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International Journal of Bioprinting 3D printing of costal cartilage models

gold-standard therapy for such diseases because it is difficult customized costal cartilage models for a large number of
for auricular cartilage tissue to repair or regenerate itself. different patients.
3,4
To successfully handcraft a realistic artificial external Anatomical models created using 3D technology
ear, surgeons should have a good understanding of the have become increasingly popular in clinical practice. 17-19
anatomy of the entire three-dimensional (3D) structure of 3D-printed models provide unparalleled tactile perception
an auricle and be capable of creating various aesthetic units and offer several advantages, such as being more cost-
of the external ear, including the helix, antihelix, superior effective and accessible than traditional methods. In
and inferior crus, triangular fossa, and crus helix, through addition, these models can be customized to replicate
sculpture and suture. However, ear framework fabrication specific anatomical structures or pathologies in life-sized
5
remains a great challenge for residents who lack experience models, making them a valuable tool in the education of
in practice. Performing procedures directly on patients is surgeons and pre-operative simulation. For instance,
20
risky and may contribute to decreased therapeutic efficacy. a randomized control trial suggests that 3D-printed
Even experienced surgeons need pre-operative planning or models can be a more beneficial tool than cadaveric-based
simulated surgery to achieve satisfactory outcomes.
21
models for students and a large number of applications
A critical challenge for surgical training and pre- of patient-specific 3D-printed models in cardiac surgical
operative simulation is to provide conditions for effective procedures. 20,22
education without putting patients’ health at risk. A range Silicone (polysiloxane) has been widely used in various
6
of simulated handcrafting models offer a safe, nonclinical applications due to its biocompatibility and thermal
environment and immediate feedback designed to meet stability, and altering the amount of these components
23
the educational needs of learners and the simulative needs can modify the mechanical and rheological properties of
of surgeons. Surgeons tried soap, fruits, and vegetables the silicone elastomer, 24,25 which makes it attractive for
(e.g., carrots, apples, and potatoes) in early attempts to use mimicking biological tissue. For example, in the field
26
simulated models because they were inexpensive and easy of facial plastic surgery, one significant application of
to obtain. Compared with soap, the mechanical properties silicone is in the fabrication of auricular prostheses. 27,28
of fruits and vegetables were significantly better for this Since the industrialization in 2015, material extrusion, 29-32
purpose. However, fruits and vegetables were harder vat photopolymerization, 33,34 inkjet printing, 35,36 and other
and less elastic and failed to mimic the shape of costal technologies have been developed for the direct printing
cartilage. Then, surgeons started to work on the native of silicones. One of the most promising techniques
7-9
37
cartilage harvested from the scapula and ribs of animal and to ensure high printing fidelity is freeform additive
38
human carcasses, which met the basic requirements for manufacturing printing (FAM), defined as a variant of
the mechanical properties and 3D structure. Nonetheless, the material extrusion technique, which involves directly
in most cases, cartilage calcifications were observed in depositing liquid raw materials (generally termed “ink”)
elderly cadavers. Moreover, the storage and application of into temporary or permanent supports. 39-41 The versatility
isolated cartilage have some serious problems, such as high of FAM technology and the unique properties of silicone
costs, the risk of spreading diseases, and related ethical make it an attractive combination for a wide range
issues. Using synthetic polymer materials eliminated the of applications in fields, such as biomedicine, 42,43 soft
10
problems of disease transmission and ethics. However, the robotics, 44,45 and wearable devices. 46,47 The use of silicone
problems with costal cartilage models made of manually in FAM has the potential to create complex, flexible, and
cut rectangular polyvinyl chloride rubber or polyamide biocompatible structures that cannot be easily produced
and starch include an unsophisticated morphological with traditional manufacturing methods.
structure and unsatisfactory tear resistance of the surgical
knot. 11,12 To accurately reproduce costal cartilage, some In this study, we aimed to use 3D-printable (3DP)
researchers injected polyurethane, vinyl polysiloxane, silicone to fabricate biomimetic costal cartilage models.
or silicone into computer-assisted fabricated negative The mechanical properties of costal cartilage and these
impressions. 13-15 They replicated the shape of costal silicone materials, including hardness, stiffness, and suture
cartilage well. However, poor rigidity and strength kept retention ability, were comprehensively appraised in vitro.
them from imitating the texture of natural costal cartilage. Then, rheological tests and 3D comparison methods are
Recently, we further produced costal cartilage models by used to evaluate the printing performance of silicone
indirect 3D printing that are satisfactory in subjective or materials. Finally, we used direct 3D printing biomimetic
even objective evaluation. However, the fabrication of cartilage models in clinical practice to validate their value
16
negative models makes the process tedious, which restricts in surgery education and personalized surgical planning
pre-operative simulation because it requires personalized (Figure 1).

Volume 10 Issue 1 (2024) 215 https://doi.org/10.36922/ijb.1007