Metallic implants with a low effective modulus can provide early load-bearing and reduce stress shielding, which is favorable for increasing in vivo life-span. In this research, porous Ti6Al4V scaffolds with three pore sizes (300~400, 400~500 and 500~700 μm) were manufactured by Electron Beam Melting, with an elastic modulus range of 3.7 to 1.7 GPa. Cytocompatibility in vitro and osseointegration ability in vivo of scaffolds were assessed. hBMSCs numbers increased on all porous scaffolds over time. The group with intended pore sizes of 300 to 400 μm was significantly higher than that of the other two porous scaffolds at days 5 and 7. This group also had higher ALP activity at day 7 in osteogenic differentiation experiment. The scaffold with pore size of 300 to 400 μm was implanted into a 30-mm segmental defect of goat metatarsus. In vivo evaluations indicated that the depth of bone ingrowth increased over time and no implant dislocation occurred during the experiment. Based on its better cytocompatibility and favorable bone ingrowth, the present data showed the capability of the additive manufactured porous Ti6Al4V scaffold with an intended pore size of 300 to 400 μm for large segmental bone defects.

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.