Page 182 - IJB-9-6

International Journal of Bioprinting 3D-printed assembly anatomical patella fracture bone plate

Figure 3. Illustration of the gap distance measurement between the AATBP and the patella at the positions of the four vertices of a 15 mm × 15 mm square
in the AATBP center.
distal direction) of the AATBP was adjusted using its and enable the commercial screw to fit the hole within an
attached ratchet to allow two pairs of hooks to grip at acceptable error range.
relative positions on the proximal and distal ends of the Our 3D printer and CNC machining laboratories
three patellae. The gap distances between the AATBP and were certified under the Good Manufacturing Practice
each patella at four vertices of a 15 mm × 15 mm square (GMP) quality management system (Certificate Number:
defined the AATBP center (Figure 3). QMS0940; A Plus Biotechnology Co. Ltd, Taipei, Taiwan).
This ensured that the bone plate manufactured using
2.2. AATBP 3D printing 3D printing and CNC drilling can provide a practical
The AATBP without screw holes was manufactured using foundation for approaches that meet GMP regulations,
selective laser melting of a metal powder bed fusion such as printing biocompatible materials in a biologically
machine (AM250; Renishaw, Wotton-under-Edge, UK), safe manner to meet the ISO10993 standard, as well as
noted as a 3D printing system with commercial titanium demonstrating a commitment to safety and quality.
alloy powder (diameter of Ti6Al4V powder ranges between
15 μm and 45 μm). The 3D printing system was operated at The AATBP in this study was designed using computer-
a laser power of 400 W, a scanning rate of 0.6 m/s, and an aided design (CAD) software. The detailed dimensions of
exposure time of 125 s . The metal powder was selectively all AATBP features in the CAD software were defined as
[13]
scanned and melted by a laser during the process. The the actual dimensions. The height, width, and thickness
component was complete after the powder was crystallized. dimensions of the PP and DP as well as the ratchet and
In the present study, the manufacturing accuracy, hatching cone height pitch (shown in Figure 5 and defined in
space, and layer thickness were 30, 90, and 30 μm, Table 1) were measured using a precision measuring
respectively. The 3D-printed AATBP surface burring system (ARCS Precision Technology Co., Ltd., Taiwan) on
without screw holes was removed and polished using a three randomly selected AATBP samples and compared
magnetic polisher with stainless steel pins (Ø =1 mm, with the corresponding actual values. We defined that
L = 3 mm) at a speed of 2,700 rpm. The device was then the error for each dimension to be within 5%, namely the
cleaned using ultrasonic oscillations (Figure 4) . printed accuracy of our assembly bone plate should meet
[13]
the requirements for implant manufacture.
There were high demands for screw holes with thread
accuracy down to 0.02 mm and screw hole surface without 2.3. AATBP bending strength and surface roughness
cracks. All PP and DP screw holes were generated using tests
traditional XXX (CNC) positioning drilling to control To provide a comprehensive mechanical strength reference
the manufacturing accuracy within a small error margin for the AATBP used in the patella fracture cases, four-point

Volume 9 Issue 6 (2023) 174 https://doi.org/10.36922/ijb.0117