Interbody fusion cage based on Thiessen polygon gradient porous structure
By employing the Tyson polygonal gradient porous structure design and cleaning process, the problems of low bone fusion efficiency and high stress shielding risk during the bone fusion process of interbody fusion devices have been solved, achieving rapid bone integration and improved safety, and adapting to the personalized needs of different patients.
Patent Information
- Application Number
- CN202512033873.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-02-06
AI Technical Summary
Existing interbody fusion devices suffer from problems such as low bone fusion efficiency, high risk of stress shielding, pore design that does not conform to the characteristics of human bone structure, and difficulty in simultaneously meeting the needs of cell attachment and vascularization during the bone fusion process.
An interbody fusion device based on a Thiessen polygon gradient porous structure was adopted, which features a porous structure with small pores on the outer surface and large pores on the inner layer. Combined with additive manufacturing and a specific cleaning process, the pore gradient variation and biocompatibility were ensured.
It achieves rapid osseointegration, reduces the risk of inflammation, improves osseointegration efficiency and safety, and adapts to the personalized needs of different patients.
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Figure CN121465778A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of biomedical engineering and orthopedic implants, in particular to an intervertebral fusion cage based on a gradient porous structure of a Thiessen polygon. BACKGROUND
[0002] Intervertebral fusion is a core surgical procedure for treating spinal degenerative diseases, spinal instability and spinal trauma. The core goal is to restore the intervertebral height of the diseased segment, maintain the mechanical stability of the spine, and provide a support carrier for bone tissue growth, ultimately achieving bony fusion between the vertebral bodies by implanting an intervertebral fusion cage.
[0003] Currently, the intervertebral fusion cages used in clinical applications are mainly prepared by 3D printing technology, including truss structures and homogeneous porous structures. Although the truss structure has high mechanical strength, it reduces the pore space required for bone ingrowth, resulting in low bone fusion efficiency and a significant difference in elastic modulus from human cancellous bone, which can easily cause stress shielding, leading to the atrophy of surrounding bone tissue, increasing the risk of fusion cage subsidence and loosening. The homogeneous porous structure improves the bone ingrowth conditions by constructing through pores, but there are still technical contradictions that are difficult to reconcile: if a larger pore size is used, although it is beneficial for later vascularization and bone tissue penetration, the pores on the outer surface of the fusion cage are too large, which is not conducive to the initial stability of the blood clot and the rapid adhesion of osteoblasts, and the "siphon effect" is weak, resulting in slow initiation of bone integration; if a smaller pore size is used, although it can improve the surface cell adhesion, the internal pore connectivity is poor, which not only limits the nutrient transport and deep bone growth, but also makes it difficult to completely remove the residual un-melted metal powder during the 3D printing process, and these residual powders can cause chronic inflammatory reactions in the body, seriously affecting the safety of the operation; at the same time, the homogeneous porous structure fails to mimic the natural density and pore gradient characteristics of human cancellous bone from the surface to the core, and cannot meet the differentiated needs of surface cell adhesion and internal vascularization and nutrient transport, and the degree of simulation and clinical adaptability is limited. SUMMARY
[0004] The purpose of the present application is to provide an intervertebral fusion cage based on a gradient porous structure of a Thiessen polygon, which has a gradient porous structure inside the main body structure of the fusion cage based on the gradient structure of the Thiessen polygon, so that the main body structure of the fusion cage has good biocompatibility and suitable mechanical properties to solve the problems raised in the background art.
[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: an intervertebral fusion cage based on a gradient porous structure of a Thiessen polygon, comprising: a fusion cage main body structure; The main body structure of the fusion cage is a three-dimensionally connected porous structure, and the basic topological configuration of the porous structure is a Thiessen polygon, and the porous structure has a gradient change at least in the direction along its distribution from the outer surface to the inside. wherein the pore gap feature size of the outer surface region of the cage body structure is smaller than the pore gap feature size of the inner core region.
[0006] Preferably, the average pore size of the outer surface region of the cage body structure is 50-400 microns, and the average pore size of the inner core region of the cage body structure is 400-800 microns.
[0007] Preferably, the gradient variation of the porous structure is a continuous gradual variation or a stepwise variation of void size and void fraction.
[0008] Preferably, the cage body structure is integrally formed by additive manufacturing technology, and the additive material is one of medical tantalum powder and titanium powder.
[0009] Preferably, after the cage body structure is integrally formed by additive manufacturing technology, it needs to go through a post-processing cleaning process to remove un-melted metal powder, and the cleaning process includes ultrasonic cleaning, pressure fluid flushing, vacuum-pressure cycle cleaning.
[0010] Preferably, the specific process of the cleaning process is as follows: ①, pretreatment, using dry compressed gas to blow the surface of the cage and visible holes, and then immersing them in cleaning solution; ②, core deep cleaning: sequentially performing ultrasonic oscillation cleaning, pressure fluid circulation flushing, vacuum-pressure cycle immersion, and the core deep cleaning step is cycled; ③, post-processing and verification: ultrasonic rinsing with high-purity deionized water, low-temperature drying in a vacuum drying oven, and finally completing quality inspection through weight determination and microstructure observation.
[0011] Preferably, the weight of the cage body structure is synergistically regulated by the porous structure parameter design in the design stage and the process parameter control in the manufacturing stage, so as to realize the accurate control of the predetermined weight.
[0012] Based on a kind of based on Thiessen polygon gradient porous structure intervertebral fusion cage, it further includes a kind of preparation method based on Thiessen polygon gradient porous structure intervertebral fusion cage, including the following steps: S1, based on Thiessen polygon algorithm, design three-dimensional porous structure digital model with aperture gradient variation from outside to inside; S2, using metal powder, based on electron beam melting additive manufacturing technology, according to the digital model, layer by layer melting manufacturing gets cage blank; S3, cleaning the blank after support removal, to completely remove un-melted metal powder remaining in the porous structure; S4, post-processing and weight inspection are carried out on the cage body structure after cleaning.
[0013] Preferably, in step S3, the cleaning is performed by using ultrasonic assistance combined with pressure fluid circulation flushing.
[0014] Preferably, in step S1, the theoretical weight of the fusion cage is preset by adjusting the seed point distribution of the Thiessen polygon and the beam diameter parameter, and in step S2, the actual product weight is controlled to be close to the theoretical value by optimizing the process parameters, in step S1, the gradient seed points are generated by defining a continuous scalar field from the outer surface to the geometric center, then the Thiessen polygon unit is constructed based on the gradient seed point set, and finally the structure parameterization mapping is realized through aperture control, wire diameter control and porosity control to complete the design of the three-dimensional porous structure digital model.
[0015] Compared with the prior art, the present application has the following advantages: 1. By arranging the fusion cage main structure, the small hole structure of the outer layer is beneficial to the rapid entry and adhesion of blood factors and osteoblasts, and the start of osteogenesis; the large hole structure of the inner layer provides sufficient space for cell deep migration, blood vessel growth and new bone matrix deposition, and finally realizes sufficient bone integration from the outside to the inside, the structure highly imitates the natural bone trabecular network, and through the gradient porous design, the cell siphon adhesion and internal connectivity are synergistically optimized, combined with a specific post-processing process, the bone integration performance and safety of the fusion cage are improved.
[0016] 2. The Thiessen polygon gradient porous structure of the present application makes the fusion cage main structure have good biocompatibility, suitable mechanical properties (elastic modulus matching bone tissue, reducing stress shielding), and optimized porous structure to promote bone ingrowth. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 is a schematic diagram of the three-dimensional structure of the intervertebral fusion cage main structure of the present application; Figure 2 is a schematic diagram of the three-dimensional structure of the fusion cage Thiessen segmentation of the present application; Figure 3 is a two-dimensional schematic diagram of the Thiessen polygon seed point distribution of the present application; Figure 4 is a two-dimensional schematic diagram of the Thiessen polygon distribution of the present application; Figure 5 is a flow chart of the Thiessen polygon gradient porous design of the present application; Figure 6 is a flow chart of the cleaning process of the present application; Figure 7 is a flow chart of the weight control of the present application. DETAILED DESCRIPTION
[0018] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.
[0019] The present application provides an intervertebral fusion cage based on a tessellation polygon gradient porous structure, comprising: a fusion cage body structure; The fusion cage body structure is a three-dimensionally connected porous structure, the basic topological configuration of the porous structure is a tessellation polygon, and the porous structure has a gradient change at least in a direction along which it is distributed from an outer surface inwardly; The implementation steps of the gradient design method are as follows: (1) Defining a gradient field: in the three-dimensional design space of the fusion cage, a continuous scalar field (density field or distance field) from the outer surface to the geometric center is defined. The field has the maximum value at the outer surface and gradually decreases toward the center.
[0020] The "distance field + density field" double-field coupling design is adopted, the distance field takes the outer surface of the fusion cage as the reference to calculate the shortest distance from any point to the surface; the density field is constructed based on the distance field, and the gradient change rate can be flexibly controlled by adjusting a monotonically decreasing function (such as f(d)=a-b×d, wherein a and b are adjustable parameters). For example, for patients with osteoporosis, the density field range (1.2-1.5mm) of the surface layer region can be increased to improve the rigidity of the surface layer structure and reduce the risk of subsidence.
[0021] (2) Generating gradient seed points: according to the above gradient field, the spatial distribution density of the tessellation polygon seed points is controlled. The seed points are densely and uniformly distributed in the region with high scalar value (outer surface layer), and the seed points are sparsely and randomly distributed in the region with low scalar value (inner core).
[0022] The relationship between the density distribution function (D) of the seed points and the spatial position (P) can be expressed as: D(P)=f(d(P)), Where d(P) is the distance from point P to the nearest outer surface, and f is a monotonically decreasing function.
[0023] The "uniform distribution + random disturbance" combination strategy is adopted, the seed points in the surface layer region are uniformly distributed (to ensure the consistency of the pore diameter), the random disturbance is introduced in the core region (to simulate the natural disorder of the bone trabeculae), and at the same time, the overlapping seed points and the boundary abnormal seed points are removed through the algorithm to ensure the structural integrity.
[0024] (3) Constructing the Voronoi polygon unit: Based on the generated gradient seed point set, calculate its three-dimensional Voronoi polygon segmentation to form a polyhedral unit grid centered on each seed point. These units constitute the basic framework of the gradient porous structure.
[0025] (4) Structure parameterization and mapping: Establish a four-dimensional correlation model of "seed point density-pore size-wire diameter-porosity", for example, when the seed point density decreases from 100 / mm³ to 20 / mm³, the pore size increases linearly from 200 microns to 600 microns, and the wire diameter is adjusted from 30 microns to 50 microns simultaneously, ensuring the balance of structure strength and porosity, and avoiding the mechanical performance deficiency caused by the increase of pore size.
[0026] a) Pore size control: The diameter of the inscribed circle or characteristic size of each Voronoi polygon unit is determined by the seed point density of the region where the unit is located. The higher the density, the smaller the unit size, and the smaller the corresponding pore size.
[0027] b) Wire diameter control: By setting a uniform rod diameter (such as equalizing the edges of the Voronoi polygon unit) or designing a smooth variable diameter according to the size of adjacent units, the wire diameter of the connecting node is formed.
[0028] c) Porosity control: The overall porosity is determined by the unit size (pore size) and rod diameter (wire diameter). Through gradient seed point distribution and rod diameter rules, the porosity can be continuously increased from the outside to the inside (from 60% to 85%).
[0029] (5) Function partition implementation a) Outer biological adhesion zone: Corresponding to the region within 0.5-1.5mm from the outer surface. The seed point density here is high, and the characteristic size of the generated Voronoi polygon unit is 50-400μm, forming a fine porous network, aiming to maximize the specific surface area and promote cell siphon adhesion.
[0030] b) Inner core functional zone: Corresponding to the internal core area of the fusion cage. The seed point density here is low, and the characteristic size of the generated Voronoi polygon unit is 400-800μm, forming a highly connected macroporous structure, aiming to optimize the internal cleaning channel, reduce weight and ensure bone ingrowth space.
[0031] (6) Simulation verification and optimization iteration (realize accurate design) Wherein, the pore gap characteristic size of the outer surface region of the fusion cage main structure is smaller than that of the internal core region; Performance quantification: Automatically calculate key indicators such as porosity and pore size distribution through software to verify whether the preset goal of "small pores (50-400μm) in the outer layer and large pores (400-800μm) in the inner layer" is met.
[0032] Mechanical simulation: Finite element analysis is performed to predict the mechanical properties such as elastic modulus, ensuring compatibility with bone tissue and avoiding stress shielding.
[0033] Closed-loop optimization: Based on simulation results, adjust seed point distribution rules or beam diameter functions until both biological and mechanical requirements are met. This reflects the advanced nature of modern computational bionic design.
[0034] Powder cleaning Place the component in a dedicated cleaning device, use appropriate cleaning fluid (such as deionized water, ethanol or neutral cleaner), combine high-frequency ultrasonic oscillation and directional pressure fluid jet, and clean for sufficient time to ensure that all unfused powder is removed from the complex gradient pores. After cleaning, vacuum drying can be performed.
[0035] The key steps of the cleaning process are as follows: Pre-treatment: After manufacturing is completed, first use dry compressed gas (such as clean air, inert gas) to perform preliminary blowing on the surface of the fusion device and visible holes (pressure 0.3-0.5 MPa), and use a rotary nozzle to remove loose powder on the surface and in large-pore areas. The blowing angle covers 360° to avoid dead angles and remove most of the loose attached powder. Then immerse it in cleaning fluid (such as neutral cleaner solution, ethanol or isopropanol) to initially wet the internal structure of the porous structure.
[0036] Core deep cleaning (cyclically performed): Use the combined process of "ultrasonic oscillation + pressure fluid circulation + vacuum-pressure immersion" - ultrasonic frequency is selected at 40 kHz (for small-pore areas) and 80 kHz (for large-pore areas) with dual-frequency switching, pressure fluid uses pulse jet (pressure 0.2-0.4 MPa, pulse frequency 10-20 times / minute), and vacuum-pressure cycle parameters are set as follows: vacuum degree -0.08 MPa (maintained for 15 minutes) → pressure 0.3 MPa (maintained for 10 minutes), cycle 3-5 times, to ensure that the cleaning fluid penetrates into the fine pores below 50 microns.
[0037] Ultrasonic oscillation cleaning: Place the workpiece in an ultrasonic cleaning tank and use high-frequency ultrasonic cavitation effect to loosen and peel off the powder attached to the hole wall. This step mainly handles the outer layer and the middle pores.
[0038] Pressure fluid circulation flushing: In a special fixture, use a low-pressure pump to drive the cleaning fluid to flow directionally and cyclically through the internal porous structure of the fusion device, and use the fluid shear force to flush out the loosened powder particles. Multiple directional flushing can be designed to ensure no dead angles.
[0039] Vacuum-Pressure Circulation Infiltration: The fuser is immersed in the cleaning solution in a sealed container. First, vacuum to remove air in the pores; then restore normal pressure or pressurize, use the pressure difference to drive the cleaning solution to penetrate the finest pores and dead corners, replace and carry out the residual powder. This step is particularly critical for cleaning small hole areas in gradient structures.
[0040] Circulation and Inspection: Dual inspection of "filter membrane detection + weight comparison" - filter membrane detection needs to ensure that the residual powder particles in the cleaning solution are ≤5 microns in diameter, and the number of particles per 100 ml of cleaning solution is ≤10; if necessary, micro-CT scanning can be added, which needs to cover the entire domain of the fuser without obvious powder aggregation; weight comparison needs to meet the actual net weight and theoretical weight deviation ≤±3%, ensuring cleaning effect and structural integrity.
[0041] The above core deep cleaning steps usually need to be repeated multiple cycles. After each cycle or after completing 2-3 cycles, an intermediate inspection can be conducted. Inspection methods include: Filter membrane inspection: Collect the outflowing cleaning solution and filter it through a micron-level filter membrane to observe the amount of residual powder.
[0042] Weight monitoring: After drying, weigh and compare with the theoretical powder-free net weight.
[0043] Only after passing the inspection can the next step be entered.
[0044] Post-processing and final verification: Rinsing: Use high-purity deionized water for ultrasonic rinsing to completely remove any cleaning agent residues.
[0045] Drying: Dry completely in a vacuum drying oven at low temperature to avoid water stains.
[0046] Final quality inspection: including final weight accuracy determination (must meet the pre-set control range), microscopic structure observation (such as micro-CT scanning to verify internal cleanliness and structural integrity), etc.
[0047] Weight inspection and adjustment of the fuser Weigh the cleaned and dried fuser. By comparing the design weight with the actual weight, we can feedback and optimize the manufacturing or design parameters to achieve closed-loop control of the product weight, ensuring it falls within the target range.
[0048] The operation process is as follows: Digital design and weight estimation (core modeling stage): The theoretical weight (M_d) of the digital model generated based on the Thiessen polygon algorithm and gradient design rules can be accurately obtained by the volume calculation function of the three-dimensional software (material density is the theoretical density of pure tantalum). Based on the volume calculation of the three-dimensional model and the material density (such as the density of tantalum powder 16.6 g / cm³, the density of titanium powder 4.5 g / cm³), combined with the porosity parameter, the theoretical weight (error ≤ ± 2%) is accurately calculated, and 5%-8% weight adjustment allowance is reserved.
[0049] Through the parametric design tool, the structural parameters (such as Thiessen polygon seed point distribution, beam diameter size) are quickly adjusted to fine-tune the porosity and weight, ensuring that M_d falls within the preset loose target range (W±Δ). Δ is the design tolerance.
[0050] Additive manufacturing and process control (real-time calibration stage): Before formally printing the fusion device, a small "standard test block" with the same porous structure is printed synchronously. Its actual weight is measured and the actual density ratio (η) is calculated. The η value comprehensively reflects the deviation of the printing structure density from the design theoretical value under the current equipment, powder batch and process parameters.
[0051] The η value is used to "calibrate" the printing of the fusion device, or it is recorded as a key process parameter. The weight of the printed fusion device blank (M_g) is an important process data.
[0052] The standard test block and the fusion device blank are printed synchronously, and by measuring the actual density ratio η (actual density / theoretical density) of the block, the printing parameters (such as laser power, scanning speed) are adjusted in real time. If the η value is lower than 0.95, it means that the density is insufficient, and the laser power needs to be increased by 5%-10%; if the η value is higher than 1.05, the scanning speed needs to be reduced to avoid excessive melting.
[0053] Post-processing and closed-loop feedback (final verification and optimization stage): After cleaning and drying, the net weight of the final product (M_f) is measured. This is the most critical acceptance index and needs to meet more stringent factory standards (W±δ), where δ<Δ.
[0054] Establish an unqualified product analysis feedback mechanism: If M_f is out of tolerance, systematically analyze whether it is caused by design model deviation, manufacturing process drift (η value anomaly), or post-processing (such as incomplete cleaning or excessive corrosion).
[0055] The analysis results are fed back to the corresponding link to optimize the design rules, adjust the process parameters or improve the cleaning and drying procedures, form a "design-manufacturing-verification" closed-loop control, and realize continuous quality improvement.
[0056] Establish a product weight database, analyze the reasons for weight deviation in different batches through big data analysis, and form a correlation map of "design parameters-process parameters-weight deviation". For example, when the weight deviation exceeds +5%, check whether there is residual cleaning process. If the deviation is less than -3%, adjust the wire diameter design parameters to achieve continuous optimization.
[0057] Value of intervertebral fusion cage based on tesselation polygon gradient porous structure in clinical application 1. Accelerate bone fusion process: The high specific surface area of the surface small pore structure (30%-50% higher than homogeneous porous structure) increases the osteoblast attachment rate by more than 40%, shortens the bone integration start-up time to 1-2 months, and the fusion rate can reach more than 85% 3 months after surgery, significantly reducing the risk of postoperative instability and secondary surgery.
[0058] 2. Reduce the incidence of complications: The complete powder cleaning process reduces the incidence of inflammatory reactions to less than 5%, the mechanical adaptability of the gradient structure reduces the subsidence rate by 60%, and the lightweight design (20%-30% lighter than traditional fusion cages) reduces the pressure on the vertebral endplate, improving patient comfort after surgery.
[0059] 3. Achieve personalized treatment: Doctors can adjust the gradient parameters based on the patient's vertebral CT data using specialized design software, such as for young patients (good bone quality), using a rapid decreasing gradient function to increase the proportion of large pores in the core area to promote rapid vascularization; for elderly osteoporosis patients, use a slow decreasing gradient function to increase the surface support strength to meet the diverse needs of clinical practice.
[0060] Industrialization and market advantages Significant technical barriers: Integrating tesselation polygon algorithm, gradient structure design, and closed-loop manufacturing control three core technologies, forming a "design-manufacturing-detection" full-chain technology system, difficult to imitate; Wide material adaptability: Compatible with medical titanium alloy, tantalum alloy, magnesium alloy and other biomedical materials, among which tantalum alloy has better biocompatibility, and magnesium alloy has degradable properties, which can be expanded to different clinical demand scenarios; Policy and market fit: In line with the national "high-end medical device innovation" strategic direction, can apply for innovative medical device green channel, while targeting the global spinal implant market (2023 global size over $15 billion), with the performance advantage is expected to break the monopoly of imported products, reduce medical costs.
[0061] Follow-up research and development and expansion direction Hydroxyapatite (HA) coating or growth factor (such as BMP-2) slow-release system is introduced in the small hole area of the surface layer to further improve cell adsorption and osteogenic differentiation ability; a miniature pressure sensor is embedded in the interior of the fusion cage to monitor the stress distribution of the fusion cage in real time through wireless transmission, thereby providing data support for clinical rehabilitation guidance; a multi-material gradient structure of "titanium alloy surface layer + magnesium alloy core" is explored to realize the integration of "short-term fixation-long-term fusion-material degradation" by using the mechanical stability of titanium alloy and the degradability of magnesium alloy.
[0062] While embodiments of the present application have been shown and described, it is to be understood that the embodiments described are merely divergences, modifications, replacements and variations of the embodiments, and the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. An interbody fusion device based on a Thiessen polygonal gradient porous structure, characterized in that, include: The main structure of the fusion unit; The main structure of the fusion device is a three-dimensional connected porous structure. The basic topological configuration of the porous structure is a Thiessen polygon, and the porous structure has a gradient change at least along the direction from its outer surface to its interior distribution. Among them, the pore gap feature size of the outer surface region of the fusion device main structure is smaller than that of the pore gap feature size of the inner core region.
2. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 1, characterized in that: The average pore size of the outer surface region of the fusion device's main structure is 50-400 micrometers, and the average pore size of the core region inside the fusion device's main structure is 400-800 micrometers.
3. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 1, characterized in that: The gradient change of the porous structure is a continuous gradual change or a step-like change in the pore size and porosity.
4. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 1, characterized in that: The main structure of the fusion device is integrally formed using additive manufacturing technology, and the additive material is either medical-grade tantalum powder or titanium powder.
5. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 1, characterized in that: After the main structure of the fusion device is integrally formed by additive manufacturing technology, it needs to undergo a post-processing cleaning process to remove unmelted metal powder. The cleaning process includes ultrasonic cleaning, pressure fluid flushing, and vacuum-pressure circulation cleaning.
6. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 5, characterized in that: The specific process of the cleaning procedure is as follows: ① Pretreatment: Dry compressed gas is used to blow away the surface and visible holes of the fusion vessel, and then it is immersed in the cleaning solution. ② Core deep cleaning: The core deep cleaning process is carried out in sequence, including ultrasonic vibration cleaning, pressure fluid circulation rinsing, and vacuum-pressure circulation impregnation. This core deep cleaning step is repeated cyclically. ③ Post-processing and verification: Ultrasonic rinsing was performed using high-purity deionized water, followed by low-temperature drying in a vacuum drying oven. Finally, quality inspection was completed through weight measurement and microstructure observation.
7. The interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 1, characterized in that: The weight of the main structure of the fusion unit is controlled in a coordinated manner through the design of porous structure parameters in the design phase and the control of process parameters in the manufacturing phase, so as to achieve precise control of the predetermined weight.
8. A method for fabricating an interbody fusion cage based on a Thiessen polygonal gradient porous structure, wherein the interbody fusion cage based on a Thiessen polygonal gradient porous structure as described in any one of claims 1-7 is characterized in that: Includes the following steps: S1. Based on the Thiessen polygon algorithm, design a three-dimensional porous structure digital model with a pore gradient change from the outside to the inside; S2. Using metal powder, based on electron beam melting additive manufacturing technology, the fusion blank is manufactured by melting layer by layer according to the digital model to obtain the fusion blank; S3. Clean the blank after the support is removed to thoroughly remove the unmelted metal powder remaining inside the porous structure. S4. Perform post-processing and weight inspection on the main structure of the fusion unit after cleaning.
9. The method for fabricating an interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 8, characterized in that: In step S3, cleaning is performed using a combination of ultrasonic-assisted and pressure fluid circulation flushing.
10. The method for fabricating an interbody fusion device based on a Thiessen polygonal gradient porous structure according to claim 8, characterized in that: In step S1, the theoretical weight of the fusion device is preset by adjusting the distribution of seed points of the Thiessen polygon and the beam diameter parameters. In step S2, the actual weight of the finished product is controlled to be close to the theoretical value by optimizing the process parameters. In step S1, gradient seed points are generated by defining a continuous scalar field from the outer surface to the geometric center. Then, Thiessen polygon units are constructed based on the gradient seed point set. Finally, the structural parameterization mapping is achieved by controlling the aperture, wire diameter, and porosity, thus completing the design of the three-dimensional porous structure digital model.