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An Innovative Model for Microsurgical Training at a Spine Surgery Center in Mexico City

International Microsurgery Journal. 2022;6(1):2
DOI: 10.24983/scitemed.imj.2022.00161
Article Type: Original Article

Abstract

Objective: Microsurgery is an advanced surgical procedure which requires advanced skills and techniques. These skills and techniques can generally be learned, practiced, replicated, improved, and evaluated. The majority of models and training pads in microsurgery have been reported to be used in fields other than spine surgery. This study was designed to develop and evaluate a portable, reusable and economical microsurgery training model that can be used by spinal surgery trainees in order to learn basic skills and gain self-confidence within microsurgery.
Methods: We developed a simulation training program that was implemented at a spine surgery center in Mexico City. The study involved six residents from the center who volunteered to participate in a 5-day assessment before and after the implementation of our model. The students were instructed in a simulation of laminectomy and repair of the dura mater during their training. A 5-point Likert scale was used to determine the level of confidence of surgical trainees in performing laminectomy and dural repair using microsurgical technique (where 1 represents no confidence and 5 represents excellent confidence). Five experienced spinal surgeons evaluated trainees blindly using the Stanford Microsurgery and Resident Training (SMaRT) scale. There are nine categories in the SMaRT scale, each of which is graded on a 5-point Likert scale. Results from quantitative and categorical data were analyzed using Student's t-tests and two-sample tests of proportions.
Results: The residents evaluated were aged 31 ± 1.4 years. None of them had previously undergone microsurgery. Training took an average of 4.75 hours. All participants were unable to complete the exercise before the training model, but all completed it afterward, with a mean time of 22.3 minutes. The median self-confidence score of surgical trainees increased from 1.5 to 3.5 after the exercise (P = 0.026). After the dural repair exercise, the participants completed an average of 5 ± 0 stitches, which was significantly higher than their initial average of 0.5 ± 0.8 stitches (P <0.001). The SMaRT score increased from 13.7 to 28.3 after training (P = 0.0001).
Conclusion: Training with simulated models can standardize skills and increase confidence. With the training model proposed in the study, participants are able to develop the skills necessary to perform spine microsurgery. A further study is needed to establish the validity of our training model for spine microsurgery.

Keywords

  • Artificial; microsurgery; model; simulation training; spine, surgery

Introduction

Microsurgery has become a significant component of several surgical specialties [1]. As a complex surgical procedure, microsurgery requires highly advanced skills that can be taught, reproduced, improved, and assessed [2,3]. A traditional approach to microsurgery training is based on the Halsted model, which emphasizes the need for residents to repeatedly undergo surgery under the supervision of experienced surgeons to become proficient in performing operations [1,4]. However, the ethical concern for patient safety along with the reduction in surgical procedures resulting from the COVID-19 pandemic results in an insufficient number of trainees being exposed to surgical procedures. The training and attainment of skills in both basic and advanced surgical techniques are therefore highly limited [5-8].

The need for microsurgical skill development, teaching, and maintenance has compelled surgical training centers to implement innovative training strategies that provide a secure, controlled, and effective learning environment. A wide variety of training models have been developed, but most of them have examined areas other than spine surgery, for example, gauze exercises to improve revascularization techniques, mannequin heads with small balloons to improve deep microsurgical skills in neurosurgery, silastic tubes and chicken wings arteries for performing anastomosis, and the chicken egg and skull model to support endoscopy using the endonasal transsphenoidal approach [9-11].

Therefore, the authors developed a simulation training model in which spinal surgical trainees can acquire and enhance basic microsurgery skills during the training process, as well as enhance their self-confidence as they take part in the training process. This study aims to evaluate the effectiveness of this model for training in spinal microsurgery.

Methods

During the study, we evaluated residents from a spine surgery center in Mexico City. In the exercise, the participant was required to complete a laminectomy with a high-speed burr and repair the dura with five 10-0 nylon stitches within a time limit of 30 minutes. A performance evaluation of the participant was conducted prior to and five days after the exercise.

We used a 5-point Likert scale to assess the level of confidence among surgical trainees regarding performing laminectomy and dural repair using microsurgical technique (with 1 being no confidence and 5 being an excellent level of confidence). The study defined previous surgical experience as performing at least five microsurgical procedures as the primary surgeon (i.e., performing more than 80% of all procedures) [12].

The video recordings of the exercises were taken and examined by five experienced spine surgeons who are professors at the Spine Surgery Course and members of the Mexican Association of Spine Surgeons. The Stanford Microsurgery and Resident Training (SMaRT) rating scale was used to evaluate the performance of the participants in this study [13]. Based on the SMaRT scale, nine categories were evaluated on a Likert scale of 1 to 5. These categories include instrument handling, respect for tissue, efficiency, suture handling, suturing technique, quality of knot, final product, operation flow and overall performance. We blinded the evaluators by concealing information about both the participants and the timing of the study (before or after the training).

Step-by-step Instructions for Each Exercise
There were five basic exercises and a final exercise performed on a 30 x 30 x 7 cm foam pad with a stereomicroscope (Zeigen™, Mexico City). There was a 10x magnification on the objective, and the working distance between the objective and the objective lens was 30 cm (12 inches). Figure 1 shows the microscope, the instruments, and basic exercises placed in the proper arrangement, as they should be used. The final activity served as an evaluation exercise because it allowed the skills developed in the previous exercises to be incorporated into the final one.

 

Figure 1. Arrangement of the microscope, instruments, and basic exercises. (A) Microscope and microsurgical training pad equipped with basic microsurgical instruments, including micro scissors, dissection forceps, and a microsurgical needle holder. (B) A single training pad can accommodate six different exercises, allowing trainees to practice with both hands to simulate the patient's back, and to practice fine movements only using the wrist and fingers to reduce physiological tremor.

 

Round the clock
We arranged sewing needles of normal size in a circular pattern to form a circle with a diameter of 3.4 cm. The 10-0 suture was tied at 12:00 o'clock as the starting point and passed through the sewing needle holes clockwise and counterclockwise (Figure 2A) [13].

Three towers
There was a cubic space measuring 2 x 2 x 4 cm, containing two parallel needles arranged vertically and a third needle arranged horizontally. Ten acrylic beads were placed on one of the needles. During the training, the trainees were required to move the 10 beads from one needle to another (Figure 2B).

Erasing letters
In a cardboard card printed in Arial 12 font and measuring 9 x 5 cm, the caption reads "Mexico City Spine Clinic: Microsurgical training pad". The trainee had to use a needle to erase the letters without damaging the cardboard that surrounds the letters (Figure 2C) [14].

Bubble wrap cutting and suturing
The trainee was presented with a cardboard card measuring 9 x 5 cm, enclosed with bubble wrap measuring 1 cm in diameter. The trainee was instructed to cut the bubble wrap with micro scissors and suture it with simple (interrupted), continuous, or anchored stitches (Figures 2D-E) [15].

Eggshell drilling
An eggshell was positioned in a 4 x 4 x 6 cm space. The image of a vertebra was then drawn on the eggshell. The eggshell should be drilled using a high-speed microsurgical drill (32,000 revolutions per minute) along the edges of the vertebra on the eggshell without rupturing the membrane (Figure 2F).

 

Figure 2. A step-by-step description of each exercise. (A) Round the clock. The needles are arranged in a circular pattern to create a circle with 3.4 cm (1.33 inches) diameter. In this procedure, the first suture is tied at 12:00 o'clock as the starting point, followed by the sutures passing through the sewing needle holes clockwise and counterclockwise. (B) Three towers. In a cubic space measuring 2 x 2 x 4 cm, two parallel needles are arranged vertically, and a third needle is arranged horizontally. A total of ten acrylic beads are placed on one needle. Participants in the training session are required to move ten beads from one needle to another. (C) Erasing the letters. The card measures 9 x 5 cm and has a caption in Arial 12 that reads "Mexico City Spine Clinic: Microsurgical training pad". In this exercise, the trainee is required to erase the letters using a needle without damaging the cardboard that surrounds them. (D) Bubble wrap cutting. Each trainee receives a cardboard card measuring 9 x 5 cm, enclosed in bubble wrap measuring 1 cm in diameter. The trainee is required to cut the bubble wrap using micro scissors. (E) Bubble wrap suturing. The trainee is then instructed to suture the bubble wrap either with simple (interrupted), continuous, or anchored stitches after cutting it. (F) Eggshell drilling. During the process, a shelled egg is placed in a space that measures 4 x 4 x 6 cm. An image of a vertebra is then drawn on the eggshell. Using a high-speed microsurgical drill (32,000 revolutions per minute), the edge of the vertebra on the eggshell is drilled through without causing any damage to the membrane.

 

Final activity
This step involved the simulation of laminectomy and duraplasty in order to evaluate the performance of incorporated skills which were developed in the earlier exercises. An anatomical model of vertebrae was made of polyvinyl chloride with a silicone pad in the middle. The laminectomy was simulated using a microsurgical drill, followed by simulated dura repairs completed with 10-0 nylon interrupted stitches (Figure 3).

 

Figure 3. A final activity is used to assess all the earlier skills. (A) With the assistance of a microsurgical drill, a simulated laminectomy is performed. (B) Simulation of laminectomy with silicone pad exposure. (C) Simulated dura repair with interrupted stitches.

 

Statistical Analysis 
We reported parametric quantitative variables with the means and standard deviations, and categorical variables with the frequency and percentage. Non-parametric, quantitative variables were expressed as medians and interquartile ranges. The participants were categorized based on their age, previous training experience, exercise duration, and training hours. Students' t-tests were used to analyze quantitative data, and an immediate form of the two-samples test of proportions was used to analyze categorical data. A Wilcoxon Signed Rank test was used to compare the magnitude of the quantitative variables before and after the intervention. The interobserver agreement was measured with Cohen's kappa. Statistical analyses were conducted with Stata 14 (Stata Corporation, TX 77845, USA).

Results

The average age of the six residents evaluated was 31 ± 1.4 years. None of these residents had any previous experience performing microsurgery. An average of 4.75 ± 0.9 hours was devoted to the training program by each participant.

After the training model was implemented, 100% of the participants completed the exercise within their maximum time limit of 30 minutes, compared to 0% of participants before the training model, with a mean time of 22.3 minutes.

According to the self-confidence scale used for surgical trainees, a median rating of 1.5 was reported before the exercise; however, after the exercise the median rating was 3.5 (P = 0.026).

As a result of the dural repair exercise, the participants completed an average of 5 ± 0 stitches, which is significantly higher than the average of 0.5 ± 0.8 stitches they completed before the exercise (P <0.001). According to Table 1, the SMaRT scores improved from 13.7 to 28.3 before and after the training process (P = 0.0001).

 

Discussion

Microsurgery is an extremely specialized field that requires a high level of skill and knowledge. These skills include microdissection, handling instruments and tissues, adaptation to microscopic vision, and the coordinated use of the hand and eye. A wide variety of training methods may be used in microsurgery training programs, including animals, virtual models, and artificial models [1,9]. These types of programs provide trainees with the opportunity to become familiar with basic surgical techniques in a laboratory environment before applying that knowledge to actual patients in the operating room [2].

In this study, we seek to design a training program through a simulation training model, which would enable spinal surgery trainees to acquire early experience with microsurgery as well as improve their confidence. Following completion of the training, the participants demonstrated significant improvements in the time required to complete the exercise, the number of knots successfully tied, and the items assessed on SMaRT scales, as well as the participants' perceptions of their confidence as a result of the training. In the present study, a 5-day microsurgery training program was implemented based on previous studies [2-4,9,12-15]. Nevertheless, there has not yet been a consensus regarding the ideal duration of a microsurgery course.

Due to the ethical issues associated with animal models, and the fact that virtual models are currently expensive and not widely accessible, artificial models are highly appealing since they do not have these disadvantages [1,2,10]. In one study, the use of animal models was reduced on the first day of training when an artificial model was used, while on the third day of training, the number of patent anastomoses increased [2]. In the present study, an innovative training pad was developed which has the potential of being widely available as well as affordable. In addition, a key benefit of this model is that it features a sponge surface that allows us to include six different exercises (Figure 1). It is therefore possible for trainees to place both hands on the pad to simulate a patient's back and to reproduce fine movements using only their wrists and fingers, thereby decreasing physiological tremor [16].

Handling sutures is one of the first challenges trainees encounter in microsurgery. Considering this issue, it has been recommended that the first exercises be focused on handling instruments and sutures (under control, in single passes, never grasp the needle tip, pull the needle out on a curve). Our simulation model began with a validated exercise called "round the clock", which enables trainees to become familiar with the use of micro-sutures [17]. The "three towers" exercise was specifically designed to improve movement in a restricted space with varying depths and directions [16]. In the next exercise, trainees erased letters, which was intended to teach them how to handle tissue in a careful, appropriate, and safe manner while causing the least amount of damage to it [14]. A bubble wrap suturing procedure involved cutting, dissecting, and suturing. It was initially intended to simulate arachnoids and blood vessels [10,15]. The model used egg shield drilling as a prelude to the last activity, which was simulation of laminectomy and duraplasty. Egg shield drilling was initially described as a way to simulate the delicate membrane in the transsphenoidal approach [11,16].

Study Limitations
It has been argued that trainee performance should be monitored immediately after training as well as after a certain period of time, in order to measure retention over time [12]. The main reason for this is that practice alternating with periods of rest (distributed practice) creates a constructive environment in which skills are acquired as well as retained more effectively than practice delivered continuously (massed practice). This study, however, did not examine the effects of training immediately following training, which constituted one of its limitations. A further limitation was that only a pre- and post-evaluation was conducted following the five consecutive days of practice (mass practice), thus the gradual efficacy of the training could not be measured.

Models may be validated in a variety of ways, including content validity (the ability to measure a specific skill), construct validity (the test is designed to assess the skill level for which it was designed), concurrent validity (the model produces the same results as the gold standard) and predictive validity (the model can produce the same results in the operating room) [1,9,13]. In this study, a blind evaluation was presented with both content and construct validity. However, the study was unable to assess concurrent validity because there has not been a gold standard for microsurgical practice in the field of spine surgery. There is also a need for further studies to assess the retention of acquired skills and the predictive validity of the results [1,4,9].

Conclusion

The proposed training model provides a unique opportunity for trainees to acquire and develop advanced skills related to spine microsurgery, which are required in the clinical practice of the specialty. A training program with artificial models allows for the standardization of skills and the improvement of confidence through a consistent training approach. Further research is necessary to develop new and validated training models for spine microsurgery.

References

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Editorial Information

Publication History

Received date: January 05, 2022
Accepted date: April 01, 2022
Published date: June 01, 2022

ORCID iDs

Oscar Josue Montes Aguilar (https://orcid.org/0000-0002-5500-3052).

Acknowledgments

Our team wishes to thank the residents and professors from the Dr. Manuel Dufoo Olvera Spine Clinic of the Health Department of Mexico City for their participation in the evaluation. We appreciate their generous support and participation. Their efforts were imperative to the success of this work.

Disclosure

Neither the study nor its findings have been presented at any meetings or conferences.

Ethics Approval and Consent to Participate

The study is in accordance with the ethical standards of the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Funding

This research has received no specific grant from any funding agency either in the public, commercial, or not-for-profit sectors.

Conflict of Interest

There are no conflicts of interest declared by either the authors or the contributors of this article, which is their intellectual property.

Publisher Disclaimer

It should be noted that the opinions and statements expressed in this article are those of the respective author(s) and are not to be regarded as factual statements. These opinions and statements may not represent the views of their affiliated organizations, the publishing house, the editors, or any other reviewers since these are the sole opinion and statement of the author(s). The publisher does not guarantee or endorse any of the statements that are made by the manufacturer of any product discussed in this article, or any statements that are made by the author(s) in relation to the mentioned product.

Copyright

© 2022 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY). In accordance with accepted academic practice, anyone may use, distribute, or reproduce this material, so long as the original author(s), the copyright holder(s), and the original publication of this journal are credited, and this publication is cited as the original. To the extent permitted by these terms and conditions of license, this material may not be compiled, distributed, or reproduced in any manner that is inconsistent with those terms and conditions.

Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Department of Neuroanestesiology, La Raza National Medical Center, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico
Department of Neurosurgery, La Raza National Medical Center, Mexico City, Mexico
Spine Clinic, Department of Health, Dr. Manuel Dufoo Olvera, Mexico City, Mexico

Address: Mexico City Spine Clinic, Calz. San Juan de Aragón 285, Granjas Modernas, Gustavo A. Madero, 07460 Mexico City
Table 1.jpgA Comparison of SMaRT Scores Before and After Training

Figure 1.JPG
Figure 1. Arrangement of the microscope, instruments, and basic exercises. (A) Microscope and microsurgical training pad equipped with basic microsurgical instruments, including micro scissors, dissection forceps, and a microsurgical needle holder. (B) A single training pad can accommodate six different exercises, allowing trainees to practice with both hands to simulate the patient's back, and to practice fine movements only using the wrist and fingers to reduce physiological tremor.
Figure 2.JPG
Figure 2. A step-by-step description of each exercise. (A) Round the clock. The needles are arranged in a circular pattern to create a circle with 3.4 cm (1.33 inches) diameter. In this procedure, the first suture is tied at 12:00 o'clock as the starting point, followed by the sutures passing through the sewing needle holes clockwise and counterclockwise. (B) Three towers. In a cubic space measuring 2 x 2 x 4 cm, two parallel needles are arranged vertically, and a third needle is arranged horizontally. A total of ten acrylic beads are placed on one needle. Participants in the training session are required to move ten beads from one needle to another. (C) Erasing the letters. The card measures 9 x 5 cm and has a caption in Arial 12 that reads "Mexico City Spine Clinic: Microsurgical training pad". In this exercise, the trainee is required to erase the letters using a needle without damaging the cardboard that surrounds them. (D) Bubble wrap cutting. Each trainee receives a cardboard card measuring 9 x 5 cm, enclosed in bubble wrap measuring 1 cm in diameter. The trainee is required to cut the bubble wrap using micro scissors. (E) Bubble wrap suturing. The trainee is then instructed to suture the bubble wrap either with simple (interrupted), continuous, or anchored stitches after cutting it. (F) Eggshell drilling. During the process, a shelled egg is placed in a space that measures 4 x 4 x 6 cm. An image of a vertebra is then drawn on the eggshell. Using a high-speed microsurgical drill (32,000 revolutions per minute), the edge of the vertebra on the eggshell is drilled through without causing any damage to the membrane.
Figure 3.JPG
Figure 3. A final activity is used to assess all the earlier skills. (A) With the assistance of a microsurgical drill, a simulated laminectomy is performed. (B) Simulation of laminectomy with silicone pad exposure. (C) Simulated dura repair with interrupted stitches.

Reviewer 1 Comments

  1. The authors developed an inexpensive method to assist spinal surgery trainees in gaining and developing microsurgery skills in an inexpensive and portable manner, so that they can improve their self-confidence and learn microsurgery skills. A simulation training model was evaluated for its effectiveness on the performance of six residents at a spine surgery center who were assessed before and after the training program. After the training model was introduced, all the participants were able to complete the exercise in less than 22 minutes, while none of the participants could complete the exercise in less than 30 minutes before the training model. Researchers conducted an innovative study, and the teaching model was designed to provide junior surgeons with a unique opportunity to learn and master advanced skills that are crucial for spine microsurgery. This article may be of interest to the readers of this journal. There are, however, a few concerns that must be addressed before it can be considered for publication. First, the eggshell drilling step was described by the authors as follows: "an eggshell is placed on a 4x4x6 cm space, a vertebra is drawn on the egg shield. Using a high-speed microsurgical drill (32,000 rpm), the eggshell should be drilled lining the borders of the vertebra, without membranous rupture of the eggshell." Does the author mean to say, “The eggshell should be drilled along the borders of the vertebra figure on the eggshell without rupturing the membrane of the eggshell”? To clarify this point, I would like to suggest rephrasing the sentence.
    ResponseWe would like to thank you for taking the time to review our manuscript. Our team found that every one of your comments was extremely helpful and we have made all changes suggested by you in accordance with your kind comments. As for the first issue. the sentences has been rephrased in the following manner: Using a high-speed microsurgical drill (32,000 rpm), the eggshell should be drilled along the borders of the vertebra figure on the eggshell without rupturing the membrane of the eggshell (Page 6, paragraph 2).
     
  2. The authors mention in the Discussion that “Some other advantages of our model include the incorporation of six different exercises in one training pad. This allows the trainee to recruit the minimum number of motor units (according to microsurgery principles, each contracted muscle fiber contributes to the sum of physiological tremor), and place both hands in the table simulating the patient’s back using only movements of the wrists and fingers.” There is a lack of readability in these sentences, and they should be rephrased.
    ResponseWe have rephrased the sentences in the following way in order to clarify it: Some other advantages of our model include the incorporation of six different exercises on a sponge surface. This allows the trainee to place both hands in the training pad, simulating the patients back and recreating the fine movements using only the wrist and fingers which reduced the physiological tremor (page 9, paragraph 2).
     
  3. As stated in the Discussion, "some pitfalls in the present study include the evaluation of the effect immediately after training. Some authors proposed a delay between learning skills at the laboratory and their use in the operating room, these authors also proposed that residents retain and transfer skills better if taught in a distributed manner.” There is an ambiguity in these sentences, which needs to be clarified. In addition, what do the authors mean when they refer to a "distributed manner"?
    ResponsePlease find below rephrased version of the sentence in order to make it more clear: Some limitations in the present study include the evaluation of the effect immediately after training. Some authors proposed that performance should be measured immediately after training and after a time delay, to evaluate how much is retained. This author proposes that practice interspersed with periods of rest (distributed practice), leads to better acquisition and retention of skills compared with practice delivered in continuous blocks (massed practice). Also, since there were five continuous days of practice (massed practice), only pre and post evaluation were carried out, so the gradual effect of training could not be assessed (page 9, paragraph 3).
     
  4. As the authors state, the gradual nature of the effect cannot be assessed since only pre and post measurements were made. This study, however, only analyzes pre- and post-training measures in a comparable fashion. I am not sure exactly what the authors are trying to convey.
    ResponseThere is no doubt that this limitation is acknowledged, so it has been decided to address it in the Discussion section (page 9, paragraph 3).
     
  5. In the Discussion, the authors should clearly describe the limitations that have been identified during their research.
    ResponseWe discussed some limitations in the discussion in the sixth paragraph and at the end of the last paragraph.

Reviewer 2 Comments

  1. In this study, the authors designed for spine surgery trainees to gain and develop basic microsurgery skills in an inexpensive and portable manner, so that they can improve their self-confidence and gain skills in microsurgery. Researchers studied the effectiveness of a simulation training model on the performance of six residents at a spine surgery center who were assessed before and five days after the training program had started. During the training model, the laminectomy and repair of the dura were simulated. Stanford microsurgery and residency training scale (SMaRT) was used to evaluate the trainees blindly by five experienced spinal surgeons. According to the study, none of the participants before the training model were able to complete the exercise in less than 30 minutes, but after the training model, 100% were able to complete the exercise in less than 22 minutes. There was also a significant rise in the SMaRT score from 13.7 to 28.3. The study was innovative, and the teaching model offers a unique opportunity for junior surgeons to learn and master advanced skills that are critical for spine microsurgery. Nevertheless, there are some major issues to be resolved before publication can be considered. First of all, this study investigated self-confidence among surgical trainees by using a self-confidence scale. The authors need to clarify what trainees in the study expressed confidence in. For instance, trainees expressed confidence in their ability to complete all the steps in the study.
    ResponseOur team wishes to thank you for your review of our manuscript. All of the comments that we have received from you have been helpful, and we have implemented the necessary changes based on the suggestions you have made. As for the first issue, we have addressed it. The following sentences have been reformulated in order to clarify and make them easier to understand: A self-confidence scale for surgical trainees was used to rate their level of confidence in performing the laminectomy and dural repair with microsurgical technique (1= no confident, 5= very confident)(page 4, paragraph 1).
     
  2. Based on the data shown in Table 1, it appears that the statistical analysis is not reasonable. The authors are requested to describe the statistical test that was used to analyze the difference in the distribution of confidence scores before and after training.
    ResponseWe realized that the table was confusing, therefore we decided to replace it with these words in order to provide a clearer explanation: a median of 1.5 (1-2) compared to 3.5 (3-4) after the exercise were reported (P = 0.026). We assessed before and exercise self-confidence scores with the Wilcoxon Signed Rank test (page 8, paragraph 1).
     
  3. The studies found that participants completed on average 0.5 knots before training, as compared to a mean of 5 knots after training. Can you clarify the meaning of "completing knots"? Is this step part of the round-the-clock procedure as well?
    ResponseDue to the confusion arising from this point, we have clarified it as follows: Before the training, participants completed a mean of 0.5 (± 0.8) stitches in the dural repair exercises, compared to 5 stitches (±0) after training (P <0.001)(page 8, paragraph 1).
     
  4. The previous experience was defined as more than five surgeries performed as a leading surgeon. Why was the number of cases defined as five by the authors? Are there any references to support the definition?
    ResponseBased on Moulton et al.'s definition, previous experience was defined as performing more than five microsurgical cases in the role of a primary surgeon (i.e., > 80% of the procedures) (page 4, paragraph 1).

Reviewer 3 Comments

  1. The authors designed an inexpensive method to boost spinal surgery trainees' self-confidence and help them master microsurgery skills in a portable manner. Six residents at a spine surgery center were evaluated before and after simulation training for its effectiveness. Participants who used the training model were able to complete the exercise in less than 22 minutes, while none of them could finish the exercise in less than 30 minutes before. Using an innovative teaching model, researchers gave junior surgeons a chance to learn and master advanced skills that are essential for spine microsurgery. Readers of this journal may find this article valuable. However, some points must be addressed before the paper can be published. In the first place, due to the limited number of cases, Fisher's exact tests should be used to determine the difference between the distribution of confidence scores before and after training, as shown in Table 1. Therefore, there should be only one P value, rather than four P values.
    ResponseYour review of our manuscript has been greatly appreciated by our team. You have provided us with excellent comments, and we have implemented the changes necessary based on your suggestions. In regards to the first issue, we have resolved it. In order to clarify the information in table 1, we have changed it to the following text: a median of 1.5 (IQR 1), compared to 3.5 (IQR 1) after the exercise were reported (P = 0.026). We assessed before and exercise self-confidence scores with the Wilcoxon Signed Rank test (page 8, paragraph 1).
     
  2. Are there any training models available for spine surgery that have already been developed?
    ResponseDuring our search, we did not find any published papers that described other training models specifically geared toward spine surgery.
     
  3. It is crucial to explain in the Method section precisely what an experienced spine surgeon is, and what his or her qualifications are.
    ResponseThe sentences have been changed in the following way: The exercises were video-recorded and evaluated by five experienced spine surgeons who are professors of the Spine Surgery Course and are members of the Mexican Association of Spine Surgeons (page 4, paragraph 2).
     
  4. Each of the steps will have a task that needs to be completed, such as tying knots in the round-the-clock step, and rearranging the beads in the three towers step. Nevertheless, the tasks used to analyze each participant's performance only consist of completing the knots. As part of the performance evaluation, why didn't the authors include the other tasks?
    ResponseIn order to clarify this issue, we have added the following text: The final activity was used as an evaluation, since it allows integrating the skills developed by the other exercises (page 4, paragraph 3).
     
  5. In the study, how was the Shapiro-Wilk test used to test the degree of normality among variables by examining measures such as skewness and kurtosis? Due to the small number of six cases involved in this study, it is questionable whether the test should be applied. Clarification of this point is necessary.
    ResponseTo avoid any confusion caused by this, we have decided to remove it from the methods.

Reviewer 4 Comments

  1. I carefully read the manuscript with much interest. It is an investigation of a training model for basic skills in spine microsurgery. It is a successful study from the standpoint of research, as reflected in the following characteristics. In the first place, this study offers a novel, inexpensive, and easy-to-develop experimental training model. Blinded assessments have been conducted with the objective of ensuring objectivity. I believe that the study has practical value in meeting the training needs of spinal microsurgeons, especially in the context of the COVID-19 pandemic. As such, the study will be able to contribute to the existing literature. However, to ensure a better readability of the manuscript, it must be proofread by an English native speaker to correct a few typographical errors and improve readability.
    ResponseI would like to thank you for taking the time to review our manuscript. In order to improve readability and to correct a few typographical errors, the article has been proofread by an English native speaker.

Editorial Comments

  1. For the authors' description of the Round-the-clock step, they stated that they should "make a surgical knot and pass a 10-O needle through the eyes of 12 needles placed in a circle of 3.4 cm (1.33 inches), clockwise and counterclockwise." There is an ambiguity in this sentence, and it should be rephrased. In addition, the phrase "12 sewing needles required" should be clarified.
    ResponseThe sentences regarding round-the-clock have been revised to read as follows: Ordinary sewing needles placed in clock-pattern in a circle of 3.4 cm. A 10/0 suture was tied at 12 o'clock as the starting point and passed through the eyes of the sewing needles, clockwise and counterclockwise (Figure 3)(page 5, paragraph 2).
     
  2. In the Bubble wrap suturing step, a 9x5cm cardboard card with a "1 cm depth" bubble wrap. To be accurate, the authors should ensure that the bubble wrap measures one centimeter in "diameter" rather than one centimeter in "depth".
    ResponseOur corrections have been made as follows: A 9x5cm cardboard card with a 1 cm diameter bubble wrap (page 6, paragraph 1).
     
  3. There is no need to include a Discussion section in an Abstract.
    ResponseThe Abstract has been updated to remove this section.
     
  4. A description of the Stanford Microsurgery and Resident Training Scale should be included, as well as a citation to the associated reference.
    ResponseThere is a citation to be made to the associated reference, once we add the following sentences: The SMaRT scale consists of 9 categories graded on a 5-point Likert scale, it evaluates: instrument handling, respect for tissue, efficiency, suture handling, suturing technique, quality of knot, final product, operation flow and overall performance. Evaluators were blinded to participants and timing (before or after training)(page 4, paragraph 2).
     
  5. The authors only present the mean time of 22.3 minutes needed for the completion of each exercise after training. It would be appropriate for the authors to provide information on the average time taken by trainees to complete the exercises before training.
    ResponseAfter the training model was implemented, 100% of the participants completed the exercise within their maximum time limit of 30 minutes, compared to 0% of participants before the training model, with a mean time of 22.3 minutes.
     
  6. The authors state in the Introduction of the study that multiple training models have been developed, but that most of them are aimed at areas other than spine surgery. The authors should cite references to support this point.
    ResponseIn support of this point, we included the following section and cited references: Multiple training models have been developed, but most models are focused on areas different from spine surgery, like the gauze exercise design for revascularization techniques, the mannequin head with small balloons to improve deep microsurgical skills in neurosurgery, silastic tubes and chicken wing arteries to perform anastomosis, chicken egg and skull model for endoscopic endonasal transsphenoidal approach; for example (page 3, paragraph 1).

Montes Aguilar OJ, Alaniz Sida KK, Dufoo Olvera M, Collado Arce MGL, Ladewig Bernaldez GI, Oropeza Oropeza E, Gómez Flores G, Pérez Rios JJ, Zambrano AM, Ambrosio Vicente MDJ, Silva Chavez R, Ochoa González MV. An innovative model for microsurgical training at a spine surgery center in Mexico City. Int Microsurg J. 2022;6(1):2. https://doi.org/10.24983/scitemed.imj.2022.00161