Low-cost synthetic model for skin flap training

Introduction: The search for learning surgical techniques within the operating room is linked to difficulties, such as reducing teaching time by surgeons and ethical problems. Models have already been developed to facilitate the practice of surgical techniques, however, with high cost, difficult access, and ethical and moral complications. The present work aims to present a synthetic model, unpublished and practical for the training of skin flap techniques, formulated to be easy to reproduce and low cost, allowing its feasibility. Methods: In the model, fabric, sponge for car washing, latex elastic, fine-tipped brush, scalpel, and surgical suture instruments were used. The fabric is fixed by the elastic on the surface of the sponge, simulating skin and subcutaneous. The flap to be made on the surface of the fabric is then drawn. Results: The model created was satisfactory, since it improves the handling of surgical instruments and the learning of the proposed flap technique, besides having demonstrated good elasticity and tensile strength. In medical schools, there is a lack of approach to essential topics in plastic surgery. The importance of low-cost and easy-to-execute models, such as the above, is emphasized to facilitate the learning of students interested in the subject, seeking to fulfill the educational function without breaking ethical principles. Conclusion: The proposed model is an excellent form of training because it presents logistical and instructive benefits, facilitating learning, without causing harm to animals. ■ ABSTRACT


INTRODUCTION
The surgical flap consists of a tissue mobilized from one part of the body to another with a vascular peduncle and can be kept intact or sectioned, to perform vascular anastomosis and maintain the blood supply of that tissue. These can be classified according to the composition of the tissue found in it (cutaneous, musculocutaneous, fasciocutaneous, osteocutaneous and sensory), and according to the movement of the skin towards the receptor area (advance, rotation, transposition, and interpolation) 1,2 . They are a choice to reconstruct a defect on vital structures, tissues devoid of a perivascular membrane, or implants.
After assembly, the fine-tipped brush is used to draw on the fabric's surface the type of flap to be made. Finally, the model can already be used to train the various techniques described using the appropriate surgical instruments ( Figure 2D). Thus, the model mentioned above was made with a maximum cost of 10 reais and simulates this procedure's technique. It is worth mentioning that the fabric is the only component that cannot be reused after use, and that needs replacement.
The model was made at the University of Fortaleza (UNIFOR) by the university's academic league of plastic surgery in January 2019. Moreover, the study mentioned above did not specify the involvement of humans and animals, so there was no need for approval by the Ethics Committee to prepare the skin flap model, which is obtained through synthetic materials.
The model was used in extracurricular activities elaborated by the academic league of plastic surgery of the university; the activities took place in a 4-hour shift under the supervision of academic members of the academic league who had teaching guidance.

RESULTS
The model was used in the event of the academic surgical leagues of a Private University of Fortaleza/ CE, in which students from various school periods, approximately 50 students, had contact with the proposed model ( Figure 3).   allowed the development of skills also by the instructor students, such as interpersonal communication.
It is added that the presence of students more experienced and trained by the teacher, contributed to the elaboration of a less hostile environment for learning, facilitating the clarification of doubts in a simple and accessible language.

DISCUSSION
During the medical career, most surgical practices are restricted to the hours destined to general surgery and are often insufficient for academics interested in the surgical field. Regarding plastic surgery, there is a lack of treatment for essential themes in this area, such as the cutaneous flap 7 .
Microsurgery is an area of paramount importance in the plastic surgeon curriculum. Many models that allow the practice of this flap have already been developed and tested, demonstrating efficacy in the development of skills in microsurgery. According to the systematic review of non-biological models by Abi-Rafeh et al., in 2019 8 , simulation models should play an even more significant role in developing a microsurgery training curriculum. The model developed in this article was planned for the technique of cutaneous flap; unfortunately, it does not meet the specificities and characteristics of a model that allows the practice of free flap.
The model described was presented to a plastic surgeon, a professor of medicine at the University of Fortaleza. The professor evaluated the simulator and admitted the possibility of applying this model to teaching the procedure since the designs and geometries of some flaps are relatively complex to understand. Moreover, due to its high relevance, being one of the pillars of skin surgery, it is essential to the academic interested in the specialty, the knowledge of its execution through training in practical models of low cost and easy maintenance 9 , since, for better learning, the training repeated several times, with a low-cost material, is something that proves indispensable.
The model also allows the execution of rotation, transposition, interpolation, and simple advancement flaps, as shown in Figure 4, and can be used to train various types of flaps.
The model proposed by Denadai et al., In 2012 5 , made from chicken skin, proved to be a complementary alternative to the arsenal of existing simulation models due to its similarity, in texture and consistency, to human tissue 10 . However, when it comes to its continuous use in teaching programs, the animal model can be expensive, since it needs a collection and storage service so that it does not bring biological risk to the students of the institutions. Besides, its preparation is time-consuming and delicate, since it is necessary to defrost the parts in advance, a process that, when not done well, can leave the material hardened, causing the loss of needle threads during training and further increasing it cost.
The use of animal material also presents several ethical and bureaucratic complications, since besides being questionable, they conflict with modern concepts of animal welfare. With this, the current diversity and complexity of surgical medical knowledge require a new direction in teaching through innovative means, seeking to fulfill the educational function without harming the animals.
The proposed model, which is based on the use of synthetic fabric overlapping a layer of sponge for car wash, proved to be entirely objective regarding the execution of the technique, as the chosen fabric has good resistance to suture, reducing the probability of dehiscence, doing the practice aimed at improving the skin flap technique viable and safe. Besides, the model is easy to prepare and store, as it does not need to be conserved, and its assembly is simple, practical, and fast.
The proposed model is easy to perform and assembled to facilitate the understanding of the skin flap technique.

CONCLUSION
It is believed that the use of this synthetic model becomes relevant in the training of medical students and residents in plastic surgery, because it allows the practice of this medical skill, with minimal ethical conflicts and without the need to train in animals or the patient himself.
Besides, the surgical simulation of the cutaneous flap, using the proposed synthetic model, is a suggestion for the exercise of this technique because it presents logistical and instructive benefits, such as the use of low-cost materials, easy storage, and preparation.
However, further studies on the effectiveness of training with synthetic models for undergraduate medical students are needed, with the elaboration of questionnaires evaluating students' perception and instructors' perception.