Abstract
This study proposes and evaluates a physical cleft lip repair simulator for trainee education.
Surgical simulators have the potential to support safe, standardized, competency-based surgical education. For training in cleft lip repair, adult cadaveric simulators lack accurate representation of this predominately pediatric procedure. Cleft lip repair educational devices are almost exclusively virtual reality based, using computer graphics with real-time haptic feedback.1,2 Only 1 physical model that lacks validation for surgical rehearsal exists in the literature.3 This study proposes and evaluates a cleft lip repair simulator for trainee education.
Methods
Simulator Development
A computer model of a neonatal skull and a cleft lip were obtained from the National Institutes of Health 3D Print Exchange (https://3dprint.nih.gov/) and modified using Materialise 3-Matic computer-aided design software (Materialise) (Figure, A and C). Bony and skin mold components were produced on a 3-dimensional (3-D) printer with polylactic acid (Figure, B). Dyed silicone was cured in the molds to create the soft tissue envelope (Figure, D). The assembled bony and soft tissue components constitute the final simulator prototype (Figure, E). This study was determined to be exempt by the University of Michigan Medical School Institutional Review Board.
Figure. Additive Manufacturing and Repair of the Cleft Lip Simulator.
A, Computer-aided design (CAD) rendering of skull base. B, Three-dimensional (3-D) printed polylactic acid skull base. C, CAD rendering of soft tissue envelope. D, Composite soft tissue envelope. E, Complete, assembled cleft lip simulator. F, Repaired simulator.
Study Design
From March 6 to 27, 2017, a total of 5 cleft surgeons from 3 academic institutions and several subspecialties independently repaired the simulator using their preferred technique and surgical equipment (Figure, F). They rated the simulator using a survey and provided suggestions for improvement.
Survey and Rating Procedures
The rating survey was based on a cognitive task analysis independently reviewed by 3 cleft surgeons for language clarity and the items’ alignment of critical features and tasks with learning objectives and clinical practice.4 The final 22-item survey used a 4-point rating scale (depending on the domain being assessed, 1 indicated “not at all realistic,” “no value,” “no relevance,” “very difficult to perform,” and “requires number of improvements before use in training” and 4 indicated “highly realistic with no changes needed,” “a great deal of value,” “a great deal of relevance,” “very easy to perform,” and “can be used as is with no improvements made”) to assess the simulator across 5 domains (physical attributes, realism of experience, value, relevance to practice, and ability to perform tasks) and 1 overall or global domain.
Statistical Analysis
Previously validated methods applying the Standards framework to simulator validation processes were followed for this analysis.5,6 Evidence relevant to test content was evaluated using raters’ means, with a higher mean suggesting a higher perceived value of a feature or characteristic.
Results
Faculty self-reported a mean (SD) of 6.4 (3.5) years in practice and performed between 40 and 150 cleft lip repairs (mean [SD] number of repairs, 72.0 [51.7]). The 4 fidelity domains had sufficient to excellent means (3.0-3.7), which indicates that the physical attributes and experience were adequate as is and that the simulator has a great deal of value as a training and testing tool and some relevance to the practice environment (Table). The rating mean for the ability domain was 3.4, indicating that the repair was easy to perform. The mean of global ratings was 2.4, suggesting that evaluators thought the simulation required only slight improvements before use in training. Lower means correlated with written comments for improvement. The overall manufacturing costs are low: $11.43 for the reusable molding system and $4.59 for the consumable cleft lip model.
Table. Means for Domains and Individual Items From the Cleft Lip Repair Simulator Survey.
| Domain or Characteristic | Rating, Mean (SD) (95% CI) (N = 5) |
|---|---|
| Fidelity: physical attributes (domain mean, 3.2) | |
| Anatomical landmark: vermilliocutaneous lip border | 2.6 (0.9) (2.2-3.0) |
| Anatomical landmark: dry and wet lip border | 4.0 (0.0) (4.0-4.0) |
| Anatomical landmark: alar base | 3.2 (0.8) (2.8-3.6) |
| Skin depth and density | 3.8 (0.3) (3.5-4.0) |
| Skin flexibility | 3.5 (0.6) (3.2-3.8) |
| Underlying maxillofacial landmarks | 2.8 (0.4) (2.4-3.2) |
| Underlying orbicularis oris musculature | 2.8 (0.2) (2.6-3.0) |
| Fidelity: realism of experience (domain mean, 3.1) | |
| Tatouage or skin marking | 3.0 (0.0) (3.0-3.0) |
| Incision pressure | 3.6 (0.5) (3.4-3.8) |
| Dissection of muscle layer | 2.6 (0.8) (2.2-3.0) |
| Muscle layer closure | 2.4 (0.4) (2.0-2.8) |
| Mucosa layer closure | 3.2 (0.8) (2.8-3.6) |
| Subdermal layer closure | 3.0 (1.4) (2.3-3.7) |
| Epidermal layer closure | 3.8 (0.4) (3.6-4.0) |
| Fidelity: value (domain mean, 3.7) | |
| Value of the simulator as training tool | 3.8 (0.4) (3.6-4.0) |
| Value of the simulator as testing tool | 3.6 (0.5) (3.4-3.8) |
| Fidelity: relevance to practice | 3.0 (1.2) (3.4-3.8) |
| Ability (domain mean, 3.4) | |
| Marking | 3.0 (0.3) (2.7-3.3) |
| Incisions | 3.6 (0.2) (3.4 -3.8) |
| Dissection | 3.4 (0.2) (3.2-3.6) |
| Closure | 3.4 (0.4) (3.0-4.0) |
| Global rating | 2.4 (0.5) (2.2-2.6) |
Discussion
This study suggests that this novel cleft lip repair simulator is a high-fidelity, low-cost educational tool for trainees. This model may accelerate and enhance trainees’ exposure to the execution of this advanced procedure. The use of readily available materials, compatibility with standard surgical equipment, and the reusable-replaceable modular design result in a relatively low overall cost, making it accessible to many training environments in the future. The additive manufacturing process demonstrates strong potential for rapid prototyping in patient-specific scenarios for surgical planning and for caregiver education.
Several minor modifications to the simulated muscle layer dissection and closure would enhance the model for use in a truly emulative training environment, although we aim to balance necessary features with added cost. Future studies will investigate the role of this cleft lip repair simulator as a tool for training and evaluation of resident physicians and its effect on surgical education and patient outcomes.
References
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