A preparation method and system of a self-stable intervertebral cage based on 3D printing

Abstract

The application relates to the technical field of intervertebral fusion cages, and particularly discloses a preparation method and system of a self-stabilizing intervertebral fusion cage based on 3D printing, which comprises the following steps: obtaining medical image data of a target patient; reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data; performing finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution nephogram; dividing functional zones according to the stress distribution nephogram, wherein the functional zones comprise a high-stress support zone, a bone ingrowth induction zone and a critical transition zone; configuring differentiated hole structures for the functional zones, and setting a self-stabilizing structure at the junctions of the functional zones to generate a three-dimensional digital model of the self-stabilizing intervertebral fusion cage; and performing 3D printing based on the three-dimensional digital model to obtain the self-stabilizing intervertebral fusion cage. Through personalized modeling, mechanics simulation functional zone division, multi-target optimization hole structure and self-stabilizing design, the application solves the problems of insufficient mechanical stability and poor bioactivity of existing intervertebral fusion cages.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intervertebral fusion cage, in particular to a preparation method and system of a self-stable intervertebral fusion cage based on 3D printing. BACKGROUND

[0002] Intervertebral fusion is a key means for treating spinal degenerative diseases (such as intervertebral disc herniation and spondylolisthesis), and its efficacy is closely related to the structural design of the intervertebral fusion cage and the implant stability. At present, the intervertebral fusion cages commonly used in clinical practice are mostly made of metal materials such as titanium alloy, and the biocompatibility is improved by designing a porous structure, but the existing preparation methods still have the following problems: on the one hand, the standardization design has low matching degree with the individual anatomical morphology of the patient, which leads to loose fitting with the bone surface after implantation and easy early loosening; on the other hand, the internal pore structure is single, which has problems such as insufficient support and obvious stress shielding. SUMMARY

[0003] In order to overcome the above technical problems in the prior art, the embodiments of the present application provide a preparation method and system of a self-stable intervertebral fusion cage based on 3D printing.

[0004] In a first aspect, the embodiments of the present application provide a preparation method of a self-stable intervertebral fusion cage based on 3D printing, which comprises:

[0005] obtaining medical image data of a target patient;

[0006] reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data;

[0007] performing finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution cloud map;

[0008] dividing functional zones according to the stress distribution cloud map, wherein the functional zones include high-stress support zones, bone ingrowth induction zones and critical transition zones;

[0009] configuring differentiated pore structures for each of the functional zones based on a multi-objective optimization model, and setting a self-stable structure at the junction of each of the functional zones to generate a three-dimensional digital model of the self-stable intervertebral fusion cage;

[0010] performing 3D printing based on the three-dimensional digital model to obtain a self-stable intervertebral fusion cage.

[0011] Preferably, the medical image data includes CT images and MRI images, and reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data comprises:

[0012] registering the CT images and the MRI images;

[0013] extracting bone tissue features from the registered CT image and extracting soft tissue features from the registered MRI image, and fusing the bone tissue features and the soft tissue features;

[0014] inputting the registered CT image, the registered MRI image and the fused features into a preset segmentation model to obtain an initial personalized intervertebral three-dimensional geometric model;

[0015] post-processing the initial personalized intervertebral three-dimensional geometric model to obtain a personalized intervertebral three-dimensional geometric model.

[0016] Preferably, the segmentation model comprises an input layer, a plurality of encoding layers, a plurality of decoding layers and an output layer, and an output end of an i-th encoding layer is connected to input ends of an i-th decoding layer and an i+1-th decoding layer.

[0017] Preferably, a differentiated pore structure is configured for each of the functional areas based on a multi-objective optimization model, comprising:

[0018] configuring a pore structure configuration for each of the functional areas;

[0019] obtaining stress target constraints and biological target constraints for each of the functional areas;

[0020] taking pore structure parameters of each of the functional areas as optimization variables, and constructing a multi-objective optimization model comprising a stress target function and a biological target function, the pore structure parameters comprising porosity, pore size, pore wall thickness and connectivity;

[0021] solving the multi-objective optimization model by using a multi-objective optimization algorithm to obtain optimal pore structure parameters;

[0022] determining a pore structure based on the optimal pore structure parameters and the pore structure configuration.

[0023] Preferably, a 3D printing is performed based on the three-dimensional digital model to obtain a self-stable intervertebral cage, comprising:

[0024] performing layer slicing processing on the three-dimensional digital model to generate a printing layer;

[0025] configuring a printing parameter set for each of the printing layers, the printing parameter set comprising a scanning path strategy, an energy density parameter and a preset interlayer temperature;

[0026] performing 3D printing according to the scanning path strategy and the energy density parameter;

[0027] monitoring a current printing layer surface temperature in real time;

[0028] comparing the surface temperature with the preset interlayer temperature, and performing temperature compensation control according to a comparison result;

[0029] Repeat the above steps until the last layer is printed, and an intervertebral cage embryo is obtained.

[0030] Preferably, the surface temperature is compared with a preset interlayer temperature, and temperature compensation control is performed according to the comparison result, including:

[0031] The energy density compensation amount of the next layer is calculated based on the temperature deviation of the surface temperature and the preset interlayer temperature;

[0032] The energy density of the next layer is corrected based on the energy density compensation amount;

[0033] The next layer printing is performed based on the corrected energy density.

[0034] Preferably, the 3D printing is performed based on the three-dimensional digital model to obtain a self-stable intervertebral cage, and further includes:

[0035] The intervertebral cage embryo is pretreated, and the pretreatment includes ultrasonic cleaning and surface strengthening;

[0036] The pretreated intervertebral cage is subjected to micropore etching;

[0037] The pretreated intervertebral cage embryo is subjected to biomimetic mineralization treatment to obtain a self-stable intervertebral cage.

[0038] Preferably, the pretreated intervertebral cage is subjected to micropore etching, including:

[0039] The pretreated intervertebral cage is analyzed to determine the pore depth and the shielding condition;

[0040] A laser etching strategy is generated according to the pore depth and the shielding condition;

[0041] The pretreated intervertebral cage embryo is subjected to micropore etching based on the laser etching strategy;

[0042] The micropore etching result is analyzed to determine the micropore coverage rate;

[0043] When the micropore coverage rate does not meet a preset coverage rate, the laser etching strategy is updated and re-etched

[0044] In a second aspect, an embodiment of the present application provides a self-stable intervertebral cage preparation system based on 3D printing, including:

[0045] A data acquisition module is configured to acquire medical image data of a target patient;

[0046] A geometric model construction module is configured to reconstruct a personalized intervertebral three-dimensional geometric model based on the medical image data;

[0047] a stress simulation module, which performs finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution chart;

[0048] a functional area division module, which divides functional areas according to the personalized intervertebral three-dimensional geometric model, the stress distribution chart and a preset bone tissue biological activity requirement map, the functional areas including a high stress support area, a bone ingrowth induction area and a critical transition area;

[0049] a digital model construction module, which configures differentiated pore structures for each functional area based on a multi-objective optimization model, and sets a self-stabilizing structure at the junction of each functional area to generate a three-dimensional digital model of the self-stabilizing intervertebral cage;

[0050] a 3D printing module, which performs 3D printing based on the three-dimensional digital model to obtain the self-stabilizing intervertebral cage.

[0051] In a third aspect, the embodiments of the present application also provide a computer readable storage medium, which stores the method as described in any one of the above embodiments.

[0052] Through the technical solutions provided by the present application, the present application has at least the following technical effects:

[0053] Through personalized modeling and differentiated design of functional area pore structures, the biological activity and mechanical properties of the self-stabilizing intervertebral cage are improved, the fit of the self-stabilizing cage with the bone surface is significantly improved, and the risk of early loosening is reduced.

[0054] Other features and advantages of the embodiments of the present application will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF DRAWINGS

[0055] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific implementation part to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0056] Figure 1 is a flowchart of a self-stabilizing intervertebral cage preparation method based on 3D printing provided by the embodiments of the present application;

[0057] Figure 2 is a structural schematic diagram of a personalized porous structure self-stabilizing intervertebral cage preparation system based on 3D printing provided by the embodiments of the present application. DETAILED DESCRIPTION

[0058] The specific implementation of the embodiments of the present application is described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiments of the present application, and is not used to limit the embodiments of the present application.

[0059] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "Multiple" means two or more, and in view of this, "multiple" can also be understood as "at least two" in the embodiments of the present application. "And / or", which describes the association relationship of the associated objects, means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / ", if not specially stated, generally represents that the associated objects before and after it are in an "or" relationship. In addition, it should be understood that in the description of the embodiments of the present application, "first", "second", etc. are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating or implying order.

[0060] The traditional intervertebral fusion cage adopts standardized design, and the matching degree with the individual anatomic morphology of the patient is low, which leads to that the intervertebral fusion cage is not tightly fitted with the bone surface after implantation, and early loosening is prone to occur; the internal hole structure is single, and problems such as insufficient support and collapse or stress shielding exist.

[0061] Based on the above reasons, please refer to Figure 1 The embodiments of the present application provide a preparation method of a self-stable intervertebral fusion cage based on 3D printing, which comprises the following steps: acquiring medical image data of a target patient; reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data; performing finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution cloud diagram; dividing functional zones according to the stress distribution cloud diagram, wherein the functional zones include a high-stress support zone, a bone ingrowth induction zone and a critical transition zone; configuring differentiated hole structures for each of the functional zones based on a multi-objective optimization model, and setting a self-stable structure at the junction of each of the functional zones to generate a three-dimensional digital model of the self-stable intervertebral fusion cage; and performing 3D printing based on the three-dimensional digital model to obtain the self-stable intervertebral fusion cage.

[0062] In a possible implementation, medical image data of an intervertebral space of a patient is collected by a CT or MRI device; a personalized three-dimensional geometric model of the intervertebral space that completely matches the medical image data is reconstructed by using Mimics / 3D Slicer software; finite element simulation is performed based on the personalized three-dimensional geometric model of the intervertebral space, and a plurality of working conditions of a human lumbar vertebra are input into a finite element simulation software, for example, forward flexion 15° / backward extension 10° / lateral flexion 10°, load 200-500 N, to simulate stress distribution of a fusion cage-bone tissue, and a stress distribution cloud chart is generated; the intervertebral fusion cage is divided into a high-stress support area, a bone ingrowth induction area, and a critical transition area according to the stress cloud chart, low porosity (30-40%) and small pore size (200-300 μm) structures are configured for the high-stress support area to ensure strength, high porosity (60-70%) and large pore size (400-600 μm) structures are configured for the bone ingrowth induction area to promote bone ingrowth, and a porosity gradient (30-70%) is set in the transition area to avoid stress concentration; and barbs / mortise microstructures are designed at the junctions of the functional areas to enhance the bonding strength of different areas, so as to obtain a three-dimensional digital model of the self-stabilizing intervertebral fusion cage, and finally the self-stabilizing intervertebral fusion cage is printed by using a laser selective melting technology based on the three-dimensional digital model.

[0063] The embodiment significantly improves the fit of the self-stabilizing fusion cage and the bone surface and reduces the risk of early loosening by personalized modeling and differential design of the pore structures of the functional areas.

[0064] A single CT image can only show the outline of bone tissue and cannot reflect the distribution of surrounding soft tissues such as ligaments and nerves; a single MRI image can show soft tissues but the boundary of bone tissue is blurred. A personalized three-dimensional geometric model of the intervertebral space reconstructed only by using CT image data or only by using MRI image data may cause a conflict between the self-stabilizing intervertebral fusion cage and the surrounding soft tissues, increasing the risk of surgical damage. Therefore, the embodiment of the present application provides a method for reconstructing a model based on CT image data and MRI image data.

[0065] In the embodiment of the present application, the medical image data includes CT images and MRI images, and the personalized three-dimensional geometric model of the intervertebral space is reconstructed based on the medical image data, which includes: registering the CT images and the MRI images; extracting bone tissue features from the registered CT images and extracting soft tissue features from the registered MRI images, and fusing the bone tissue features and the soft tissue features; inputting the registered CT images, the registered MRI images, and the fused features into a preset segmentation model to obtain an initial personalized three-dimensional geometric model of the intervertebral space; and post-processing the initial personalized three-dimensional geometric model of the intervertebral space to obtain a personalized three-dimensional geometric model of the intervertebral space.

[0066] In a possible implementation, first, the CT image and the MRI image are spatially registered, and then bone tissue features such as cortical features and cancellous bone features are extracted from the registered CT image, and soft tissue features such as dural sac features and nerve root features are extracted from the registered MRI image; the bone tissue features and the soft tissue features are fused through Boolean operation, and the fused features are input into a segmentation model such as U-Net to generate an initial three-dimensional model; finally, the initial three-dimensional model is optimized through morphological filtering and surface smoothing to obtain a high-precision personalized intervertebral three-dimensional geometric model.

[0067] The embodiment solves the problem of "missing bone-soft tissue relationship" caused by single image data, avoids the spatial conflict between the fusion cage and the nerve / ligament caused by the blurred model boundary, and reduces the pain caused by the implant compression of soft tissue after the operation.

[0068] However, in actual application, the traditional U-Net segmentation model only extracts features through a single layer of encoder-decoder connection, and the detail capturing capability for the complex intervertebral anatomical structure is insufficient, which leads to a large deviation between the generated model after segmentation and the actual anatomical structure.

[0069] In the embodiment of the application, the segmentation model includes an input layer, a multi-level encoder, a multi-level decoder, and an output layer, and the output end of the i th layer encoder is connected to the input ends of the i th layer decoder and the i+1 th layer decoder.

[0070] In a possible implementation, the input layer inputs the registered CT image, the registered MRI image, and the fused features respectively, the multi-level encoder (3 layers) extracts edge contour, texture details, and global structure features in sequence, the multi-level decoder (3 layers) restores the resolution through deconvolution + upsampling and fuses the local features of the adjacent layer encoders and the global features of the upper layer decoder, and the output layer generates a segmentation probability map through a Softmax activation function, and finally obtains a high-precision personalized three-dimensional model.

[0071] For example, in the edge segmentation of the intervertebral disc annulus fibrosus, the first layer (256x256) of the encoder extracts the edge details of the annulus fibrosus to generate an intermediate feature map F1, the second layer (128x128) of the encoder extracts the local structure (such as the annular trend) of the annulus fibrosus to generate an intermediate feature map F2, and the second layer of the decoder restores the resolution (128x128→256x256) while fusing not only the F2 of the same level but also the F1 from the first layer of the encoder (through nested connection), so that the edge details are retained at a high resolution; finally, the segmentation result (256x256) contains both "edge details" (from F1) and "structure semantics" (from F2), and the segmentation accuracy of the annulus fibrosus edge is improved.

[0072] The segmentation model of the embodiment adopts a multi-level encoder-decoder structure, improves the segmentation accuracy of complex anatomical structures, reduces the design deviation of the corresponding three-dimensional digital model of the self-stable interbody fusion cage caused by the loss of details of the personalized intervertebral three-dimensional geometric model, and reduces the risk of surgical implant failure caused by inaccurate three-dimensional digital models.

[0073] In the embodiment of the application, the differential pore structure is configured for each of the functional zones, including: configuring a pore structure configuration for each of the functional zones; obtaining stress target constraints and biological target constraints for each of the functional zones; taking pore structure parameters of each of the functional zones as optimization variables, constructing a multi-objective optimization model containing a stress target function and a biological target function, the pore structure parameters including porosity, pore size, pore wall thickness and connectivity; solving the multi-objective optimization model by using a multi-objective optimization algorithm to obtain optimal pore structure parameters; and determining the pore structure based on the optimal pore structure parameters and the pore structure configuration.

[0074] In a possible implementation, the high-stress support zone adopts a 45° / 135° orthogonal honeycomb pore configuration; the bone ingrowth induction zone adopts a randomly distributed porous configuration; and the critical transition zone adopts a honeycomb pore configuration with a gradient change in pore size. By adopting a 45° / 135° orthogonal honeycomb pore in the high-stress support zone, dynamic load is dispersed by using the regular arrangement, and high strength is maintained to meet the support requirement. By adopting a randomly distributed porous configuration in the bone ingrowth induction zone, the irregular pore environment of natural bone is simulated to promote the multi-directional ingrowth and integration of bone tissue. By adopting a honeycomb pore configuration with a gradient change in pore size in the critical transition zone, the smooth transition of mechanical properties and biological activity is achieved by linearly changing the pore size and porosity, and the interface stress concentration is avoided and the structural continuity is enhanced. Further, for each of the functional zones, stress target constraints and biological target constraints are obtained; the stress target constraints include but are not limited to a stress concentration coefficient threshold and a mechanical strength threshold; the biological target constraints include but are not limited to a bone ingrowth rate threshold, a pore size threshold, and a connectivity threshold; and the pore structure parameters include porosity (P), pore size (D), and connectivity (C). A multi-objective optimization model containing a stress target function and a biological target function is constructed; the stress target function is a stress concentration coefficient minimization function, and the expression is: wherein, is the maximum stress of the functional zone pore edge, is the average stress of the functional zone; and the biological target function is a bone ingrowth rate maximization function, and the expression is wherein, is the weight coefficient of the experiment calibration, The optimal pore diameter is best for bone ingrowth; the multi-objective optimization algorithm is used to solve the multi-objective optimization model to obtain a Pareto optimal solution set satisfying all constraint conditions, wherein the multi-objective optimization algorithm is a non-dominated sorting genetic algorithm or a multi-objective particle swarm optimization algorithm; and then, according to the core requirements of the self-stable intervertebral fusion cage in clinic, the optimal solution, i.e., the optimal pore structure parameters, is determined.

[0075] The multi-objective optimization model is used to design the pore structure parameters, and the synergistic promotion of mechanical support and biological activity is realized.

[0076] After the three-dimensional digital model for printing is determined, the 3D printing of the intervertebral fusion cage can be performed; when the self-stable intervertebral fusion cage is printed, the SLM printing process is usually selected for 3D printing; however, the conventional SLM printing usually adopts a fixed layer thickness, which can cause obvious step effect on the surface of the printing layer; in addition, the conventional SLM printing does not have temperature compensation, and the temperature fluctuation between layers is large, which can cause poor fusion effect between layers and reduce the mechanical properties of the self-stable intervertebral fusion cage.

[0077] In the embodiment of the present application, the 3D printing is performed based on the three-dimensional digital model to obtain the self-stable intervertebral fusion cage, which comprises: performing layering and slicing processing on the three-dimensional digital model to generate a printing layer; configuring a printing parameter set for each printing layer, wherein the printing parameter set comprises a scanning path strategy, an energy density parameter and a preset interlayer temperature; performing 3D printing according to the scanning path strategy and the energy density parameter; monitoring the surface temperature of the current printing layer in real time; comparing the surface temperature with the preset interlayer temperature, and performing temperature compensation control according to the comparison result; repeating the above steps until the last layer is printed, and obtaining the intervertebral fusion cage blank.

[0078] In a possible implementation, a first layer thickness and a second layer thickness are set, the first layer thickness is a multiple of the second layer thickness, the three-dimensional digital model is subjected to preliminary slicing processing according to the first layer thickness to obtain a plurality of initial printing layers, an edge profile of the initial printing layer is obtained, and surface complexity analysis is performed on the edge profile. When the surface complexity is greater than a set surface complexity, the initial printing layer is subjected to slicing processing according to the second layer thickness. Then, printing parameter configuration is performed according to the layer thickness and a functional area. The scanning path strategy is configured as follows: the high-stress support area adopts an orthogonal 45° / 135° cross scanning strategy to enhance isotropy, the bone ingrowth induction area adopts random scanning to simulate the direction of bone trabeculae, and the critical transition area also adopts an orthogonal 45° / 135° cross scanning strategy, but the honeycomb holes gradually become sparse and the hole walls gradually become thick during the scanning process, forming honeycomb holes with gradually changing size gradients. A possible configuration parameter is as follows: the high-stress support area has a laser power of 14 W and a speed of 700 mm / s, the bone ingrowth induction area has a laser power of 10 W and a speed of 900 mm / s, and the critical transition area has a laser power decreasing from 14 W to 10 W and a speed increasing from 700 mm / s to 900 mm / s. Further, in order to ensure the fusion effect between layers, a preset interlayer temperature is also needed. The high-stress support area needs a higher temperature to ensure support force, and the bone ingrowth induction area needs a relatively lower temperature to ensure support force and vitality. The temperature of the critical transition area is smoothly transitioned, and the corresponding preset interlayer temperature is set based on this. The current layer surface temperature is monitored in real time by an infrared thermal imager. If the temperature deviates from the preset value, temperature compensation is performed by adjusting the laser power or inert gas cooling. Layer-by-layer printing is performed until completion, and an intervertebral cage blank is obtained.

[0079] Further, the surface temperature is compared with the preset interlayer temperature, and temperature compensation control is performed according to the comparison result, including: calculating an energy density compensation amount of the next layer based on the temperature deviation between the surface temperature and the preset interlayer temperature; correcting the energy density of the next layer based on the energy density compensation amount; and performing printing of the next layer based on the corrected energy density.

[0080] The embodiment reduces the step effect through adaptive layering, improves the fusion effect between layers through dynamic temperature compensation, solves defects such as micro-cracks caused by interlayer temperature fluctuations, and avoids the decline in mechanical properties caused by mismatched energy density.

[0081] The surface of the 3D-printed intervertebral cage blank is covered with metal powder, and the surface is metal inert. After the intervertebral cage blank is obtained, the intervertebral cage blank needs to be processed to obtain a final self-stable intervertebral cage. However, in actual application, the self-stable intervertebral cage processed by the existing method may have ion precipitation problems during use.

[0082] In the embodiment of the present application, based on the three-dimensional digital model, 3D printing is performed to obtain a self-stable intervertebral fusion cage, and the method further comprises: pre-treating the intervertebral fusion cage embryo, wherein the pre-treatment comprises ultrasonic cleaning and surface strengthening; performing micro-hole etching on the intervertebral fusion cage after the pre-treatment; and performing biomimetic mineralization treatment on the intervertebral fusion cage embryo after the etching to obtain the self-stable intervertebral fusion cage.

[0083] In a possible implementation, a multi-frequency ultrasonic cleaning process is used to clean the intervertebral fusion cage embryo in a mixed solution of deionized water and a biocompatible surfactant, and through cavitation effect, the surface residual metal powder and the attached printing slag are completely stripped, while surface corrosion caused by traditional strong acid cleaning is avoided; by argon / oxygen plasma bombarding the surface of the embryo, a nanoscale oxide film is formed on the titanium alloy metal surface to enhance the surface corrosion resistance, which not only inhibits ion precipitation, but also improves the subsequent coating adhesion. The intervertebral fusion cage embryo is pre-treated by ultrasonic cleaning, and then etched with micro-holes, in the high stress support area, a shallow hole with a pore size of 10-30 μm and a depth of ≤20 μm is generated by laser energy density of 20-25 J / cm2 and scanning pitch of 0.10 mm, to avoid weakening the structural strength, in the bone ingrowth induction area, a deep hole with a pore size of 30-60 μm and a depth of 30-50 μm is generated by laser energy density of 25-30 J / cm2 and scanning pitch of 0.05 mm, to increase cell adhesion sites, and then biomimetic mineralization treatment is performed, the etched intervertebral fusion cage embryo is immersed in a solution simulating human body fluid, the solution is a standard simulated body fluid with additional ions such as magnesium and silicon contained in human bone, and the solution is continuously and slowly stirred in a constant temperature water bath at a temperature close to human body temperature, so that calcium and phosphorus ions in the solution gradually deposit on the surface of the embryo to form a hydroxyapatite coating similar to bone composition; finally, drying is performed in a low-temperature vacuum environment of 40-50°C to prevent the coating from cracking due to high temperature, and a dense and uniform bioactive layer is formed on the surface of the intervertebral fusion cage embryo.

[0084] The embodiment solves the inflammation reaction caused by the surface residual powder in the traditional processing method, the bone fusion delay caused by the metal surface inertness, and the risk of metal ion precipitation.

[0085] In the actual laser etching process, since the holes in the bone ingrowth area are random hole structures, some of the functions of the holes are blind holes, which causes the laser to be unable to directly irradiate some areas, thereby forming a blind area of micro-holes. In addition, in the gradient change honeycomb holes in the critical transition area, if the spacing between adjacent holes is too small, the laser incidence angle may be blocked by the adjacent holes, and the target hole wall cannot be reached.

[0086] In the embodiment of the present application, the micropore etching is performed on the pretreated intervertebral fusion cage, including: analyzing the pretreated intervertebral fusion cage to determine the channel depth and the shielding condition; generating a laser etching strategy according to the channel depth and the shielding condition; performing micropore etching on the pretreated intervertebral fusion cage blank based on the laser etching strategy; analyzing the micropore etching result to determine the micropore coverage; and updating the laser etching strategy and re-etching when the micropore coverage does not meet the preset coverage.

[0087] In a possible implementation, for the relatively regular honeycomb holes in the high-stress support area, a combined path of vertical scanning + 45° oblique scanning is adopted, for example, vertical incidence along the X / Y axis, and then incidence along the X+45° / Y+45° direction, and for the random porous structure, the laser incidence angle is adjusted by a 3D dynamic focusing system to bypass the blind angle area, thereby increasing the micropore coverage. Further, for the channels with a depth greater than a preset depth, a layered etching strategy is adopted, and the deeper the depth, the higher the energy density during laser etching.

[0088] The embodiment effectively provides the micropore coverage by means of multi-directional scanning and layered etching.

[0089] Please refer to Figure 2 The embodiment of the present application provides a self-stable intervertebral fusion cage preparation system based on 3D printing, which comprises: a data acquisition module configured to acquire medical image data of a target patient; a geometric model construction module configured to reconstruct a personalized intervertebral three-dimensional geometric model based on the medical image data; a stress simulation module configured to perform finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution chart; a functional area division module configured to divide functional areas according to the personalized intervertebral three-dimensional geometric model and the stress distribution chart, and a preset bone tissue biological activity requirement map, wherein the functional areas include a high-stress support area, a bone ingrowth induction area, and a critical transition area; a digital model construction module configured to configure a differentiated pore structure for each functional area based on a multi-objective optimization model, and set a self-stable structure at the junction of each functional area to generate a three-dimensional digital model of the self-stable intervertebral fusion cage; and a 3D printing module configured to perform 3D printing based on the three-dimensional digital model to obtain the self-stable intervertebral fusion cage.

[0090] It should be understood that the embodiment of the present application provides a preparation system of a personalized porous structure self-stable intervertebral fusion cage based on 3D printing, and the preparation method of the self-stable intervertebral fusion cage based on 3D printing provided in the above embodiment is based on the same inventive concept, and the more specific working principles of each module in the embodiment of the present application can be referred to the above embodiment, which will not be described herein.

[0091] The embodiment of the present application further provides a computer readable storage medium, which stores the method executed by the processor when running.

[0092] The optional implementation of the embodiment of the present application is described in detail above in combination with the drawings, but the embodiment of the present application is not limited to the specific details in the above implementation, and various simple modifications can be made to the technical solution of the embodiment of the present application within the technical concept range of the embodiment of the present application, and these simple modifications all belong to the protection range of the embodiment of the present application.

[0093] In addition, it should be noted that each specific technical feature described in the above specific implementation can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the embodiment of the present application.

[0094] Those skilled in the art can understand that all or part of the steps of the methods described in the above embodiments can be completed by using programs instructing related hardware, the programs are stored in a storage medium, and the programs include a plurality of instructions for making a single-chip microcomputer, a chip or a processor execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk and various storage medium capable of storing program codes.

[0095] In addition, various different implementations of the embodiment of the present application can also be combined in any manner, as long as it does not deviate from the idea of the embodiment of the present application, and it should be considered as the disclosed content of the embodiment of the present application.

Claims

1. A method for preparing a self-stable intervertebral cage based on 3D printing, characterized in that, The method comprises the following steps: obtaining medical image data of a target patient; reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data; performing finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution cloud chart; dividing functional zones according to the stress distribution cloud chart, wherein the functional zones include a high stress support zone, a bone ingrowth induction zone, and a critical transition zone; configuring differentiated pore structures for each of the functional zones based on a multi-objective optimization model, and setting a self-stabilizing structure at the junction between each of the functional zones to generate a three-dimensional digital model of the self-stabilizing intervertebral fusion cage; performing 3D printing based on the three-dimensional digital model to obtain the self-stabilizing intervertebral fusion cage; wherein configuring differentiated pore structures for each of the functional zones based on a multi-objective optimization model comprises: configuring pore structure configurations for each of the functional zones according to the types of the functional zones, wherein the high stress support zone adopts an orthogonal honeycomb pore configuration, the bone ingrowth induction zone adopts a randomly distributed porous configuration, and the critical transition zone adopts a honeycomb pore configuration with a gradient change in pore size; obtaining stress target constraints and biological target constraints for each of the functional zones; taking pore structure parameters of each of the functional zones as optimization variables to construct a multi-objective optimization model containing stress target functions and biological target functions, wherein the pore structure parameters include porosity, pore size, pore wall thickness, and connectivity; solving the multi-objective optimization model using a multi-objective optimization algorithm to obtain optimal pore structure parameters; determining pore structures based on the optimal pore structure parameters and the pore structure configurations.

2. The method of claim 1, wherein the self-stable 3D-printed intervertebral cage is prepared by the steps of: The medical image data includes CT images and MRI images, and reconstructing a personalized intervertebral three-dimensional geometric model based on the medical image data comprises: registering the CT images and the MRI images; extracting bone tissue features from the registered CT images and soft tissue features from the registered MRI images, and fusing the bone tissue features and the soft tissue features; inputting the registered CT images, the registered MRI images, and the fused features into a pre-set segmentation model to obtain an initial personalized intervertebral three-dimensional geometric model; post-processing the initial personalized intervertebral three-dimensional geometric model to obtain a personalized intervertebral three-dimensional geometric model.

3. The method for fabricating a self-stabilizing interbody fusion device based on 3D printing according to claim 2, characterized in that, The segmentation model includes an input layer, multiple levels of encoders, multiple levels of decoders, and an output layer, and the output end of the i-th level of encoder is connected to the input ends of the i-th level of decoder and the i+1-th level of decoder.

4. The method for fabricating a self-stabilizing interbody fusion device based on 3D printing according to claim 1, characterized in that, Performing 3D printing based on the three-dimensional digital model to obtain the self-stabilizing intervertebral fusion cage comprises: performing layering and slicing processing on the three-dimensional digital model to generate printing layers; configuring a printing parameter set for each of the printing layers, wherein the printing parameter set includes a scanning path strategy, an energy density parameter, and a pre-set interlayer temperature; performing 3D printing according to the scanning path strategy and the energy density parameter; monitoring the surface temperature of the current printing layer in real time; comparing the surface temperature with the pre-set interlayer temperature and performing temperature compensation control according to the comparison result; repeating the above steps until the last layer is printed to obtain an intervertebral fusion cage blank.

5. The method for fabricating a self-stabilizing interbody fusion device based on 3D printing according to claim 4, characterized in that, Comparing the surface temperature with the pre-set interlayer temperature and performing temperature compensation control according to the comparison result comprises: calculating an energy density compensation amount of the next layer based on a temperature deviation of the surface temperature from a preset interlayer temperature; correcting the energy density of the next layer based on the energy density compensation amount; performing printing of the next layer based on the corrected energy density.

6. The method of claim 4, wherein the self-stable 3D-printed intervertebral cage is prepared by the steps of: performing 3D printing based on the three-dimensional digital model to obtain the self-stable intervertebral fusion cage, further comprising: preprocessing the intervertebral fusion cage blank, the preprocessing including ultrasonic cleaning and surface strengthening; performing micropore etching on the preprocessed intervertebral fusion cage; performing biomimetic mineralization processing on the etched intervertebral fusion cage blank to obtain the self-stable intervertebral fusion cage.

7. The method for fabricating a self-stabilizing interbody fusion device based on 3D printing according to claim 6, characterized in that, performing micropore etching on the preprocessed intervertebral fusion cage, comprising: analyzing the preprocessed intervertebral fusion cage to determine the pore depth and the shielding condition; generating a laser etching strategy according to the pore depth and the shielding condition; performing micropore etching on the preprocessed intervertebral fusion cage blank based on the laser etching strategy; analyzing the micropore etching result to determine the micropore coverage rate; when the micropore coverage rate does not meet a preset coverage rate, updating the laser etching strategy and re-etching.

8. A 3D printing based self-stable intervertebral cage preparation system suitable for the method of any one of claims 1-7, characterized in that, The system comprises: a data acquisition module configured to acquire medical image data of a target patient; a geometric model construction module configured to reconstruct a personalized intervertebral three-dimensional geometric model based on the medical image data; a stress simulation module configured to perform finite element mechanics simulation based on the personalized intervertebral three-dimensional geometric model to generate a stress distribution chart; a functional area division module configured to divide functional areas according to the personalized intervertebral three-dimensional geometric model and the stress distribution chart, and a preset bone tissue biological activity requirement map, the functional areas including a high stress support area, a bone ingrowth induction area, and a critical transition area; a digital model construction module configured to configure a differentiated pore structure for each functional area based on a multi-objective optimization model, and set a self-stable structure at the junction of each functional area to generate a three-dimensional digital model of the self-stable intervertebral fusion cage; a 3D printing module configured to perform 3D printing based on the three-dimensional digital model to obtain the self-stable intervertebral fusion cage.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores, and the processor executes, the method of any one of claims 1 to 7 when running. The computer readable storage medium stores, and the processor executes, the method of any one of claims 1 to 7 when running.

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