In Vitro and in Vivo Study of 3D-Printed Porous Tantalum Scaffolds for Repairing Bone Defects

Abstract

Porous tantalum (Ta) scaffold is a novel implant material widely used in orthopedics including joint surgery, spinal surgery, bone tumor surgery, and trauma surgery. However, porous Ta scaffolds manufactured using the traditional method have many disadvantages. We used selective laser melting (SLM) technology to manufacture porous Ta scaffolds, and the pore size was controlled to 400 μm. The compressive strength and elastic modulus of the porous scaffolds were evaluated in vitro. To evaluate the osteogenesis and osseointegration of Ta scaffolds manufactured by SLM technology, cytocompatibility in vitro and osseointegration ability in vivo were evaluated. This porous Ta scaffold group showed superior cell adhesion and proliferation results of human bone mesenchymal stem cells (hBMSCs) compared with the control porous Ti6Al4V group. Moreover, the alkaline phosphatase (ALP) activity at day 7 and the semiquantitative analysis of Alizarin red staining at day 21 demonstrated that osteogenic differentiation of hBMSCs was enhanced in the Ta group. The porous Ta scaffold was implanted into a cylindrical bone defect with a height and diameter of 1 and 0.5 cm, respectively, in the lateral femoral condyle of New Zealand rabbits. Radiographic analysis showed that the new bone formation in Ta scaffolds was higher than that in Ti6Al4V scaffolds. Histological images indicated that compared with porous Ti6Al4V scaffolds, Ta scaffolds increased bone ingrowth and osseointegration. The porous Ta scaffold manufactured by SLM not only has a regular pore shape and connectivity but also has controllable elastic modulus and compressive strength. Moreover, the osteogenesis and osseointegration results in vitro and in vivo were improved compared with those of the porous Ti6Al4V scaffold manufactured using the same technology. These findings demonstrate that the porous Ta scaffold manufactured by SLM is potentially useful for orthopedic clinical application.

The Clinical Application of Porous Tantalum and Its New Development for Bone Tissue Engineering

“…Except for conventional techniques including CVD [30,174], foam impregnation [175] and powder metallurgy [176], various additive manufacturing methods have been introduced to produce novel porous Ta scaffolds with different pore size and porosity, but comparable mechanical properties with human cortical and trabecular bones [177] (see Table 1). Comparison tests performed with cellular and animal models have revealed similar or even better biological and mechanical performance of printed porous Ta scaffolds than their porous Ti counterparts with the same porosity and pore diameter (see Table 2) [178][179][180][181][182]. Moreover, as a high-end technique, additive manufacturing can help manufacturers to produce porous Ta implants with tailored pore size and porosity to resist different biomechanical loading stress in different parts of the human body.…”

Recent Trends in the Development of Bone Regenerative Biomaterials

“…In recent years, a new type of "bone trabecular metal"porous tantalum (Ta) has attracted great attention, because it has good biocompatibility, ideal modulus of elasticity, corrosion resistance, and high porosity (Han et al, 2019), which promote cell adhesion, growth, and differentiation; form rich extracellular matrix; and enhance the early biological fixation in both research and clinical applications (Balla et al, 2010a,b;Fraser et al, 2019;Tang et al, 2020). Guo et al (2019) used selective laser melting (SLM) technology to manufacture porous Ta scaffolds with a pore size of 400 µm. The porous Ta scaffold was implanted into a cylindrical bone defect with a height and diameter of 1 and 0.5 cm, respectively, in the lateral femoral condyle of New Zealand rabbits.…”

Biomedical Applications of Metal 3D Printing

“…AM circumvents the complexity of machining Ta, while mimicking the morphology of the most common Ta-based orthopedic material (Trabecular Metal TM -a Ta-coated carbon matrix; see 141), which is used in more than 800,000 acetabular cup surgeries worldwide (140). PBF-L-printed Ta implants show increased bone growth and osseointegration in vivo (142). PBF-L-printed tantalum implants interface well with the bone, enabling continuous load transfer; furthermore, the fatigue limit (10 6 cycles) is 58% of the yield stress, compared with just 12% for Ti-64 scaffolds (140).…”