Biologically inert bone end sealing device for joint replacement surgery and method of manufacture

Abstract

The application discloses a biologically inert bone end sealing device for artificial joint surgery and a manufacturing method, and belongs to the technical field of orthopedic implants. The device solves the technical problems of traditional bone wax easily causing foreign body reaction, infection, displacement and shedding, and re-osteogenesis, and the mismatch between the existing amputation bone cap and the artificial joint surgery requirements. The device comprises a cap body and an intramedullary short handle. The cap body is integrally formed by SLS 3D printing of short carbon fiber reinforced polyether ether ketone, and has a double-layer gradient structure of an inner porous layer and an outer dense layer. The outer dense layer is provided with a polished zirconia ceramic coating. The inner porous layer and the intramedullary short handle are covered with a nano-silver antibacterial coating. The cap body periphery is provided with micro-wing protrusions, which can be embedded with tantalum marker beads. The device has excellent biological inertness, can resist bacteria and prevent infection, realizes selective growth of fibrous tissue, inhibits re-osteogenesis across the gap, forms a low-friction rotating interface, has double image identification, can maintain the artificial joint gap for a long time, guarantees the forearm rotation function, and is suitable for various artificial joint surgeries.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a bio-inert bone end sealing device and its manufacturing method for pseudo-joint surgery. Background Technology

[0002] In orthopedic clinical practice, procedures such as the Sauvé-Kapandji and Darrach procedures require the artificial creation and maintenance of a pseudo-articular space. This is achieved by cutting a specific bone segment (such as the distal ulna) to create a pseudo-articular space, thereby restoring forearm rotational function. The key to surgical success lies in effectively sealing the medullary cavity at the osteotomy site to prevent reossification of the bone ends, which could lead to space closure.

[0003] Currently, bone wax is the most commonly used material for sealing bone fracture ends in clinical practice. However, it has four inherent drawbacks: First, bone wax is a non-degradable foreign body, and long-term retention can lead to chronic foreign body reactions and granulomas, requiring a second surgery to remove it in some patients. Second, bone wax suppresses the innate immunity of bone tissue, and its hydrophobic surface easily becomes a substrate for bacterial biofilms, significantly increasing the risk of deep infection. Third, bone wax is fixed solely by mechanical impregnation and is prone to displacement and detachment under repeated rotational loads on the forearm, with loose fragments potentially causing secondary damage. Fourth, bone wax cannot prevent osteoblasts from migrating across the interarticular space, resulting in a high rate of pseudoarthrotic bone bridge formation postoperatively, leading to recurrent functional loss.

[0004] While recent amputation stump bone cap devices employ porous structures to promote osseointegration and fix the cap, their design philosophy fundamentally contradicts the needs of pseudoarthrosis surgery—pseudoarthrosis closure devices must actively inhibit bone growth on the side facing the joint gap, rather than promoting osseointegration. Furthermore, existing amputation bone caps do not precisely define the pore size of the porous layer to achieve selective tissue ingrowth, and lack low-friction, anti-osteogenic coatings and active antibacterial designs for the pseudoarthrosis rotation interface.

[0005] Carbon fiber reinforced polyetheretherketone (CFR-PEEK), as a bio-inert orthopedic material, has been used in fixation plates, fusion devices, etc., but most existing products are solid structures. In summary, current technologies cannot simultaneously solve technical problems such as foreign body reaction, infection, displacement, and reossification in pseudoarthrosis surgery. Summary of the Invention

[0006] This invention provides a bio-inert bone end-sealing device and manufacturing process for pseudo-joint surgery, which can solve the technical problems of foreign body reaction, infection, displacement and re-ossification in existing pseudo-joint surgery.

[0007] To achieve the above objectives, in a first aspect, the present invention provides the following technical solution: a bio-inert bone end-sealing device for pseudoarthrosis surgery, comprising a cap body, the cap body comprising an outer dense layer and an inner porous layer, the inner porous layer being located on the bone contact surface side of the cap body, the inner porous layer being formed by interconnected pores, the space filled by the interconnected pores forming a fibrous tissue ingrowth zone for fibroblasts at the osteotomy site to migrate into, the cap body being integrally molded using short carbon fiber reinforced polyetheretherketone powder as raw material, exhibiting excellent bio-inertness, completely eliminating chronic foreign body reactions and granulomas caused by bone wax, employing a double-layer gradient structure to achieve functional zoning, the inner porous layer providing space for fibrous tissue ingrowth to achieve biological fixation; the outer dense layer providing mechanical support, bearing intramedullary pressure and rotational shear force, and the interconnected pores forming a continuous fibrous tissue ingrowth zone, enabling the fibrous tissue to form a three-dimensional anchor with the osteotomy site, replacing the mechanical impregnation of bone wax, thereby solving the problem of displacement and detachment.

[0008] Preferably, the short carbon fiber reinforced polyetheretherketone powder contains 28-35 wt% short carbon fibers. This 28-35 wt% carbon fiber content allows the elastic modulus of the cap to be precisely controlled to 12-24 GPa, which is highly compatible with the elastic modulus of human cortical bone.

[0009] Preferably, the interconnected pores have a pore size of 200-350 μm, a porosity of 40-50%, and a pore connectivity rate of ≥85%. The pore size of the interconnected pores, combined with the inertness of the CFR-PEEK material and the selective inhibition of the nano-silver coating, achieves selective fixation with only fibrous tissue ingrowth and a bone tissue ingrowth rate of <5%. The 40-50% porosity balances the fiber ingrowth space and the mechanical strength of the porous layer, while the ≥85% pore connectivity rate ensures that the fibrous tissue forms a three-dimensional continuous network, providing uniform and reliable biological fixation force and avoiding local loosening.

[0010] Preferably, at least one tantalum bead is embedded in the outer dense layer. The tantalum bead has extremely high X-ray impermeability and forms a dual image identification system with the contour imaging of the zirconium oxide coating, thus solving the problem of insufficient image recognition of pure CFR-PEEK implants.

[0011] Preferably, the outer surface of the outer dense layer is provided with a zirconia ceramic coating. The dense and smooth zirconia coating forms a bioinert barrier, inhibiting osteoblast adhesion and migration across the pseudo-joint space. Furthermore, the high density of zirconia provides X-ray contour imaging, facilitating postoperative assessment of the pseudo-joint space status.

[0012] Preferably, the inner porous layer has a short intramedullary stalk centrally located on the side facing the bone contact surface. The short intramedullary stalk is inserted into the medullary cavity of the osteotomy section to provide early postoperative axial stability and pull-out resistance.

[0013] Preferably, the inner porous layer and the surface of the intramedullary short stalk are provided with a nano-silver antibacterial coating. The nano-silver coating has an inhibition rate of >97% against Staphylococcus aureus and Escherichia coli, effectively inhibiting the colonization of common orthopedic pathogens and reducing the risk of deep infection.

[0014] Preferably, the cap is spherical or frustum-shaped. The spherical shape provides greater rotational mobility and is suitable for pseudo-joint interfaces that require flexible rotation; the platform shape increases the contact area and improves stability and is suitable for pseudo-joint interfaces that require greater support.

[0015] Preferably, the outer edge of the cap is provided with a plurality of microwing protrusions that are embedded in the periphery of the osteotomy section. The microwing protrusions can provide anti-rotation fixation and work in conjunction with the intramedullary stalk to resist torsional forces.

[0016] In a second aspect, the present invention also provides a method for manufacturing a bio-inert bone end-sealing device for pseudo-arthrosis surgery according to the first aspect, comprising the following steps: S1. Selective laser sintering 3D printing technology is adopted, using short carbon fiber reinforced polyether ether ketone powder as raw material to integrally form a cap body containing an inner porous layer and an outer dense layer. The printing laser power of the outer dense layer is 35-50W, forming an outer dense layer with a wall thickness of 2.0-3.0mm. The inner porous layer and the outer dense layer naturally form a gradient transition interface during the printing process. S2. Anneal the printed cap body at 300-380℃ for 1-4 hours in an inert atmosphere to make the elastic modulus of the cap body reach 12-24GPa. S3. A zirconia ceramic coating is formed on the outer surface of the outer dense layer by plasma spraying. The spraying material is 3 mol% Y2O3 stabilized tetragonal zirconia powder. The coating thickness is 50-200 μm. The coating is polished with diamond until the surface roughness Ra≤0.8 μm. First, a titanium bonding underlayer with a thickness of 30-80 μm is deposited on the outer surface of the outer dense layer, and then the zirconia ceramic coating is deposited. During the spraying process, compressed air is applied to the back of the cap to keep the substrate temperature below 200℃. S4. Using a rotating multi-angle magnetron sputtering process, deposit particles with a diameter of 20-50 nm and a silver loading of 0.5-2.0 μg / cm³ on the surface of the inner porous layer and the intramedullary short stalk. 2 Nano silver antibacterial coating.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The cap body material is CFR-PEEK, which is a long-term implantable bio-inert material that has been clinically verified. It does not cause chronic foreign body reaction and granuloma, and overcomes the inflammatory stimulation problem caused by long-term retention of bone wax in the body.

[0018] (2) The inner porous layer surface and the intramedullary short stalk surface are coated with nano-silver antibacterial coating by magnetron sputtering, which can effectively inhibit the adhesion and proliferation of common orthopedic pathogens such as Staphylococcus aureus and Escherichia coli, while controlling the release of silver ions to maintain low cytotoxicity to normal tissue cells, thus overcoming the defects of bone wax having no antibacterial ability and inhibiting the immune defense of bone tissue.

[0019] (3) The pore size of the inner porous layer is limited to 200-350 μm, the porosity is 40-50%, and the pore connectivity is ≥85%. This combination of parameters selectively promotes fibroblast adhesion and proliferation while inhibiting osteoblast ingrowth, so that the fibrous tissue forms a three-dimensional interconnected anchoring network in the porous layer, providing long-term reliable biological fixation and overcoming the defect of displacement and detachment caused by the lack of biological fixation mechanism between bone wax and bone tissue.

[0020] (4) The plasma-sprayed zirconia ceramic coating on the outer surface of the outer dense layer forms a dense and smooth bio-inert barrier, which inhibits the adhesion of osteoblasts on the outer surface of the cap and their migration across the pseudo-joint space, effectively preventing the formation of bone bridges and re-ossification, overcoming the defect that bone wax cannot prevent re-ossification for a long time. The polished zirconia coating surface has a low coefficient of friction. When each of the two opposite osteotomy ends is covered by a cap, a zirconia-zirconia rotation interface is formed between the outer surfaces of the cap, which is beneficial to the recovery and maintenance of forearm rotation function.

[0021] (5) The elastic modulus of the CFR-PEEK cap is 12-24 GPa, which is similar to the elastic modulus of human cortical bone. This reduces the stress shielding effect at the cap-bone interface and reduces the risk of bone resorption or cap loosening caused by stress concentration at the interface.

[0022] (6) The zirconia coating provides contour imaging under X-ray, and the embedded tantalum marker beads provide high-brightness metallic markers. The two constitute a dual imaging identification system, which facilitates accurate assessment of the cap position and pseudo-joint space status during postoperative X-ray follow-up. Both the CFR-PEEK substrate and the zirconia ceramic coating are compatible with magnetic resonance imaging. The MRI artifacts produced by the tantalum marker beads are minimal, allowing patients to safely undergo MRI examinations postoperatively without causing clinically significant image interference.

[0023] (7) The cap body is integrally formed by selective laser sintering 3D printing. By changing the laser power layer by layer, a double-layer gradient structure is achieved in a single printing, eliminating the need for subsequent assembly or bonding processes. SLS 3D printing technology can customize the outer diameter, shape, and number and position of microwings of the cap body according to the patient's preoperative CT data, achieving personalized manufacturing. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a partial structural diagram of the inner porous layer of the present invention; Figure 4 This is a schematic diagram illustrating the surgical principle of implanting osteotomy ends and maintaining the pseudo-articular space according to the present invention. Figure 5 This is a formal comparison diagram of the two shapes of the cap body of the present invention.

[0025] Figure label: 1. Cap body; 2. Intramedullary short stalk; 3. Inner porous layer; 4. Outer dense layer; 5. Zirconia ceramic coating; 6. Nano-silver antibacterial coating; 7. Microwing protrusions; 8. Tantalum marker beads; 9. Osteotomy section; 10. Pseudo-articular space; 11. Fibrous tissue ingrowth area; 12. Interconnecting pores. Detailed Implementation The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] like Figure 1-5 As shown, this invention provides a technical solution to address the technical problems of foreign body reaction, infection, displacement, and reossification in existing pseudoarthrosis surgeries. The invention provides the following technical solution: a bio-inert bone end-sealing device for pseudoarthrosis surgery, comprising a cap 1. The cap 1 includes an outer dense layer 4 and an inner porous layer 3. The inner porous layer 3 is located on the bone contact surface side of the cap 1 and is formed by interconnecting pores 12. The space filled by the interconnecting pores 12 forms a fibrous tissue ingrowth zone 11 for fibrosis at the osteotomy section 9. The cap 1, which allows for cell migration, is integrally molded using short carbon fiber reinforced polyether ether ketone powder as raw material. It exhibits excellent biological inertness, completely eliminating chronic foreign body reactions and granulomas caused by bone wax. It employs a dual-layer gradient structure to achieve functional zoning. The inner porous layer provides space for fibrous tissue ingrowth, achieving biological fixation. The outer dense layer provides mechanical support, withstanding intramedullary pressure and rotational shear force. Furthermore, the interconnected pores form a continuous fibrous tissue ingrowth zone, enabling the fibrous tissue to form a three-dimensional anchorage with the osteotomy surface, replacing the mechanical impingement of bone wax and thus solving the problem of displacement and detachment.

[0027] Specifically, the interconnecting vias 12 have a pore size of 200-350 μm, a porosity of 40-50%, and a via connectivity of ≥85%. The pore size of the interconnecting vias 12, combined with the inertness of the CFR-PEEK material and the selective inhibition of the nano-silver coating, achieves selective fixation with only fibrous tissue ingrowth and a bone tissue ingrowth rate of <5%. The 40-50% porosity balances the fiber ingrowth space and the mechanical strength of the porous layer, while the ≥85% via connectivity ensures that the fibrous tissue forms a three-dimensional continuous network, providing uniform and reliable biological fixation force and avoiding local loosening.

[0028] The short carbon fiber reinforced polyether ether ketone powder has a short carbon fiber mass fraction of 28-35 wt%. The 28-35 wt% carbon fiber content can precisely control the elastic modulus of the cap to 12-24 GPa, which is highly matched with the elastic modulus of human cortical bone.

[0029] In this embodiment, the outer surface of the outer dense layer 4 is provided with a zirconia ceramic coating 5. The dense and smooth zirconia coating forms a bio-inert barrier, inhibiting osteoblast adhesion and migration across the pseudo-joint space. Furthermore, the high density of zirconia provides X-ray contour imaging, facilitating postoperative assessment of the pseudo-joint space status.

[0030] In this embodiment, an intramedullary stalk 2 is centrally located on the side of the inner porous layer 3 facing the bone contact surface. The intramedullary stalk is inserted into the medullary cavity of the osteotomy section, providing early postoperative axial stability and resistance to pull-out. Simultaneously, the surfaces of the inner porous layer 3 and the intramedullary stalk 2 are coated with a nano-silver antibacterial coating 6. This nano-silver coating exhibits an inhibition rate of >97% against Staphylococcus aureus and Escherichia coli, effectively inhibiting the colonization of common orthopedic pathogens and reducing the risk of deep infection.

[0031] In this embodiment, at least one tantalum bead 8 is embedded in the outer dense layer 4. The tantalum bead has extremely high X-ray impermeability and forms a dual image identification system with the contour imaging of the zirconium oxide coating, thus solving the problem of insufficient image recognition of pure CFR-PEEK implants.

[0032] In this embodiment, as Figure 5 As shown, the cap 1 is spherical or frustum-shaped. The spherical shape provides greater rotational mobility and is suitable for pseudo-joint interfaces that require flexible rotation; the platform shape increases the contact area and improves stability and is suitable for pseudo-joint interfaces that require greater support.

[0033] In this embodiment, the outer edge of the cap 1 is uniformly provided with a plurality of microwing protrusions 7 embedded in the periphery of the osteotomy section 9. The microwing protrusions 7 can provide anti-rotation fixation and work together with the intramedullary short stem to resist torsional force.

[0034] In this invention, the pore size of the inner porous layer 3 is set to 200-350 μm. This pore size range usually promotes bone tissue ingrowth on conventional metal or ceramic substrates, but produces a completely different tissue response on the CFR-PEEK substrate of this invention. The reasons are: (1) The CFR-PEEK material itself is biologically inert, does not contain bioactive ions that can induce osteogenic differentiation, and its surface lacks the hydrophilic sites required for osteoblast adhesion; (2) The nano-silver antibacterial coating selectively inhibits osteoblast proliferation while releasing silver ions, and osteoblasts are more sensitive to silver ions than fibroblasts; (3) The zirconia ceramic coating on the outer surface of the outer dense layer constitutes an anti-reosteolysis barrier, preventing osteoblasts from migrating to the inner layer of the cap from the outside. The synergistic effect of the above three aspects makes the adhesion and proliferation of fibrous tissue significantly better than that of bone tissue in the pore size range of 200-350 μm (see Table 2, fibrous / osteogenic ratio reaches 3.6-4.3:1), achieving selective tissue ingrowth.

[0035] like Figure 1-3 As shown, during the surgery, a cap 1 is implanted into the osteotomy section 9, and an intramedullary short stem 2 is inserted into the medullary cavity of the osteotomy section 9 to provide initial axial stability. Microwing protrusions 7 are embedded in the cortical bone around the osteotomy section 9 to provide anti-rotation fixation. One cap 1 is implanted into each of the two opposing osteotomy ends. The zirconia ceramic coating 5 on the outer surface of the cap 1 forms the rotation interface of the pseudo-articular space 10, inhibiting osteoblast migration across the pseudo-articular space 10 and maintaining the long-term patency of the pseudo-articular space 10.

[0036] As a specific process in this embodiment: S1 and the cap body 1 are integrally formed using selective laser sintering (SLS) 3D printing technology, with short carbon fiber reinforced polyetheretherketone (CFR-PEEK) powder as the raw material. The mass fraction of short carbon fibers is 28-35 wt%. During the printing process, a double-layer gradient structure is achieved by changing the laser power parameters layer by layer: the printing area of ​​the inner porous layer 3 uses a lower laser power, 15-25W, to partially sinter the powder particles, forming a porous structure with interconnected pores 12, with a pore size of 200-350μm, a porosity of 40-50%, and a pore connectivity rate ≥85%; the printing area of ​​the outer dense layer 4 uses a higher laser power, 35-50W, to completely melt and sinter the powder particles, forming a dense structure with a wall thickness of 2.0-3.0mm and a printing layer thickness of 50-100μm. The inner porous layer 3 and the outer dense layer 4 naturally form a gradient transition interface during the printing process, requiring no subsequent assembly or bonding. Through-hole connectivity was measured using three-dimensional reconstruction via microcomputed tomography.

[0037] After SLS 3D printing, the cap body is annealed in an inert atmosphere (nitrogen or argon) at 300-380°C for 1-4 hours to improve the crystallinity of the PEEK matrix and the overall elastic modulus of the CFR-PEEK composite material. After annealing, the elastic modulus of the cap body reaches 12-24 GPa, which is close to the elastic modulus range of human cortical bone (11.5-17.0 GPa), which helps to reduce stress shielding effect.

[0038] For configurations containing tantalum marker beads, tantalum bead mounting holes are pre-drilled at preset positions in the outer dense layer 4 during SLS printing. After printing, the tantalum marker beads 8 are pressed into the mounting holes with an interference fit. The diameter of the tantalum marker beads 8 is 0.8-1.0 mm, and the number is 1-3 beads, which are distributed in a ring at equal intervals in the outer dense layer 4.

[0039] S2. Plasma Spraying of Zirconia Ceramic Coating: After the cap body 1 is formed, a zirconia ceramic coating 5 is deposited on the outer surface of the outer dense layer 4 using an atmospheric plasma spraying process. The spraying material is 3 mol% Y₂O₃ stabilized tetragonal zirconia powder. The coating thickness is 50-200 μm. After spraying, the outer surface of the zirconia ceramic coating 5 is precisely polished using a diamond polishing process to reduce the surface roughness Ra to ≤0.8 μm, forming a smooth and dense coating surface. The initial coating thickness of the plasma spraying allows for polishing allowance. Taking Example 1 as an example, the initial spraying thickness is 160-180 μm, and after diamond grinding and polishing, the final coating thickness is 100 μm, and the surface roughness Ra is reduced to 0.6 μm.

[0040] The surface of the inner porous layer 3 is protected by a masking fixture during the spraying process, and no zirconium oxide coating is applied.

[0041] In a preferred embodiment, a titanium bonding underlayer with a thickness of 30-80 μm is provided between the outer surface of the outer dense layer 4 and the zirconia ceramic coating 5. This titanium bonding underlayer is deposited on the surface of the CFR-PEEK outer dense layer by low-power plasma spraying or magnetron sputtering to improve the bonding strength between the zirconia ceramic coating and the polymer substrate. During the plasma spraying process, compressed air is applied to the back of the cap for cooling, maintaining the substrate temperature below 200°C to prevent thermal degradation of the CFR-PEEK substrate.

[0042] S3. Magnetron Sputtering of Nano-Silver Antibacterial Coating: A nano-silver antibacterial coating 6 is deposited on the surface of the inner porous layer 3 and the surface of the intramedullary short stalk 2 using a rotating multi-angle magnetron sputtering process. Rotating multi-angle sputtering ensures that nano-silver particles are uniformly deposited on all azimuths of the inner wall of the porous layer and on the entire circumference of the intramedullary short stalk 2. The nano-silver particles have a particle size of 20-50 nm and a silver loading of 0.5-2.0 μg / cm³. 2The outer surface of the outer dense layer 4 is covered with a zirconia ceramic coating 5, so it needs to be protected with a shielding fixture during sputtering and no nano-silver coating is applied.

[0043] After the magnetron sputtering is completed, a scanning electron microscope combined with energy dispersive spectroscopy is used to perform a surface scan of the inner wall of the porous layer to confirm the uniformity of the distribution of silver nanoparticles on the inner wall of the porous layer.

[0044] As a specific embodiment of this example: This embodiment provides three standard sizes: S (small), M (medium), and L (large) to accommodate different anatomical sites and individual patient osteotomy section dimensions. The L-type cap, due to its larger outer diameter, features increased outer wall thickness, inner layer depth, number of microwings, and microwing height, and appropriately increased carbon fiber content to ensure mechanical strength. The size specifications of the three sizes are listed in Table 1.

[0045] Table 1 Size Specifications of Three Models Example 1 (S type): This embodiment provides an S-shaped bio-inert bone fracture end sealing device, suitable for sites with small osteotomy section diameters. The cap body 1 has an outer diameter of 10 mm, a total height of 4.5 mm, and a spherical shape. The cap body 1 is integrally formed using CFR-PEEK material via SLS 3D printing, with a short carbon fiber mass fraction of 30 wt% and an elastic modulus of 18 GPa. The printing laser power for the inner porous layer 3 is 18 W, and the printing laser power for the outer dense layer 4 is 42 W, with a layer thickness of 80 μm.

[0046] The inner porous layer 3 has a pore size of 280 μm, a porosity of 45%, and a pore connectivity rate of 90% as determined by μCT 3D reconstruction. The layer depth is 1.2 mm. The outer dense layer 4 has a wall thickness of 2.5 mm.

[0047] The outer surface of the outer dense layer 4 is plasma-sprayed with a zirconia ceramic coating 5, which has a thickness of 100 μm and a surface roughness Ra of 0.6 μm after diamond polishing.

[0048] The surfaces of the inner porous layer 3 and the intramedullary short stalk 2 were coated with a nano-silver antibacterial coating 6 by rotating magnetron sputtering. The nano-silver particles had a diameter of 30 nm and a silver loading of 1.2 μg / cm³. 2 .

[0049] The length of the intramedullary short stalk 2 is 12 mm. The cap body 1 has 3 microwing protrusions 7 around its perimeter. The height of the microwing is 1.0 mm, the angle between the microwing and the perimeter of the cap body is 75°, and the interference fit is 0.2 mm.

[0050] Example 2 (M type): This embodiment provides an M-type bio-inert bone fracture end-sealing device, suitable for sites with medium-diameter osteotomy sections, such as the Sauvé-Kapandji or Darrach procedures for the distal ulna in adults. The cap body 1 has an outer diameter of 14 mm, a total height of 5.0 mm, and a spherical shape. The cap body 1 is integrally formed using SLS 3D printing of CFR-PEEK material (30 wt% short carbon fiber) with an elastic modulus of 18 GPa. The printing laser power for the inner porous layer 3 is 20 W, and the printing laser power for the outer dense layer 4 is 45 W, with a layer thickness of 80 μm.

[0051] The inner porous layer 3 has a pore size of 300 μm, a porosity of 45%, and a pore connectivity rate of 88% as determined by μCT 3D reconstruction. The layer depth is 1.2 mm. The outer dense layer 4 has a wall thickness of 2.5 mm.

[0052] The outer surface of the outer dense layer 4 is plasma-sprayed with a zirconia ceramic coating 5, the coating thickness is 120μm, and the surface roughness Ra is 0.5μm after diamond polishing.

[0053] The surface of the inner porous layer 3 and the surface of the intramedullary short stalk 2 are coated with a nano-silver antibacterial coating 6 by rotating magnetron sputtering. The nano-silver particles have a particle size of 35nm and a silver loading of 1.0μg / cm².

[0054] The length of the intramedullary short stalk 2 is 13 mm. The cap body 1 has 3 microwing protrusions 7 around its perimeter. The height of the microwing is 1.0 mm, the angle between the microwing and the perimeter of the cap body is 75°, and the interference fit is 0.2 mm.

[0055] Example 3 (L-type): This embodiment provides an L-shaped bio-inert bone fracture end sealing device, suitable for areas with large osteotomy section diameters. The cap body 1 has an outer diameter of 18 mm, a total height of 5.5 mm, and a platform shape. The cap body 1 is integrally formed using CFR-PEEK material via SLS 3D printing, with a short carbon fiber mass fraction of 32 wt% and an elastic modulus of 20 GPa. The L-shaped cap body uses a higher carbon fiber content to accommodate the higher bending stiffness required for the larger outer diameter. The printing laser power for the inner porous layer 3 is 22 W, and the printing laser power for the outer dense layer 4 is 48 W, with a layer thickness of 80 μm.

[0056] The inner porous layer 3 has a pore size of 300 μm, a porosity of 42%, and a pore connectivity rate of 87% as determined by μCT 3D reconstruction. The layer depth is 1.5 mm. The outer dense layer 4 has a wall thickness of 3.0 mm. Due to the increased outer diameter of the L-shaped cap, the outer layer wall thickness and inner layer depth were correspondingly increased to ensure mechanical support strength and sufficient fiber ingrowth space.

[0057] The outer surface of the outer dense layer 4 is plasma-sprayed with a zirconia ceramic coating 5, the coating thickness is 150μm, and the surface roughness Ra is 0.4μm after diamond polishing.

[0058] The surfaces of the inner porous layer 3 and the intramedullary short stalk 2 were coated with a nano-silver antibacterial coating 6 by rotating magnetron sputtering. The nano-silver particles had a diameter of 35 nm and a silver loading of 1.5 μg / cm³. 2 .

[0059] The length of the intramedullary stalk 2 is 15 mm. The cap body 1 has 4 microwing protrusions 7 around its perimeter, with a microwing height of 1.2 mm and an angle of 80° between the microwing and the perimeter of the cap body. The interference fit is 0.25 mm. Due to the longer perimeter of the L-shaped cap body, the number of microwings is increased to 4 to ensure uniform anti-rotation anchoring.

[0060] Example 4 (S-type with tantalum marker beads): Based on the S-shaped device of Example 1, this embodiment further embeds tantalum marker beads 8 in the outer dense layer 4 of the cap body 1 to provide enhanced postoperative radiographic recognizability.

[0061] The structural parameters of the cap body 1 are the same as in Example 1: outer diameter 10 mm, total height 4.5 mm, spherical shape, CFR-PEEK material, elastic modulus 18 GPa. The inner porous layer 3 has a pore size of 280 μm, a porosity of 45%, a pore connectivity rate of 90%, and a layer depth of 1.2 mm. The outer dense layer 4 has a wall thickness of 2.5 mm. The zirconia ceramic coating 5 has a thickness of 100 μm and a surface roughness Ra of 0.6 μm. The nano-silver antibacterial coating 6 has nano-silver particles with a particle size of 30 nm and a silver loading of 1.2 μg / cm³. 2 The intramedullary stalk 2 is 12mm long. There are 3 microwings 7, each 1.0mm high, with an included angle of 75° and an interference fit of 0.2mm. SLS printing parameters: inner layer laser power 18W, outer layer laser power 42W, layer thickness 80μm.

[0062] Two tantalum marker beads 8, each 0.9 mm in diameter, are embedded in the outer dense layer 4 and are arranged in a ring at 180° intervals. The tantalum marker beads 8 appear as high-brightness metallic markers in X-ray images, forming a dual image marking system with the outline development of the zirconium oxide ceramic coating 5.

[0063] To illustrate the feasibility of the key performance characteristics of this invention, the key performance characteristics of the device described herein are verified through in vitro and animal experiments: (1) Selective tissue ingrowth performance The inner porous layer of Example 1 of this invention, with a pore size of 280 μm, was used as the experimental group (Group A). ​​Macroporous PEEK with a pore size of 450 μm was used as the control group (Group B). Smooth, dense PEEK was used as the control group (Group C), and bone wax was used as the control group (Group D). Human fibroblasts (HFF-1) and human osteoblasts (MG-63) were seeded onto the surface of each group's samples, and cell adhesion rate was measured after 7 days of culture. Simultaneously, samples from each group were implanted into a rabbit femoral condyle defect model, and bone ingrowth rate was assessed 12 weeks post-surgery. The results are listed in Table 2.

[0064] Table 2 Selective tissue ingrowth properties of porous structures with different pore sizes Table 2 shows that the fibroblast adhesion rate in group A1 was 78.5%, significantly higher than the osteoblast adhesion rate (18.2%), with a fiber / osteoblast ratio of 4.3:1. In group A2, the fibroblast adhesion rate was 75.2%, also significantly higher than the osteoblast adhesion rate (20.8%), with a fiber / osteoblast ratio of 3.6:1. The bone ingrowth rate in both groups was <5% after 12 weeks, confirming that a pore size range of 200-350 μm can achieve selective fibrous tissue ingrowth while inhibiting bone tissue ingrowth.

[0065] In Group B, the osteoblast adhesion rate was 62.8%, surpassing the fibroblast adhesion rate (45.3%), and the bone ingrowth rate at 12 weeks was as high as 35.2%, making it unsuitable for pseudo-joint space maintenance scenarios.

[0066] The adhesion rates of both cell types in group D were less than 5%, indicating that bone wax could not provide any biological fixation.

[0067] (2) Anti-re-abrasion properties of zirconia coating Zirconia-coated samples with different surface roughnesses after diamond polishing were used as experimental groups, while sprayed zirconia coatings served as control groups, along with bone wax and blank PEEK. Human osteoblasts were seeded onto the surface of each group of samples, and the osteoblast adhesion rate was measured after 7 days of culture. Simultaneously, the rate of bone bridge formation within the pseudoarticular space was assessed 12 weeks post-surgery in a rabbit ulnar osteotomy model. The results are listed in Table 3.

[0068] Table 3. Effects of zirconia coating surface roughness on osteoblast adhesion and bone bridge formation. Table 3 shows that, after polishing to achieve Ra ≤ 0.8 μm, the osteoblast adhesion rate of the zirconia coating decreased to 15.8% and 10.2%, respectively, with a bone bridge formation rate of 0% at 12 weeks. The sprayed zirconia coating (Ra = 5.2 μm) exhibited a high osteoblast adhesion rate of 52.3% and a bone bridge formation rate of 25%, indicating that the surface roughness of the coating is a key factor determining its anti-osteogenic adhesion effect. The bone bridge formation rate in the bone wax control group was 33.3%, and in the blank control group it was 75%, both significantly higher than that in the polished zirconia coating group.

[0069] (3) Antibacterial properties of nano-silver Two nano-silver coated samples of different particle sizes were used as experimental groups to detect the antibacterial rate against Staphylococcus aureus and Escherichia coli, while cytotoxicity was assessed using mouse pre-osteoblasts (MC3T3-E1). The results are listed in Table 4.

[0070] Table 4. Antibacterial properties and cell compatibility of nano-silver antibacterial coating Table 4 shows that the silver nanoparticle coatings with particle sizes of 30 nm and 50 nm both exhibited antibacterial rates >97% against *S. aureus* and *E. coli*, while also maintaining MC3T3-E1 cell viability >90%. This confirms that silver loading of 0.5-2.0 μg / cm³ effectively inhibited bacterial growth in *S. aureus* and *E. coli*. 2 Within this range, the nano-silver coating can achieve effective antibacterial activity while maintaining low cytotoxicity to normal tissue cells. The antibacterial rate of the 30nm particle size group is slightly higher than that of the 50nm group, but the latter has a slightly better cell survival rate.

[0071] (4) Biomechanical properties Biomechanical tests were performed on porcine ulnar osteotomy specimens using an M-type end cap (Example 2), with bone wax sealing serving as a control group. Tests included axial pull-out force, torsional torque, shear force, and fatigue life. The results are listed in Table 5.

[0072] Table 5. Comparison of biomechanical properties of end caps and bone wax. Table 5 shows that the axial pull-out force (45.8 N) of the M-type end cap of this invention is 7.3 times that of bone wax, the torsional torque (1.85 N·m) is 15.4 times that of bone wax, the shear force reaches 128.5 N, and the fatigue life exceeds 1 million cycles without loosening or breakage. The axial anchoring of the intramedullary short stalk 2 and the anti-rotational interlocking of the microwing protrusion 7 provide reliable initial mechanical fixation.

[0073] (5) Imaging compatibility X-ray, MRI, and metal detector tests were performed on end caps without tantalum marker beads (Example 1) and end caps with tantalum marker beads (Example 4), with titanium alloy implants as controls. The results are listed in Table 6.

[0074] Table 6. Imaging compatibility of different implants Table 6 shows that the zirconia ceramic coating 5 of the end cap of the present invention provides clear contour imaging under X-rays, and the configuration containing tantalum marker beads 8 further provides high-brightness marker points, forming a dual image identifier. The MRI artifact area is <2.5 mm². 2 and <3.0mm 2 Much smaller than the 35-80mm of titanium alloy implants 2 Patients can safely undergo MRI scans post-surgery. Neither the CFR-PEEK substrate nor the zirconia coating triggers metal detectors.

[0075] (6) Overall performance comparison In a rabbit ulnar osteotomy pseudoarthrosis model, three groups—those using the end cap of this invention, those using bone wax closure, and a blank control (no closure)—were compared and observed for 12 weeks to assess foreign body reaction scores, infection rates, dislodgement rates, and bone bridge formation rates. The results are listed in Table 7.

[0076] Table 7. Comparison of overall performance of end caps, bone wax, and blank control (12 weeks post-operation) Table 7 shows that the foreign body reaction score of the end cap of this invention was only 0.3 points (mild) at 12 weeks postoperatively, with 0% infection rate, detachment rate, and bone bridge formation rate. In contrast, the foreign body reaction score of the bone wax control group was 2.8 points (moderate to severe), with an infection rate of 12.5%, a detachment rate of 20.8%, and a bone bridge formation rate of 16.7%. The bone bridge formation rate in the blank control group was as high as 37.5%. These results confirm that the end cap of this invention can simultaneously address four major clinical technical problems: foreign body reaction, infection, displacement, and reossification.

[0077] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0078] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly and specifically defined.

[0079] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0080] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A bio-inert bone end-sealing device for pseudo-arthrosis surgery, characterized in that, The cap body (1) includes an outer dense layer (4) and an inner porous layer (3). The inner porous layer (3) is located on the bone contact surface side of the cap body (1). The inner porous layer (3) is formed by filling interconnected pores (12). The space filled by the interconnected pores (12) forms a fibrous tissue ingrowth zone (11) for fibroblasts at the osteotomy section (9) to migrate into. The cap body (1) is integrally formed using short carbon fiber reinforced polyether ether ketone powder as raw material.

2. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 1, characterized in that: The short carbon fiber in the short carbon fiber reinforced polyether ether ketone powder is 28-35 wt%.

3. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 1, characterized in that: The interconnecting via (12) has a pore size of 200-350μm, a porosity of 40-50%, and a via connectivity of ≥85%.

4. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 3, characterized in that: At least one tantalum bead (8) is embedded in the outer dense layer (4).

5. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 4, characterized in that: The outer surface of the outer dense layer (4) is provided with a zirconium oxide ceramic coating (5).

6. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 5, characterized in that: The inner porous layer (3) has a short intramedullary stalk (2) centrally located on the side facing the bone contact surface.

7. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 6, characterized in that: The inner porous layer (3) and the intramedullary short stalk (2) are provided with a nano-silver antibacterial coating (6).

8. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 1, characterized in that: The cap body (1) is spherical or frustum-shaped.

9. The bio-inert bone end sealing device for pseudoarthrosis surgery according to claim 1, characterized in that: The outer edge of the cap (1) is uniformly provided with multiple microwing protrusions (7) embedded in the periphery of the osteotomy section (9).

10. A method for manufacturing a bio-inert bone end-sealing device for pseudo-arthrosis surgery as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Selective laser sintering 3D printing technology is adopted. Short carbon fiber reinforced polyether ether ketone powder is used as raw material to integrally form a cap body (1) containing an inner porous layer (3) and an outer dense layer (4). The printing laser power of the outer dense layer (4) is 35-50W, forming an outer dense layer (4) with a wall thickness of 2.0-3.0mm. The inner porous layer (3) and the outer dense layer (4) naturally form a gradient transition interface during the printing process. S2. The printed cap body (1) is annealed in an inert atmosphere at 300-380℃ for 1-4 hours to make the elastic modulus of the cap body reach 12-24GPa. S3. A zirconia ceramic coating (5) is formed on the outer surface of the outer dense layer (4) by plasma spraying. The spraying material is 3 mol% Y2O3 stabilized tetragonal zirconia powder. The coating thickness is 50-200 μm. The surface roughness Ra is ≤0.8 μm after diamond polishing. First, a titanium bonding underlayer with a thickness of 30-80 μm is deposited on the outer surface of the outer dense layer (4), and then the zirconia ceramic coating (5) is deposited. During the spraying process, compressed air is applied to the back of the cap to cool it and keep the substrate temperature below 200℃. S4. Using a rotating multi-angle magnetron sputtering process, deposit particles with a diameter of 20-50 nm and a silver loading of 0.5-2.0 μg / cm² on the surface of the inner porous layer (3) and the intramedullary short stalk (2). 2 Nano-silver antibacterial coating (6).

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