Bilateral Cleft lip Simulation

Abstract

Objective

To evaluate the features, anatomic accuracy, and educational value of a high-fidelity bilateral cleft lip simulator.

Design

Evaluation of the simulator by expert cleft surgeons after performing a simulated bilateral cleft lip repair.

Setting

The simulator was evaluated by the surgeons during the Latin American Craniofacial Association meeting.

Participants

Eleven experienced cleft surgeons evaluated the simulator. The cleft surgeons were selected based on their availability during the meeting.

Interventions

The participants performed a simulated bilateral cleft lip repair. They were each provided with a questionnaire assessing the simulator's features, realism and value as a training tool.

Main Outcome Measure (s)

The main outcome measure are the scores obtained from a Likert-type questionnaire assessing the simulators features, realism and value.

Results

Overall, the surgeons agreed with the simulator's realism and anatomic accuracy (average score of 3.7 out of 5). Overall, the surgeons strongly agreed with the value of the simulator as a training tool (average score of 4.6 out of 5).

Conclusions

A high-fidelity bilateral cleft lip simulator was developed that is realistic and valuable as a training tool. The simulator provides a comprehensive training platform to gain hands-on experience in bilateral cleft lip repair before operating on real patients.

Introduction

Cleft lip surgery is technically challenging to perform requiring an understanding of three-dimensional (3D) morphology, dissection of multiple tissue planes, the interaction of different tissue types, and proficiency in techniques that requires precision to obtain an optimal result. ¹ Bilateral cleft lip repair is particularly challenging ² requiring an understanding of morphological characteristics that differ from unilateral cleft lip repair. ³ This includes varying protrusion of the premaxilla and therefore prolabium (especially for cases without naso-alveolar molding) that increases tension on the repair. There is absent muscle within the prolabium and a deficient upper labial sulcus in the midline. The cutaneous roll and vermillion of the prolabium are of inadequate quality and dimensions and there is absence of a cupids bow that needs to be created. ⁴ In addition, case volumes for bilateral cleft lip are lower^5,6 than unilateral repairs reducing operating experience, which prolongs the learning curve to become competent and proficient in bilateral cleft lip repair techniques.

Surgical simulation is becoming increasingly utilized to augment real operating experience.^7,8 A bilateral cleft lip simulator would provide a platform to practice the procedure, understand it's specificities and gain experience before operating on patients. Simulation in cleft lip and palate surgery has significantly advanced in recent years with several physical and virtual simulators available.^9–19 However, previously described bilateral cleft lip physical models^20,21 were developed only as teaching aids, are of low fidelity and were never intended for use as surgical simulators. Thus, there is a need to develop and evaluate a high fidelity bilateral cleft lip simulator for surgical training.

The following study presents a novel, high-fidelity bilateral cleft lip simulator. The simulator was evaluated by a group of experienced surgeons to determine its ability to emulate a bilateral cleft lip repair, its anatomical accuracy and realism as well as its value as a training tool.

Methods

Simulator Development

Ethics approval was obtained from the institution research ethics board. A physical bilateral cleft lip simulator was developed using 3D printing, polymer, and adhesive techniques. A computer model of a bilateral cleft lip was developed using 3D animation software Zbrush (Maxon, Germany). The morphological characteristics of the model were developed in consultation with expert cleft surgeons (authors RAH, DMF, KWW, DJP, RT) and required multiple iterations. The anterior projection (posterior palatal width to premaxilla distance) of the premaxilla of the simulator is 32 mm. El-Kassaby et. al demonstrated an average pre-orthopedic and post-orthopedic molded premaxillary projection of 35.8 ± 3.6 mm and 33.1 ± 3.1 mm, respectively. ²² Thus, the simulators premaxillary projection is within the average projection of pre-operative pre and post orthopedic molding. The bony components of the simulator (premaxilla, vomer, maxilla) were printed using an Ultimaker (Utrecht, Netherlands) fused deposition modelling 3D printer. The synthetic soft tissue was casted using platinum cured silicone (Smooth-On, Pennsylvania, United States). The components were assembled using adhesive and release agents to simulate dissection planes. The simulator also includes a bilateral cleft palate similar to the Simulare Medical (Smile Train, New York, United States) palate simulator ¹⁰ with the addition of bilateral clefts of the primary palate. The simulator presented here is produced by the Simulare Medical division of Smile Train (New York, United States). The simulator comprises a one-time use cartridge that inserts into a reusable base and stand to adjust the flexion/extension of the model (Figure 1). The features of the simulator are described in Supplemental, Table 1.

Figure 1.

Overall design of the bilateral cleft lip simulator demonstrating the cartridge that fits into the base. A platform allows for adjustment of the flexion and extension angle of the simulator.

Simulated Bilateral Cleft lip Repair Technique

The simulator allows performance of an end-to-end bilateral cleft lip repair using real surgical instruments. A modified Mulliken lip repair described by Fisher ⁴ was performed on the simulator to demonstrate its features. A full description of this repair has previously been described. ⁴ Highlights of the technique are described here to illustrate the features of the simulator. It is important to note that any bilateral cleft lip repair technique can be performed on the simulator.

Skin markings on the lateral lip elements and prolabium are first performed (see Video accompanying Figure 2 highlighting the performance of bilateral cleft lip markings). The skin is incised on the markings on the prolabium using a scalpel down to subcutaneous tissue. De-epithelialization can be performed lateral to the prolabium markings if necessary to widen the base of the prolabium. A mucosal flap is dissected from the subcutaneous tissue of the prolabium first using a scalpel followed by dissection scissors (see video accompanying Supplemental Figure 1 demonstrating dissection of the prolabium to create a mucosal flap). The subcutaneous tissue of the prolabium can be debulked to aid with closure. The lateral lip incisions are performed followed by removal of marginal tissue. The orbicularis oris muscle is released from its abnormal insertion at the base of the nose and is released from the skin and mucosa using dissection scissors (see video accompanying Supplemental Figure 2 demonstrating lateral lip element incisions and dissection of the orbicularis oris muscle). Bilateral upper buccal sulcus incisions are performed along the lateral lip elements through the mucosa using a scalpel. A primary rhinoplasty is performed by releasing the lower lateral-accessory cartilage complex from the piriform rim using dissection scissors to anteriorly reposition the alar base. The normal scroll area is recreated by performing a horizontal mattress suture between the upper and lower lateral cartilages bilaterally. Nasal floor closure was performed as described by Tse et al.. ²³ Lateral nasal wall flaps are created using an elevator by releasing the mucosa from the lateral nasal wall. The base of the flap at the level of the hard palate is incised posteriorly using scissors. A back cut is made using scissors posteriorly towards the inferior turbinate to advance the lateral nasal wall flap anteriorly. The mucoperichondrium of the caudal septum is incised where the septum meets the maxillary crest and elevated two mm cephalad from the cartilaginous septum using an elevator. The lateral nasal wall flap and septal mucoperichondrial flap are sutured together to close the nasal floor. The mucosal flap from the prolabium is used to create the posterior wall of the upper labial sulcus by suturing the distal end to the premaxilla (see video accompanying Supplemental Figure 3 demonstrating creation of the posterior wall of the upper labial sulcus). Closure begins by performing a three-point suture to create the anterior wall of the upper labial sulcus by bringing the mucosa of the lateral lip elements to the midline sutured to deep tissue over the premaxilla superiorly. The mucosa of the lateral lip elements are then sutured together followed by the muscle (see video accompanying Figure 3 demonstrating nasal floor closure and suturing the muscle together). The vermillion is reapproximated and the skin of the lateral lip elements are sutured to the skin of the prolabium completing the repair (see video accompanying Figure 4 demonstrating skin and vermillion closure). Supplemental, Table 2 summarizes the procedural steps that can be performed on the simulator.

Figure 2.

Performance of bilateral cleft lip markings.

Figure 3.

Nasal floor closure and suturing the muscle together.

Figure 4.

Skin and vermillion closure.

Simulator Evaluation

The Simulator was evaluated during the LATICFA (Latin American Craniofacial Association) meeting in Cancun, Mexico. Eleven surgeons from six countries (Brazil, Chile, Colombia, Mexico, Italy, and Peru) were recruited and participated in the study. The surgeons were asked to perform a simulated bilateral cleft lip repair using their own technique (Supplemental Figure 4). They were then given a questionnaire evaluating their level of experience followed by a Likert-type questionnaire assessing the simulators anatomic accuracy, realism, and value as a training tool. None of the surgeons participating in the study were involved in the simulator's development.

Results

All participants successfully completed a bilateral cleft lip repair using the simulator. The demographics of the participants (Table 1) demonstrated a high level of experience with the majority (54.5%) having more than 20 years of experience in cleft surgery. Eighty-two percent of the participants had more than 10 years of experience and 82% had pediatric plastic surgery fellowship training.

Table 1.

Demographics of the Eleven Participants.

	0–5	5–10	10–15		15–20	>20
Number of years performing pediatric cleft surgery.	1 (9.1%)	1 (9.1%)	2 (18.2%)		1 (9.1%)	6 (54.5%)
	0–20	20–40	40–60		60–80	>80
Number of bilateral cleft lip repairs previously performed.	1 (9.1%)	1 (9.1%)	0 (0%)		2 (18.2%)	7 (63.6%)
	Yes			No
Previous pediatric plastic surgery fellowship training.	9 (81.8%)			2 (18.2%)

Overall, the participants agreed with the simulator's realism and anatomic accuracy with an average score amongst all items assessed of 3.7 out of 5 (Table 2). The position and orientation of the prolabium was rated highest at 4.1 out of 5. Suturing of the mucosa was rated lowest at 3.0 out of 5 (neutral response). The participants strongly agreed with the simulator's value as a training tool with an average score of 4.6 out of 5 (Table 2).

Table 2.

Questionnaire Responses Amongst the Eleven Expert Surgeons Evaluating the Simulators Anatomical Accuracy and Value as a Training Tool.

	5-Strongly agree	4-Agree	3-Neutral	2-Disagree	1-Strongly disagree	Avg.
The prolabium is realistic.	4 (36.4%)	4 (36.4%)	1 (9.1%)	2 (18.2%)	0 (0%)	3.9
The position and orientation of the prolabium is realistic.	5 (45.5%)	4 (36.4%)	2 (18.2%)	0 (0%)	0 (0%)	4.3
The tissue layers within the prolabium are realistic.	1 (9.1%)	6 (54.5%)	3 (27.3%)	1 (9.1%)	0 (0%)	3.6
The anatomy of the premaxilla is accurate.	3 (27.3%)	6 (54.5%)	1 (9.1%)	1 (9.1%)	0 (0%)	4.0
Cutting through the simulated mucosa feels realistic.	1 (9.1%)	4 (36.4%)	5 (45.5%)	1 (9.1%)	0 (0%)	3.5
The musculature appears anatomically accurate.	0 (0%)	8 (72.7%)	3 (27.3%)	0 (0%)	0 (0%)	3.7
Releasing/incising through the muscle feels realistic.	0 (0%)	9 (81.8%)	2 (18.2%)	0 (0%)	0 (0%)	3.8
The dissection plane between mucosa and muscle feels realistic.	0 (0%)	9 (81.8%)	1 (9.1%)	1 (9.1%)	0 (0%)	3.7
The dissection plane between the muscle and the skin feels realistic.	1 (9.1%)	10 (90.9%)	0 (0%)	0 (0%)	0 (0%)	4.1
Suturing the muscle together feels realistic.	1 (9.1%)	5 (45.5%)	4 (36.4%)	1 (9.1%)	0 (0%)	3.6
Suturing the mucosa together feels realistic.	0 (0%)	5 (45.5%)	2 (18.2%)	3 (27.3%)	1 (9.1%)	3.0
Suturing the skin together feels realistic.	1 (9.1%)	3 (27.3%)	6 (54.5%)	1 (9.1%)	0 (0%)	3.4
Is the overall morphology of the bilateral cleft lip simulator accurate?	2 (18.2%)	8 (72.7%)	1 (9.1%)	0 (0%)	0 (0%)	4.1
Average						3.7
	5-Strongly agree	4-Agree	3-Neutral	2-Disagree	1-Strongly disagree	Avg.
The bilateral cleft lip simulator is a valuable training tool.	7 (63.6%)	4 (36.4%)	0 (0%)	0 (0%)	0 (0%)	4.6
Use of this model will increase resident/fellow competency of performing a bilateral cleft lip repair.	7 (63.6%)	4 (36.4%)	0 (0%)	0 (0%)	0 (0%)	4.6
I would be interested in using this model to train residents/fellows.	8 (72.7%)	2 (18.2%)	1 (9.1%)	0 (0%)	0 (0%)	4.6
Average						4.6

Discussion

We present a novel high-fidelity bilateral cleft lip simulator. The simulator was successfully tested by experienced surgeons and was found to be anatomically accurate, realistic, and valuable as a training tool.

The use of surgical simulators for training is well established ²⁴ and has gained widespread adoption within the field of cleft surgery.^9,10 However, only a few low-fidelity physical bilateral cleft lip models have previously been described.^20,21 These lower fidelity 3D models incorporate multiple different materials but were developed as visual aids to help understand the cleft lip and palate condition as opposed to utilization as surgical simulators. This study presents the first bilateral cleft lip simulator that allows an end-to-end performance of a bilateral cleft lip repair allowing trainees to practice the critical steps of the procedure.

Bilateral cleft lip repair is challenging to perform^2,6,25 with unique technical nuances distinct from unilateral lip repairs. ⁴ The simulator incorporates realistic morphology including a multilayered prolabium and lateral lip elements, complete nasal anatomy including the nasal cartilages and integration within a bony soft tissue construct. The comprehensiveness of the simulator provides a valuable training experience specific to bilateral cleft lip repair techniques. This includes marking, handling, and dissection of the prolabium as well as creation of a labial sulcus over the premaxilla. Furthermore, the user can perform closure of the mucosa and muscle over the premaxilla and suturing the skin of the lateral lip elements to the prolabium.

Overall, the participants had significant experience in bilateral cleft lip repair and were suitable to provide feedback on the simulators features and value. Although the simulator was well received overall, there were features that require improvements. Suturing the mucosa (average of 3 out of 5) and skin (average of 3.4 out of 5) together scored the lowest. This is likely due to increased tension when bringing the mucosal and skin edges of the lateral lip elements over the premaxilla resulting in synthetic tissue tearing. Design improvements will utilize more elastic silicone and mesh to minimize tearing during mucosal and skin closure. Despite this feedback, only 7.7% of the responses disagreed with the simulator's realism and anatomic accuracy. Only one surgeon scored a strong disagreement (0.7% of all responses) in relation to the feel of suturing the mucosa together.

An assessment of a simulator's realism and accuracy in comparison to the actual task using expert subjective ratings is a common method of preliminary simulator evaluation.^26,27 This method of simulator evaluation is commonly known as face validity. However, the use of this term is antiquated ²⁸ and many now subscribe to the unitary framework proposed by Messick. ²⁹ Within this framework, there are five sources of evidence. This study fits within the “content” sources of evidence, which includes an assessment tool developed by experts used to measure a targeted construct. ³⁰ In this case, the Likert-type questionnaire was developed by experts in cleft lip repair and utilized by participants who are experts to measure the realism and value of the simulator. It is important to note that these assessments are still subjective and represent a preliminary evaluation of the simulator's effectiveness and value. Further evaluation of the simulator is necessary including objective measurement of technical skill, its ability to discriminate skill level, an assessment of the learning curve and ultimately its ability to improve performance and outcomes when operating on real patients.

Conclusions

Despite the preliminary nature of this evaluation, the bilateral cleft lip simulator presented in this study is the most advanced, realistic, and comprehensive simulator available for this procedure. The simulator provides a valuable training platform for practicing bilateral cleft lip repair in a highly realistic environment.

Financial Disclosure

Simulare Medical is a division of Smile Train, a not-for-profit entity that disseminates and distributes cleft surgical simulators that includes the bilateral cleft lip simulator in this study. Dr. Dale Podolsky is on the Board of Directors of Simulare Medical. Anne Arnold is the senior director of education & training at Smile Train. Smile Train generously provided the simulators utilized in this study. Dr. Raymond Tse, Dr. Richard Hopper, Dr. David Fisher, and Dr. Karen Wong Riff have no relevant financial relationships to disclose.