Abstract
Simulation seems to be the best method of improving medical attitude, technical skills, and operating times. A literature review of the available data in simulation for hernia surgery was performed. Surgical simulation has been included as a main requirement in residency programs and endorsed by several surgical societies. However, evaluating how simulation affects patient's outcomes is challenging. In addition, simulation training represents an institutional economic burden that could undermine its implementation and development. Published data support that simulation-based training is a highly efficient tool, thus, its implementation should be strongly encouraged.
Introduction
There is robust evidence confirming the effectiveness of simulation training.1–5 However, lack of simulation time and proctored trainers often hamper obtaining adequate competence. Furthermore, changes in work hours and low faculty's perception of the residents have a deleterious impact in self-confidence of the residents and their operative skills.6–8 For instance, Fonseca et al. 9 conducted a national survey of graduated chief residents and found a significantly lack of confidence in performing the majority of operations included in the survey.
There are several modalities in surgical simulation such as box trainers, virtual reality simulators, animal models, and cadavers, and each of these could offer specific skill improvements.3,4,6,10 However, availability, costs, ethical aspects, and deficiency in simulating specific features of a procedure may explain why most institutions advocate for simply and locally made simulators.6,11
Abdominal wall surgery is one of the most common elective procedures.12,13 A wide variety of new techniques have been described in the past decades, and thereby an adequate training and high surgical volume are required to obtain proficiency.5,6,11 The learning curve for minimally invasive hernia repair is demanding, with reports suggesting that ∼250 cases are needed to have similar recurrence rate when comparing with open approach.11,14 These reasons could partially explain why laparoscopic techniques are utilized only in 20% of the cases.1,5,6,11 Simulation programs may play a key role in reducing learning curves.
Material and Methods
We performed a comprehensive review of the data available in simulation for hernia surgery. In order to elucidate its current status, the most common procedures in abdominal wall surgery were reviewed as well as their open, laparoscopic and robotics approaches. The IRB approval was waived for this retrospective review of the literature.
Results
Open inguinal hernia repair
Since its introduction by Lichtenstein in 1984, 15 the open tension-free repair with mesh has been accepted worldwide and it is one of the most common procedures in hernia field. The last updated groin hernia guideline 16 recommended this technique, as well as the laparoendoscopic repair as the best evidence-based options. The open technique seems to be easier to teach and has a shorter learning curve as compared with minimally invasive procedures. 17
There are several alternatives available to train open inguinal technique such as simulation models, 18 virtual reality,19–21 and animal models. 22 The virtual reality simulator for the Lichtenstein procedure (VREST) 19 uses a haptic device (enabling touch feedback) mimicking real surgery. This type of simulator replaces the real “master” surgeon and can give instructions and feedback, and it could be set to three levels of difficulty. Animal and cadaveric models have shown high fidelity 23 and both trainees and faculties feel comfortable with these models suggesting that they are useful tools for both training and assessing learning objectives. However, availability, high costs, and ethical issues often affect their use and development. In addition, there is a lack of evidence in the literature regarding the assessment of trainees' proficiency after using these types of models.
Recently, Nazari et al. 18 developed and evaluated the fidelity of a new low-cost simulator model for open hernia repair. They found high fidelity and high perceived usefulness for residents training, as their model accomplished the three domains of fidelity (model, equipment, and psychological). Considering that the fidelity of any model is associated to the learning process, the greater resemblance offered by the simulator model will determine greater fidelity. 24 Therefore, this simulator seems to be an adequate platform for resident simulation-based training. Its low-cost, easiness to reproduce, and high fidelity makes this simulation model a very interesting tool to improve residents' proficiency and patient's safety in the operating room (OR).
Open ventral hernia repair
Ventral hernias are frequent with an incidence at the umbilical site of 6% in normal population, 25 whereas incisional ventral hernias rise up to 15% after a laparotomy. 26
Despite its wide understanding and technical development, there is scarce evidence for validated simulators in open surgery27,28 and even lower for open ventral hernia repairs. Recently, Friedrich et al. 29 conducted a study evaluating the validation and educational impact of a silicon-based simulation model for open mesh hernia repair. The study included medical students, senior residents, and attending surgeons, and compared the results after performing an open preperitoneal mesh repair in the NANEP model (NANEP stands for the German acronym: Nabelhernien-Netzimplantation-Präperitonal, English: Umbilical hernia mesh implantation preperitoneal). The authors observed high-fidelity full-procedural benchtop model that meets the main needs of surgical educational courses. Moreover, beginners (medical students) showed a more pronounced learning curve and had significant learning growth in instrument use and tissue handling.
Regarding open incisional ventral hernia repair, the retromuscular mesh reinforcement (Rives-Stoppa-Wantz) is considered one of the standard procedures.30–32 In 2020, Zipper et al. 33 developed a silicone-based simulator for retromuscular mesh repair. This simulator covers all the steps from the skin to the peritoneum with a very realistic construct. The study enrolled both beginners (medical students) and experts (general surgeons), and the results showed significant improvement in experts, confirming its construct validity. The authors concluded that their full-procedure simulation model has high fidelity suitable for both beginners and experts to perform a complete retromuscular ventral hernia repair with mesh.
Laparoscopic inguinal hernia repair
The two most utilized laparoscopic approaches for the treatment of inguinal hernias, totally extraperitoneal (TEP) and transabdominal preperitoneal (TAPP), have shown several benefits such as less postoperative pain and early return to daily activities, as compared with the open repair.34–37 However, it has been stablished a case load of 30–50 in TAPP and 100–250 in TEP to obtain similar recurrence rate when comparing with the open approach. 14 This explains, in part, that only 15% of the inguinal hernias are performed laparoscopically. 38 In addition, in a national survey in Canada, 39 the vast majority of the residents were primary operators in <5 cases during their residency program. Overall, it is clear that further simulation is needed to acquire at least the fundamental surgical skills in laparoscopic inguinal hernia repair.
Hamilton et al. 40 observed the impact of simulation training in the performance in the OR. They randomized residents into a standardized novel training program (rubber TEP simulator, videos, and interactive CD-ROM) and regular training. The training group with simulation showed better performance in TEP repair using the Objective Structured Assessment of Technical Skills (OSATS) rating scale. In 2009, Jain et al. 41 created a hernia endotrainer that permits to perform bilateral inguinal hernia repair (TAPP) and also intraperitoneal onlay mesh (IPOM). The study enrolled 40 participants and two hernia training programs (didactics lectures, live surgery, and hands-on training) of 2 days each. There was high subjective satisfaction in all the participants, and both global and task-specific scores were significantly improved on day 2, resulting in a good alternative to train residents and practicing surgeons. In 2011, Zendejas et al. 42 conducted a randomized study challenging a structured mastery training versus standard practice to evaluate the influence of TEP simulation training. The curriculum of the mastery learning program included an online course and skills practice using a TEP simulator (the Guilford MATTU TEP hernia task trainer 43 ). In their study, the training group showed significant improvements in the OR: shorter operative time and better performance in TEP procedure measured by laparoscopy-specific general global rating scale (GOALS). Furthermore, the authors were able to demonstrate the influence of simulation training on patient outcomes, showing fewer postoperative complications and a reduction in the need for overnight stay.
In 2011, Kurashima et al. 44 at the McGill University in Canada developed a physical low-cost simulator for laparoscopic inguinal hernia repair (MLIHS), which allows to train the entire procedure in both TEP and TAPP techniques. In their study, 6 experienced surgeons performed TAPP repairs to validate the simulator, and the MLIHS proved to be an excellent training tool with a Likert-type score of 24 out of 25. Subsequently, in 2014 the same group 45 conducted a prospective randomized trial to evaluate the transference of the skills learned in the MLIHS to the OR for clinical TEP repair. The intraoperative performance during TEP was assessed using the GOALS-GH 46 and a score of 24 within 15 minutes was considered the proficiency goal. Although the training group showed better scores comparing with a control group, this difference was not statistically significant. This could be partially explained by the small sample size included in the study, as some participants did not complete the study mainly for logistical issues.
In 2017, Nishihara et al. 47 developed a new laparoscopic simulator to train TAPP repair. It is made by three-dimensional printing technology and allows to learn the whole procedure, including the fundamental steps in TAPP: trocar location, creation of a peritoneal flap, hernia sac identification and reduction, mesh placement and fixation, and peritoneal closure. In their study, 15 general surgeons tested the simulator in a 40-minutes task to perform a right-sided TAPP. All surgeons strongly agreed (Likert-scale, median 5 points) that the simulator was a valuable tool for training in TAPP repair.
Laparoscopic ventral hernia repair
Since its introduction in the early 1990s, the laparoscopic approach for repairing ventral hernias has been gained popularity because it has shown fewer postoperative complications, reduced postoperative pain, and shorter length of hospital stay, as compared with the conventional approach.48–50 Given that laparoscopic ventral hernia repair (LVHR) is a very demanding procedure, simulation training at least to understand the anatomy, mesh positioning and suturing skills is essential to improve proficiency.
Jain et al. 41 developed the hernia endotrainer that allows to perform an IPOM repair of ventral hernia with defect closure. In this study, all participants significantly improved the specific tasks after a 2-day training course. This simulator is easy to replicate, and can be used for training residents and practicing surgeons to improve psychomotor skills that could potentially translate into better performance in the OR. Schimpke et al. 5 conducted a study to assess a simulated-based curriculum to improve resident’ confidence when performing LVHR. Their study enrolled residents (junior and senior) and faculty surgeons, and included web-based lectures, inanimate model simulation, and self-confidence questionnaires. The authors found a significant improvement in proficiency and self-confidence after the implementation of their curriculum, suggesting that it is a potential way to integrate procedure-specific simulation models.
Recently, Nurczyk et al. 51 at the University of North Carolina developed a novel laparoscopic ventral hernia simulator. It is based on a porcine tissue block that is mounted into a mannequin. It offers a very realistic training, allowing even to close the hernia defect. The 4 participants enrolled in the study felt high fidelity of the simulator in terms of operative space, tissue compliance, and haptic feedback. Based on this preliminary report, it seems to be an interesting tool for training in laparoscopic ventral hernia.
Robotic hernia surgery
In the past decade, robotic surgery has become more popular among general surgeons. Specifically, in hernia field, the robotic platform has shown to be comparable with other minimally invasive approaches in terms of postoperative complications.52,53 However, operative times, the initial investment of the robot, and its maintenance make difficult the implementation of this technology in many institutions, mainly in developing countries.54,55
Besides these disadvantages, the robot offers better visualization, detailed dissection, and minimization of the risk of nerve trauma.52,53 Furthermore, a previous survey study showed that inguinal hernia repair was the most common procedure among robotic surgeons (49% of the operations). 54 Interestingly, despite being a frequent robotic operation, there is scarce data regarding robotic hernia surgery training.
In 2018, Gonzalez-Hernandez et al. 56 conducted a retrospective study for robotic TAPP repair and compared senior residents performance versus attending surgeons, and no difference between groups was observed, suggesting that trained residents did not alter OR experience or patient outcomes when comparing with attending surgeons. Tam et al. 4 evaluated the impact of a structured proficiency-based robotic training on clinical outcomes and hospital costs for robotic inguinal hernia repair. Training curricula included a virtual reality simulator with an inanimate hernia model and live OR proctorship. The authors found that surgeons who completed the robotic training performed better with a significant reduction in operative time and cost per hernia repair.
Recently, Schlottmann et al. 57 observed a significant improvement of proficiency after 3-day robotic training course in all robotic skills evaluated. The authors concluded that a formal robotic simulation program should be incorporated in the residency curriculum to increase the confidence level of trainees.
Future Directions
In the last decade a significant effort to implement surgical simulation training programs and their certification 6 have been observed. Although we strongly believe that simulation-based training may improve patient outcomes and efficiency in the OR, its implementation is still challenging. 58 Limited resources, lack of trained trainers, and residents' workload are some of the variables that undermine the embracement of simulation10,59,60 In addition, how simulation effectively translates into better patient outcomes has been scarcely proven.4,42,56
Regarding hernia surgery, it is clear that better simulation programs and more realistic models are still needed. Long learning curves and new techniques for complex abdominal wall repairs make difficult to adapt a standardized hernia simulation training. Learning is a behavioral-cognitive experience, and simulation-based training will set an appropriate environment where the trainee can practice and reinforce task-specific skills. In addition, experts, masters, or proctors are needed for assisting the trainee to articulate their tasks requirements. As simulating an entire procedure is often not possible, breaking down the operation into core components is possibly a valuable first step in simulation. 61 For instance, peritoneum incision, mesh placement and fixation, and peritoneum closure might be adequate simulated scenarios for laparoscopic TAPP repair.
Finally, lack of realistic models with proper feedback can affect how trainees perform in the OR. Virtual-reality platforms, ex vivo tissue models, cadavers, and new simulation platforms can definitely be used to create realistic hernia models. Unfortunately, simulation models are often expensive and further research focused in developing cost-effective simulator is still needed.
Conclusions
Published data support that simulation-based training is a highly efficient tool to improve trainees' confidence and autonomy. In fact, there are several simulator models that have shown to improve proficiency in hernia field. Learning is a complex process and new techniques are constantly emerging; therefore, articulating these demands and including simulation into surgeons' curricula will be the challenge for the next years.
Footnotes
Disclosure Statement
The authors have no conflict of interest or financial ties to declare.
Funding Information
This manuscript was not funded.