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Zhang, et al.
for anti-reflux surgery training [21-23] . Therefore, a lack of gel layer simulating the abdominal wall. The printed
alternative models for anti-reflux surgery has driven us organs inside the box include: (i) Diaphragm, simulated
to generate a new dry laboratory model. A 3D-printed by a silicone gel of 3 mm layer, which was made into
pancreaticojejunostomy model for use in robotic-assisted a curved shape to simulate the shape of crus in real
surgery training was generated in our previously work . surgery, coupled with a hole with 5 cm diameter through
[24]
To extend the application of 3D-printed model in surgical which the esophageal part of the stomach can be pulled,
training, we designed a new LNF model with a curriculum simulating the hiatal hernia; (ii) stomach; (iii) liver;
that incorporates the key steps in Nissen fundoplication to and (iv) mesentery, the surrounding connective part of
address the key issues related to failure during LNF, and esophagus and stomach, attaching both side of curvature
conducted a trial to estimate the validity and efficacy of of stomach and linking diaphragm with the angle of His.
this model . In compliance with the suturing requirements, we used
[25]
a square-shaped mesh during the simulation surgery and
2. Methods removed a U-shaped piece from the mesh. In this study,
2.1. Model establishment we assume that the model needs mesh and manual suture
although it is optional in real situation (Figure 1).
(1) Mold print

Anonymized Digital Imaging and Communication 2.2. Criteria for selecting participants
in Medicine files were obtained using Mimic 23.0 The present study was approved by Zhejiang
system from 3D computed tomography scans of disease- Provincial People’s Hospital to carry out experiments
free human esophageal-gastric fundus and extracted/ within its facilities. All procedures followed were in
remodeling anatomy models of esophagus, stomach, accordance with the ethical standards of the responsible
diaphragm, spleen, and surrounding tissues. STL file committee on human experimentation (institutional and
abstracted was imported to Magic 24. The model was national) and with the Helsinki Declaration of 1975, as
repaired to obtain a watertight structure. Then, OBJ files revised in 2000. All volunteers were PYG-3 residents
were exported from Magic 24 and imported to Zbush for from the standardized training program of general
further modification. Mold designations were completed surgery department from June 2020 to March 2021.
by NX 1899 and either positive mold or negative mold All selected participants had individually performed
was designed depending on the shape of organs. The STL more than 30 laparoscopic cholecystectomy cases
files of designed mold were imported to Magic 24 for but never participated or preformed any laparoscopic
further designation of support structure and positioning. fundoplication. Participants’ performance was evaluated
Next, FDM 3D printer was used to print the mold based on by two experts. Sixteen residents were assigned into the
the sliced data, which would be given surface treatment experimental group (n = 8) and control group (n = 8)
and support structure removement after printing. based on their basic conditions, such as age, gender, and
number of laparoscopic surgeries they have attended
(2) Model formation (Table 1).
Resembled mold was treated with Vaseline on the
build face to ensure smooth removal of the models from
the mold. Silicone gel was poured into the mold from
vacuum bin and cured under 25°C for 1 h. Finally, a model
was obtained by removing the mold after solidification.
Additional changes after initial palpation (by percentages)
of silicon oil in silicone materials were implemented to
manually adjust the texture until all experts agreed on the
texture of the model.

(3) Model properties
The silicone material used for the stomach was
pink, with modulus of elasticity of 0.15 MPa and a tensile
strength of 0.95 MPa. The silicone material used for
diaphragm was red, with modulus of elasticity of 0.18
MPa and a tensile strength of 0.82 MPa. The 3D-printed
box simulates the abdomen, with 2 mm perforated silicone Figure 1. 3D-printed Nissen fundoplication training model. Blue
gel for the placement of laparoscopy and 5 mm silicone arrow: Diaphragm; black arrow: Stomach.

International Journal of Bioprinting (2022)–Volume 8, Issue 2 63