High-strength porous metal bone filler block

Abstract

The present application relates to a kind of high-strength porous metal bone filling block. The bone filling block includes reinforcing frame and the porous metal material of porosity 60-95% filled inside reinforcing frame;Reinforcing frame and porous metal material material are same. The porous metal bone filling block of the present application can improve compression strength and bone tissue regeneration capacity.

Description

Technical Field

[0001] This invention relates to the field of porous materials, and more specifically to porous metal bone filler blocks. Background Technology

[0002] Bone fillers are frequently used in the treatment of relatively regular lacunar bone defects, including those at the metaphysis, caused by trauma, tumors, infections, congenital malformations, etc. They are also commonly used to fill lacunar bone defects in the joint space during arthroplasty.

[0003] Bone filler materials include commonly used medical-grade metals such as titanium and titanium alloys, and stainless steel. Titanium has good corrosion resistance and low cytotoxicity, but it is not wear-resistant and is prone to loosening. Making titanium alloys can greatly improve hardness and corrosion resistance, making them the most commonly used material in clinical practice. However, the vanadium and aluminum components in titanium alloys are harmful to the human body. Stainless steel is even more prone to corrosion, leaching metal ions and loosening. Tantalum and niobium are ideal orthopedic materials, being hard, chemically stable, highly corrosion-resistant, and having good osteoinductive properties, and are non-cytotoxic. However, the processing of tantalum and niobium is very difficult, which prevents their widespread clinical use.

[0004] Currently, Chongqing Runze Company has independently developed a medical porous tantalum material whose product performance exceeds the international standard (ISO 13782-1996 Surgical implants—Metallic materials—Pure tantalum materials for surgical implants). However, as a medical orthopedic material used in the human body, in order to achieve the most ideal performance that is completely consistent with human bone tissue, the product still needs to be continuously improved.

[0005] The applicant previously disclosed (CN108452385A) a multi-level porous material prepared by cross-weaving two diameters of polymer filaments into a mesh, simultaneously injecting slurry, and then sintering. This material has interconnected channels within its cavity walls and pores on its walls with diameters smaller than the pores enclosed by the cavity walls. The pore structure on the cavity walls is a multi-level porous structure graded according to the material's pore size, with at least two levels. The prepared porous tantalum material has an interconnected pore diameter of 550 μm, and the equivalent diameter of the interconnected channels within the cavity walls is 90 μm. The cavity walls have two levels of pores with diameters smaller than the pores enclosed by the cavity walls. The largest pore has a diameter of 20 μm, and on the cavity walls of the 20 μm pores are even smaller pores, i.e., the smallest level pores, with a diameter of 400 nm. The porous material prepared by this method can achieve rapid and uniform distribution of cells and tissue fluid within the porous material bulk. However, the method of cross-weaving polymer filaments into a web requires a relatively large diameter polymer filament. For small-diameter polymer filaments, the production operation and control of this method are quite difficult. The compressive strength of the multi-level porous material prepared in this patent is about 20 MPa. In order to meet more application scenarios, the preparation process, pore structure, pore size distribution and cavity wall thickness of the multi-level porous material still need further improvement.

[0006] The applicant previously disclosed (CN108452386A) a porous tricalcium phosphate material prepared using polyurethane foam with an edge diameter of 25μm-50μm, achieving a compressive strength of 3.74MPa; and a porous niobium material prepared using polyurethane foam with an edge diameter of 50μm-90μm, achieving a compressive strength of 25.3MPa. The through-pore diameter was 300μm-600μm, the equivalent diameter of the channels penetrating the cavity wall was 40μm-70μm, and the first-order pores on the cavity wall had a diameter of 10μm-20μm. Smaller pores, i.e., minimum-order pores, with a diameter of 400nm-700nm, were also present on the cavity wall surrounding the 10μm-20μm pores. This patent used a foam impregnation method to prepare multi-level porous materials, but the pore structure and pore size distribution were still not sufficiently optimized. The two-level pores on the cavity wall limited the compressive strength, and it could only produce materials with a uniform porosity distribution, failing to adjust and fully simulate the morphology of bone tissue.

[0007] The applicant has previously prepared porous materials with gradient distributions. For example, CN108201635A discloses a porous metal material layer as a gradient porous metal material layer. Although the porous metal material in this patent adopts a gradient structure, its gradient is mainly formed by welding or powder sintering. The resulting porous material has interfaces between the gradient pores, and true integrated, interface-free fusion has not yet been achieved. Moreover, the aforementioned prepared gradient porous materials do not achieve multi-level pore distribution, have low three-dimensional pore connectivity, and the overall performance of the material is still not ideal. Summary of the Invention

[0008] The purpose of this invention is to provide a high-strength porous metal bone filler block, which improves the compressive strength and three-dimensional connectivity of the pores, thereby enhancing the bone tissue regeneration capacity.

[0009] The main technical solution of this invention is as follows:

[0010] A high-strength porous metal bone filler block, comprising a reinforcing frame and a porous metal material with a porosity of 60-95% filling the interior of the reinforcing frame; the reinforcing frame and the porous metal material are made of the same material.

[0011] The bone filling blocks are cylindrical, rectangular, or irregular in shape.

[0012] The formation of the reinforcing framework and the porous metallic material are not done in the same step.

[0013] Optionally, the reinforcing framework and the porous metal material are prepared in two steps. The porous metal material can be prepared first, and then the reinforcing framework can be bonded to its outer surface. Alternatively, the reinforcing framework can be prepared first, and then the porous metal material can be filled inside the reinforcing framework.

[0014] The reinforcing frame is prepared by 3D printing and / or weaving.

[0015] The porous metal material filled inside has the following characteristics: the pores formed by the cavity wall are interconnected open pores, the cavity wall is an axially hollow structure, the cavity wall has pores in the radial direction, the porosity of the porous metal material is uniformly distributed or gradient distributed, the gradient distribution can be a gradient change along one direction or a three-dimensional gradient change, and the pores in the radial direction of the cavity wall are single-stage pores.

[0016] Three-dimensional gradient variation refers to changes in multiple directions within three-dimensional space. Single-level is the opposite of multi-level; multi-level refers to a specific multi-scale aperture structure, while single-level refers to a structure without multi-scale apertures.

[0017] The porous metal material was prepared by foam impregnation.

[0018] 3D Printing: 3D printing technology emerged in the mid-1980s, when researchers began experimenting with printing digital resources into three-dimensional models. With the deepening of tissue engineering research, 3D printing technology has proven applicable to the three fundamental elements of tissue engineering: cells, biological scaffold materials, and cell-active factors. Biological scaffold materials are generally porous. Methods such as selective laser melting (SLS), solidification by light (SLA), and three-dimensional printing (3DP) can all be used to prepare biological scaffolds. Currently, 3D printing of hard tissues such as bone is relatively mature, with materials typically being titanium-magnesium alloys or composites of hydroxyapatite and polymers. This technology is well-established and has been successfully applied clinically. Porous metal 3D printing technology is a type of 3D printing that uses powdered metal as the material. It involves converting digital model files and stacking them layer by layer to create the desired three-dimensional porous metal structure. Porous metal 3D printing technology can obtain personalized porous biological scaffolds, better addressing the challenges of precision medicine.

[0019] The braiding method uses metal wire as raw material and weaves a specific structure through methods such as wire winding. As needed, it can be further processed by pressing, rolling or high temperature.

[0020] Foam impregnation method: The organic foam impregnation method was proposed by Schwartzwalder in 1963. It involves impregnating ceramic slurry with organic foam, drying it, and then burning off the organic foam to obtain porous foam ceramics. The organic foam impregnation method is simple and has significant advantages in preparing high-porosity materials, especially interconnected open-pore materials. However, the collapse problem is a major challenge in the firing step of the foam impregnation method, and solving this problem is one of the keys to its success. In a sense, the process ideas and methods of the foam impregnation method in the green body preparation stage differ from those of powder sintering. Although both powder sintering and organic foam impregnation methods rely on the firing process to achieve a certain degree of pore structure modification, fundamentally, foam impregnation and powder sintering are different porous material preparation processes. The initial green body preparation directly determines the conditions for subsequent firing processes. Green body-firing and pore structure modification is a complete process, not a arbitrarily fragmented combination of processes.

[0021] The metal used in this invention is tantalum, niobium, or an alloy thereof.

[0022] Furthermore, the metal can be a tantalum-niobium alloy. The size of the openings formed by the cavity walls of the porous metal material of this invention is 200-1500 μm, the size of the hollow pores in the cavity walls is 4-50 μm, and the size of the radial pores in the cavity walls is 0.2-15 μm.

[0023] Optionally, the size of the opening formed by the cavity wall is preferably 400-900 μm, more preferably 600-800 μm, the size of the hollow hole in the cavity wall is preferably 15-40 μm, and the size of the radial hole in the cavity wall is preferably 4-10 μm.

[0024] The distance between the radial holes in the cavity wall of the present invention is 2-15 μm, and optionally, 5-10 μm.

[0025] The gradient distribution of this invention is a fused structure of interface-free gradient holes. The gradient distribution of this invention does not require connection by methods such as welding.

[0026] The gradient distribution can be asymptotic, non-asymptotic, or a combination of asymptotic and non-asymptotic gradients.

[0027] Non-gradient porosity refers to abrupt changes in porosity, which can fully simulate the morphology of cortical and cancellous bone tissues in the human body, achieving a high degree of biomimicry. Gradient porosity refers to continuous changes in porosity, which can fully simulate the pore structure of different regions of a type of bone tissue.

[0028] Three-dimensional gradient change refers to changes in multiple directions in three-dimensional space.

[0029] The gradient distribution can be an asymptotic gradient change, a non-asymptotic gradient change, or a combination of asymptotic and non-asymptotic gradient changes in multiple directions in three-dimensional space.

[0030] The porosity of the porous metal material filling the cuboid frame of the present invention is preferably 60-95%, more preferably 70-90%, and more preferably 75-85%.

[0031] When the porosity is distributed in a gradual and / or non-gradual gradient along one direction or along multiple directions in three-dimensional space, the porosity of the region with the largest porosity in the porous metal material is preferably 80-95%, more preferably 85-90%, and the porosity of the region with the smallest porosity is 60-75%, more preferably 65-70%.

[0032] When the porosity gradient distribution is used, the radial thickness gradient of the cavity wall is preferred.

[0033] The radial thickness of the cavity wall is 50-1000 μm.

[0034] Optionally, the porous metal material with non-gradually varying porosity includes 2-4 layers of porous metal structures with different porosities.

[0035] Optionally, in each layer of the porous metallic material with a non-gradually varying porosity, the porosity is either uniformly distributed or combined with a gradual gradient variation.

[0036] Optionally, a reinforcing frame composed of reinforcing ribs is first prepared using 3D printing or weaving, and a porous metal material bonded to the reinforcing frame is prepared inside the reinforcing frame using a foam impregnation method.

[0037] Optionally, a porous metal material is first prepared using a foam impregnation method, and then a reinforcing frame is combined with the outer surface of the porous metal material using a 3D printing or weaving method. Optionally, the outer surface of the porous metal material may or may not have grooves that match the positions of the reinforcing ribs of the reinforcing frame.

[0038] Optionally, the bone filling block of the present invention includes a cuboid reinforcing frame composed of 12 cuboid edge reinforcing ribs, and a porous metal material with a porosity of 60-95% filling the frame; the metal purity of the bone filling block is greater than 99%, and the top and bottom surfaces of the cuboid frame are both square.

[0039] Optionally, each of the four vertical sides of the cuboid frame has a number of equally distributed vertical side stiffeners, or each side may not contain any side stiffeners, and the length of the side stiffeners may be equal to that of the vertical cuboid edge stiffeners.

[0040] Optionally, when none of the four vertical sides contain side stiffeners, the top and bottom surfaces of the cuboid frame also do not contain bottom stiffeners; when each of the four vertical sides has a number of equally distributed vertical side stiffeners, the top and bottom surfaces of the cuboid frame also have an n*n grid-shaped bottom stiffener evenly distributed, where n is equal to the number of side stiffeners in each vertical side, and the endpoints of the bottom stiffeners are all connected to the side stiffeners.

[0041] There are several roots, which can be 1, 2, 3, 4, 5 or 6.

[0042] Optionally, the cuboid edge stiffeners, optional side stiffeners, and bottom stiffeners are connected to each other without joints, making the structure more robust.

[0043] Optionally, the porous metal material is machined into a cuboid shape, and a 3D model of cuboid edge reinforcing ribs, optional side reinforcing ribs, and bottom reinforcing ribs connected to its outer surface is constructed using modeling software. The cuboid edge reinforcing ribs, optional side reinforcing ribs, and bottom reinforcing ribs are then fabricated on the outer surface of the cuboid porous metal material using 3D printing technology. No grooves are machined on the outer surface of the porous metal material.

[0044] Optionally, after machining the porous metal material into a cuboid shape, grooves are machined in the area where reinforcements are to be added via 3D printing, so that cuboid edge reinforcements, optional side reinforcements, and bottom reinforcements can be 3D printed therein. The porous metal material and the reinforcements together form a cuboid shape.

[0045] Optionally, metal powder with a particle size of 20-30μm is added to a laser selective sintering molding machine, and parameters such as laser power and scanning speed are set to 3D print reinforcing ribs on the surface of porous metal materials. The entire molding process is carried out in an argon protective atmosphere.

[0046] Optionally, the porous metal material is machined into a cylindrical shape. The outer surface of the porous metal material may or may not have grooves to accommodate the reinforcing ribs. 3D models of the upper, lower, and side circular reinforcing ribs connected to the outer surface are constructed using modeling software. The upper, lower, and side circular reinforcing ribs are then fabricated on the outer surface of the cylindrical porous metal material using 3D printing technology. The side reinforcing ribs can be two, four, or six vertically symmetrically distributed ribs; they can also be mesh-like or other shapes.

[0047] Optionally, the volume ratio of the reinforcing ribs in the reinforced frame of the present invention is 5%-30% of the total material.

[0048] Optionally, the porous metal material can be prepared by foam impregnation. Specifically, a double-roller foam impregnation method is used.

[0049] More specifically, it is prepared through processes such as surface treatment, slurry impregnation, roller pressing, liquid film breaking, cross-linking curing, and three-stage sintering.

[0050] More specifically, the surface-treated polymer scaffold is immersed in a slurry of metal powder, metal oxide, or metal carbide. The slurry also includes a crosslinking agent, defoamer, and dispersant. After the polymer scaffold is immersed in the slurry, it is rolled, the liquid film is broken, crosslinked and cured, dried, and finally sintered and cooled.

[0051] The porosity distribution of the porous metal material of this invention is mainly achieved by adjusting the radial thickness distribution of the cavity wall. Specifically, the porosity distribution of the porous metal material is adjusted by changing the shape of the polymer scaffold and the distance between the rollers during rolling. Preferably, the rollers are arranged in parallel. When preparing a porous metal material with a uniform porosity distribution, the polymer scaffold is a structure with two parallel surfaces, such as a cube or cuboid, and the rollers contact the two parallel surfaces during rolling. When preparing a porous metal material with a gradually increasing porosity gradient, the polymer scaffold can be a structure where the distance between the two opposite sides in contact with the rollers gradually changes. When the distance between the two opposite sides gradually changes along one direction, a porous metal material with a gradually increasing porosity gradient along one direction can be prepared. When the distance between the two opposite sides gradually changes along multiple directions, a porous metal material with a gradually increasing porosity gradient (three-dimensional gradually increasing gradient) along multiple directions can be prepared. Optionally, the polymer scaffold is a trapezoidal structure with two inclined sides. During rolling, the rollers can contact the two sides of the trapezoid, and through extrusion, the thickness distribution of the metal powder slurry layer on the inner surface of the polymer scaffold changes, thereby changing the thickness distribution of the cavity wall of the finally sintered porous metal material and causing a change in porosity. When preparing porous metal materials with non-gradually varying (abrupt) porosity distribution, the polymer scaffold can be a structure where the distance between the two opposite sides in contact with the rollers does not change gradually. When the distance between the two opposite sides changes non-gradually in one direction, porous metal materials with non-gradually varying porosity in one direction can be prepared. When the distance between the two opposite sides changes non-gradually in multiple directions, porous metal materials with non-gradually varying porosity in multiple directions (three-dimensional non-gradually varying porosity) can be prepared. Optionally, the polymer scaffold can be convex, have multiple stepped shapes on the sides, etc. When preparing porous metallic materials that combine gradual and non-gradual porosity changes, the polymer scaffold can be a structure where the distance between the two opposing sides in contact with the rollers simultaneously exhibits both non-gradual and gradual changes. When the distance between the two opposing sides exhibits both gradual and non-gradual changes along one direction, a porous metallic material combining gradual and non-gradual porosity changes along one direction can be prepared. When the distance between the two opposing sides exhibits both gradual and non-gradual changes, and these changes occur in multiple directions, a porous metallic material combining three-dimensional gradual and non-gradual porosity changes can be prepared.

[0052] Optionally, the porous metal material with a porosity of 60-95% can be subjected to cryogenic milling to obtain a porous metal material of target size such as a cuboid or cylinder. The cryogenic milling temperature is -80 degrees Celsius. This processing technology can produce a smooth processing surface and can process porous metal materials like dense materials without the phenomenon of material blockage caused by the removal of pores, and without reducing porosity and open area.

[0053] Optionally, after processing, the porous metal material is annealed at a temperature of 1000-1500℃ for 1-5 hours, followed by slow cooling; this process can remove residual impurities and eliminate processing stress.

[0054] Optionally, the reinforcing frame is prepared using 3D printing or weaving methods. The reinforcing frame has a shape that matches the porous metal material. Optionally, the reinforcing frame includes an upper circular reinforcing rib, a lower circular reinforcing rib, and four evenly distributed side reinforcing ribs connecting the upper and lower circular reinforcing ribs. The reinforcing frame is cylindrical, but optionally, it can be cuboid or other shapes. Optionally, when preparing the porous metal material using the foam impregnation method described above, the shape of the polymer scaffold used is a shape that matches the size of the reinforcing frame. After the blank is removed by roller pressing, the reinforcing frame is impregnated in the metal powder slurry including the crosslinking agent, defoamer, and dispersant. Then, it is removed, and the blank after roller pressing is placed into the reinforcing frame that matches it after being impregnated with the metal powder slurry. Then, high-pressure gas is used to blow air onto the surface of the blank and the reinforcing frame to break the liquid film on the surface. Then, it is allowed to stand for crosslinking and curing, dried, sintered, and cooled to prepare a bone-filling block filled with porous metal material inside the reinforcing frame.

[0055] Beneficial effects:

[0056] 1. This invention combines porous metal materials with a reinforcing frame, giving full play to their respective advantages. The high-strength porous metal bone filler block prepared has the characteristics of high mechanical strength and high three-dimensional pore connectivity, which greatly improves the compressive strength of the bone filler block and has strong long-term implantation stability. Compared with porous metal materials without a reinforcing frame, it significantly improves compressive strength and is especially suitable for parts that need to bear a lot of weight.

[0057] 2. The porous metal material filling the reinforced frame of this invention has a porosity of 60-95%, making it suitable for application in various locations and promoting bone integration and inward growth of intracellular tissues.

[0058] 3. The porous metal material filling the reinforced frame of this invention includes three types of pores, particularly axially hollow pores and radial pores in the cavity wall. Due to the presence of axially hollow pores and radial pores of specific sizes in the cavity wall, this invention improves porosity and fluid transport capacity. The porous metal material contains at least two continuous channels: a three-dimensionally connected channel enclosed by the cavity wall and axially hollow pores in the cavity wall.

[0059] 4. The gradient porous metal material prepared by the method of the present invention, especially the three-dimensional gradient porous metal material, can highly mimic the bone tissue structure and has many advantages such as strong bone fusion and regeneration ability and good matching with autologous bone after implantation.

[0060] 5. The compressive strength of the bone filling block of the present invention can reach more than 80 MPa. Detailed Implementation

[0061] The technical solution of the present invention will be further illustrated by the following examples.

[0062] Example 1

[0063] Mix 80g of tantalum powder with a particle size of 10μm with 20ml of polyethylene glycol 400 aqueous solution (0.1M) and stir until homogeneous. While stirring, add 50ml of PVA aqueous solution (0.2M), 0.1g of trimethylsiloxy-terminated polydimethylsiloxane and 0.3g of glyoxal in sequence to prepare tantalum powder slurry. After cleaning the surface of a cubic polyurethane polymer scaffold with an edge diameter of 30 μm, it was immersed in a 1M polyethylene glycol 400 aqueous solution for surface treatment. The scaffold was then removed and dried. After drying, the surface-treated scaffold was immersed in tantalum powder slurry, and gently squeezed to ensure full absorption of the slurry. Once saturated, the saturated scaffold was removed and placed in a roller mill for pressing. During pressing, the distance between the rollers remained constant, squeezing out excess tantalum powder slurry. This process of slurry immersion and roller pressing was repeated five times. The preform was then removed, and high-pressure gas was used to blow air onto its surface to break the surface liquid film. It was then left to stand in air to allow the PVA in the preform to cross-link and cure. After full curing, the preform was placed in a vacuum drying oven at 60℃ for 4 hours. After drying, the green body is sintered under vacuum conditions by slowly heating from room temperature to 580°C at a heating rate of 2°C / min and holding for 6 hours. Then, it is sintered by slowly heating to 1500°C at a heating rate of 2°C / min and holding for 6 hours. Then, it is sintered by slowly heating to 1900°C at a heating rate of 6°C / min and holding for 6 hours. Finally, it is cooled in the furnace.

[0064] The prepared porous tantalum has a porosity of 75% and a compressive strength of 65 MPa. The size of the openings enclosed by the cavity walls is 200-500 μm, the size of the hollow pores in the cavity walls is approximately 30 μm, and the size of the radial pores in the cavity walls is 5-10 μm. The distance between the radial pores in the cavity walls is 3-6 μm. The radial thickness of the cavity walls is 150 μm.

[0065] Example 2

[0066] Mix 80g of tantalum powder with a particle size of 5μm with 20ml of polyethylene glycol 400 aqueous solution (0.1M) and stir until homogeneous. While stirring, add 50ml of PVA aqueous solution (0.2M), 0.15g of trimethylsiloxy-terminated polydimethylsiloxane and 0.3g of glyoxal in sequence to prepare tantalum powder slurry. After cleaning the surface of a 15μm diameter cubic polyurethane polymer scaffold, it was immersed in a 1M polyethylene glycol 400 aqueous solution for surface treatment. The scaffold was then removed and dried. After drying, the surface-treated scaffold was immersed in tantalum powder slurry, and gently squeezed to ensure full absorption of the slurry. Once saturated, the saturated scaffold was removed and placed in a roller mill for pressing. The roller spacing remained constant during pressing to squeeze out excess tantalum powder slurry. This process of slurry immersion and roller pressing was repeated five times. The preform was then removed, and high-pressure gas was used to blow air onto its surface to break the surface liquid film. It was then left to stand in air to allow the PVA in the preform to cross-link and cure. After full curing, the preform was placed in a vacuum drying oven at 60℃ for 4 hours. After drying, the green body is sintered under vacuum conditions by slowly heating from room temperature to 580°C at a heating rate of 3°C / min and holding for 6 hours. Then, it is sintered by slowly heating from room temperature to 1600°C at a heating rate of 3°C / min and holding for 6 hours. Then, it is sintered by slowly heating from room temperature to 1850°C at a heating rate of 8°C / min and holding for 6 hours. Finally, it is cooled in the furnace.

[0067] The prepared porous tantalum has a porosity of 85% and a compressive strength of 56 MPa. The size of the openings enclosed by the cavity walls is 250-550 μm, the size of the hollow pores in the cavity walls is approximately 15 μm, and the size of the radial pores in the cavity walls is 4-8 μm. The distance between the radial pores in the cavity walls is 2-5 μm. The radial thickness of the cavity walls is 135 μm.

[0068] Example 3

[0069] The porous tantalum material with a porosity of 85% prepared in Example 2 was cryogenically machined at -80°C into a cuboid shape. The top and bottom sides of the cuboid were both 10 mm long, and the height was 12 mm, with a tolerance of ±0.2 mm. After machining, it was annealed at 1000°C for 2 hours, followed by slow cooling. A 3D model of the cuboid-shaped porous tantalum material's outer surface was constructed using modeling software, with the diameter of the cuboid ribs being 2 mm. Tantalum powder with a particle size of 20 μm was added to a laser selective sintering machine. The laser power was set to 70-90 W, and the scanning speed to 5-10 mm / s. Twelve interconnected but knot-free cuboid ribs were 3D printed at the positions of the cuboid edges on the surface of the porous tantalum material. The entire molding process was carried out under an argon protective atmosphere. The compressive strength of the prepared porous tantalum filler block was tested to be as high as 95 MPa.

[0070] Example 4

[0071] A niobium-reinforced frame was prepared by a braiding method. The reinforced frame includes an upper circular reinforcing rib, a lower circular reinforcing rib, and four evenly distributed side reinforcing ribs connecting the upper and lower circular reinforcing ribs. The reinforced frame is cylindrical, and the diameter of the reinforcing ribs is 2 mm.

[0072] 80g of niobium powder with a particle size of 15μm was mixed with 20ml of polyethylene glycol 400 aqueous solution (0.1M) and stirred until homogeneous. While stirring, 50ml of PVA aqueous solution (0.2M), 0.1g of trimethylsiloxy-terminated polydimethylsiloxane, and 0.3g of glyoxal were added sequentially to prepare niobium powder slurry. A cylindrical polyurethane polymer scaffold with an edge diameter of 35μm, matching the size of the reinforcing frame, was cleaned and then immersed in polyethylene glycol 400 aqueous solution (1M) for surface treatment. After removal and drying, the surface-treated polymer scaffold was immersed in the niobium powder slurry and gently squeezed to ensure full absorption of the niobium powder slurry. Once saturated, the polymer scaffold filled with niobium powder slurry was removed and placed in a roller mill for pressing. During the pressing process, the distance between the rollers remained constant, squeezing out excess niobium powder slurry. This process of slurry immersion and roller pressing was repeated 5 times before the preform was removed. The reinforcing frame was impregnated in the aforementioned niobium powder slurry, then removed. The preform was placed into the matching niobium powder-impregnated reinforcing frame, and then the liquid film on the surface of the preform and reinforcing frame was broken by blowing high-pressure gas. It was then left to stand in air to allow the PVA to crosslink and cure. After full curing, it was placed in a vacuum drying oven at 60°C for 4 hours. After drying, under vacuum conditions, the temperature was slowly increased from room temperature to 600°C at a rate of 2°C / min and held for 6 hours. Then, the temperature was slowly increased to 1600°C at a rate of 2°C / min and held for 6 hours. Finally, the temperature was increased to 1900°C at a rate of 6°C / min and held for 6 hours, and then cooled in the furnace. Testing showed that the compressive strength of the prepared bone filler block reached 100 MPa.

[0073] Example 5

[0074] Using the process and raw materials of Example 1, the shape of the polyurethane polymer scaffold was changed to a stepped platform. During rolling, the rollers contacted both sides of the stepped platform, resulting in porous tantalum with a gradually increasing porosity. The stepped platform scaffold sponge was subjected to varying degrees of compression from top to bottom by the rollers, causing the thickness of the slurry layer on the upper and lower surfaces to gradually decrease, i.e., the radial thickness of the cavity wall of the polymer scaffold slurry gradually decreased, leading to a gradual increase in porosity from top to bottom. The porosity on the upper surface of the prepared porous tantalum was 70%, and the radial thickness of the cavity wall was approximately 200 μm, while the porosity on the lower surface was 90%, and the radial thickness of the cavity wall was approximately 100 μm.

[0075] The porous tantalum material with a progressively gradient distribution and a trapezoidal shape, prepared above, was cryogenically milled at -80°C into a cuboid shape. The top and bottom sides of the cuboid were both 10 mm long, and the height was 12 mm, with a tolerance of ±0.2 mm. After machining, it was annealed at 1000°C for 2 hours, followed by slow cooling. A 3D model of the cuboid-shaped porous tantalum material's outer surface was constructed using modeling software, with the cuboid ribs having a diameter of 2 mm. Tantalum powder with a particle size of 20 μm was added to a laser selective sintering machine. The laser power was set to 70-90 W, and the scanning speed to 5-10 mm / s. Twelve interconnected but knot-free cuboid ribs were 3D printed at the positions of the cuboid edges on the surface of the porous tantalum material. The entire molding process was carried out under an argon protective atmosphere. The compressive strength of the prepared porous tantalum filler block was tested and found to be as high as 97 MPa.

Claims

1. A high-strength porous metal bone filler block, characterized in that: The bone-filling block comprises a reinforcing frame and a porous metal material with a porosity of 60-95% filling the interior of the reinforcing frame; the reinforcing frame and the porous metal material are made of the same material; the formation of the reinforcing frame and the porous metal material are not performed in the same step; the reinforcing frame is prepared by 3D printing and / or weaving; the porous metal material is prepared by foam impregnation: the surface-treated polymer scaffold is impregnated in a slurry of metal powder, which also includes a crosslinking agent, defoamer, and dispersant; after the polymer scaffold filled with slurry is removed, it is subjected to roller pressing, liquid film breaking, crosslinking and curing, drying, and finally sintering and cooling. The porous metal material filling the cavity has the following characteristics: the pores formed by the cavity wall are interconnected open pores, the cavity wall is an axially hollow structure, the cavity wall has pores in the radial direction, the porous metal material has a porosity gradient distribution, the gradient distribution is a gradient change along one direction or a three-dimensional gradient change, and the pores in the radial direction of the cavity wall are single-level pores; the porosity gradient distribution of the porous metal material is achieved by adjusting the radial thickness distribution of the cavity wall.

2. The high-strength porous metal bone filling block according to claim 1, characterized in that: The bone filling blocks are cylindrical, rectangular, or irregular in shape.

3. The high-strength porous metal bone filler block according to claim 1, characterized in that: The metal is tantalum, niobium, or an alloy thereof.

4. The high-strength porous metal bone filling block according to claim 1, characterized in that: The metal is a tantalum-niobium alloy.

5. The high-strength porous metal bone filler block according to claim 1, characterized in that: The size of the openings enclosed by the cavity wall is 200-1500μm, the size of the hollow holes in the cavity wall is 4-50μm, and the size of the radial holes in the cavity wall is 0.2-15μm.

6. The high-strength porous metal bone filling block according to claim 1, characterized in that: The distance between the radial holes in the cavity wall is 2-15 μm.