The mapping relationship function between the degree of anisotropy coefficient of the mechanical properties of the porous lattice unit and the geometric characteristic parameter is jointly constructed by the relationship function between the relationship function and the degree of anisotropy coefficient f. When n = 1, i.e. 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, C2 are constants. When n = 2, i.e. 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, where A1, A2, A3, A4, B1, B2, C1, C2, C3, C4, D1, D2 are constants.

[0045] In the optimization and adjustment process of the geometric characteristic parameters, the numerical value of the geometric characteristic parameter is increased or decreased according to the preset adjustment change value to obtain a new geometric characteristic parameter for iterative adjustment, such as X1n = X1(n-1) + N, where X1n is the specific value of the first geometric characteristic parameter in the current nth adjustment, X1(n-1) is the specific value of the first geometric characteristic parameter in the current (n-1)th adjustment, and N is the adjustment change value. The corresponding mapping relationship database is established by n groups of optimization and adjustment data for subsequent use.

[0046] S202, in the optimization process of the geometric characteristic parameter adjustment, it is judged whether the elastic modulus and the yield strength anisotropy parameter of the output porous lattice unit match the mechanical property anisotropy parameter of the host bone, and if 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 the yield strength anisotropy parameters of each porous lattice unit in the porous structure region match the mechanical property anisotropy parameters of the host bone, it means that the porous region in contact with the host bone has a similar elastic modulus and yield strength anisotropy property of the porous structure, and the uniform porous implant geometric model is reconstructed according to the plurality of porous lattice units and the geometric feature parameters in the porous structure region.

[0048] Specifically, the step of judging whether the elastic modulus and the yield strength anisotropy parameters of the output porous lattice unit match the mechanical property anisotropy parameters of the host bone includes: judging whether the difference percentage of the elastic modulus extreme value mean, the difference percentage of the elastic modulus extreme value variance, and the difference percentage of the elastic modulus anisotropy degree coefficient f e of the porous lattice unit and the host bone are all in the preset percentage range, and whether the yield strength extreme value mean, the yield strength extreme value variance, and the yield strength anisotropy degree coefficient f σ of the porous lattice unit are all higher than the yield strength extreme value mean, the yield strength extreme value variance, and the yield strength anisotropy degree coefficient f σ of the host bone, and if yes, it means that the two match successfully, otherwise it means that the two do not match.

[0049] It should be noted that whether the two match the matching requirements is determined by the comparison and judgment of the plurality of parameters between the porous lattice unit and the host bone, when the difference percentage of the elastic modulus extreme value mean, the difference percentage of the elastic modulus extreme value variance, and the difference percentage of the elastic modulus anisotropy degree coefficient f e of the porous lattice unit and the host bone are all in the preset percentage range (such as 0-30%), and the yield strength extreme value mean, the yield strength extreme value variance, and the yield strength anisotropy degree coefficient f σ of the porous lattice unit are all higher than the yield strength extreme value mean, the yield strength extreme value variance, and the yield strength anisotropy degree coefficient f σ of the host bone, it means that the two match successfully, and the elastic modulus and the yield strength anisotropy parameters of the current porous lattice unit are close to the mechanical property anisotropy parameters of the host bone, which can ensure that the stress distribution of the region of the uniform porous implant geometric model is consistent with the host bone during actual bearing, so as to promote the effective stress stimulation of bone ingrowth, and is beneficial to promote the host bone to grow into / ingrowth into the uniform porous structure region.

[0050] It needs to be explained that the elastic modulus extreme value mean is the mean value calculated by the elastic modulus maximum and minimum of the elastic modulus spatial distribution, the elastic modulus extreme value variance is the variance calculated by the elastic modulus maximum and minimum of the elastic modulus spatial distribution; the yield strength extreme value mean is the mean value calculated according to the maximum and minimum of the yield strength spatial distribution, and the yield strength extreme value variance is the variance calculated according to the maximum and minimum of the yield strength spatial distribution.

[0051] Wherein, the performance approximation between the two can be accurately determined by the comparison judgment mode of multiple parameters. When each porous lattice unit in the porous structure region meets the matching requirement, it indicates that the porous structure with similar elastic modulus and yield strength anisotropy properties in the contact area with the host bone, according to the multiple porous lattice units and their geometric feature parameters in the porous structure region, a uniform porous implant geometric model can be reconstructed, thereby improving the bearing safety of the porous implant and the good mechanical repair ability in the body, and the use stability is high.

[0052] S103, according to the uniform porous implant geometric model, the non-uniform porous structure region in the bone implant model can be determined, and the preset material performance parameters are introduced into the non-uniform porous structure region for optimization calculation to obtain the stress distribution result of the non-uniform porous structure region, wherein the material performance parameters include elastic modulus and yield strength anisotropy parameters;

[0053] It needs to be explained 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, which is the non-uniform porous structure region not in contact with the host bone. By introducing the preset material performance parameters into the non-uniform porous structure region for finite element optimization calculation, the stress distribution result of the current optimized non-uniform porous structure region is output, and whether the mechanical performance anisotropy of the current optimized non-uniform porous structure region meets the required functional requirements, such as reliable bearing safety, is determined through the stress distribution result. Wherein, the preset material performance parameters are the elastic modulus and yield strength anisotropy parameters of the healthy host bone, such as the elastic stiffness matrix [C] and yield strength matrix [σ] parameters of the healthy host bone.

[0054] S104, judging whether the stress distribution result of the non-uniform porous structure region meets the preset constraint condition, if yes, executing step S105, if no, screening out the distribution region not meeting the constraint condition and adjusting the material performance parameters thereof, 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 condition comprises:

[0056] Step 1, stress data of each porous lattice unit can be obtained according to the stress distribution result of the porous structure region;

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

[0058] Step 2, it is judged whether the stress of at least one direction of each porous lattice unit is less than or equal to a preset percentage (such as 50%-80%) of the yield strength parameter. If yes, it means that the stress distribution result of the non-uniform porous structure region meets the preset constraint condition. If no, it means that the non-uniform porous structure region does not meet the preset constraint condition.

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

[0060] Further, the step of screening out the distribution region that does not meet the constraint condition and adjusting the material performance parameter thereof comprises:

[0061] Step 1, the porous lattice unit that does not meet the constraint condition is screened out, and a preset elastic modulus parameter is added to the current elastic modulus parameter thereof to obtain a current adjusted elastic modulus parameter;

[0062] Step 2, the screened porous lattice unit and the current adjusted material performance parameter thereof are output.

[0063] It should be noted that, for the porous lattice unit that does not meet the constraint condition, the current elastic modulus parameter thereof is adjusted, that is, each parameter of the current elastic stiffness matrix [C] is adjusted, a preset stiffness change parameter is added to each parameter of the current elastic stiffness matrix [C] to obtain each parameter of the current adjusted elastic stiffness matrix [C], that is, to obtain the current adjusted elastic modulus parameter. Wherein, the current adjusted elastic stiffness matrix [C] corresponds to any elastic stiffness matrix [C] obtained after the optimization and adjustment of the above geometric feature parameters, that is, the adjusted elastic stiffness matrix [C] belongs to the above established mapping relationship database.

[0064] By re-inputting the screened porous lattice unit and its current adjusted material performance parameter into the non-uniform porous structure region, the finite element analysis optimization calculation processing is circularly performed until the overall stress distribution result of the non-uniform porous structure region meets the preset constraint condition, so that the non-uniform porous structure region as a whole meets the required functional requirement.

[0065] S105, according to the distribution result of the material performance parameter in the non-uniform porous structure region, corresponding geometric feature parameters are screened from the mapping relationship database of the mechanical performance anisotropy degree coefficient and the geometric feature parameter of the porous lattice unit, so as to reconstruct the non-uniform porous implant geometric model.

[0066] It should be noted that, according to the distribution result of the material performance parameter in the non-uniform porous structure region obtained by optimizing in the real environment (i.e. the material performance parameter of each porous lattice unit in the non-uniform porous structure region, wherein the elastic modulus anisotropy degree coefficient f e and the yield strength anisotropy degree coefficient f σ can be calculated from the corresponding elastic stiffness matrix [C] and yield strength matrix [σ] parameters respectively), the geometric feature parameter corresponding to the material performance parameter of each grid unit is screened from the above-mentioned mapping relationship database of the mechanical performance anisotropy degree coefficient and the geometric feature parameter of the porous lattice unit, and the geometric feature parameter and other porous structure data of each porous lattice unit are imported into the non-uniform porous structure region for model reconstruction, so as to reconstruct the required non-uniform porous implant geometric model.

[0067] S106, the bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model is subjected to 3D printing processing to obtain a porous implant.

[0068] It should be noted that the bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model designed by partitioning is subjected to 3D printing processing to obtain the actual required porous implant. The base material of the porous implant is metal, specifically Ti6Al4V titanium alloy. The porous structure of the porous implant manufactured by the present application has different mechanical performance anisotropy in different regions, effectively avoiding the problem of insufficient strength in the actual service process due to different directions being overlooked, and improving the overall safety of the porous implant.

[0069] As Figure 5 shown, Figure 5The assembly diagram of the defective mandible and the porous implant is shown. Among them, the surrounding bone area is a uniform porous implant geometric model, which has similar mechanical properties of anisotropy with the host bone, and can ensure that the stress distribution of the uniform porous implant geometric model in the area is consistent with the host bone in the actual bearing process, so as to promote the effective stress stimulation of bone growth, and is beneficial to promote the host bone to grow into the uniform porous structure area; and the non-uniform porous design area is a non-uniform porous implant geometric model, which can ensure that the effective distribution of stress can meet the actual bearing strength requirement, improve the bearing safety of the porous implant, and thus ensure the safety and stability of the entire service process.

[0070] Preferably, the structure type of the porous lattice unit in the bone implant geometric model includes a solid feature geometry unit and a curved surface unit controlled by an implicit function, the length, width and height of the porous lattice unit are 1-5mm, the pore size range is 100-1000μm, 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 result.

[0071] In summary, according to the mechanical function requirement of the porous implant replacing the bone defect, the porous structure with different mechanical properties of anisotropy in different areas is reasonably designed, the problem of insufficient strength in the actual service process caused by different directions is effectively avoided, and the overall safety of the porous implant is improved; and based on the uniform porous implant geometric model in contact with the host bone and having similar mechanical properties, the stress distribution of the uniform porous implant geometric model in the area can be ensured to be consistent with the host bone in the actual bearing process, so as to promote the effective stress stimulation of bone growth, and is beneficial to promote the host bone to grow into the uniform porous structure area; at the same time, the non-uniform porous implant geometric model can ensure that the effective distribution of stress can meet the actual bearing strength requirement, improve the bearing safety of the porous implant, and thus ensure the safety and stability of the entire service process.

[0072] The above only discloses the preferred embodiments of the present application, and of course cannot limit the scope of the rights of the present application, so the equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A method for manufacturing a porous implant, characterized in that, include: S101. Obtain a three-dimensional model of the bone defect site, and perform finite element model construction processing based on the three-dimensional model of the bone and the simulation environment parameters to obtain a bone implant model, wherein the anisotropy of mechanical properties includes the anisotropy of the elastic modulus and the yield strength of the bone. S102. Perform uniform porous processing on the porous structure region in the bone implant model that is in contact with the host bone to adapt to the host bone performance, so as to obtain a mapping relationship database of the anisotropy coefficient of the mechanical properties of porous lattice units and geometric characteristic parameters, as well as a uniform porous implant geometric model adapted to the mechanical properties of the host bone. S103. Determine the non-uniform porous structure region in the bone implant model based on the geometric model of the uniform porous implant, and import the preset material performance parameters into the non-uniform porous structure region for optimization calculation to obtain the stress distribution result of the non-uniform porous structure region. 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 region meets the preset constraint conditions. If the determination is yes, proceed to step S105. If the determination is no, filter out the distribution regions that do not meet the constraint conditions and adjust their material performance parameters, then return to step S103. S105. Based on the distribution results of material property parameters in the non-uniform porous structure region, the corresponding geometric feature parameters are selected from the mapping relationship database of the anisotropy coefficient of the mechanical properties of the porous lattice unit and the geometric feature parameters to reconstruct the geometric model of the non-uniform porous implant. S106. The bone implant geometric model composed of the uniform porous implant geometric model and the non-uniform porous implant geometric model is subjected to 3D printing to obtain a porous implant.

2. The method for manufacturing a porous implant according to claim 1, characterized in that, The steps for obtaining a three-dimensional model of the bone at the bone defect site include: Medical imaging technology is used to obtain skeletal 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 based on the three-dimensional bone model and simulation environment parameters to obtain a bone implant model includes: An initial model construction process is performed based on the 3D skeletal model to construct an initial bone implant model, wherein the initial model construction process includes surface smoothing and precise surface fitting and solidification. The initial bone implant model was adjusted using anisotropic finite element analysis and the simulation environment parameters to obtain the final bone implant model.

4. The method for manufacturing a porous implant according to claim 1, characterized in that, Step S102 includes: The geometric characteristic parameters of the porous lattice units in the porous structure region that contacts the host bone in the bone implant model are adjusted to construct the mapping relationship between the anisotropy coefficient of the mechanical properties of the porous lattice units and the geometric characteristic parameters, and a corresponding mapping relationship database is established. During the optimization process of adjusting geometric feature parameters, it is determined whether the anisotropic parameters of elastic modulus and yield strength of the output porous lattice unit match the anisotropic parameters of mechanical properties of the host bone. If the determination is yes, a uniform porous implant geometric model that is adapted to 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 units in the porous structural region of the bone implant model that is in contact with the host bone to construct the mapping relationship between the anisotropy coefficient of the mechanical properties of the porous lattice units and the geometric characteristic parameters includes: The geometric characteristic parameters of the porous lattice units in the porous structure region of the bone implant model that contacts the host bone are adjusted to output different anisotropic parameters of elastic modulus and yield strength of the porous lattice units. The elastic modulus anisotropic parameter is determined by the stiffness matrix […]. C The yield strength anisotropy parameter is characterized by the strength matrix [ ]. σ To represent; According to the elastic stiffness matrix of the porous lattice unit [ C The anisotropy coefficient of the elastic modulus of the porous lattice unit was calculated. f e And establish the anisotropy coefficient of the elastic modulus of porous lattice units. f e With geometric feature parameter set x i Relationship functions: f e = F ep ( x 1, x 2, …, x i , …, x n ), wherein, the F ep This is the control function for the elastic modulus performance. x n For the first n One geometric feature parameter, n It is a positive integer; According to the yield strength matrix of the porous lattice unit [ σ The anisotropy coefficient of the yield strength of the porous lattice unit was calculated. f σ And establish the anisotropy coefficient of yield strength of porous lattice unit f σ With geometric feature parameter set x i Relationship functions: f σ = F eσ ( x 1, x 2, …, x i , …, x n ), wherein, the F eσ This is the control function for yield strength performance.

6. The method for manufacturing a porous implant according to claim 5, characterized in that, The elastic stiffness matrix based on the porous lattice unit [ C Calculate the elastic modulus anisotropy coefficient of the porous lattice unit. f e The steps include: According to the elastic stiffness matrix of the porous lattice unit [ C Calculate the spatial distribution of the elastic modulus and the extreme range of the spatial distribution of the elastic modulus. E min , E max The anisotropy coefficient of the elastic modulus of the porous lattice unit was analyzed using Zener coefficients. f e ; The yield strength matrix of the porous lattice unit [ σ The anisotropy coefficient of the yield strength of the porous lattice unit was calculated. f σ The steps include: According to the yield strength matrix of the porous lattice unit [ σ The spatial distribution of yield strength is calculated, and the anisotropy coefficient of the yield strength of the porous lattice unit is calculated based on the maximum and minimum values ​​of the spatial distribution of yield strength. f σ .

7. The method for manufacturing a porous implant according to claim 6, characterized in that, The step of determining whether the anisotropy parameters of the elastic modulus and yield strength of the output porous lattice unit match the anisotropy parameters of the mechanical properties of the host bone includes: The percentage difference between the mean extreme values ​​of elastic modulus and the mean extreme values ​​of elastic modulus between the porous lattice unit and the host bone, the percentage difference between the variances of the extreme values ​​of elastic modulus, and the coefficient of elastic modulus anisotropy are determined. f e Whether the percentage difference is within the preset percentage range, and whether the mean extreme yield strength, variance of extreme yield strength, and anisotropy coefficient of the yield strength of the porous lattice unit are all within the preset percentage range. f σ Whether all values ​​are higher than the mean extreme yield strength of the host bone, the variance of the extreme yield strength, and the coefficient of yield strength anisotropy. f σ If the condition is met, it means that the two are successfully matched; otherwise, it means that the two are not matched.

8. The method for manufacturing a porous implant according to claim 1, characterized in that, The step of determining whether the stress distribution result of the non-uniform porous structure region meets the preset constraint conditions includes: The stress data of each porous lattice unit can be obtained from the stress distribution results of the porous structure region. Determine whether each 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. If the determination is yes, it indicates that the stress distribution of the non-uniform porous structure region meets the preset constraint conditions. If the determination is no, it indicates that the non-uniform porous structure region does not meet the preset constraint conditions.

9. The method for manufacturing a porous implant according to claim 8, characterized in that, The step of screening out distribution regions that do not meet the constraints and adjusting their material property parameters includes: The porous lattice units that do not meet the constraints are selected, and a preset elastic modulus parameter is added to their current elastic modulus parameter to obtain the current adjusted elastic modulus parameter. Output the filtered porous lattice units and their currently adjusted material property parameters.

10. The method for manufacturing a porous implant according to claim 1, characterized in that, The porous lattice unit structure in the bone implant geometric model includes solid feature geometric configuration units and implicit function controlled surface units. The length, width and height of the porous lattice unit range from 1 to 5 mm, the pore size ranges from 100 to 1000 μm, and the porosity ranges from 0 to 90%.

Images