Utilization of animal experiment-based simulation surgery platforms in the education of endoscopic thyroidectomy: a preliminary study

Abstract

Background

Endoscopic thyroidectomy, due to its superior cosmetic outcomes and improved postoperative quality of life, is increasingly in demand, especially among young female patients. However, performing the procedure while protecting crucial structures such as parathyroid glands and laryngeal nerves remains challenging. Consequently, comprehensive training is crucial for developing experienced endoscopic thyroidectomy surgeons. The main goals are to provide realistic intraoperative environments for surgeons and shorten the learning curve.

Methods

An animal experiment-based simulation platform has been developed in this study. Sixty trainees were equally allocated to either experimental group (surgeons received training using animal experiments before performing actual surgical procedures) or control group (surgeons participated in actual endoscopic thyroidectomy directly). Theoretical and surgical performance scores and trainees’ subjective assessments were compared between the two groups.

Results

There was no significant difference in gender, age, and baseline theoretical scores between the two groups. Theoretical and surgical performance scores in the experiment group were significantly higher than those of the control group, including anatomy scores (P = 0.01), specialty theory scores (P < 0.01), and surgical proficiency ratings (P < 0.01). Trainees’ subjective assessment scores in the experiment group were significantly higher than those in the control group, including satisfaction with the teaching program (P < 0.01), perceived enjoyment of learning (P < 0.01), proactive learning behavior (P < 0.01), self-assessed theoretical knowledge acquisition (P = 0.04), and self-reported improvement in operational skills (P < 0.01).

Conclusion

The utilization of animal experiment-based simulation surgery platform has a positive impact on increasing trainees’ engagement in surgical learning and enhancing the outcomes of training program.

Background

According to the GLOBOCAN database of thyroid cancer incidence and mortality rates for 2020, increasing incidence rates were observed in numerous regions and countries [1]. Differentiated thyroid cancer (DTC) constitutes 95% of all thyroid cancer cases, and thyroidectomy is recognized as an effective treatment option [2]. However, the noticeable neck scar resulting from the conventional open approach has raised significant concerns. Patients, especially young female patients, are particularly focused on achieving a radical cure with favorable cosmetic results [3]. In recent decades, endoscopic thyroidectomy, including transoral, trans-breast (areolar), and trans-axillary approaches, has developed rapidly and been found to improve postoperative quality of life [4].

Endoscopic thyroidectomy has notable advantages in protecting intricate structures, such as the parathyroid glands (PGs) and the recurrent laryngeal nerve (RLN), due to the enhanced visualization provided by endoscopic imaging [5, 6]. Specifically, the transoral approach allows for clear dissection of lymph nodes in the central compartment owing to its cranial-to-caudal view [7]. However, the procedures involved in endoscopic thyroidectomy are challenging for most surgeons and require extensive practice [8]. Recent studies indicate that an experienced thyroid surgeon needs to perform approximately 38 cases to complete the learning curve for most approaches [9], with the transoral approach potentially requiring 52–55 cases [10, 11]. Accelerating the learning curve is essential because it reduces the number of cases required to stabilize operative time and minimize complications [12]. However, current training methods lack the realistic bleeding, tissue handling, and dynamic decision-making required for live surgery. This gap leads to prolonged skill acquisition and higher iatrogenic risks during early clinical practice. Therefore, it is crucial to develop a surgical platform for endoscopic thyroidectomy to shorten the learning curve and reduce iatrogenic risks during the training process.

We propose an animal-experiment-based simulation platform using porcine models, which closely mimic human thyroid anatomy and provide an immersive, high-fidelity training environment. Animal experiments have significantly advanced modern medicine by enhancing our understanding of human anatomy and physiology [13]. Novel surgical techniques, including endoscopy, have been advanced significantly through animal experimentation [14]. During endoscopic training, particularly in advanced stages, live animal models are preferred for their realistic simulation of the operative environment, with porcine models being particularly valuable due to their anatomical similarities to the human thyroid region. Surgeons can experience the entire procedure on animals, which allows them to create the working space, coagulate blood vessels, identify and preserve crucial structures such as the PGs and laryngeal nerves, and perform thyroidectomy with lymph node dissection independently. The realistic operative environment provides immersive practice and appropriate pressure, motivating surgeons to master the techniques and the entire process of endoscopic thyroidectomy [15]. The implementation of an animal-experiment-based surgical simulation platform has the potential to decrease reliance on trial-and-error approaches in clinical practice, thus accelerating the learning curve, and reducing the incidence of iatrogenic complications (Fig. 1). Additionally, simulating endoscopic thyroidectomy using different approaches, such as cranial-to-caudal, caudal-to-cranial, and lateral perspectives, provides a comprehensive foundation for performing endoscopic thyroidectomy independently.

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Methods

Participants

A total of 60 medicine trainees, aged 23–35 years, were voluntarily recruited from the Department of Thyroid Surgery at the Second Affiliated Hospital of Zhejiang University School of Medicine. These trainees underwent a standardized surgical training program in the Department of Thyroid Surgery that spanned August 1, 2022, through August 30, 2024.

Study design

After obtaining informed consent, the 60 participants were randomly assigned to two groups: an experimental group (n = 30) and a control group (n = 30). Randomization was performed with computer-generated random numbers by an independent statistician, with allocation concealed in sealed, opaque envelopes. In the experimental group, trainees underwent animal-based simulation training before performing actual surgeries, whereas those in the control group proceeded directly to endoscopic thyroidectomy without prior simulation training.

Assessment system

A pre-training assessment of thyroid-related knowledge (baseline theoretical score) was conducted to gauge each trainees’ baseline understanding of thyroid surgery. At the conclusion of the rotation (using one month of training as the benchmark), a post-training evaluation of anatomical and specialized theoretical knowledge was conducted. Surgical proficiency was rated by senior surgeons, and a structured questionnaire (see Supplementary Questionnaire) was utilized to assess the teaching approach, encompassing domains such as satisfaction with the teaching program, perceived enjoyment of learning, proactive learning behavior, self-assessed theoretical knowledge acquisition, and self-reported improvement in operational skills.

Sample size justification

A priori power analysis was conducted using PASS software 2020 (NCSS LLC., Kaysville, UT, USA) to determine the minimum sample size required. Based on prior studies comparing simulation-based versus conventional surgical training [16], we assumed a moderate effect size (Cohen’s d = 0.65) for improvements in surgical proficiency scores. With α = 0.05 and power (1-β) = 0.80, the analysis indicated a minimum requirement of 26 participants per group. Our final sample size of 30 per group exceeds this threshold, ensuring adequate power to detect clinically meaningful differences.

Data evaluation and statistical analysis

Statistical analysis was performed using the IBM SPSS software package (version 22.0). All continuous variables were represented as Mean ± Standard Deviation. Continuous data were analyzed with an independent-samples t-test when normally distributed and with Wilcoxon rank-sum test when non-normally distributed. Categorical variables were analyzed using χ2 test or Fisher’s exact test depending on expected cell counts. A P-value < 0.05 was deemed statistically significant. All analytical methods were conducted in accordance with relevant guidelines and regulations.

Results

There were no statistically significant differences in gender distribution (Female proportion 46.7% vs. 40.0%, P = 0.60) or age (28.9 ± 3.6 vs. 29.7 ± 3.5, P = 0.39) between the experimental and control groups. Baseline theoretical scores showed no significant difference between the experimental (61.6 ± 6.3) and control groups (63.0 ± 6.6) (P = 0.39) (Table 1).

Comparative analysis of the test scores

Upon completion of the training, the experimental group, which trained with the animal- experiment-based simulation platform, achieved significantly higher anatomy scores (81.5 ± 7.6) compared to the control group (76.7 ± 6.3) (P = 0.01). In the specialized theoretical assessment of thyroid surgery, the experimental group outperformed the control group (83.6 ± 6.2 vs. 78.4 ± 6.1, P < 0.01). Senior surgeons also rated surgical proficiency significantly higher in the experimental group (83.6 ± 5.9) than that in the control group (79.2 ± 4.7) (P < 0.01) (Table 1).

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Comparative analysis of subjective questionnaire results

In subjective evaluations of the teaching approaches, the experimental group reported higher teaching satisfaction (4.2 ± 0.7 vs. 3.5 ± 0.7, P < 0.01), greater enjoyment of learning (4.2 ± 0.7 vs. 3.5 ± 0.7, P < 0.01), and enhanced proactive learning behavior (4.4 ± 0.8 vs. 3.4 ± 0.6, P < 0.01) compared to the control group. Furthermore, the experimental group rated their self-assessed theoretical knowledge acquisition (4.2 ± 0.7 vs. 3.8 ± 0.7, P = 0.04) and self-reported improvement in operational skills (4.4 ± 0.7 vs. 3.6 ± 0.6, P < 0.01) more favorably than the control group (Table 2).

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Discussion

Surgery is a broad, integrative clinical discipline that places high demands on trainees, requiring them to strengthen their theoretical knowledge, practical skills, and overall competencies during standardized training programs [16]. However, the growing clinical and research burdens in tertiary hospitals have reduced the time that instructors can dedicate to bedside teaching, compromising teaching quality. Meanwhile, the growing number of trainees has limited individual access to hand-on clinical practice opportunities [17]. Continued reliance on traditional teaching models, such as “one-on-one” instruction, will make it increasingly difficult to meet the needs of large-scale training programs. Additionally, conventional bedside surgical teaching faces challenges such as instructor fatigue and waning trainee interest, hindering the achievement of consistent training outcomes [18].

Endoscopic thyroid surgery imposes significant technical demands on surgeons, necessitating comprehensive knowledge of thyroid anatomy and advanced skills in locating and protecting vital structures, including the parathyroid glands, recurrent laryngeal nerve, and superior laryngeal nerve [19]. Mastery of endoscopic surgical techniques is also essential. Prior studies indicated that the learning curve for this procedure typically plateaus after more than 50 completed cases [10]. Consequently, a major area of interest in current research is the development of strategies to accelerate the learning curve and minimize the risk of iatrogenic injuries during the training phase.

The innovative animal-experiment-based simulation platform helps overcome constraints in surgical education. By coupling realistic procedural simulation with scenario-based and theoretical instruction, the approach mitigates the shortage of hands-on opportunities for trainees. Using live-tissue models renders otherwise tedious anatomy more engaging, thereby boosting trainees’ interest in learning. Moreover, within the simulation platform, all trainees have the chance to shoulder the role of the “primary surgeon”, fostering a surgeon’s perspective in problem-solving. The challenges encountered during simulation further increase trainee engagement. The blend of independent in-session operating and self-directed after-session study yielded significantly higher self-rated mastery of theory and practical skills than traditional teaching methods. In the final evaluation, trainees in the simulation surgery platform group outperformed those in the traditional teaching group in anatomical knowledge, specialized thyroid theory, and surgical proficiency assessments.

The primary objective of surgical training is to develop trainees’ clinical reasoning and operative competency [20]. However, conventional observation-based teaching methods often fail to stimulate student engagement or facilitate the improvement of practical skills, frequently resulting in suboptimal educational outcomes [21]. In contrast, the animal-experiment-based simulation surgery platform offers trainees an immersive, three-dimensional anatomical experience and ample opportunities for repeated observation and practice, thereby fostering greater interest in anatomical and specialized knowledge acquisition and enhancing surgical proficiency. Furthermore, trainees can undertake targeted self-directed learning to address challenges encountered during practical operation, significantly boosting learning efficiency and accelerating the learning curve.

Our findings demonstrated the efficacy of the animal-experiment-based simulation platforms, and placed its value in context with established alternatives. Cadaveric workshops offer anatomically accurate human tissue but lack perfusion and realistic bleeding dynamics, limiting their utility for hemostasis training [22]. Virtual reality (VR) platforms provide endlessly repeatable scenarios free of ethical constraints, yet current systems struggle to replicate tissue feedback or psychological pressure of real-time complication management [23]. Phantom models, though cost-effective and accessible, oversimplify anatomical complexity and cannot simulate critical steps like nerve identification [24].

Limitations

While our findings demonstrate the efficacy of the animal-experiment-based surgery simulation platform, several limitations warrant consideration. The single-center design poses a risk of selection bias and may limit generalizability to other practice settings. Anatomical disparities between porcine models and human thyroid anatomy—particularly vascular variability—warrant caution when translating skills into clinical practice. Non-blinded assessment of surgical proficiency, though standardized, could introduce measurement bias. Additionally, long-term competency retention beyond the 1-month evaluation remains uncertain. Future multicenter trials that track longitudinal performance along with cost-effectiveness analyses (≈ $400/session) are warranted to confirm clinical translatability.

Conclusion

In summary, the development of an animal-experiment-based surgery simulation platform is beneficial for increasing trainees’ engagement in surgical learning and enhancing training outcomes, thereby contributing to a more effective training system for endoscopic thyroidectomy surgeons.

Data availability

The related materials including teaching materials, examination materials, and teaching satisfaction surveys were kept in hard copies in the Department of Thyroid Surgery, the Second Affiliated Hospital of Zhejiang University, School of Medicine. The original datasets of the study are available from the corresponding author on reasonable request.

References

Pizzato M, Li M, Vignat J, Laversanne M, Singh D, La Vecchia C, Vaccarella S. The epidemiological landscape of thyroid cancer worldwide: GLOBOCAN estimates for incidence and mortality rates in 2020. LANCET DIABETES ENDO. 2022;10(4):264–72.

Kheng M, Manzella A, Chao JC, Laird AM, Beninato T. Reoperation rates after initial thyroid lobectomy for patients with thyroid cancer: A National cohort study. THYROID. 2024;34(8):1007–16

Nagururu NV, Seo S, Ding AS, Grogan R, Wolfe SA, Harbison RA, Tufano RP, Russell JO. Long-term quality of life after thyroidectomy: transoral endoscopic thyroidectomy vestibular approach versus transcervical approach. OTOLARYNG HEAD NECK. 2024;171(1):45–53.

Zhou S, Wu P, Li W, Li H, Wang Z, Zhang L, Li J, Peng X. Challenging routine: technical difficulties and solutions of endoscopic thyroidectomy via a combined transoral and breast approach - a case-series and learning curve. INT J SURG. 2023;109(11):3273–82.

Yu X, Zhu R, Zhu P, Du Y, Tanu C, Han Z, Jiang N, Pan L, Xie C, Zhao Q, et al. Effectiveness and feasibility of nerve real-time monitoring and intermittent monitoring in endoscopic thyroidectomy: A multicenter retrospective cohort study of 1621 patients. INT J SURG. 2024;111(1):904–12.

Nguyen VC, Song CM, Ji YB, Oh S, Jeong JH, Tae K. Comparison of surgical outcomes of transoral robotic and endoscopic thyroidectomy: A systematic review and network meta-analysis. HEAD NECK-J SCI SPEC. 2024;46(3):688–701.

Oh MY, Chai YJ, Yu HW, Kim SJ, Choi JY, Lee KE. Transoral endoscopic thyroidectomy vestibular approach as a safe and feasible alternative to open thyroidectomy: a systematic review and meta-analysis. INT J SURG. 2023;109(8):2467–77.

Taher A, Chow J, Kwon MS, Hunter D, Lucewicz A, Samarawickrama C. Determining the learning curve for a novel microsurgical procedure using histopathology. BMC MED EDUC. 2022;22(1):342.

Fassari A, Gurrado A, Iossa A, Micalizzi A, Polistena A, Sibio S, Crocetti D, Bononi M, Testini M, Avenia N, et al. Definition of learning curve for thyroidectomy: systematic review on the different approaches. GLAND SURG. 2023;12(7):989–1006.

Kim KH, Ji YB, Song CM, Kim E, Kim KN, Tae K. Learning curve of transoral robotic thyroidectomy. SURG ENDOSC. 2023;37(1):535–43.

Dabsha A, Khairallah S, Elkharbotly I, Hossam E, Hanafy A, Kamel M, Amin A, Mohamed A, Rahouma M. Learning curve and volume outcome relationship of endoscopic trans-oral versus trans-axillary thyroidectomy; A systematic review and meta-analysis. INT J SURG. 2022;104:106739.

Sachdeva AK, Tekian A, Park YS, Cheung J. Surgical skills training for practicing surgeons founded on established educational theories and frameworks. MED TEACH. 2024;46(4):556–63.

Costea R, Ene I, Pavel R. Pig sedation and anesthesia for medical research. ANIMALS-BASEL. 2023;13(24):3807.

Dominguez-Oliva A, Hernandez-Avalos I, Martinez-Burnes J, Olmos-Hernandez A, Verduzco-Mendoza A, Mota-Rojas D. The importance of animal models in biomedical research: current insights and applications. ANIMALS-BASEL. 2023;13(7):1223.

Lukas M, Kolar M, Ryska O, Juhas S, Juhasova J, Kalvach J, Pazin J, Kocisova T, Foltan O, Kristianova H, et al. A novel postgraduate endoscopic course using a large animal model of secondary crohn’s disease stricture. SURG ENDOSC. 2021;35(6):3199–204.

Allott H, Smith A, White S, Nyaoke I, Evans O, Oduor MO, Karangau S, Sawe S, Shaaban N, Ephraim O, et al. Improving capacity for advanced training in obstetric surgery: evaluation of a blended learning approach. BMC MED EDUC. 2025;25(1):80.

Shahrezaei A, Sohani M, Taherkhani S, Zarghami SY. The impact of surgical simulation and training technologies on general surgery education. BMC MED EDUC. 2024;24(1):1297.

Mauiliu-Wallis MC, Park B, Hill AG, Jin JZ, Unasa H, Locke M. Have factors influencing female medical students’ intention to pursue a career in surgery changed over the last 10 years?? A systematic review. J AM COLL Surg. 2022;234(6):1221–37.

Yu JF, Huang WY, Wang J, Ao W, Wang SS, Cai SJ, Lin SY, Zhou CP, Li MY, Cao XS, et al. Detailed analysis of learning phases and outcomes in robotic and endoscopic thyroidectomy. SURG ENDOSC. 2024;38(11):6586–96.

Tohmasi S, Cullinan DR, Naaseh A, Awad MM, Klingensmith ME, Wise PE. Flexibility in surgical training does not affect American board of surgery board eligibility or certification: Long-term outcomes from a prospective, Multi-Institutional study of general surgery residents. J SURG EDUC. 2025;82(3):103390.

White A, Moran H, Rami Z, Moon MC, Zheng B, Turner SR. Autonomy and competence in cardiac surgical training: A qualitative analysis. J SURG EDUC. 2024;81(12):103274.

Araki Y, Oda Y, Kitagawa M, Aoki K, Komiya T, Kikuchi M, Shirai T, Kawata S, Itoh M, Matsumura H. Water-soluble dye staining of the flap nutrient artery and its perforator branch in cadavers embalmed using saturated salt solution and Urea methods: does demonstration using a dye-stained cadaver increase a trainee’s level of skill acquisition? ANAT SCI INT. 2025;100(3):347–53.

Groves H, Fuller K, Mahon V, Butkus S, Varshney A, Brawn B, Heagerty J, Li S, Lee E, Murthi SB, et al. Assessing the efficacy of a virtual reality lower leg fasciotomy surgery training model compared to cadaveric training. BMC MED EDUC. 2025;25(1):269.

Saeed M, Quarez J, Irzan H, Kesavan B, Elliot M, Maccormac O, Knight J, Ourselin S, Shapey J, Granados A. Blood harmonisation of endoscopic transsphenoidal surgical video frames on Phantom models. Proc IEEE Int Symp Biomed Imaging. 2024;2024:1–4.