CN204581484U - A kind of 3D with three-dimensional through loose structure prints bone screw - Google Patents

Abstract

The utility model discloses a 3D printed bone screw with a three-dimensional penetrating porous structure. The screw comprises a nail head, a nail body and a nail cap. The nail body consists of a porous network of interconnected micropores. The porous bone screw of the utility model is made of medical materials that can be implanted into the human body. The interconnected micropore structure on the porous bone screw provides more space for the growth of bone cells, and promotes the implantation of the screw and human bone. The combination of tissues makes the anchor firm.

Description

A 3D printed bone screw with a three-dimensional penetrating porous structure

technical field

The utility model belongs to the technical field of medical devices and relates to a porous bone screw, in particular to a 3D printed bone screw with a three-dimensional penetrating porous structure. The bone screw can be applied to the repair of clinical bone tissue damage.

Background technique

As aging becomes more and more serious, more and more people develop osteoporosis (OP), which is characterized by decreased bone mass, degeneration of bone microstructure, increased bone fragility, and susceptibility to fracture after reaching middle-aged and elderly people. According to statistics, there are about 200 million people in the world suffering from osteoporosis, and its incidence rate has jumped to the seventh place among common diseases in the world. It is one of the most common diseases among middle-aged and elderly people. my country has the largest number of osteoporosis patients in the world The country, the International Osteoporosis Foundation and the China Health Promotion Foundation jointly issued the "White Paper on Osteoporosis Prevention and Control in China" in 2008, pointing out that there are currently 90 million osteoporosis patients in my country, accounting for 7.1% of the total population. Osteoporosis patients Fractures are prone to occur, which are common in the spine, hip joints and limbs, etc., and due to insufficient holding force of the screws on the bone, postoperative osteoporosis patients often have screw loosening, screw withdrawal and the resulting secondary surgery, which is a great concern for both doctors and patients. It brings huge physical and mental distress, and its high cost of treatment also brings a heavy economic burden to patients and society.

At present, the methods to improve the stability of the screw-bone interface mainly include: (1) Bone cement strengthening technology, such as using polymethyl methacrylate (PMMA) bone cement material to strengthen the screw track, but this method is prone to bone cement solidification. Exothermic heat causes damage to surrounding bone and nerve tissue, and PMMA material has poor biocompatibility, hinders bone tissue from growing into the material, and the interface is not strong; and bone cement leakage can easily cause serious complications in the nerve, respiratory and cardiovascular systems; at the same time, This type of technology has high requirements for doctors to operate. Once the bone cement solidifies and the implantation position is not ideal, it will face great challenges for revision again. On this basis, a method of hollow side hole pedicle screw combined with bone cement perfusion was developed. However, in this technology, the effective dosage of bone cement is very close to the leakage dosage, and the stability of the screw can be significantly improved only when the dosage of PMMA is greater than 1.5mL. However, when the dose is 2.02±0.56mL, about 33% of the patients will leak. Therefore, this technique needs to be operated carefully, and this technique still cannot avoid the problems faced by the aforementioned bone cement nail channel reinforcement techniques. (2) The improvement of the screw itself mainly includes changing the length and diameter of the screw, changing the shape of the thread, designing the end of the screw as an expandable structure, and giving the screw a biological coating, etc., but the above-mentioned methods still cannot solve the problem of insufficient force. Both (too large or too small), bone healing at the contact interface, etc., and require high surgical techniques, can easily lead to secondary fractures, important organs such as paravertebral blood vessels, spinal nerve roots, and even spinal cord injuries in the spinal canal. To sum up, the current improved techniques for various screws cannot meet the clinical needs of osteoporosis patients.

Contents of the invention

In order to solve the defects of the prior art, the utility model provides a 3D printing bone screw with a three-dimensional penetrating porous structure. The porous structure of the screw allows new bone to grow into the screw, realizes the biological anchoring of the screw-bone interface, greatly improves the holding force of the screw to the bone, and can effectively prevent screw loosening and screw withdrawal after fixation. clinical application value.

The bone screw with interconnected micropore structure provided by the utility model includes a nail head, a nail body, and a nail cap; the nail body includes a porous network composed of interconnected micropore structures; the aperture of the porous network is 200 μm- 900μm or 1100μm-2500μm, porosity 78%-92%. The advantages of adopting the above-mentioned pore size are: providing multi-hole communication, high porosity and sufficient bone ingrowth, and meeting clinical needs.

Preferably, the pore size of the porous network is 600 μm.

Preferably, the porosity of the porous network is 80%.

Further, the nail body may also include a central body, and the porous network is located outside the central body. In a specific embodiment of the present invention, the porous network is independent from the surface of the central body and surrounds the central body. In another specific embodiment of the present invention, the porous network is a porous surface formed on the surface of the central solid.

Further, the nail body may also include a thread structure on the surface of a porous network formed by interconnected microporous structures.

Further, the pore shape of the porous network includes but not limited to polyhedron, sphere, and irregular shape.

Preferably, the polyhedron is a regular dodecahedron, and the advantage of adopting a regular dodecahedron-shaped pore structure is that the regular dodecahedron can provide a multi-level porous structure connected to each other, which is beneficial to the adhesion and proliferation of early cells, and has a large Good mechanical stability.

Further, the raw material for the porous bone screw can be a non-degradable material or a degradable material. The raw materials for the preparation of the porous bone screw include, but are not limited to: medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body.

Preferably, the medical metal material is titanium alloy.

Further, the diameter range of the nail body is: 2-8mm.

Further, the cross-sectional shape of the nail body is various: circular, elliptical, triangular, square, polygonal, and the length of the nail body is in the range of 1-10 cm.

Further, the nail cap is a solid structure with various cross-sectional shapes: circular, elliptical, square, triangular, and polygonal.

The surface of the porous bone screw of the present invention can be covered with a biological coating to further promote bone integration and growth. These biological coatings include, but are not limited to: hydroxyapatite coatings, calcium titanate coatings, titanium coatings, titanium and hydroxyapatite composite coatings, wollastonite coatings, hydroxyapatite and bisphosphonates Active coatings of salt mixed materials, magnesium fluoride/fluoroapatite composite coatings.

The surface of the interconnected microporous structure of the porous bone screw of the utility model can be attached with a modification material to induce bone cells to grow in. The modified materials include but are not limited to: natural polymer derived materials, such as collagen, fibrin, chitosan; cell growth factors, such as bone morphogenetic protein (BMP), basic fibroblast growth factor (bFGF), PDGF , VEGF; Polylysine; Polypeptides.

The above-mentioned biological coatings and modified materials can also be applied in combination to double promote the integration and growth of bone.

The porous bone screw of the present utility model can be prepared by 3D printing technology, and the production steps are: (1) carry out three-dimensional design and modeling of the porous bone screw with porous structure in the computer; (2) use the metal rapid prototyping method to directly produce Metal powders form finished products. The metal powder is preferably titanium alloy (Ti6Al4V).

The metal rapid prototyping method adopted by the utility model is the laser melting method, and the specific steps of using this method to prepare the porous bone screw of the utility model are as follows:

1) Through the proe three-dimensional design software, establish the three-dimensional model of the porous matrix structure building unit in the computer, construct the unit elements, and set the porosity and pore size;

2) According to the three-dimensional building unit in step 1), use the magics three-dimensional design software to fill and expand the central part of the screw with the three-dimensional design software, and generate the central part of the screw into a porous matrix structure;

3) According to the three-dimensional model in step 2), use Concept laser Mlab metal material 3D printer to print screws;

4) After heat-treating the printed screws obtained in step 3), cool to room temperature;

5) Cut the printed screws obtained in step 4) from the working platform by wire cutting;

6) Sandblasting the printing screws obtained in step 5) to remove excess raw materials sticking and melting on the printing surface;

7) Clean the printed screws obtained in step 6) with ultrasonic waves to remove surface impurities;

8) Put the above-mentioned screws into an ethylene oxide sterilization box for sterilization, and pack them separately.

Further, the process flow of step 3 is as follows: use 10-60 μm normally distributed titanium alloy powder, set the product printing layer thickness to 0.015-0.05 mm, and set the edge compensation to 0.02-0.08 mm; support the printing layer thickness setting to 0.015～0.05mm; additional contours are set to 1-5 inwards or outwards, and the distance is set to 0.02～0.1mm; using the island mode, set the XY direction size to 0.5～10mm, the angle to 0～180 degrees, and the XY deviation The displacement is 0~5mm.

Further, the detailed process flow of step 4 is as follows: heat-treat the printed screw obtained in step 3), and heat it up to 840 degrees within 4 hours under the protection of argon, keep it for 2 hours, and then cool it to 500 degrees in the furnace. Take it out and let it cool down to room temperature naturally.

The utility model also provides the application of the porous bone screw in preparing materials for repairing bone tissue damage. Usually used for fracture internal fixation, spinal internal fixation, and prosthesis fixation screws.

Advantage of the utility model and beneficial effect are as follows:

(1) Titanium alloy has good biocompatibility and is a good implant material; the porous titanium alloy screw can be controlled by controlling the porosity, pore size, pore size distribution, and void morphology of the porous titanium alloy screw. Reasonable design and matching of mechanical properties, so that it has comparable mechanical properties to bones in different parts of the human body.

(2) The pores of the porous bone screw of the present utility model are interconnected microporous structures, the pore diameter is 200 μm-900 μm or 1100 μm-2500 μm, and the porosity is 78%-92%. This pore structure and characteristics fully meet the requirements of bone ingrowth, and are conducive to the transmission of body fluids in the implanted body. It can make osteoblasts adhere, differentiate and grow, and at the same time allow bone tissue to grow into the pores of the porous bone screw, so that the bone-implant interface area is greatly increased, coupled with the mechanical insertion between the bone and the porous structure, so that Biofixation is formed between the implant and the bone tissue, improving the bonding strength of the implant-bone interface.

(3) The porous bone screw of the present utility model can be used in conjunction with absorbable bone cement such as calcium phosphate, calcium sulfate, and hydroxyapatite, and such materials can be filled in the pores of the porous bone screw, thereby further promoting bone integration and growth .

(4) Compared with the technical parameters of 3D printing commonly used in this field, the process parameters adopted in the preparation of the porous bone screw of the present invention greatly improve the precision of the finished product.

Description of drawings

Figure 1 shows the structural diagram of a porous bone screw with a porous network and thread structure composed of interconnected microporous structures; A: overall view, B: cross-sectional view;

Fig. 2 shows the structural view of a porous bone screw with a porous network composed of interconnected microporous structures; A: overall view, B: cross-sectional view;

Fig. 3 shows the structural view of a porous bone screw with a porous network composed of interconnected microporous structures and a central entity; A: overall view, B: cross-sectional view;

Fig. 4 shows a structure diagram of a porous bone screw with a porous network composed of interconnected microporous structures, a central solid and a thread structure; A: overall view, B: cross-sectional view.

Detailed ways

The specific implementation of the porous bone screw of the present invention will be further described below in conjunction with the accompanying drawings.

Example 1 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure. The porous bone screw is composed of a nail head, a nail body, and a nail cap; the nail body is composed of a porous network composed of interconnected microporous structures; was 78%. The nail body diameter range is: 2mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length range of the nail body is: 1cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys.

Example 2 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure, the porous bone screw is composed of a nail head, a nail body, and a nail cap; the nail body is composed of a porous network composed of interconnected microporous structures and threads on the surface of the porous network; The pore size is 600 μm, the porosity is 80%, and the diameter of the nail body is 5 mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length of the nail body is 5 cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys.

Example 3 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure, the porous bone screw is composed of a nail head, a nail body, and a nail cap; the nail body is composed of a porous network composed of a central entity and interconnected microporous structures located outside the central entity ; The porous network is independent of the central solid surface and surrounds the central solid. The pore size of the interconnected microporous structure is 900 μm, the porosity is 92%, and the diameter of the nail body is 8 mm. The cross-sectional shape of the nail body is various: circle, ellipse, triangle, square, polygon, and the range of the nail body length is 10cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys.

Example 4 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure. The porous bone screw is composed of a nail head, a nail body, and a nail cap; And the composition of threads on the surface of the porous network; the porous network is independent of the surface of the central solid and surrounds the central solid. The pore size of the interconnected microporous structure is 1100 μm, and the porosity is 78%; the diameter of the nail body is 3 mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length of the nail body is 3 cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys.

Example 5 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure, the porous bone screw is composed of a nail head, a nail body, a nail cap, and a modification material on the surface of the nail body; A porous network composed of interconnected microporous structures and threads on the surface of the porous network; the porous network is independent of the surface of the central solid and surrounds the central solid; the modification material is attached to the threads and/or to the pore columns of the porous structure . The pore size of the interconnected microporous structure is 1500 μm, the porosity is 80%, and the diameter of the nail body is 7 mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length of the nail body is 9 cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys. Modification materials include but are not limited to: natural polymer derived materials, such as collagen, fibrin, chitosan; cell growth factors, such as bone morphogenetic protein (BMP), basic fibroblast growth factor (bFGF), PDGF, VEGF ; Polylysine; Polypeptides.

Example 6 A 3D printed bone screw with a three-dimensional penetrating porous structure

A porous bone screw with a three-dimensional through hole structure, the porous bone screw is composed of a nail head, a nail body, a nail cap, and a modification material on the surface of the nail body; The porous network formed by the through-hole structure and the threads on the surface of the porous network; the porous network is independent from the surface of the central body and surrounds the central body; the modification material is attached to the thread and/or attached to the hole column of the porous structure. The pore size of the three-dimensional through-hole structure is 2000 μm, the porosity is 85%, and the diameter of the nail body is 7 mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length of the nail body is 9 cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys. Modification materials include but are not limited to: natural polymer derived materials, such as collagen, fibrin, chitosan; cell growth factors, such as bone morphogenetic protein (BMP), basic fibroblast growth factor (bFGF), PDGF, VEGF ; Polylysine; Polypeptides.

Example 7 A 3D printed bone screw with a three-dimensional penetrating porous structure

A 3D printed bone screw with a three-dimensional penetrating porous structure, the porous bone screw is composed of a nail head, a nail body, a nail cap, and a modification material on the surface of the nail body; A porous network composed of a three-dimensional through-hole structure and threads on the surface of the porous network; the porous network is independent from the surface of the central solid and surrounds the central solid; the modification material is attached to the threads and/or attached to the pore columns of the porous structure. The pore size of the three-dimensional through-hole structure is 2500 μm, the porosity is 92%, and the diameter of the nail body is 7 mm. The cross-sectional shape of the nail body is various: circular, oval, triangular, square, polygonal, and the length of the nail body is 9 cm. The nail cap is a solid structure with a variety of cross-sectional shapes: circular, oval, square, triangular, and polygonal. The pore shape of the porous network is polyhedron, sphere or irregular shape. The raw materials for the preparation of the porous bone screw are medical metal materials, bioceramics, and medical polymer materials that can be implanted in the human body. Medical metal materials include but are not limited to titanium and titanium alloys. Modification materials include but are not limited to: natural polymer derived materials, such as collagen, fibrin, chitosan; cell growth factors, such as bone morphogenetic protein (BMP), basic fibroblast growth factor (bFGF), PDGF, VEGF ; Polylysine; Polypeptides.

The preparation method of embodiment 8 porous bone screws

In this example, 3D printing technology is used to prepare the porous bone screws described in Examples 1-8 using titanium alloy as a raw material. The specific operation steps are as follows:

1) Through the proe three-dimensional design software, establish a three-dimensional model of the building unit of the porous matrix structure in the computer, build the building unit elements with a volume XYZ direction of 0.5-5mm, set the pore size to 0.25-5mm, and the porosity to 78-92%;

2) According to the three-dimensional building unit in step 1), use the magics three-dimensional design software to fill and expand the central part of the screw with the three-dimensional design software, and generate the central part of the screw into a porous matrix structure;

3) According to the 3D model in step 2), use Concept laser Mlab metal material 3D printer to print screws. The condition parameters in the process are set as follows: use 10-60μm normally distributed titanium alloy powder, set the product printing layer thickness to 0.015-0.05mm, and set the edge compensation to 0.02-0.08mm; support the printing layer thickness to 0.015-0.05mm ;Set 1-5 additional contours inward or outward, and set the distance to 0.02-0.1mm; use the island mode, set the XY direction size to 0.5-10mm, the angle to 0-180 degrees, and the XY offset to 0 ~5mm, other conditional parameters are set according to the routine;

4) Heat the printed screw obtained in step 3), under the condition of argon protection, heat up to 840 degrees within 4 hours, keep it for 2 hours, then cool it to 500 degrees in the furnace, take it out, and cool it naturally to room temperature;

5) Cut the printed screws obtained in step 4) from the working platform by wire cutting;

6) Sandblasting the printing screws obtained in step 5) to remove excess raw materials sticking and melting on the printing surface;

7) Clean the printed screws obtained in step 6) with ultrasonic waves to remove surface impurities;

8) Put the above-mentioned screws into an ethylene oxide sterilization box for sterilization, and pack them separately.

In order to verify the significant technical effects produced by the processing parameters provided by the embodiments of the present invention, the inventors conducted detailed comparative experiments. The specific comparison data are shown in Table 1.

The processing parameter of table 1 present embodiment and the comparison of the technical effect that conventional processing parameter obtains

Set the aperture diameter of the 3D through-hole 200 600 900 1100 2500 Actual pore diameter under normal (μ gauge m processing) processing parameters 162 488 732 896 2049 Actual pore diameter under optimized (μm) processing parameters 198±8 596±17 894±24 1092±28 2413±31

(μM Note): The conventional processing parameters refer to the processing parameters commonly used in the prior art, and the pore diameter values in the table are the average values of the pore diameters of the porous bone screws processed by using multiple groups of different conventional processing parameters; the optimized processing parameters refer to the It is the processing parameter provided by the embodiment of the utility model, and the corresponding aperture value is the average value of the aperture of the porous bone screw processed by using multiple groups of different optimized processing parameters. At the same time, the table also shows the error of the aperture under the optimized processing parameters value.

It can be seen from the experimental results that, at least from the value of the aperture, the aperture of the porous bone screw processed using the processing parameters provided by the embodiment of the present invention is closer to the aperture of the target three-dimensional model, and the accuracy is at least 10%.

The performance of embodiment 9 porous bone screws

According to the literature (SL.Zhua et al.Effect of porous NiTi alloy on bone formation: a comparative investigation with bulk NiTi alloy for 15weeks in vivo, materialsscience and engineering C, 2008,28(8):1271-1275; Liu binding, porous Effect of titanium alloy pore size on new bone formation, master's degree thesis) to establish a femoral injury model and observe the growth of new bone after implanting porous bone screws with different porosities. The fixed aperture is 600 μm, and porous bone screws with different porosities are prepared according to the method of the previous example, and the porosities are 35%, 50%, 77%, 78%, 79%, 80%, 82%, 85%, and 90% respectively , 92%, , 93%, 94%. The results showed that, after implantation, porous bone screws with a porosity in the range of 78%-92% had more bone ingrowth, stronger bonding strength at the bone-screw material interface, and more blood vessel growth than porous bone screws with other porosities. A lot. Porous bone screws with a porosity of 80% resulted in the best damage repair.

According to the literature (SL.Zhua et al.Effect of porous NiTi alloy on bone formation:a comparative investigation with bulk NiTi alloy for 15weeks in vivo,materials science and engineering C,2008,28(8):1271-1275; Effect of titanium alloy pore size on new bone formation, master's degree thesis) to establish a femoral injury model, and observe the growth of new bone after implanting porous bone screws with different pore sizes. The fixed porosity is 80%, and porous bone screws with different pore diameters are prepared according to the method in the previous example. , 1500μm, 2000μm, 2500μm, 2700μm, 3000μm. The results showed that after implantation, porous bone screws with pore diameters in the range of 200 μm-900 μm and 1100 μm-2500 μm, compared with other porous bone screws with other pore diameters, had more bone ingrowth, stronger bonding strength at the bone-screw material interface, and blood vessel growth. A lot. Porous bone screws with a pore size of 600 μm resulted in the best damage repair.

The above-mentioned embodiments only express several implementations of the utility model, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the patent scope of the utility model. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the utility model patent should be based on the appended claims.

Claims (9)

1. A 3D printing bone screw with a three-dimensional porous structure, characterized in that, the bone screw comprises a nail head, a nail body, and a nail cap; the nail body comprises a porous network composed of interconnected micropores; the The pore diameter of the porous network is 200 μm-900 μm or 1100 μm-2500 μm, and the porosity is 78%-92%. 2. The bone screw of claim 1, wherein the screw body includes a central body, the porous network being located on the outside of the central body. 3. The bone screw of claim 2, wherein the porous network is independent of the surface of the central body and surrounds the central body. 4. The bone screw of claim 2, wherein said porous network is a porous surface created on said central solid surface. 5. The bone screw according to any one of claims 1-4, wherein the screw body comprises threads on the surface of the porous network. 6. The bone screw according to any one of claims 1-4, characterized in that, the hole shape of the porous network is polyhedron, sphere or irregular shape. 7. The bone screw of claim 6, wherein the polyhedron is a regular dodecahedron. 8 . The bone screw according to claim 1 , wherein the raw material for the bone screw is selected from the following group: medical metal materials, bioceramics, and medical polymer materials. 9. The bone screw according to claim 8, wherein the medical metal material is titanium alloy.