Tantalum powder- Application of porous tantalum in cervical spine fusion

Application of porous tantalum in cervical spine fusion

King et al retrospectively studied 34 patients treated with porous tantalum independent cages and conducted a 2-year follow-up. The study found that the subsidence rate of the cage decreased over time, and that the fusion rate could eventually reach 100%, with zero patients requiring revision surgery. The data confirms that there is no problem in using porous tantalum fusion alone for ACDF within 2 segments.

Fernández-Fairen et al studied the improved clinical outcomes of single-level ACDF using porous tantalum cages and autologous bone grafting. The study was followed up for 11 years and found that the porous tantalum group had a higher cage subsidence rate, with 44% of patients experiencing an average subsidence of 2.2 mm, while 33% of patients in the autologous bone graft group had an average subsidence of 0.5 mm. Shen's condition did not progress after 6 weeks. The incidence of ASD was similar in the two groups, and the occurrence of ASD was not related to postoperative sagittal alignment and cage subsidence (>0.05). The researchers believe that ASD may not cause significant clinical deterioration, and in this study all ASD patients were successfully treated conservatively and did not undergo revision surgery. The study also found that the fusion rates of the porous tantalum group and the autologous bone graft group were similar (2018: 96% vs. 100%, 2008: 89.3% vs. 84.4%, the difference was not statistically significant). It can be seen from the data that after 11 years of follow-up, both groups achieved higher fusion rates in the 2018 study, indicating that bony fusion, especially porous tantalum, may require 2 years or more of fusion.

3. Material advantages of tantalum metal

According to the above data:

(1) As a "biophilic" metal, tantalum has good corrosion resistance and biocompatibility. It has outstanding affinity for bone tissue, excellent osteoconduction and osteoinduction capabilities, and promotes bone ingrowth and bone fusion;
(2) The three-dimensional bionic bone trabecular microporous structure is conducive to bone fusion and vascularization; the porosity is as high as 68%-78%, promoting bone ingrowth and blood vessel formation, and increasing the fusion rate;
(3) The elastic modulus is close to that of human cancellous bone and trabecular bone, with high biomechanical adaptability and reduced stress shielding;
(4) High anatomical morphological matching, micron- and nano-level surface roughness, high friction coefficient with human bones, which is conducive to improving the fusion rate and stability, and has outstanding anti-sinking ability;
(5) Excellent load-bearing capacity, enabling immediate load-bearing; high toughness and plasticity, and excellent fatigue resistance. and many other advantages.
4. Difficulties in the application of tantalum metal materials in the country.

Tantalum is a refractory metal with a melting point close to 3000°C. The forming of this material places high requirements on the spot quality of the equipment and requires stable energy output. During the forming process of tantalum, due to the high forming stress, parts are prone to cracking. The forming process needs to be optimized to avoid such problems. And based on the special application scenarios of medical devices, the materials used to produce medical devices have higher and more stringent requirements than materials used for other purposes. From a global perspective, the biomedical materials market is highly monopolized by developed countries. The top 30 companies in terms of market share, such as Johnson & Johnson, Medtronic, Zimmer Biomet, Stryker, B. Braun, and Cook, occupy more than 70% of the global biomedical materials market.

Porous tantalum is an ideal orthopedic implant material. However, due to the differences in the human body and the randomness of the shape of bone defect sites, such as patients with bone tumors and bone deformities, standardized porous tantalum can no longer meet the personalized treatment requirements of patients. From the development trend of clinical medicine, the best treatment method should be personalized treatment, and the best implant should be personalized implant. As 3D printing technology matures, the country vigorously promotes precision medicine. Traditional technology cannot achieve personalization. 3D printing can be used for both personalization and mass production. At the same time, in order to break the monopoly, the country established a key research and development project on 3D printing porous tantalum at the end of 2016 to encourage innovation.