Page 128 - IJB-9-2

International Journal of Bioprinting Design and manufacture of high-performance bone plate

(2) Pore feature: since the laser spot has a limiting size GYD150 SLM, manufactured by Shenzhen Sunshine
affected by the diffusion of the heat-affected zone during Laser & Electronics Technology Co., Ltd., was used as the
laser processing, the width of the welding bead is larger molding equipment. Argon was used as the protective gas,
than the spot size; if the pore size is too small, the weld while the oxygen content was controlled below 0.03%. The
bead will block the pore, and the size of the pore feature processing laser power was 180 W, the scanning speed
perpendicular to the molding direction has a minimum was 500 mm/s, the scanning interval was 80 µm, the layer
limit. thickness was 20 µm, and the X–Y interlayer interlacing

(3) Biocompatibility requirement: the optimal range strategy was adopted. There were no fewer than three
of pore sizes of porous structure for osteocytes to grow is experimental samples for each group.
about 100 to 1000 μm, and cancellous bone structures can 2.3. Analysis methods
be simulated at a porosity of 50% to 90%, which is most Mimics 20.0 and Inspire 2021 were used for the reverse
beneficial for new bone to grow in; a larger surface-area-to- reconstruction of the femoral prosthesis. The finite
volume ratio of porous implants with larger contact areas element analysis software Inspire was used for the
between the surface of porous implanted bone correlates plate’s optimization design (topology optimization).
with a more significant mechanical stimulus applied to The optimization method used was the variable density
new bone. method. Biological fixation plates with optimized topology
(4) Draft constraint: for fracture surgeries that require were reconstructed using Rhino software. Data processing
removing the internal fixation plate, shielding should be and processing risk analysis were conducted on 3D-printed
avoided in the removal direction; however, designs that parts using Magics 22.0.
do not require removing the internal fixation plate are not The surface of the 3D-printed plate was treated as
subjected to this constraint. follows: sandblasting was performed, followed by rough
polishing with sandpaper, and finally, a polishing cloth
2.2. Materials and manufacturing methods was used for further polishing. The surface roughness
The host bone was printed using an industrial high- of the bone plate was measured using a 3D topography
precision desktop 3D printer Z-603S made by JG Maker instrument (MIAOXAM2.5X – 0X). After surface
Co., Ltd. to reduce cost. The molding material was treatment, the surface morphology of the 3D-printed
polylactic acid, the layer thickness was 0.15 mm, and the parts was observed using a high-definition VGA electron
filling density was 20%.
microscope manufactured by Bocheng Co., Ltd. The SLM
Ti-6Al-4V alloy metal powder produced by molding process parameters were optimized to produce
Wuxi FalconTech Co., Ltd., Jiangsu Province, was used as optimized molded parts.
the molding material of the plate. The composition satisfies
the requirements of ASTM F136 and GB/T 13810-2007. The 3. Results and discussion
comparison of the compositions is shown in Table 1. The
spherical powder was prepared by gas atomization, with 3.1. Reverse reconstruction and simulated repair of
an apparent density of ρ of 2.55 g/cm . The particle size femoral prosthesis
3
s
distribution was narrow and concentrated, −22 μm for 3.1.1. Reverse reconstruction of femoral prosthesis
90% and −28.5 μm for D50. Since the affected sites vary across patients and have
complex geometric or curved shapes, in order to increase
Table 1. Comparison of powder material manufactured in the degree of fit between the designed implant and affected
SLM and ASTM F136 standard site, lower the risk of implant loosening, and improve
the success rate of implant surgery, it is best to locate
Element Ti-6Al-4V powder ASTM F75 standard the patient’s affected site using medical imaging, such
as computed tomography (CT) or magnetic resonance
Al 5.5%–6.5% 5.5%–6.5% tomography, for 3D reconstruction. In order to obtain
V 3.5%–4.5% 3.5%–4.5% the image of the affected site, we used CT or nuclear
Fe 0.25% < 0.3% magnetic resonance to scan the patient’s affected site. We
C 0.08% < 0.08% then imported the CT scan images of the affected site of
N 0.03% < 0.05% the femur into Mimics. Subsequently, the CT scan images
H 0.012% < 0.012% in Mimics were subjected to threshold segmentation,
O < 0.08% < 0.13% physique manipulation, smoothing, denoising, and other
operations. An optimized 3D model was then obtained
Ti Balance Balance (Figure 1).

Volume 9 Issue 2 (2023) 120 https://doi.org/10.18063/ijb.v9i2.658