Page 462 - IJB-10-1

International Journal of Bioprinting Efficacy of 3D-printed customized titanium implants

surgeon should actively change the mindset of traditional so the customized implant can achieve high yield strength,
technology practitioners so that they would fully realize low elastic modulus, and high fatigue resistance. This is one
that the core competitiveness of 3D-printed products lies of the intrinsic reasons 3D-printed customized titanium
in the customized precise treatment, and play a leading role implants can achieve the excellent clinical performance.
in the product design. For example, Ren et al. applied 3D The 3D-printed customized plate can provide accurate
10
technology to foot and ankle surgery for the 3D display of fixation according to the local anatomy of bone tissue.
rare tumors of the calcaneus, and successfully performed a Reshaping the plate during surgery is not necessary,
complete resection of the tumor. which could save the operation time. There has been
4.2. The 3D-printed customized metal plate for no report on the application of this customized plate in
arthrodesis TTC arthrodesis. Such plate precisely demonstrates the
Most orthopedic metal plates are made of titanium alloy. advantage of the 3D printing technology. Compared
Commercial titanium plates prepared by traditional with the traditional method, although the surface of the
techniques have achieved very good results in the treatment implant produced by SEBM 3D printing technology is
of long bone shaft fractures of the limbs. However, it slightly rougher, it does not cause adverse reactions such
29
is not frequently used in foot and ankle surgery because as inflammation; meanwhile, due to the special nature of
the fixation plate is short and the fixation strength is the 3D printing process, columnar crystals, and basket-
insufficient. TTC arthrodesis is one of the common surgical weave microstructure, which have excellent mechanical
methods in foot and ankle surgery, but its local fixation has properties, can be generated. The application of such
always been controversial. 14,15,29-31 In the implementation customized plate for fixation can avoid the disadvantages
of TTC arthrodesis, the surface of the bone is rough and of trimming the patient’s tissue to meet the conditions
uneven; even if the commercial plate is shaped during the of the commercial plate. Of course, since it is difficult to
operation, it is difficult to perfectly match the plate with reshape the customized plates during surgery, at present, it
the patient’s bony anatomy. Besides, studies have shown is recommended that surgeons print the disease model and
that the biomechanical strength of screw fixation in TTC plate samples for surgical simulation in order to reduce the
arthrodesis is lower than that of the plate. 32-36 Therefore, risk. 10
there is a huge demand for ideal plate for foot and ankle
surgery. 4.3. The 3D-printed metal implants to treat bone
Ti-6Al-4V is a widely used orthopedic implant material defects
and has good biocompatibility. 37-40 In this study, columnar Bone defects due to trauma, degeneration, and tumor
crystals and basket-weave microstructure are formed resection are common problems in foot and ankle
13,45,46
inside the customized plate with Ti-6Al-4V material. The surgery. At present, autologous, allograft or synthetic
46
hardness result of the screw was 282.95 ± 2.22 HV, while bone graft are usually used to solve these problems.
the hardness result of the 3D-printed plate was 327.50 ± Autologous bone grafts might result in complications of
3.14 HV, which was higher than that of the screw. Bobbert bone removal, increased surgical trauma, and prolonged
et al. conducted the triply periodic minimal surface operation time; besides, its sources are rather limited.
41
lattices with Ti-6Al-4V material, which achieved high yield Allografts has disadvantages such as immunological
strength and extremely high fatigue. Li et al. designed rejection, disease transmission, and insufficient tissue
42
a Ti-6Al-4V porous microstructure by electron beam support strength. For synthetic grafts, the shortcomings
melting (EBM), the uniform porosity was approximately are low ability in osteogenesis and limited support
66%, and the achieved sample elastic modulus (2.5 GPa) strength.
was similar to human trabecular bone. Furthermore, The 3D-printed metal implants have great advantages
Feng et al. used selective laser melting (SLM) to in treating bone defect. For instance, theoretically, it can be
43
design TiNbTaZrMo high-entropy alloy (HEA), whose used to fill in large bone defects and is a graft with higher
mechanical properties closely resemble those of human support strength. The surface structure of the graft has an
trabecular bone with Young’s modulus (6.71–16.21 GPa). important influence on osteogenesis. With reasonable
47
Currently, 3D-printed customized titanium implants can treatment of the micropores on the graft surface, it can
be made by some additive manufacturing technologies, induce bony ingrowth. However, the 3D-printed metal
48
such as electron beam melting (EBM), SLM, and selective implants also have some disadvantages. For example, the
laser sintering (SLS). Additive manufacturing technologies cage cannot be trimmed during surgery, so different sizes
can provide more compatible mechanical properties and of implants need to be prepared preoperatively. Li et al.
11
customized complex geometries porous microstructure, used SLS of 3D printing technology to fabricate customized
44

Volume 10 Issue 1 (2024) 454 https://doi.org/10.36922/ijb.0125