Sequential learning of psychomotor and visuospatial skills for laparoscopic suturing and knot tying – study protocol for a randomized controlled trial “The shoebox study”

The primary goal of this study is to identify if students in group 1, who learn the surgical C-loop technique using a transparent shoebox before using a box trainer with laparoscopic view, have a shorter learning curve than students in group 2, who learn the technique using solely a box trainer with laparoscopic view (Fig. 1). Secondary endpoints include number of attempts taken to gain proficiency, and examining procedural and knot quality subscore differences. In subgroup analyses we will separately explore possible gender differences and influence of previous video game experience on training time, number of attempts needed to reach proficiency and knot quality respectively.

This is a registered prospective, single-center, two-arm, parallel group randomized controlled trial.

The inclusion criterion mandates that participants are medical students in their clinical years (third to sixth year) at Heidelberg University. Exclusion criteria include students who have previously participated in a laparoscopic training course of more than 2 hours duration or who had training in laparoscopic surgery in the OR.

All students receive a standardized video-based introduction to the suturing and knot tying technique at the start of the study. Students may refer to this video throughout the course of their participation.

Trained student tutors provide a standardized introduction for the box trainer, shoebox, and laparoscopic instruments, as well as instructions for their use. Students can, therefore, familiarize themselves with the training modalities, workspace, and terminology prior to the induction of their training.

Participants are randomly allocated to either the sequential learning group (group 1) or control group (group 2) in a 1:1 ratio. The randomization of subjects is performed by an employee otherwise not involved in the study using sealed envelopes labeled by block. Trainees are allocated to groups without stratification by gender or gaming experience. Although this study would benefit from a 1:1 ratio of men to women, this cannot be mandated since the data is collected through participation in a university elective course which is offered on a first-come-first-serve basis. Consequentially, we cannot explore outcome differences in heterogeneous or homogeneous groups, e.g., male-female, male-male, female-female, in a standardized manner; there may be an influencing factor that stems from the communication dynamic, previous experience of a partner, etc. We aim to explore these differences by comparing outcomes between pair group subgroup analysis following data acquisition. An employee of the Department of Medical Biometry at Heidelberg University, who is otherwise not involved with the training, tests, or data collection from the present study, assigned block randomization.

The sequential learning group (group 1) learn the psychomotor aspects of laparoscopic suturing and knot tying first on the transparent shoebox without having to adjust to the visuospatial orientation inherent to the laparoscopic view of a box trainer. Once they reach the predefined proficiency criteria explained below (Tables 1, 2 and 3), these students then train on the box trainer with laparoscopic view until proficient (Fig. 2). The control group (group 2) learn the psychomotor skills and visuospatial aspects of laparoscopy simultaneously, as is traditionally done. They train using the box trainer with laparoscopic view until proficient in the predefined criteria. Specially trained peer tutors assist trainees during the course of the study and are available on demand in the training room for both groups; this has proven to be beneficial to trainee learning [19].

Following randomization, participants are put into training pairs, which is a common practice within surgical training [20, 21]. This allows the trainees to give each other real-time competency assessment and feedback, which is motivational [22, 23], in addition to saving time for the trainers, and space in the training center. We recently explored the difference between laparoscopic training alone and in pairs and found there to be no distinction in outcome between the two groups (protocol, own data, unpublished). It has been shown that students – whether alone or in a collaborative pair – can learn as much by observing their peers learn a task as they can by performing the task themselves [24, 25]. This is known as vicarious learning, which typically does not provide for communication between the student being tutored and the student watching. It should be made clear that students in our training environment can communicate directly with one another, which may prove even more useful. Based on these grounds, we believe that the pragmatic aspect of saving time and resources in a busy training center outweighs the potentially confounding effect of partner training.

The student who is watching records the time taken for each attempt of the operating partner, starting from when the needle is grasped and ending once the final knot is tied. All attempts must be completed and the time per attempt must be recorded for each trainee. In the event of technical or instrument failure, e.g., the suture thread getting stuck in the grooves of the instrument, time is stopped and recorded, and “N/A” and a brief description of what happened are written next to the attempt. Rather than mass practice, we implement the more effective interval training [26‐28]; trainees are required to switch positions at least every five completed knot attempts. Students train using two laparoscopic needle holders (KARL STORZ GmbH & Co. KG, Tuttlingen, Germany) and a standardized silicone suture pad with diagonal incisions and predefined suture entry and exit points (Fig. 3) (Big Bite Medical GmbH, Heidelberg). The suture material is a Polysorb 3-0 braided absorbable suture with a CV-23 taper ½ 17-mm needle (Covidien^TM, Minneapolis, MN, USA).

Training pairs are required to rate each other throughout the training process until they reach the predefined competency levels for knot quality, suture position, and time. Procedural competency is assessed using a previously validated modified 23-point implementation checklist [14] (Table 1), originally published by Munz et al. [29].

Knot quality is scored using a 5-point scale designed by Muresan et al. [10], which assesses a knot’s throws, tightness, edge opposition, and ability to hold under tension (Table 2). Furthermore, accuracy is recorded by measuring the distance (mm) of the stitch from the edge of the entry and exit points of the standardized suture pad. Operative time is also recorded.

A trainee demonstrates competency for the C-loop upon finishing it in ≤01:15 (min:sec), attaining ≥18 points on the procedural implementation checklist, scoring ≥4 on the knot quality scale, and maintaining stitching ≤2 mm from the edge of the suture pad’s entry and exit points (Table 3). According to the available medical literature, experienced surgeons (expert level) reach these goals for the surgical C-loop [14]. Once a student has reached competency according to his or her training partner, a specially trained peer tutor is asked to provide expert assessment. If the participant then performs a C-loop, attaining the aforementioned competency criteria under supervision of the tutor, he or she is considered proficient in the technique; thus proficiency is achieved once a trainee completes the C-loop suturing technique on two consecutive occasions with the predefined competency criteria – once for the partner and once for the peer tutor assessment.

The primary endpoint is total training time needed to reach proficiency in a predefined standardized suturing and knot tying technique.

Secondary endpoints include the number of attempts, procedure subscore differences, and knot quality subscore differences.

Tertiary endpoints involve subanalyses of gender differences and the influence of video game experience. Surgery has traditionally been a male-dominated field and research has demonstrated that male medical students are faster at acquiring surgical skills and demonstrate superior visuospatial skills in comparison to their female peers [30‐33]. We will explore this further by comparing male and female performance in both groups for total time taken and number of attempts. Furthermore, we will explore the influence of video game experience, in years, on total time taken and number of attempts, for both groups.

The empirical distributions of all parameters of interest are described using mean and standard deviation in case of continuous data, with absolute and relative frequencies in case of categorical parameters. Possible difference in the primary outcome, time to reach proficiency, will be tested using a two-sided t test. All secondary parameters including subgroup analyses will be descriptively analyzed according to their underlying distribution, two-sided Mann-Whitney U tests in case of continuous parameters, and Chi-square test in case of categorical data. Graphical statistical methods will illustrate the findings, whenever appropriate.

Sample size calculation was done with respect to the primary endpoint. A previously evaluated pilot study showed the following data for total training time needed to reach proficiency: mean difference between group 1 and group 2 was 15 seconds; standard deviation in group 1 was 15.6 seconds, whereas it was 22.2 seconds in group 2. This difference can be detected with a two-sided significance level α = 0.05 and a power of 1 − β = 0.8, with a group size of 27 participants randomized to each group.

All data for the study is recorded anonymously, treated confidentially, and is evaluated by authorized staff for scientific purposes only. Participants’ names are kept separate from all study data and are not used for the study. Each participant is assigned a designated code that is used for the entire study documentation and data collection. This study is offered in addition to compulsory university courses. Participation in this study is voluntary and may be ended at any time. There are no foreseeable negative consequences related to participation. The participating staff of the Heidelberg MIS training center is experienced in the handling of training devices and in tutoring MIS. The benefits of training for students are numerous: stamina, concentration, and manual adroitness are enhanced and practiced, surgical interest may be sparked or strengthened, and students receive practical laparoscopy experience, which may be used during later work. In the event that a participant’s physical or mental health becomes jeopardized due to participation in the present study, the participant will be withdrawn immediately and excluded from the study. Written informed consent is obtained from each trainee. Ethical approval was obtained from the Ethics Committee of the Medical Faculty at Heidelberg University prior to the beginning of the study (Code S-334/2011). The Consolidated Standards of Reporting Trials (CONSORT) guidelines for randomized controlled trials and Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines for implementation of study protocols were followed [34, 35]. This trial was registered with the German Clinical Trials Register (DRKS) in Freiburg, Germany on 12 August 2015 with the trial registration number DRKS00008668.