Current status of simulation training in plastic surgery residency programs: A review

Virtual simulations

Unique to virtual simulators is the capacity to replicate rare clinical cases that surgeons would not otherwise encountered [5]. Furthermore, although the initial cost of program set up can be high—approximately $2,000 per simulator—they facilitate repetition without replacement of materials, which is cost-effective in the long run [16,34]. The potential for repetition has led opponents of virtual based learning modules to critique the potential for memorization as opposed to the active learning of new skill sets. Similarly, others maintain that the anatomical variation observable across patient populations cannot be adequately represented through simulators, and that the experience of physical resistance or recoil encountered in live surgery is impossible to accurately recreate [22,25].

Research conducted by Stern et al. [23] utilized virtual simulations to assess resident competency in the identification of complex anatomical landmarks and sequential latissimus dorsi flap reconstruction procedural steps. Residents were evaluated for their ability to correctly identify anatomy and answer a series of interactive questions. Subsequently, residents received an objective assessment of his or her cognitive competency—in terms of anatomy, procedural knowledge, indications, and complications. The scores of each participant were later stratified to indicate relative levels of surgical experience and knowledge of the test material. Pre-test versus post-test evaluation indicated that simulators had effectively improved competency; however, comparison to other simulation models has yet to be investigated [23].

Similarly, Oliker et al. [24] utilized three-dimensional (3D) virtual models to evaluate procedural knowledge for monobloc, Le Fort III, fronto-orbital advancement, and latissimus dorsi flap reconstruction. The interactive questions where designed to gauge resident knowledge of anatomical models, soft tissue deformities, surgical tool motions, chapter divisions, live surgical videos, voiceover audio, and animated transparencies. Although the simulation activity was shown to be beneficial in terms of acquiring and evaluating cognitive surgical knowledge, degree of skill transfer to the OR was not examined [24].

Spring-mass virtual simulators have been developed in an attempt to mimic recoil and tension encountered during surgery. In 2016, Mitchell et al. [26] conducted a local flaps workshop to test the efficacy of mass-spring based simulators for teaching flap designs (e.g., Z-plasty, rhomboid flaps, S-plasty, etc.), allowing participants to perform techniques through a web-based platform. Feedback regarding the simulator was positive for its ability to facilitate step-by-step practice for a given procedure, but the development of a more detailed assessment of resident skill improvement to evaluate its use is needed [35]. The benefits of high resolution meshes resemble those of spring mass models, with the former emulating the physical properties of bone and soft tissue.

Schendel et al. [22] combined high resolution meshes with a spring-mass model for resident training on unilateral cleft lip repair. 3D scans of an 11-day-old patient were translated to a spring model to simulate the effects of recoiling upon incision, as well as meshes, to mimic the physical properties of the anatomical structure involved in the procedure. Six laypersons and six residents were able to rotate and interact in real time, while identifying landmarks for assessment. Each participant interacted four times, with scores improving after each interaction. While participants experienced the simulator as a useful teaching tool, it was incapable of fully mimicking the physical aspects of surgery. The authors note that while improvement in layperson performance was attributable to memorization, the residents were more likely to reflect on their mistakes and to learn new skills with each additional use [22].

Virtual simulation offers the benefit of learning through repetition, at the cost of memorizing material due to lack of variation rather than actively learning as is accomplished from apprentice based training. Applications that require the identification of surgical landmarks or sequential steps can offer residency programs the ability to gauge baseline knowledge prior to clinical application. Notable pitfalls of virtual simulation include the high cost of initial acquisition and the inability to fully simulate the experience of live surgery in an OR setting.

Synthetic models

The use of synthetic material to simulate tissues and vessels can offer residents an opportunity to practice procedural steps and simultaneously gain experience in the handling and manipulation of surgical tools (Fig. 1) [21]. Common materials, such as silicone and wax, are more affordable than virtual reality [34]. Although the cost of materials is significantly lower than in virtual simulation, synthetic materials must be replaced after each use, and the cost of frequent replacements can add up. Utilization of synthetic materials ranges from practicing sutures to performing full procedures; junior residents are able to learn at their own pace in a safe environment, and subsequently receive objective feedback on their performance [35-37]. A major obstacle in synthetic materials is synthesizing materials that feel and behave as closely as possible to human anatomy. Careful attention to texture, recoil, and anatomy must be present in order for competency to be deemed transferable to the OR [38-41].

Fig. 1.

Use of synthetic models

A resident uses a synthetic model to practice breast reconstruction at NYU Langone Health.

In an effort to simulate resident training in mammoplasty, Kazan et al. [28] developed a synthetic Mammoplasty Part-Task Trainer (MPT). Various layers were created to mimic natural anatomy, including skin, subcutaneous fat, breast tissue, and ribs. Evaluations by four board-certified plastic surgeons were scored on a scale of 0 to 5 and included physical attributes, realism of materials, realism of experience, ability to perform tasks, value, relevance to practice, and overall rating. Although the MPT was able to successfully mimic physical attributes, the realism of materials, especially the subcutaneous fat, was not deemed close enough to live versions [37]. While the model can certainly be used to facilitate procedural learning, its value in terms of transferrable competency remains in question, and realism is lacking.

Synthetic models have been widely used in craniofacial practice [1,27,37,42,43] for both implants and surgical training in complex anatomy. Zheng et al. [27] created a model to aid in the development of psychomotor and manual skills involved in cheiloplasty. Wax was utilized followed by silicone to give lifelike texture, hardness, and elasticity [27]. Additionally, a multicomponent cleft palate simulator replicating a 6-month-old’s mouth was created by Vadodaria et al [43]. The model included components to replicate the various anatomical aspects involved in the surgery, including mouth, hard palate, and soft palate. Similar to other studies, the models proved helpful in training on surgical techniques but lacked the ability to fully replicate physical tissue [27,43].

Competency in the use of surgical tools is a vital milestone in residency training, with synthetic models allowing for repeated practice. Current models allow for anatomical representation but still lack the ability to fully replicate physical attributes [27,42,43]. As a training model, most synthetic materials are far more affordable than virtual simulators, at the price of needing to constantly replace after use [34]. To date, the models made are on a smaller scale and resemble specific anatomical areas. Much research into development of life-like materials is needed, for the closer to real a surgical training is, the more transferable competency will be.

Animal models

In recent years, there has been a shift away from animal models for surgical training due to ethical concerns regarding their use [1,3-7]. Still, many argue that practice on live or cryopreserved animals provide transferrable skills to the OR. Traditionally, training involved didactic models in which different materials were used (e.g., surgical gloves, surgical gauze, and silastic tubes). However, none of these models compared to rat aortas on account of differences in softness and resistance to the needle [29]. Rat vessels are heavily used in contemporary microsurgery training, specifically for practicing anastomoses [30,37]. Many institutions implement 5-day training courses to evaluate residents on their ability to anastomose rat aortas [30,34]. Cryopreserved rat aortas are rather inexpensive, easy to obtain, and eliminate ethical issues regarding the use of live animals [6,7]. To evaluate resident ability to perform anastomoses and measure transferability to the OR, Ghanem et al. [30] developed the Anastomosis Lapse Index (ALI). The ALI scores anastomoses based on 10 common mistakes: line disruption, partial thickness stitch, unusually large bites causing infoldment, oblique stitch causing tissue distortion, tight sutures causing strangulation of edges, vessel tear, thread in lumen, gap that is more than two ideal spacing, internal valve/large flap, caught back wall or sidewall. Construct validity was carried out by comparing scores between participants of varying skills and experience; validating ALI as a method to evaluate and predict transfer of microsurgical skills to the OR [30].

To measure resident competency prior to clinical application, the development of a simple, valid, and objective low cost assessment method would prove extremely valuable. Use of animal models is not new to surgical training, but the ability to measure skill acquisition and predict the extent to which they are clinically transferable provides additional impetus for their use as a training method [1,3-7]. The cost of training programs is minimized by the use of cryopreserved specimen, and the texture, size, and recoil of vessels is close enough to humans to facilitate realistic experiences. This aspect of realism puts animal models ahead of synthetic or virtual based training; however, ethical concerns regarding the use of animals persist as a major deterrent. Still, animal models remain useful for practicing microsurgical and suturing skills, and cryopreserved models predominate among current residency programs.

Cadaver and fresh tissue

Many of the simulation models formerly discussed are limited by their lack of fidelity, which hinders their ability to facilitate surgical competence. Starting in medical school, the use of cadavers is a long standing practice utilized in all levels of medical training [44,45]. With human anatomy and physical attributes accurately represented, anatomical variation is also present, thereby challenging trainees to learn and work within these disparities [1-3]. Nonetheless, cadavers still lack physiological perfusion, the simulation of which has been accomplished and proven effective in the context of vascular, neurological, and trauma surgical procedures [32,46-48].

Perfused cadaver utilization in plastic surgery training was explored by Carey et al. [32], in a study that sought to improve the fidelity of cadavers used in microsurgical training. Regional perfusion maintained by a centrifugal circulation was administered directly to proximal vessels of extremity or neck, with full cadaveric pressurization performed via the femoral artery. Arterial pressure could be adjusted based on the procedure at hand, allowing for accurate replication of the physiologic conditions experienced in live surgery. Cutaneous bleeding was confirmed with 11 procedures being taught to residents [32]. Recreation of techniques in an environment which mimics actual surgery has been a long standing feat. By perfusing cadavers to establish physiological conditions, realistic simulation and use of instruments provides the opportunity to train residents on a high fidelity model that facilitates the acquisition of transferrable skills.

In a study by Sheckter et al. [33] incorporation of this model into residency training programs resulted in significant increases in confidence levels for all procedures among all resident training levels. Residents were required to attend weekly dissections related to their current rotation, each of which included a lab manager, surgical technician, and attending physician. Although costing over $53,000, the curriculum overcame major hurdles in increasing resident confidence over a 5-year trial period. As an alternative to the use of cadavers and as a method to cut costs, many institutions use freshly excised tissue following surgeries such as abdominoplasty and body contouring. This limits practice to specific techniques as opposed to procedures, but can be very useful for teaching competence in surgical tools [21,37]. Concern over the use of cadavers is commonplace in regards to their potential to become reservoirs for communicable disease. Despite this fear and the high cost of use, cadavers and fresh tissue models provide the closest replications of live surgery.