3D printing tantalum
3D printing is a new processing method. The most significant feature of this technology is that it can directly form the final three-dimensional sample based on the imported workpiece model. Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM) in 3D printing are often used to process tantalum implant devices. The LPBF processing equipment has three warehouses, namely the powder warehouse, the forming warehouse and the recycling warehouse. Metal powder needs to be added to the powder warehouse in advance before printing. During processing, the powder is spread evenly in the forming warehouse by a scraper, and then is processed by laser or Electron beam melting, heating and solidification into a predetermined shape. The powder bin rises layer by layer, the forming bin descends layer by layer, and the layers are superimposed and finally formed.
LPBF technology can customize metal bone implants with matching shapes and sizes according to the patient's treatment area to meet the patient's personalized customization needs. During processing, the high-energy-density laser beam scans layer by layer according to the trajectory designed by the model, and each layer is accurately superimposed into the target shape, achieving freedom in the design of the workpiece structure. Tantalum has a high melting point, and traditional processing methods are too inefficient to process tantalum. The high-energy laser beam released instantly during LPBF processing can fully and quickly melt the refractory tantalum powder, which greatly reduces the difficulty of preparing biomedical tantalum and improves implantability. Preparation efficiency, shortening the preoperative preparation cycle. The unused powder during the processing can be recycled, and the printed samples are highly accurate. Only a small amount of subsequent milling is required, and the material utilization rate is high, which greatly reduces the manufacturing cost of tantalum implants. In addition, LPBF can realize the rapid preparation of porous structures, effectively solving the problems of excessive mass and mismatched mechanical properties of solid tantalum implantable devices.
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Factors affecting 3D printing of medical tantalum
Tantalum medical metal implants prepared through 3D printing need to continuously optimize the mechanical properties and biological properties to meet the needs of practical applications and avoid potential risks. At this stage, 3D printing tantalum needs to be further improved in the following two aspects:
(1) Implants need to meet the individual needs of different patients and achieve a good match with different damaged parts and deformed bones. Therefore, the product processing technology should have a high degree of freedom to reduce restrictions on product shape and size design. The implant needs to provide basic mechanical support after being implanted into the human body, so the material should have good strength and toughness. The mechanical properties of tantalum medical metal implants prepared by 3D printing are related to the quality of the processed powder, processing parameters and heat treatment. Appropriate mechanical properties can be obtained by adjusting the corresponding process parameters. However, the process parameters are related to the actual forming performance and service performance of the material. The functional relationship is still unclear and needs further exploration.
(2) The implant needs to serve in the human body for a long time, and the impact on human tissue cells should be as small as possible to avoid infection. At this stage, most studies regulate the structure to improve the biological performance of tantalum implants. However, the structural design of 3D printed tantalum metal still requires further research.
(3) Human bones can be divided into cortical bone and cancellous bone according to their structure. Cortical bone is relatively dense and hard and is located in the outer layer of the bone; cancellous bone has a three-dimensional mesh-like trabecular structure and is located in the core of the bone. The elastic modulus of pure tantalum generally exceeds 100 GPa, which is much larger than the elastic modulus of cancellous bone (0.01~1.57 GPa) and cortical bone (5~23 GPa). The elastic modulus of the implant and human bone do not match, and different strains will be produced when subjected to stress, resulting in relative displacement between bones. Long-term implantation will cause a "stress shielding" effect. The implant bears most of the strain and may deform, affecting its service life and performance. The long-term lack of pressure stimulation on human bones will lead to reduced osteoblast activity and cause disuse atrophy of human bones. The metal implant is designed into a porous structure. By adjusting the shape and porosity of the porous structure, the elastic modulus can be changed, and more locations can be provided for bone cells to grow in and adhere, which is conducive to the close contact between the implant and cancellous bone. combine.
3D printing medical tantalum implant case
With the continuous advancement of medical standards and the implementation of "Made in China 2025", new preparation processes represented by additive manufacturing have promoted the vigorous development of my country's orthopedic implant market. Since 2015, my country has become the second largest consumer of bone implants in the world. Currently, bone implant products can be divided into spinal, joint and trauma categories based on usage scenarios. Among them, acetabular cups (joint implants) and intervertebral fusion cages (spinal implants) are the fastest growing in commercialization. Bone implant manufacturing materials include metals, ceramics, polymers and carbonaceous materials. Tantalum, as a member of metal bone implants, has great development potential.
a. Spine products
Clinical research on 3D printed all-tantalum spinal implant devices has been carried out in China. In July 2021, the Xijing Hospital of the Air Force Medical University implanted a 3D printed tantalum cone into the patient's cone defective site to promote rapid healing of the defective site. Because the patient had a tumor in the vertebra that continued to compress the spine, a three-segment posterior en bloc resection of the spinal tumor was required, and an implant was required to support the defective area. Compared with common titanium implants, tantalum cones have better ability to promote bone ingrowth, and their elastic modulus is more consistent with human bone. Therefore, the hospital finally selected tantalum artificial vertebrae as the implant. The success of this clinical implant case confirms the performance and practical feasibility of 3D printed all-tantalum implant devices.
b. Joint products
Clinical research on tantalum joint implant devices was carried out earlier. In 2017, the Army Medical University prepared a tantalum knee joint pad through 3D printing and performed a replacement surgery on an 84-year-old patient. Before 3D printing, the implant model was first built based on the patient's CT scan results, and the prosthesis implantation was simulated on the computer. After repeated simulations and modifications, personalized printing was performed. The personalized customized product has a rough surface and a trabecular structure, which contributes to the long-term stability of the implant and human bone and provides good postoperative results.
c. Trauma products
In April 2019, the 3D printed trabecular structure tantalum stent developed by Xiangya Hospital was successfully implanted into a patient with femoral necrosis. This was the world's first tantalum metal stent implantation surgery. The contact point between the top of the tantalum stent and the human bone is arc-shaped, which is similar to the curvature of the human bone. When the stent is stressed, there are many contact points with the human bone, and the pressure is relatively even, which can prevent damage to the implant.
Conclusion
The development of 3D printing technology has provided a broader space for the application of tantalum in the medical field. The application market of tantalum is currently in a stage of rapid development. On the one hand, with the continuous advancement of medical technology and the aging of the population, the demand for orthopedic implants will continue to increase; on the other hand, with the continuous development of 3D printing technology, the types and properties of printing materials will also continue to increase. Increase.
Overall, the market for 3D printed tantalum has broad prospects, but it also requires constant technological innovation and medical supervision to promote its healthy development.
Baoji Yusheng Metal Technology Co., Ltd. is an excellent supplier of rare metals. The materials include tantalum, niobium, vanadium, zirconium, hafnium, and tungsten. We can provide various profiles such as: rods, plates, wires, rings, sheets, and tubes , foil, etc. If you have any questions about the product, you can communicate with us at any time.
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