A conformal porous titanium alloy fastening structure implant and preparation method thereof

Abstract

The present invention discloses a conformable porous titanium alloy fastening structure implant, comprising an outer nail body and an inner skeleton, wherein a nail cap is provided at one end of the inner skeleton, a nail tip is provided at the other end, an outer thread structure surrounds the outer surface of the inner skeleton, one end of the outer thread structure is connected to the nail cap, and the other end of the outer thread structure is connected to the nail tip; one end of the outer nail body is connected to the outer surface of the nail tip, and the other end of the outer nail body is connected to the top cap, and a plurality of micropores are continuously distributed on the surface of the outer nail body; the thread on the inner skeleton penetrates the outer nail body and forms a thread structure on the outer side surface of the outer nail body. The present invention also discloses a preparation method of the implant. The implant is a nail-like structure, and the microporous area on the surface of the structure can effectively promote the growth of the surrounding tissue of the implant after implantation, improve the patient's recovery period, and effectively reduce the risk of "stress shielding" problems. The interior of the nail body is designed as a skeleton, which can ensure the strength of the nail body and avoid the problem of poor quality of the actual product due to the difficulty of the process.

Description

Technical Field

[0001] The invention belongs to the technical field of medical equipment, and in particular relates to a conformal porous titanium alloy fastening structure implant, and also relates to a preparation method of the implant. Background Art

[0002] For patients with orthopedic trauma and other diseases, surgery is often required to repair or adjust the bone structure. Since the bone structure is a load-bearing structure in the human body, it is necessary to ensure the structural stability of the repaired bone structure and the good integration of the bone structure with the surrounding tissue structure. In orthopedic surgery, in order to achieve the repair of the traumatic bone structure, auxiliary fastening structures or external implants are often required. At present, during orthopedic surgery, the fixation of auxiliary fastening structures (such as bone plates) and most implants in the human body requires the use of fastening structure implants, such as plate screws, intramedullary nails, interlocking nails, etc. The corresponding fastening features of implant screws or similar structures are generally metal, which are made by blank machining or casting. Some nail structures are also made of non-metal, and the processing method is powder sintering or 3D printing.

[0003] At present, the fastening structure implants used in orthopedic surgery are mainly various solid nail-shaped or regular integral honeycomb microporous structures. Most of the materials are titanium alloys, and a few are non-metallic materials. After the titanium alloy solid nail-shaped structure is implanted in the human body, the elastic modulus of titanium alloy is about 110GPa or more, which is quite different from the elastic model of human bone structure, which will cause local "stress shielding" problems, resulting in reduced bone density and osteoporosis. At the same time, due to the large weight of the solid structure titanium nail, it will increase the burden on the human body after implantation. The smooth surface of the titanium nail structure is also not conducive to the fusion of human tissue and the implanted titanium nail. Although the integral honeycomb microporous structure fastening structure reduces the elastic model of the fastening structure, the distribution of micropores promotes tissue growth and fusion, but the regular honeycomb micropores can only achieve axial two-dimensional connectivity, and cannot achieve spatial three-dimensional connectivity. The pores are in a periodic and regular distribution state, which is not conducive to the uniformity and growth effect of tissue growth. At the same time, the integral honeycomb microporous structure is used as a fastening structure. Due to the large number of pores distributed inside and outside the structure as a whole, its strength and bending resistance are poor, which may cause breakage or detachment after implantation in the human body. Nail bodies made of non-metallic materials cannot be used for a long time in areas with high strength requirements due to insufficient material strength and some materials being rejected by the human body. Summary of the invention

[0004] The purpose of the present invention is to provide a conformable porous titanium alloy fastening structure implant, which effectively promotes the growth of surrounding tissues after implantation and improves the patient's recovery period.

[0005] Another object of the present invention is to provide a method for preparing a conformable porous titanium alloy fastening structure implant, thereby achieving one-time forming of the fastening structure implant.

[0006] The technical solution adopted by the present invention is a conformable porous titanium alloy fastening structure implant, including an outer nail body and an inner skeleton, a nail cap is provided at one end of the inner skeleton, a nail tip is provided at the other end of the inner skeleton, an outer surface of the inner skeleton is surrounded by an external thread structure, one end of the external thread structure is connected to the nail cap, and the other end of the external thread structure is connected to the nail tip; one end of the outer nail body is connected to the outer surface of the nail tip, and the other end of the outer nail body is connected to the top cap, and a number of micropores are continuously distributed on the surface of the outer nail body; the thread on the inner skeleton passes through the outer nail body and forms a thread structure on the outer edge surface of the outer nail body.

[0007] The present invention is also characterized in that:

[0008] The nail tip is conical or cylindrical.

[0009] The nail cap is in the shape of a flat disc or an arc disc, a force-applying groove is arranged at the center of the outer surface of the nail cap, and the thickness of the nail cap is 1 mm to 8 mm.

[0010] The force application groove is a hexagonal force application groove.

[0011] The outer nail body is cylindrical and hollow inside. A plurality of micropores are formed by interconnecting a plurality of short rods. The pore diameter of the micropores is 80 to 300 microns. The porosity of the micropores on the surface of the outer nail body is 60% to 75%.

[0012] The inner frame is in the shape of a hollow cylinder or a solid cylinder; the diameter of the inner frame is not less than 50% of the diameter of the outer nail body.

[0013] Another technical solution of the present invention is a method for preparing a conformable porous titanium alloy fastening structure implant, the specific process comprising the following steps:

[0014] Step 1, designing a three-dimensional model of the titanium alloy fastening structure implant, converting the three-dimensional model into an STL data format, and then importing it into a commercial pre-processing software, performing section processing on the model with a selected slice thickness, and forming a slice file;

[0015] Step 2: Import the slice file into the metal 3D printer, formulate the forming process of the laser selective melting process, set the laser selective melting parameters, and use titanium alloy powder as the raw material to obtain a one-time formed conformal porous titanium alloy fastening structure implant.

[0016] In step 2, the particle size of the titanium alloy powder is 12um to 65um.

[0017] In step 2, the laser melting processing parameters are as follows: laser power: 220kW to 365kW, scanning speed: 800mm / s to 1200mm / s, layer thickness: 0.03mm to 0.06mm, overlap rate 40% to 65%.

[0018] The beneficial effects of the present invention are:

[0019] The entire fastening structure is a nail-like structure with conformal micropores on the surface of the structure. The microporous area can effectively promote the growth of the surrounding tissues of the implant after implantation, improve the patient's recovery period, and the elastic modulus of the overall structure is only 20% to 40% of that of the traditional solid metal nail body, which can effectively reduce the risk of "stress shielding" problems. The interior of the nail body is designed as a skeleton to ensure the strength of the nail body. Compared with traditional implant nails, the entire fastening structure implant has outstanding comprehensive performance. At the same time, the structure and characteristic dimensions of each part of the fastening structure implant, especially the microporous area, fully consider the process feasibility to avoid the problem of poor actual product quality due to the difficulty of implementing the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a conformal porous titanium alloy fastening structure implant according to the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the inner skeleton in a conformal porous titanium alloy fastening structure implant of the present invention.

[0022] In the figure, 1. outer nail body, 2. inner frame, 3. nail tip, 4. nail cap, 5. force groove, 6. external thread structure. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The present invention provides a conformable porous titanium alloy fastening structure implant, such as Figure 1 and Figure 2As shown, the overall shape of the fastening structure implant is a threaded nail, including an outer nail body 1 and an inner skeleton 2, a nail cap 4 is provided at one end of the inner skeleton 2, a nail tip 3 is provided at the other end of the inner skeleton 2, an outer thread structure 6 is surrounded by the outer surface of the inner skeleton 2, one end of the outer thread structure 6 is connected to the nail cap 4, and the other end of the outer thread structure 6 is connected to the nail tip 3; one end of the outer nail body 1 is connected to the outer surface of the nail tip 3, and the other end of the outer nail body 1 is connected to the top cap 4, and a plurality of micropores are continuously distributed on the surface of the outer nail body 1; the thread on the inner skeleton 2 passes through the outer nail body 1 and forms a thread structure on the outer side surface of the outer nail body 1. The outer nail body 1 is cylindrical and hollow inside. A number of micropores are continuously distributed on the surface of the outer nail body 1. The micropores are composed of a number of short rods connected to each other. The micropores are continuously and evenly distributed without periodicity, that is, they are hollowed out. The pore diameter of the micropores is 80 to 300 microns. The porosity of the micropores on the surface of the outer nail body 1 is 60% to 75%. The maximum thickness of the surface of the outer nail body 1 does not exceed 50% of the diameter of the nail body to ensure the fastening strength of the nail body. To ensure the fusion of the surrounding body tissue and the fastening structure, the minimum thickness of the surface of the outer nail body 1 is not less than 1 mm. The porous area on the surface of the outer nail body 1 is a continuously distributed microporous structure, which is distributed on the annular surface of the nail body. In the above state, the microporous area can be used as a fusion section between the matrix tissue and the implanted fastener, promoting the expansion and fusion of the matrix tissue, and at the same time can reduce the elastic modulus of the entire fastening structure implant by 60% to 80%.

[0025] The nail cap 4 is in the shape of a flat disc or an arc disc, and a force-applying groove 5 is provided at the center of the outer surface of the nail cap 4, and the force-applying groove 5 is a hexagonal force-applying groove; the thickness of the nail cap 4 is 1 mm to 8 mm; the thickness at this location is proportional to the length and diameter of the entire structure, and the hexagonal force-applying groove 5 is provided to facilitate the application of torque to the fastening structure by a standard hexagonal tool during surgery to achieve screwing in, and at the same time, the hexagonal design also makes it unnecessary to use axial force to keep the force-applying tool in the center during the actual surgery, and the environmental adaptability is higher; the nail tip 3 is conical or cylindrical; in the case where it is necessary to screw directly into hard bones, a conical shape is used, otherwise a cylindrical shape is used;

[0026] The inner frame 2 is a hollow cylinder or a solid cylinder; the diameter of the inner frame 2 is not less than 50% of the diameter of the outer nail body 1; in the case where a guide needle is required to pass through, the inner frame 2 adopts a hollow structure, otherwise a solid structure is adopted to achieve the reinforcement of the fastening structure. The inner frame 2 mainly serves as the load-bearing frame of the entire nail-shaped structure to achieve the structural reinforcement of the nail-shaped fastening structure; the threaded structure is the main fastening feature to achieve the screwing engagement and fastening of the fastening structure in the target area;

[0027] Taking into account the actual fastening effect and structural strength, the minimum diameter of the overall structure of the titanium alloy fastening structure implant is greater than 2mm; all features and dimensions of the structure can meet the 3D printing process requirements, reducing manufacturing difficulty and cost.

[0028] The present invention provides a method for preparing a conformable porous titanium alloy fastening structure implant, and the specific process comprises the following steps:

[0029] Step 1, designing a three-dimensional model of the titanium alloy fastening structure implant, converting the three-dimensional model into an STL data format, and then importing it into a commercial pre-processing software, performing section processing on the model with a selected slice thickness, and forming a slice file;

[0030] Step 2, importing the slice file into the metal 3D printer, formulating the forming process of the laser selective melting process, setting the laser selective melting parameters, and using titanium alloy powder as the raw material to obtain a one-time formed conformal porous titanium alloy fastening structure implant;

[0031] In step 2, the particle size of the titanium alloy powder is 12um to 65um;

[0032] In step 2, the laser melting processing parameters are as follows: laser power: 220kW to 365kW, scanning speed: 800mm / s to 1200mm / s, layer thickness: 0.03mm to 0.06mm, overlap rate 40% to 65%.

[0033] Example

[0034] The present invention provides a conformable porous titanium alloy fastening structure implant. First, the total length L, diameter D, thread pitch S, and nail cap thickness T of the fastening structure nail body are determined according to the object to be fastened and the implantation space environment requirements. In this embodiment, L=27mm, D=5mm, S=7mm, and T=2mm are taken, and the remaining characteristic parameters of the thread are determined with reference to relevant standards;

[0035] The features of the fastening structure were designed in the 3D modeling software, and the model was established. Without the need for a guide wire, the internal skeleton was a solid cylindrical structure with a diameter of d = 2.5 mm;

[0036] The nail tip is cylindrical. To ensure a smooth transition between the cylindrical boundary and the front nail tip, the cylindrical fillet R = 2mm;

[0037] In order to ensure that the surface porous area has space for tissue growth and avoid the strength attenuation of the fastening structure nail body due to excessive thickness of the surface porous area, the thickness of the surface porous area is 1.25mm, distributed along the cylindrical surface of the entire nail body, and the micropores are composed of a number of staggered short rod structures. Considering the error in the final process manufacturing process, the micropore design size distribution range is 120mm~360mm, the micropore contour shape is polygonal, and the porosity of the entire area is designed to be 60~70%;

[0038] The designed model is exported as STL data format and imported into commercial pre-processing software. The slice layer thickness is 0.03mm to form a slice file. The slice file is imported into the laser 3D printer, and the laser selective melting parameters are set: laser power: 290KW; scanning speed: 800mm / s; overlap rate: 40%, the powder layer thickness is kept consistent with the slice layer thickness of 0.03mm, and the laser forming parts are formed. This method can achieve the one-time forming of the fastening structure implant.

Claims

1. A conformable porous titanium alloy fastening structure implant, characterized in that: The nail body (1) comprises an outer nail body (1) and an inner frame (2), wherein a nail cap (4) is arranged at one end of the inner frame (2), and a nail tip (3) is arranged at the other end of the inner frame (2); an outer thread structure (6) surrounds the outer surface of the inner frame (2), one end of the outer thread structure (6) is connected to the nail cap (4), and the other end of the outer thread structure (6) is connected to the nail tip (3); one end of the outer nail body (1) is connected to the outer surface of the nail tip (3), and the other end of the outer nail body (1) is connected to the nail cap (4); a plurality of micropores are continuously distributed on the surface of the outer nail body (1); the thread on the inner frame (2) penetrates the outer nail body (1) and forms a thread structure on the outer surface of the outer nail body (1); the nail tip (3) is conical or cylindrical; The nail cap (4) is in the shape of a flat disc or a curved disc, a force-applying groove (5) is provided at the center of the outer surface of the nail cap (4), and the thickness of the nail cap (4) is 1 mm to 8 mm; the force-applying groove (5) is a hexagonal force-applying groove; The outer nail body (1) is cylindrical and hollow inside, and a plurality of micropores are formed by a plurality of short rods connected to each other. The pore diameter of the micropores is 80 to 300 micrometers, and the porosity of the micropores on the surface of the outer nail body (1) is 60% to 75%.

2. The conformable porous titanium alloy fastening structure implant according to claim 1, characterized in that: The inner frame (2) is in the shape of a hollow cylinder or a solid cylinder; the diameter of the inner frame (2) is not less than 50% of the diameter of the outer nail body (1).

3. A method for preparing the conformable porous titanium alloy fastening structure implant as claimed in claim 2, characterized in that: The specific process includes the following steps: Step 1, designing a three-dimensional model of the titanium alloy fastening structure implant, converting the three-dimensional model into an STL data format, and then importing it into a commercial pre-processing software, performing section processing on the model with a selected slice thickness, and forming a slice file; Step 2, importing the slice file into the metal 3D printer, formulating the forming process of the laser selective melting process, setting the laser selective melting parameters, and using titanium alloy powder as the raw material to obtain a one-time formed conformal porous titanium alloy fastening structure implant; The laser melting processing parameters are as follows: laser power: 220 kW ~365kW, scanning speed: 800 mm / s ~1200mm / s, layer thickness: 0.03 mm~0.06mm, overlap rate 40%~65%.

4. The method for preparing a conformable porous titanium alloy fastening structure implant according to claim 3, characterized in that: In step 2, the particle size of the titanium alloy powder is 12um~65um.

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