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International Journal of Bioprinting 3D printing of costal cartilage models

the fidelity of 3D-printed models. Trueness (the deviation ability in the 80 A material resulted in unexpected gaps
from the reference) and precision (the deviation from when assembling the stents with wires, which was related
repeated measurements in the same group) were quantified to a decrease in tensile strength for a higher concentration
through 3D deviation comparison of the 3D-printed of silica. The application of this kind of costal cartilage
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models reconstructed by CT data. Printing trueness was model with high satisfaction is expected to greatly shorten
displayed in the form of a deviation chromatogram, and the training period of residents.
the deviation within ±1 mm reached 96.40% (Figure 4G),
ranging from 87.20% to 96.50%. The deviation of printing We performed pre-operative planning using the
precision within ±1 mm reached 99.69% (Figure 4H), 3D-printed models on several patients eligible for inclusion
ranging from 97.64% to 100%. These results indicated that in this study, and herein, we showed one of the typical
the printing fidelity was nearly perfect. The addition of a framework carving designs. The 6th, 7th, and 8th costal
moderator prolongs the time for curing and prevents the cartilages were routinely harvested for the majority of ear
emergence of in-nozzle curing. The suitable proportions reconstruction surgeries. However, through the printed
of thixotropic agents and gas-phase silica in this formula models and pre-operative simulations, we found that the
provide good shear-thinning properties for silicone so that patient’s 8th costal cartilage was well developed and of
printed constructs retain their shape without immediate sufficient length to replace the 6th (Figure 6A and B), and
post-curing. 25,66 In addition, the supporting material only the 7th and 8th costal cartilages were harvested during
prevents collapse and deformation caused by gravity. the operation (Figure 6). Good surgical results were still
obtained, and the dimensions of cartilage and silicone ear
3.3. Ear framework handcrafting curricula and frameworks are shown in Table S5 (Supplementary File).
individually tailored surgical plans The differences were not statistically significant (p = 0.21).
It is reasonable that patients expect utmost proficiency Pertinently, harvesting costal cartilage is one of the essential
and mastery from their plastic surgeons. Additionally, steps of ear reconstruction surgery, and it inevitably gives
the assignment of works to the residents depends on the rise to multiple complications, including infection, pain,
complexity of the procedure, the patient’s condition, and pneumothorax, and chest deformity. The classical scheme
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the senior surgeons’ disposition toward entrusting the needs to collect three or four costal cartilages, 70,71 which
residents with the role of primary surgeon. The high often leads to wastage of cartilage. During the operation,
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public expectation of perfect patient outcomes and the the remaining cartilage after the fabrication of the cartilage
public awareness of surgeon-specific performance further framework can be put back into the donor site, but this
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limit the residents’ opportunities to learn by performing will still cause unnecessary damage. Thus, pre-operational
procedures in the operating room. Fortunately, 3D-printed evaluation of the costal cartilage condition and reducing
models provide a valuable opportunity to learn outside the the amount of harvested cartilage by means of simulated
operating room. As shown in Figure 5A–C, residents who operation is one of the best solutions. 3D-printed models
practice on 3D-printed models experienced fast progress. display with fine fidelity the complex anatomical structures
After six training sessions, they spent 55.50 ± 11.42 min of costal cartilage and enable a comprehensive evaluation
on the final attempt compared to 133.30 ± 12.35 min of the surgical plan that other methods cannot achieve.
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on the first attempt, and the difference was statistically By applying these models pre-operatively, fabrication
significant (p < 0.0001). Overall learner pre-training simulation allows for a more intuitive evaluation of the
confidence improved from ratings of 1.60 ± 0.70 to 4.2 ± cartilage and aids in the determination of the proper
0.79 after seven handcrafting attempts (Figure 5D). The amount of cartilage to be harvested for grafting, thereby
average improvement in confidence rating was 2.60 ± 0.97. minimizing the need for excessive logging and identifying
The printed models improved the learning efficiency of potential shortcomings or complications before applying
residents through deliberate practice and timely feedback, the procedures to patients. Reduced surgical trauma
which is comparable to findings involving our previous and a potential decrease in the occurrence of chest wall
indirectly printed models in terms of reduced study time deformity 72,73 are benefits of fewer extracted grafts. This is
and improved residents’ confidence. Table 1 demonstrates extremely important for surgeons who lack rich experience
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the subjective perception of surgeons who attempted in ear reconstruction because they can repeatedly perform
3D-printed costal cartilage models, and the 65 A material ear framework carving exercises for specific patients before
received the best feedback. In the subjective evaluation, surgery, which is of great benefit as it can increase surgical
the three formulations of 3DP silicone all achieved good confidence and be used to develop strategies that save
results, but the 65 A and 75 A materials were the better time and deliver optimum postoperative results. Based
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choice with no significant difference (Figure 5E). According on the same logic, senior surgeons could also benefit from
to the surgeons’ feedback, the weakness in suture retention individualized models. Senior surgeons are challenged

Volume 10 Issue 1 (2024) 222 https://doi.org/10.36922/ijb.1007