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International Journal of Bioprinting Design of SLM-Ta artificial vertebral body

restoration of the spinal stability through the implantation their superior specific strength and specific stiffness
of an artificial vertebral body (AVB). The AVB should relative to solid materials, lattice structures have garnered
1
possess adequate load-bearing capacity and good significant attention for applications in lightweight design,
osseointegration, with an elastic modulus that closely energy absorption, and biomedicine. 30,31 Moreover, the
matches that of human bone to avoid stress shielding. interconnected open pores within the lattice structure
2
Research aimed at enhancing the performance of AVBs facilitate the ingrowth of cells and blood vessels, thereby
has focused on innovations in materials and optimized significantly improving the osseointegration of bone
structural designs. 3–7 implants. 32–36 Therefore, incorporating lattice structures
Current studies have shown that titanium (Ti) into the Ta AVB substantially reduces its elastic modulus
37
8
9,10
and its alloys, polyetheretherketone (PEEK), and and improves its biocompatibility. Chen et al. designed
hydroxyapatite (HA) are potential materials for use in a Ta density-gradient lattice structure. The elastic moduli
11
of these lattice structures ranged from 0.22 to 0.89 GPa,
AVBs. Although PEEK has an elastic modulus close to which is similar to that of human cancellous bone. Song
that of human bone, it suffers from limited load-bearing and colleagues proposed gyroid porous Ta structures
38
capacity and poor bioactivity, factors that have become with radially graded porosity. Compression tests showed
bottlenecks in its application. In contrast, HA exhibits that the porous Ta structures had a minimum elastic
10
excellent biocompatibility, but its low fracture toughness 39
limits its use in this field. To address the limitations modulus of 0.6 GPa. Ni et al. compared the fatigue
12
associated with the performance of single materials, performance of a triple periodic minimal surface (TPMS)
researchers have attempted to develop composites based and rhombic dodecahedron Ta lattice structures. The
TPMS structure exhibited higher fatigue resistance than
on polymers or HA. 13–15
the rhombic dodecahedron and has the potential for use in
Owing to their excellent mechanical stability and load-bearing bone implants.
bioactivity, Ti and its alloys are widely used in bone Topology optimization design identifies the optimal
implants such as hip and knee replacements, dental force transfer paths and structural morphology by adjusting
implants, spinal implants, and cranial defect repairs. the distribution of materials within the design domain.
8,16
Compared to PEEK and HA, Ti alloys exhibit superior This approach reduces material usage while improving
load-bearing capacities, making them more suitable for the structural mechanical properties. When applied to
40
applications in load-bearing parts of the human body. 17,18 the structural optimization of bone implants, this design
As a result, Ti alloys have become mainstream materials for methodology enables regulation of overall stiffness,
41
the clinical application of AVBs. Furthermore, traditional achieving an optimal balance between maximizing load-
Ti alloy cages (Ti cages) have been widely adopted for the carrying capacity and minimizing stress shielding by
clinical treatment of spinal diseases. 19–21
tailoring the mechanical properties of the implant. 42,43
Tantalum (Ta), a transition metal, demonstrates notable Kök and colleagues applied topology optimization to
42
physical properties, including a high density (16.68 g/ the internal structure of dental implants and reported a
cm ) and a high melting point (2996 °C). In addition to its 30% reduction in stress shielding compared to standard
3
reliable mechanical properties, Ta demonstrates superior implants. Peng et al. implemented topology optimization
44
bioactivity, corrosion resistance, and fracture toughness in the fixation system of a mandibular implant, resulting in
compared with Ti alloys, 22–24 thereby significantly improved mechanical stability. In their work on interbody
enhancing the osseointegration of bone implants. Tantalum fusion cages, Smit and colleagues incorporated the
45
pentoxide (Ta O ) films, which form readily on the surface structural response of adjacent bone into the topology
5
2
of Ta metal, offer excellent corrosion resistance and optimization process, significantly reducing the risk of
osteoinductive function. Therefore, Ta has great potential cage subsidence.
25
for applications in AVBs. Unfortunately, the elastic moduli Owing to significant advancements in metal additive
26
of solid Ta (186 GPa) and Ti (110 GPa) considerably exceed manufacturing processes, the preparation of customized
that of human bone (0.022–21 GPa), leading to stress bone implants featuring complex structures has become
27
shielding of the vertebrae and poor integration of the AVB feasible. Selective laser melting (SLM), a representative
with the surrounding bone tissue. By utilizing topology metal additive manufacturing technology, is characterized
28
optimization and lattice design, the elastic modulus of the by high resolution and high energy input, enabled
Ta AVB can be substantially decreased, enabling better by precise laser control. This capability makes SLM
matching with that of human bone. 29 particularly suitable for producing fine and complex
The lattice structure was fabricated by a periodic structures, such as lattices and topological configurations,
arrangement of multiple identical unit cells. Thanks to even with high-melting-point materials like Ta. 46,47 Wang

Volume 11 Issue 4 (2025) 166 doi: 10.36922/IJB025150133