Acquisition of dexterity in specific surgical skills requires repeated practice by surgical trainees. Traditionally, this has been achieved through the gradual introduction and escalation of trainee involvement and independence in surgical procedures until graduation in a time-based training program. A number of factors, however, challenge this traditional training paradigm, such as the recent introduction of mandated objective assessment of skill competencies (ie, competency-based education) into most North American residency programs.1,2 An additional issue is the concomitant restriction on working hours of residents, resulting in reduced case volumes and exposure to such learning experiences.3,4 It is not surprising, then, that surgical simulation has obtained increasing attention for its role in teaching and assessing resident surgical skills.5–7
Evidence that the use of simulation in health care is linked to improvement of trainees’ performance and patients’ safety8–10 has led researchers to develop new simulators. It has been shown that training on simulators allows residents to complete the early phase of the learning curve and to acquire surgical skills related to the procedure in question.11 Furthermore, skills acquired in simulation training have been repeatedly and consistently demonstrated to be transferable to the operating room.12–15 These findings have led to the development of more sophisticated surgical simulators that allow the execution of the essential steps of a procedure, rather than training on simple tasks such as skin suturing and wound care. The simulation environment offers junior trainees the opportunity to develop the necessary skills at their own pace in a controlled environment and to receive objective feedback based on their performance.
Surgical simulation in general will be a necessity in the new environment of mandated assessment of surgical competence because of medicolegal and ethical concerns16–18 involved with trainees learning and being tested solely in the live operative setting. Particular to plastic surgery training is the additional difficulty associated with the teaching of aesthetic surgery skills18–20 because of the frequent marginalization of aesthetic surgeries to private clinics as a result of limited hospital (university) operative resources. Such learning is further burdened by the fact that patients pay out of their pocket for aesthetic procedures and thus are less keen to participate in resident training.
In this study, the authors introduce the first mammoplasty part-task trainer (MPT) with the goal of providing improved technical training experiences and objective skill assessment for plastic surgery trainees.20 Although early in its development, the MPT, with further refinements, could allow plastic surgery trainees to practice breast augmentation and acquire the basic skill sets before they apply the maneuvers in the clinical setting.
Mammoplasty Part-Task Trainer
The MPT was produced in an “anatomic” layer-by-layer manner (Fig. 1). The external appearance and shape of the breast were reproduced from the right breast of a volunteer. A mold of the breast and chest wall was taken by applying silicone to the breast in multiple layers with incremental viscosity, the first layer having the lowest viscosity to pick up the finest details, then higher viscosities to harden the mould and finally a plaster layer to solidify it.
Different anatomic layers were to be represented in the MPT: skin, subcutaneous fat, breast tissue, and ribs (Fig. 2). Each layer was represented using the material that provides the most realistic appearance, touch, and tissue dissection resistance. After the breast mold was completed, a layer of Dragon Skin (Smooth-On, Inc) silicone followed by another layer of Ecoflex (Smooth-On, Inc) was applied and waited to cure to simulate the skin. Then, subcutaneous and breast tissues were represented using Soma Foama (Smooth-On, Inc) foam silicone. A rigid base was then built using Vytaflex (Smooth-On, Inc), which was poured onto the Soma Foama in its liquid state, where plastic ribs were introduced and held in place before the silicone completely cured. Layers were dyed with the color that best mimics that of the represented tissue. When all layers cured, the MPT was taken out of the mold and was ready to use. The process to build the disposable layers is estimated to 75 minutes; the base takes 24 hours to cure.
Testing the MPT
An experienced board-certified plastic surgeon and surgical educator tested the MPT’s ability to simulate a breast augmentation procedure. An incision in the inframammary area was created with a scalpel down to simulated breast parenchyma, where dissection was continued bluntly into the subglandular plane to develop an appropriate pocket. A 90 cc textured silicone breast prosthesis (Allergan, Inc, Irvine, CA) was inserted manually with the surgeon’s digits. The position of the implant was verified to ensure appropriate placement. The incision was then closed in layers, beginning with the breast parenchyma using 3-0 Vicryl sutures (Ethicon, Inc, Cincinnati, OH) followed by a running 4-0 monofilament subcuticular suture for the skin (Fig. 3).
Survey and Rating Procedure
A breast augmentation procedure was performed by 4 independent board-certified plastic surgeons not involved with this research. Each was then asked to complete an evaluation survey composed of 16 items under 7 domains, in addition to a free observation section where they could comment on attributes that the survey did not cover. The first domain described the “physical attributes” of the MPT: chest circumference (unilateral), chest depth, intercostal space, landmark tactility, landmark visualization, and orientation of the breast (overall aspect). The second domain evaluated the “realism of material” used to simulate the skin, subcutaneous tissue, and rib cage. The third domain evaluated the “realism of experience” of establishing a submammary pocket for the implant and controlling proper implant positioning. Forth domain described the “ability to perform tasks,” which included skin suturing and breast implant insertion. The final 3 domains evaluated the MPT as a training tool, its relevance to practice breast augmentation, and a global assessment.
The physical attributes, realism of material, and realism of experience were evaluated according to the following Likert scale: 1, not at all realistic; 2, lacks too many features to be useful; 3, do not know; 4, adequate realism but could be improved; and 5, highly realistic, no changes needed. The ability to perform tasks was scaled as follows: 1, too difficult to perform; 2, very difficult to perform; 3, difficult to perform; 4, somewhat easy to perform; and 5, very easy to perform. The “value,” “relevance to practice,” and “global assessment” were scaled as follows: 1, no value, 2; little value, 3; do not know, 4; some relevance; and 5, great deal of relevance.
Four board-certified plastic surgeons evaluated the MPT on different aspects. The domains that scored the highest were the value of the MPT as a training tool with a mean value of 4.5 (range, 4–5), the relevance to practice breast augmentation with a score of 4.3 (range, 4–5), and the physical attributes with a score of 4.1 (range, 3.8–4.5). The other domains scored 3.9 (range, 3.5–4.3) for realism of experience, 3.8 (range, 3.5–4) for ability to perform tasks, and 3.7 (range, 3–4.3) for realism of material (Table 1). In descending order, the items that scored greater than 4.0 were the “physical attributes—chest circumference” and “physical attributes—intercostal space” with 4.5 each, “physical attributes—chest depth” and “realism of—establishment of implant pouch” with a score of 4.3 each, and finally, “ability to perform tasks—skin suturing” with a score of 4.0.
The observed average of the global assessment scored 4.3 (range, 4–5) of a maximum of 5, which falls between the 2 scaling criteria of “having some relevance” (score, 4) and having “a great deal of relevance” (score, 5) as a task trainer. This indicates that the current task trainer could be considered a useful tool for teaching purposes, taking into account some improvements to be made.
Evaluators commented on different aspects of the MPT that were not covered by the evaluation survey. Some of the skin characteristics were highly scored such as the ability of a puncture site created by a needle to self-seal after suturing; the good shearing property, allowing it to resist tearing forces; and its elastic property that enables it to elongate without breaking (eg, upon retraction and/or implant insertion). Another feature that was highly valued was the haptic feedback an operator gets on implant insertion, which was similar to performing the surgery in the clinical setting.
In contrast, evaluators believed that other features could be improved. One of which is the material used to simulate the subcutaneous tissue, where evaluators recommended replacing it with a material that better mimicked the breast parenchyma texture and that could resist tearing f upon suturing. Another modification recommended by the evaluators was to represent bilateral breasts on the MPT to allow comparison of symmetry and size after performing the procedure bilaterally.
The cost to assemble 1 MPT was approximated to Can $113. Broken down by individual parts, the skin was Can $20, the subcutaneous and breast tissue were Can $25, ribs were Can $5, the silicone base was approximately Can $30, and the materials used for casting were estimated to be Can $33. These numbers were estimated based on the prices of commercially available materials and the percentage of materials used from each product.
To the best of our knowledge, the model presented here is the first part-task trainer that is designed to simulate breast augmentation for the learner. Although in its preliminary stages, our study demonstrated that it would allow the trainee to simulate tissue dissection and pocket formation in the subglandular area, followed by implant insertion and tissue closure.
This early prototype part-task trainer achieved good overall evaluations by experts; in that respect, it is similar to other novel simulators, such as a recently presented simulator for thoracoscopic diaphragmatic hernia repair.21 Evaluators favored the utility of the MPT as a training tool for novices based on its ability to practice the essential steps of an augmentation mammoplasty. The physical attributes that received the highest scores were chest circumference and intercostal space, given that the thorax was created according to specific measurements of an average height and weight female. The evaluators also felt that the current MPT performed well in replicating the technique needed for implant insertion and that it generated a similar experience in terms of difficulty level and haptic feedback.
In contrast, the weakest aspect of the MPT was the realism of materials used to represent the different structures included, especially the skin and the subcutaneous tissue. This could mainly be explained by the fact that our main focus was on the ability to perform the initial steps of a mammoplasty procedure and to regenerate the overall haptic feedback from implant insertion and pocket creation rather than the realism of the individual structures that constitute the MPT.
Improvements and Limitations
At this level, the authors believe that the MPT represents a valuable early tool to practice a mammoplasty procedure, although many modifications should be made to deliver a higher level of realism. As a first improvement, it would be essential to represent bilateral breasts on the MPT, allowing to practice bilaterally and enabling the assessment of symmetry at the end of the procedure. Another essential modification will be the incorporation of a pectoralis major muscle that can be elevated to simulate a subpectoral pocket. Other modifications, such as the addition of a complete rib cage with intercostal muscles, will allow for better training in areas of potential surgical dissection errors such as improper identification of the subpectoral plane and inadvertent pneumothorax. Perforating vessels are essential structures to be represented during a mammoplasty procedure but are difficult to simulate in a part-task trainer and will eliminate the option of reusability. The final simulator system will function as a hybrid virtual-reality environment consisting of a physical simulator, which will deliver haptic feedback to the operator and a virtual-reality environment. It will simulate the occurrence of potential pitfalls such as the aforementioned perforating blood vessels and/or significant bleeding, anatomic variants, or muscle plane issues.
Despite the need for improvement, the authors foresee that junior-level residents could use such a simulator until basic technical competence is demonstrated (based on predetermined skills or steps that have been identified to require assessment) allowing subsequent participation in the clinical setting. In addition to its use for residents in training, such MPT could also be used by experienced surgeons to explore new technologies or instruments such as a Keller Funnel (Keller Medical, Inc, Stuart, FL) before using them on their own patients in the clinical setting.
Although this MPT represents an important initial step in the development of essential surgical simulators for plastic surgery trainees, a number of aspects still require further investigation. With this pilot study, the investigators only evaluated the value of the MPT as a training tool and the realism of the materials and experience. Further studies are needed to explore evidence relevant to its effect on novices training through clinical testing, where a comparison of performance could be conducted between MPT-trained and non–MPT-trained residents while performing in the operating room on real patients.
In summary, the authors present a novel prototype surgical simulator for augmentation mammoplasty, the first of its type. Preliminary testing by expert plastic surgeons demonstrated excellent potential for its use as a training tool for residents. The current MPT will continue to be developed into a more sophisticated hybrid platform combining virtual imaging and realistic haptic feedback to meet the needs of an evolving competency-based curriculum for plastic surgery training.
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