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International Journal of Bioprinting 3D-printed biodegradable metals for bone regeneration

of combining the good biocompatibility and plasticity of degradation, eliminating the need for secondary surgical
nonmetallic materials with the bioactivity of BMs. 185-187 removal. 124,193-195 The bone-enhancing properties of
These scaffolds are usually prepared by fused deposition magnesium ions can also lead to a significant increase in
modeling, in which metal powders are mixed with PEEK, the healing rate of osteoporotic fractures. In recent years,
196
PCL, etc. to form fused filaments, which are heated and successful treatment of fractures using BM materials has
extruded through a nozzle during printing and stacked been achieved in the clinic, and good therapeutic results
layer by layer to generate the finished product. 133,186,188 have been obtained. 197-201
Depending on the material used, cryogenic deposition 3D For injuries involving large bone defects, scaffolds
printing, material extrusion printing, and other methods composed of BM materials can temporarily replace bone
may also be used. 189,190 In addition, composite 3D printing tissue to provide mechanical support and simultaneously
technology for multiple materials has important potential provide attachment points for bone regeneration. For
in harsh environments, such as high temperatures, high example, when performing bone tumor surgery, which
loads, and high corrosion conditions, and is applied in fields can cause defects in a patient’s bone tissue, 3D-printed
such as aerospace, nuclear energy, marine, and offshore BM scaffolds can be used to support the bone structure
operations; among them, the multimaterial structure and promote bone regeneration; these scaffolds can
represented by NiTi/Ti6Al4V is suitable for personalized closely fit the bone defect site to prevent fracture and bone
biomedical orthopedic implants and has a stiffness similar collapse and can work in conjunction with medication
to that of human bone and excellent wear and corrosion to prevent infection. 202-204 Figure 4 shows an example of
resistance. Moreover, the precise processing of various a porous magnesium scaffold prepared by Cheng et al.
125
materials can adapt to various characteristics required However, due to the unresolved application difficulties
by human bone, such as biocompatibility, stiffness, wear of each metallic material, degradable metallic stents still
resistance, and corrosion resistance, and has controllable remain in the cell and animal experimental stage and
drug delivery potential. 191 have not been clinically applied. 125,201,205,206 Only stainless
steel materials have been used as permanent scaffolds in
5. 3D-printed BMs clinical applications. 207,208
3D-printed BM materials have a wide range of applications, In addition to bone tissue, BM materials are also
such as in orthopedics and maxillofacial surgery. expected to be useful for cartilage and ligament repair.
Table 3 displays the applications of 3D-printed BMs in Cartilage tissue is entirely nourished by the subchondral
various diseases. bone plate, and conventional permanent scaffolds
For fractures with small bone defects or no bone cannot provide access to nutrients if the bone defect
defects, screws composed of BM materials and bolts can extends to the subchondral bone plate. 3D-printed BM
be used for fixation, and when weight-bearing skeletal scaffolds can provide mechanical support for 2 months
sites are involved, a plate-screw hybrid fixation system and then gradually degrade to allow growth of cells
192
can be applied for support. For fractures located in the and blood vessels that provide nutrients for cartilage
209,210
curved part of the skeleton, the application of 3D printing tissue regeneration. Porous scaffolds can also carry
enables the implant to fit more closely to the fracture growth factors and immunoactive drugs to promote
211,212
site and provide better support. Animal experiments cartilage regeneration.
have shown that BM materials perform well and provide In the field of maxillofacial surgery, BM materials
adequate support for fracture healing, and compared to have higher biocompatibility, osteoinductivity, and
conventional titanium nails, they undergo significant biodegradability than traditional calcium phosphate

Table 3. Applications of 3D-printed biodegradable metals
Application Disease Implant References
Fractures with little or no bone defect Screws, bolts, plates 124,193-195,197-201
Osteoporotic fracture Screws, bolts, scaffolds, low-modulus bone substitutes 196
Orthopedics
Bone defect, bone tumor
Scaffolds 125,201-206
Cartilage defect
Maxillofacial surgery Low-modulus bone substitutes 215
Maxillofacial surgery
Dental implant Scaffolds 216

Volume 10 Issue 3 (2024) 49 doi: 10.36922/ijb.2460