CN114082983A

CN114082983A - Preparation method of 3D printing spine porous fixing nail rod

Info

Publication number: CN114082983A
Application number: CN202111317838.XA
Authority: CN
Inventors: 李鹏
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-11-08
Filing date: 2021-11-08
Publication date: 2022-02-25

Abstract

The invention discloses a preparation method of a 3D printing spine porous fixing nail rod, which comprises the following steps: performing preliminary modeling by using three-dimensional modeling software NX software, and segmenting parts of the product, which need the trabecular bone porous structure, by using a NX software segmentation function; exporting to an STL file; importing the two models into design software Magics, and optimizing the two models by using a model repairing function; introducing the model STL file into reverse engineering software 3-matic, designing a trabecular bone porous monospore, and replacing the introduced model with the designed trabecular bone porous structure monospore, wherein the micropore diameter is 600-micron, the filament diameter is 300-micron, and the porosity is 70-80%; and exporting the STL file, inputting the STL file into model slicing software, and then performing 3D printing. The bionic porous structure of the product is highly similar to the microstructure of human bone tissue, which is beneficial to the growth of postoperative osteoblasts, so that the bone tissue is tightly connected with a screw through multiple holes, and postoperative complications are reduced.

Description

Preparation method of 3D printing spine porous fixing nail rod

Technical Field

The invention relates to the field of preparation methods of orthopedic fixation structures through 3D printing, in particular to a preparation method of a 3D printing spine porous fixation nail rod.

Background

According to statistics, the spine disorder and the spine disease are on the trend of increasing year by year and gradually youngling at present, the spine disease is caused by poor sitting posture of students in middle and primary schools for a long time and excessive weight bearing of bodies, the high-speed development of modern society enables the living mode and the production mode of human beings to be changed, more and more people are put on a desk for a long time, and the sitting posture is incorrect, so that cervical vertebra joints and lumbar vertebra joints are in a high-pressure state for a long time, and the vertebral body structure loses moisture prematurely, osteoporosis, bone structure degeneration and the like to cause various spine diseases. When the treatment backbone disease, spinal internal fixation nail stick becomes indispensable medical instrument, but common internal fixation nail leads to the postoperative to appear the screw not hard up because the screw is not enough to centrum stationary force, complication such as nail slippage to because ordinary screw is not hard up the degree of cut not enough, can not effectively promote the fusion and the effective growth of the corresponding fixed position bone tissue of set screw, lead to patient to need carry out the secondary operation. The present internal fixation system screw rod for spinal column has the following problems: the material is mainly implantable metal material, such as titanium alloy, but the manufacturing method generally adopts a mechanical processing method, the adjacent stage is fixed by screwing into the vertebral pedicle of the vertebral column, and then the short-term fixation is carried out, the diameter of a general screw is 3.5mm to 7.5mm, the length is 35mm to 70mm, the surface of the machined screw is generally smooth, and even if the machined screw has a certain aperture, the aperture can not induce the growth of osteoblast.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a 3D printing spinal porous fixing nail rod, which overcomes the problem that the existing fixing nail often has screw looseness and slippage after operation due to insufficient fixing force of the screw on a vertebral body, has high cutting degree, and can effectively promote fusion and effective growth of bone tissues of a corresponding fixing part of the fixing screw.

The technical problem to be solved by the invention is realized by the following technical scheme:

a preparation method of a 3D printing spine porous fixing nail rod comprises the following steps:

s1, designing a screw appearance structure by using computer three-dimensional modeling software NX software to realize primary modeling of a product, and segmenting a part of the product, which needs a trabecular bone porous structure, by using a NX software segmentation function;

s2, exporting the two divided models by using NX software respectively, wherein the exported files are STL files;

s3, respectively importing the two STL files into design software Magics, and performing triangular patch surface optimization processing on the two models by using a model repairing function;

s4, exporting the optimized models into STL files respectively;

s5, importing the STL file of the bone trabecula structure of which the hole is required to be formed into the reverse engineering software 3-matic;

s6, designing a trabecular bone porous monospore by using reverse engineering software 3-matic, and replacing the introduced model by the designed trabecular bone porous structure monospore to form a trabecular bone porous structure model with the microscopic size of pores of 600-80% and the pore diameter of 500-500 μm;

the trabecular bone porous structure consists of a plurality of small holes, and an ideal pore structure is designed in the range of 1mm multiplied by 1mm, namely a porous monospore body; the combination of numerous porous monosporates is referred to as a porous structure of the invention.

S7, exporting the replaced model into an STL file, inputting model slicing software, and exporting a slicing file;

and S8, importing the slice file into 3D printing forming equipment to finish printing.

The holes are made of bionic trabeculae and are positioned at the inner lower side between the raised spiral edges.

The microscopic size of the hole is 700-800 μm; the filament diameter is 350-450 mu m, and the porosity is 72-78%.

Preferably the microscopic size of the pores is 760 μm; the diameter of the filament is 400 mu m, and the porosity is 76 percent.

The S8 printing process further includes: putting the titanium alloy powder into 3D printing and forming equipment, and filling helium into the 3D printing and forming equipment to ensure that the inside of the 3D printing and forming equipment is in a vacuum state; then heating the molding cabin to 550-850 ℃ to reduce the generation of internal stress of the product; the 3D printing and forming equipment emits electron beam light spots through the upper electron beam unit, titanium alloy powder is instantly melted by the high temperature of the electron beams, a titanium alloy solid is formed through cooling, and then the printing is finished through layer-by-layer scanning, so that the spinal column porous fixing nail rod is obtained.

The trabecular bone porous structure can be a reticular porous structure or a combination of porous and reticular porous structures.

Preferably, the shaping chamber is heated to 750 ℃.

The 3D printing and forming equipment is electron beam selective melting and forming equipment; the EBM electron beam melting 3D printing and forming equipment is preferred.

The electron beam selective melting titanium alloy solid forming principle and steps in the S8 forming cabin comprise:

laying a layer of powder with the thickness of 0.05mm on the powder taking device; scanning and melting the powder material by the electron beam according to the path planned by the slice file; and after the scanning is finished, the forming table descends, and the powder taking device lays a new layer of powder again. The process of powder spreading and melting layer by layer is repeated until the nail rod part is formed.

The titanium alloy material is preferably medical Ti6Al4V alloy powder which can be purchased from the market, and the chemical composition of the product is required to meet or be superior to the requirement of TC4 brand titanium alloy in GB/T13810-2007 titanium and titanium alloy processing materials for surgical implants, which is shown in the following table:

the invention selects the electron beam selective melting forming technical characteristics as follows:

1. the screw rod part with a complex shape can be manufactured, and comprises a cavity, a porous structure and a grid structure;

2. because the molding is carried out in a vacuum environment, the material oxidation is avoided;

3. the molding environment temperature is high (above 700 ℃), the residual stress of the molded part is small, and heat treatment is not needed;

4. the residual powder after molding can be recycled;

5. the powder is spread layer by layer, the powder is scanned layer by layer, the powder is melted layer by layer, and the powder is solidified layer by layer, so that the quality verification and monitoring layer by layer can be realized.

Compared with the prior art, the invention has the beneficial effects that:

1. this spinal internal fixation nail stick adopts 3D to print the preparation and forms, and the inboard position design bionic trabecula porous structure between the screw thread arris of fixation nail stick, this trabecula porous structure highly imitates with human bone tissue microstructure, is favorable to postoperative patient's bone to grow into for bone tissue can be through porous structure tightly with screw interconnect, reduces the appearance of postoperative complication.

2. The conventional processing mode cannot finish the processing of the porous structure, the printing of the porous structure can be accurately realized by adjusting and designing the steps and parameters of 3D printing, repeated experiments are carried out on the condition meeting the biomechanics, and the bone ingrowth effect of the spinal porous screw rod product is improved under the condition meeting the biomechanics.

3. Experiments show that when the microscopic size of the hole is 750-1000 μm, the wire diameter is 300-500 μm, and the porosity is 75% -80%, the osteoblast can be effectively induced to grow in.

4. The invention adopts an electron beam melting mode to carry out layer-by-layer 3D printing, and has the best effect of quality monitoring.

Drawings

FIG. 1 is a schematic view of a 3D-printed spine multi-hole fixing nail rod structure of the invention

FIG. 2 is a schematic view of a modeled staple bar sample shown in the software of the present invention

FIG. 3 is a schematic view of a porous monospore body for forming a trabecular bone porous fixation nail rod shown in the software of the present invention

FIG. 4 is a schematic diagram of a multi-hole post-nailing rod product model displayed by software of the present invention

FIG. 5 is a schematic view of an electron beam selective melting and forming apparatus according to the present invention

FIG. 6 is another 3D printing spine net-shaped porous fixing nail rod structure schematic diagram of the invention

FIG. 7a, FIG. 7b, FIG. 7c are 180 days X-ray development diagrams

FIG. 8a, FIG. 8b, and FIG. 8c are graphs showing the results of 180-day Micro-CT

Numbering in fig. 1: 1-screw, 2-bionic trabecular bone porous, 3-monospore body, 4-vacuum chamber, 5-powder storage chamber, 6-powder taking device, 7-heat insulation cover, 8-forming chamber, 9-lifting table, 10-substrate, 11-titanium alloy powder, 12-electron beam unit, 13-filament, 14-astigmatic coil, 15-focusing coil, 16-deflection coil and 17-electron beam selective melting forming device.

Detailed Description

Example 1

The preparation method of the 3D printing spinal porous fixation nail rod shown in the figure 1 and prepared by the method in figures 2, 3, 4 and 5 comprises the following steps:

s4, exporting the optimized models into STL files respectively;

s5, importing an STL file of a bone trabecula structure model (figure 2) of a product needing to be formed into a hole into reverse engineering software 3-matic;

s6, designing a trabecular bone porous monospora by using reverse engineering software 3-matic (figure 3), and replacing the introduced model by the designed trabecular bone porous structure monospora to form a trabecular bone porous structure model (figure 4) with the microscopic size of pores of 600-1000 mu m, 300-500 mu m and 70-80% of porosity;

s8, importing the slice file into EBM electron beam melting 3D printing and forming equipment 17 (shown in figure 5), wherein the printing process comprises the following steps: titanium alloy powder 11 meeting the national standard is placed into the 3D printing and forming equipment, helium is filled into the 3D printing and forming equipment, and the inside of the 3D printing and forming equipment is ensured to be in a vacuum state; then, the molding cabin 8 is heated to 750 degrees, so that the generation of internal stress of the product is reduced; the 3D printing and forming equipment emits electron beam light spots through the upper electron beam unit 12, the electron beams have extremely high temperature, titanium alloy powder can be instantly melted, a titanium alloy solid is formed through cooling, and then scanning and melting are carried out layer by layer to finish printing, so that a finished product (shown in figure 1) is obtained;

the electron beam selective melting titanium alloy solid forming principle and steps in the forming cabin comprise:

the selective electron beam melting and forming equipment comprises a powder storage cabin 5 in a vacuum chamber 4, a powder taking device 6 below the powder storage cabin, a forming cabin 8 separated from the powder storage cabin 5 through a heat insulation cover 7, a lifting platform 9 arranged in the forming cabin 8 and a substrate 10 above the lifting platform, titanium alloy powder 11 to be formed placed on the substrate 10, an electron beam unit 12 and a filament 13 structure channel which are communicated above the forming cabin, and the emitted electron beams pass through an astigmatic coil 14, a focusing coil 15 and a deflection coil 16 and then act on the titanium alloy powder 11 on the substrate 10 at high temperature.

In operation, the powder taking device 6 lays a layer of titanium alloy powder 11 with the thickness of 0.05 mm; the electron beam unit 12 scans and melts the powder material according to the path planned by the slice file; after the scanning is finished, the forming lifting platform 9 descends, and the powder taking device 6 lays a new layer of powder again. And the whole process of powder spreading layer by layer and melting is repeated until the part is formed and melted and printed, and the final product is obtained.

Example 2

Similar to example 1, the method for preparing the 3D printing spinal internal fixation screw rod of the reticular porous screw shown in fig. 6 comprises the following steps:

s1, designing a screw shape structure by using computer three-dimensional modeling software NX software to realize primary modeling of a product, and segmenting a part of the product, which needs a trabecular bone net-shaped porous structure, by using a NX software segmentation function;

s3, respectively importing the two STL files into design software Magics, and performing triangular patch optimization processing on the two models by using a model repairing function;

respectively exporting the optimized models as STL files by S4;

the S5 product needs the model STL file of trabecular bone mesh structure to be imported into the reverse engineering software 3-matic;

s6, designing a trabecular bone porous monospore by using reverse engineering software 3-matic, and replacing the introduced model by the designed trabecular bone mesh structure monospore, wherein the microscopic size of the pores is required to be 1000 μm in pore diameter, 500 μm in filament diameter and 80% in porosity;

s7, exporting the model as an STL file, inputting the STL file into model slicing software, and exporting a slicing file;

s8, importing the slice file into the 3D printing and forming device, wherein the printing process comprises the following steps: putting titanium alloy powder meeting the national standard into 3D printing and forming equipment, and filling helium into the 3D printing and forming equipment to ensure that the inside of the 3D printing and forming equipment is in a vacuum state; then the molding cabin is heated to 800 degrees, so that the generation of internal stress of the product is reduced; the 3D printing and forming equipment emits electron beam light spots through the upper part, the electron beams have extremely high temperature, titanium alloy powder can be instantly melted, a titanium alloy solid is formed through cooling, and then scanning and melting are carried out layer by layer to finish printing.

Example 3

Similar to example 1, the method for preparing the 3D-printed spinal internal fixation screw rod shown in fig. 1 includes the following steps:

respectively exporting the optimized models as STL files by S4;

s6, designing a trabecular bone porous monospore by using reverse engineering software 3-matic, and replacing the introduced model by the designed trabecular bone porous structure monospore, wherein the microscopic size of the pores is required to be 600 μm in pore diameter, 400 μm in filament diameter and 72% in porosity;

s8, importing the slice file into the 3D printing and forming device, wherein the printing process comprises the following steps: putting titanium alloy powder meeting the national standard into 3D printing and forming equipment, and filling helium into the 3D printing and forming equipment to ensure that the inside of the 3D printing and forming equipment is in a vacuum state; then, the molding cabin is heated to 550 degrees, so that the generation of internal stress of the product is reduced; the 3D printing and forming equipment emits electron beam light spots through the upper part, the electron beams have extremely high temperature, titanium alloy powder can be instantly melted, a titanium alloy solid is formed through cooling, and then scanning and melting are carried out layer by layer to finish printing.

To demonstrate the effect of the bionic trabecular bone ingrowth of example 1 of the preparation method of the present invention, animal tests were performed, with the following method steps.

Overall design of animal experiments:

the test adopts healthy animals, the effectiveness of the product is evaluated by the morphology and the histopathology of the implanted trabecular bone porous sample block (the aperture is 1000 mu m and the porosity is 75-80%), the safety factor of the product is evaluated by the biocompatibility of the product except the operation wound, whether the implant causes the inflammatory reaction of surrounding tissues or not is observed, and the operation complication and adverse event condition are recorded.

Animal test purposes:

1) performing image fusion;

2) maintenance of bone tissue structure and function;

3) ingrowth of bone tissue.

Test result observation indexes and periods are as follows:

the terminal observation index of the test is the osseous fusion effect of the implant after the trabecular bone porous sample block is implanted for 180 days, namely the fusion condition after the implantation is observed through CT scanning, and the growth of the bone tissue is observed through X-ray normal position and side position slice observation and pathological section observation on the implant. 30 days, 90 days and 180 days after the operation were taken as observation periods. 3 test animals were euthanized 90 days after surgery for anatomical exploration and pathological sections were prepared, and the remaining animals were raised to 180 days for corresponding examination and observation as in Table 1 below.

TABLE 1 examination and Observation items

Checking, observing items/times	Before operation	30 days after operation	90 days after operation	180 days
					Wound, daily behavior Observation	*	*	*	*
Adjacent vertebral fusion/CT scanning	*		*	*
					Vertebral body structure stabilization/X-ray	*		*	*
Bone ingrowth, inflammatory response/pathology			*	*
					Implant morphology/anatomy exploration			*	*
Adverse event logging	*	*	*	*

Item number is detection item

In the observation period, the animals need to be anesthetized in advance before Micro-CT and X-ray examination, and the anesthesia method is the same as that before the operation. Evaluating the fusion grade according to the results of Micro-CT and X-ray: (1) non-fusion: the distinct light-transmitting zone includes the periphery of the implant, the formation of boneless bridges or the absence of bone ingrowth into the pores; (2) partial fusion: a small light-transmitting area is arranged around the implant, but the range of the light-transmitting area is less than half of the material-bone contact area, so that bone tissues grow into pores and partial bone bridging is not formed; (3) fusing: there is no light transmitting area around the implant, and a complete bony bridge is formed between the vertebral bodies.

Preparing pathological sections: the animals were sacrificed with excess anesthesia. Taking out the specimen in the implantation stage, removing peripheral muscles, reserving all ligaments and joint capsules, soaking and fixing for 7 days in formaldehyde solution, dehydrating for 7 days in acetone solution, embedding in organic resin glass, observing sagittal and transverse sections respectively, and performing histological analysis by using image analysis software. The percentage of Mineralized Bone (MBF) and the percentage of material-Bone Association (BA) within the implant were calculated separately.

As shown in the X-ray shown in FIG. 7a, FIG. 7b and FIG. 7c and the Micro-CT detection results shown in FIG. 8a, FIG. 8b and FIG. 8 c:

x-ray pictures at 90 and 180 days after surgery showed that all trabecular bone porous sample masses were not displaced. After 180 days of operation, the X-ray transparent area around the porous sample block disappears, and the growth of the porous titanium-combined porous bone tissue is more obvious. Micro-CT shows that the bone growth in the pores of the porous titanium alloy material is obviously increased after 180 days of operation, and the induced bone formation effect is good.

Hard histopathology test results:

180 days after operation, the surface of the trabecular bone porous sample block is covered by continuous bone tissues, trabecular bone in pores of an internal porous structure is obviously increased, fiber and cartilage tissues are obviously less than 90 days after operation, most of the bone tissues are wrapped around the porous sample block material, and the material and bone matrix form tight combination, which is shown in tables 2 and 3.

TABLE 2 specimen bone contact Rate

Name (R)

3M1

3M2

3M3

6M1

6M2

6M3

Bone contact rate

39.09％

27.75％

40.25％

62.48％

50.00％

63.82％

TABLE 3 bone volume density of new bone inside porous Material (BV/TV)

Name (R)	3M1	3M3	6M1	6M3
					Bone bulk density	53％	52％	84％	75％

As can be seen from Table 2, the bone contact rate is obviously better than that of 90 days after operation for 180 days after operation, and Table 3 shows that the new bone growth in the trabecular bone porous sample block reaches more than 50% in three months after operation, and reaches about 80% in six months after operation, and the bone growth effect is good.

And (4) test conclusion: the trabecular bone porous sample block has the advantages of high bone growth speed and good bone-material combination interface, and the product can be preliminarily considered to be safe and effective.

Therefore, the 3D printed screw utilizes titanium alloy, titanium alloy instead of other materials, is modeled by a computer, is designed and then is printed by 3D, particularly, a porous structure of a bionic bone trabecula is designed, osteoblasts can crawl, and can rapidly grow in osteoporosis or common osteogenesis, so that the problem that the conventional technology cannot prepare a bionic porous structure is solved, and the microscopic size of the hole completely accords with the requirement for the growth of osteoblasts.

Variations, modifications, and alternatives to the embodiments described above will be apparent to those skilled in the art in light of the disclosure and teachings of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and simple changes, modifications, and substitutions of the present invention should fall within the scope of the present invention.

Claims

1. A preparation method of a 3D printing spine porous fixing nail rod comprises the following steps:

s4, exporting the optimized models into STL files respectively;

2. The preparation method of the 3D printed spinal porous fixation nail rod according to claim 1, comprising the following steps: the holes are made of bionic trabecula and are positioned at the inner lower side between the raised spiral edges.

3. The preparation method of the 3D printing spinal porous fixing nail rod according to claim 1 or 2, wherein the microscopic size of the pores is 700-800 μm; the filament diameter is 350-450 mu m, and the porosity is 72-78%.

4. The preparation method of the 3D printed spinal porous fixation nail rod according to claim 3, comprising the following steps: the microscopic size of the pores is 760 μm; the diameter of the filament is 400 mu m, and the porosity is 76 percent.

5. The preparation method of the 3D printed spinal porous fixation nail rod according to claim 3, comprising the following steps: the S8 printing process includes: putting the titanium alloy powder into 3D printing and forming equipment, and filling helium into the 3D printing and forming equipment to ensure that the inside of the 3D printing and forming equipment is in a vacuum state; then heating the molding cabin to 550-850 ℃ to reduce the generation of internal stress of the product; the 3D printing and forming equipment emits electron beam light spots through the upper electron beam unit, the titanium alloy powder is instantly melted by the high temperature of the electron beams, a titanium alloy solid is formed through cooling, and then the printing is finished through layer-by-layer scanning, so that the spinal porous fixing nail rod of the picture is obtained.

6. The preparation method of the 3D printed spinal porous fixation nail rod according to claim 1 or 3, comprising the following steps: the trabecular bone porous structure is a reticular porous structure or a combined structure of multiple holes and reticular multiple holes.

7. The preparation method of the 3D printing spinal porous fixation nail rod according to claim 5, wherein the 3D printing forming device is an electron beam selective melting forming device; the molding chamber was heated to 750 ℃.

8. The preparation method of the 3D printing spinal porous fixation nail rod according to claim 7, wherein the selective electron beam melting and forming device is an EBM electron beam melting and 3D printing and forming device.

9. The preparation method of the 3D printing spinal porous fixation nail rod according to claim 5, further comprising the step of laying a layer of powder with the thickness of 0.05mm by a powder extractor; scanning and melting the powder material by the electron beam according to the path planned by the slice file; and after the scanning is finished, the forming table descends, the powder taking device lays a new layer of powder again, and the processes of powder laying and melting layer by layer are repeated until the nail rod part is formed.

10. The preparation method of the 3D printing spinal porous fixing nail rod as claimed in claim 3, wherein the titanium alloy material is medical Ti6Al4V alloy powder, the chemical composition of the product meets or is superior to the requirement of TC4 titanium alloy in GB/T13810-2007 titanium and titanium alloy processing materials for surgical implants, and the mass fraction of the components is as follows: 5.5 to 6.75 percent of AL, 3.5 to 4.5 percent of V, less than or equal to 0.3 percent of Fe, less than or equal to 0.08 percent of C, less than or equal to 0.2 percent of O, less than or equal to 0.05 percent of N, less than or equal to 0.010 percent of H, and the balance of Ti.