## 3 Results and Discussion
### Additive Manufacturing Aspects  
Customized 3D-printed orthopedic implants in general, and those for foot arthroplasty, as discussed in this review, in particular, are manufactured from Ti6 Al4V medical-grade powder by means of three types of AM powder-bed fusion processes, namely SLM, EBM, and DMLS. [PERSON] et al. 's study from 2018 [45] showed that 66% of all FDA-cleared 3D-printed devices were produced using laser sintering, 25% using EBM, and 9% using other AM processes. In SLM (Figure 4), a thin layer of metal powder is evenly spread across the powder bed by a blade. A high-powered laser, controlled by a scanner system, selectively melts  
Figure 3: Results of the bibliometric analysis: (**a**) keyword co-occurrence network; (**b**) keyword network with temporal trends. each powder layer according to the layer data generated by the slicer. The melt pool solidifies and fuses with the previously formed layers, thus additively building the part. The process takes place in an inert gas atmosphere to prevent oxidation or contamination during melting and ensure that the material retains its purity. After each layer is completed, the building platform is lowered by the thickness of one powder layer, allowing the blade to spread a new layer of powder. The precise control of the laser and the protection provided by the inert gas ensure that SLM can produce highly detailed, accurate, and structurally sound parts. In EBM (Figure 5), an electron beam passing through lenses, to ensure precision, is directed towards the metal powder bed stored in powder hoppers and evenly distributed onto the build platform. This manufacturing process occurs in a vacuum chamber to prevent oxidation and contamination, making it suitable for reactive metals. After each layer is melted, the build platform is lowered, and a new layer of powder is spread. Figure 4: SLM working principle. Figure 5: EBM working principle. The SLM and EBM processes have commonalities but also significant differences (Table 2) [46], which dictate their selection by producers in accordance with the implant design. For instance, EBM is used by 4 Web Medical with Arcam 3D printers as this process, in comparison with SLM, requires a smaller number of supports, which cannot be eliminated in post-processing. Moreover, the high-temperature vacuum environment specific to EBM contributes to a reduction in residual stresses. EBM has lower dimensional accuracy than SLM due to its higher energy input, making it less suitable for implants with fine features or porous structures. A set of process parameters for EBM for implants composed of Ti6 Al4V is the following: layer thickness--50 \(\upmu\)m, electron beam power--50-3500 W, scan speed--0.5 m/s, baseplate temperature--700 \({}^{\circ}\)C [47]. [PERSON] et al. [48] presented the following optimized set of parameters for the SLM of medical implants: laser power--9 W, laser speed--400 mm/s, laser spacing--99 \(\upmu\)m, layer thickness--30 \(\upmu\)m.  
EBM typically uses thicker layers than SLM, which can lead to more significant pores. However, the thicker layers also allow EBM to build larger, less precise pores more quickly, which can be advantageous in applications where lightweight structures are essential but a precise pore size is not as critical. EBM operates in a vacuum, which helps to prevent oxidation, but it also results in rapid melting and solidification. The rapid melting can create coarser, less uniform microstructures, leading to larger, less controlled pores when compared to SLM. However, adjusting the beam power and scanning speed can help