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Chen, et al.

Figure 1. Detailed design concept of the hybrid suture anchor (HSA) and corresponding instrument.

internal screw within the suture anchor to open the wing The CAD file of the HSA was imported into 3D
mechanism when necessary (Figure 1). printing system in offline state, then the build chamber
was prepared with vacuum air removal and filled with
2.2. Manufacture of the novel HSA and argon inert gas to prevent oxidation and interstitial
instrument element contamination during the manufacturing process.

It is difficult to use 3D printing technique to fabricate a With the powder being selectively scanned and melted
mechanism that has different fitting components, because by a laser during the process, the component can be
the interface between different components must be made after the powder was crystallized. The hatching
controlled to be accurate in size, the surface is free of space and layer thickness in the present study were 90 μm
cracks and the fit needs to be within tolerances, etc. These and 30 μm, respectively. After process completion,
are related to many printing process parameters in LPBF residual 3D printing anchor particles were removed and
(e.g., laser power, scanning speed, hatch space, layer cleaned using magnetic surface grinding and ultrasonic
[16]
thickness, and scanning strategy). Therefore, our novel oscillations, respectively (Figure 2C) .
HSA was fabricated by metal 3D printing system, and Traditional machining was used to prepare the
internal fixation screw and instrument were manufactured internal screw because it has a regular configuration and
by traditional machining. the thread accuracy demand was high (control within
A selective laser melting of metal powder bed 0.04 mm accuracy) (Figure 2D). Traditional machining
fusion machine (AM400, Renishaw, Gloucestershire, can control manufacturing accuracy within a small error
UK), also noted as 3D printing system, was used with margin and enable the internal screw to fit the anchor
commercial titanium alloy powder (Ti6Al4V powder within acceptable error range. The instrument, including
ranges between 15 μm and 45 μm) to manufacture our the sleeve instrument and central hexagonal driver, was
novel HSA. The 3D printing system was operated at composed of 304 stainless steel and fabricated using heat
a laser power of 400 W, scanning rate of 0.6 m/s, and treatment by an ISO13485 quality management system
an exposure time of 125s . Our 3D printer laboratory company (A PLUS Biotechnology Co., LTD, Taipei,
[16]
was approved by ISO13485 quality management system Taiwan).
(Certificate Number: 1760.190828) to ensure that the 2.3. Biomechanical static/dynamic tests
anchor manufactured by 3D printing can provide a
practical foundation to meet the regulations, such as Artificial bone specimens with standardized bone densities
printing material with biocompatibility in the context of of 0.12 g/cm and 0.32 g/cm (cellular foam with 7.5 pcf and
3
3
biological safety to meet ISO10993 standard as well as solid rigid foam with 20 pcf) for mimicking the severely
demonstrating a commitment to safety and quality. osteoporotic bone and osteoporotic bone, respectively,
International Journal of Bioprinting (2022)–Volume 8, Issue 4 163