Keywords laparoscopy - box training - learning performance - surgical education - structured
training
Schlüsselwörter Laparoskopie - Boxtraining - Lernleistung - chirurgische Ausbildung - strukturiertes
Training
Introduction
The proportion of procedures performed using minimally invasive surgery (MIS) is increasing
significantly [1 ]. For a long time, the principle of apprenticeship was used in the surgical training
of doctors. This principle presupposes an intensive trainer-apprentice relationship
with intensive supervision [2 ]
[3 ]. Initially, small and simple exercises are carried out; once these have been mastered,
more complex tasks can be tackled.
To date, little is known about the learning processes in surgical training in laparoscopy.
Surgical technique improves with repetition. This is often described as a learning
curve. At the beginning, novices have a steep learning curve, but as soon as they
reach a plateau, it can be assumed that they have mastered the procedure [4 ]. The learning curve can be used to compare learning outcomes. Laparoscopic box trainers
are used to minimize the time it takes to reach the plateau of the learning curve
for operating procedures [5 ]
[6 ]
[7 ]
[8 ]
[9 ]
[10 ]
[11 ]
[12 ]. It is expected that training on the box trainer will allow time in the operating
theater to be used more efficiently, so that beginners will need less time to reliably
perform surgical steps [5 ].
Novice laparoscopists have different levels of talent and require different numbers
of repetitions before an exercise is performed reliably [3 ]
[5 ]. In Germany, a mandatory curriculum for gynecological surgeons already exists for
certification by the Endoscopy Working Group. This involves completing training on
the box trainer and submitting surgical reports [13 ].
The first surgical steps in laparoscopy usually are initially done as one-handed assistance
while the other hand of the resident continues to guide the camera. These are both
already very complex motion patterns for a novice. Introduction to simple exercises
for novices in box training emphasizes on use of both hands even in the beginning.
Students rarely have the opportunity to gain practical insights into MIS and find
a possible field of activity before starting their career [14 ]
[15 ].
Talented trainees with an intensive trainer-apprentice relationship can proceed these
motion patterns in the operating theater directly. Supposedly less talented novices
will need much more time and repetitions to fulfill the procedure. These novices can
spend additional time with box trainers in order to successfully repeat certain operational
steps. Another positive aspect of laparoscopic box trainers is that novices do not
have to carry out their first experience under time pressure and with the fear of
harming the patient. The influence of time pressure is greater for novices than for
experienced surgeons, even shown in simulated box training [16 ].
The advantage of these trainers is that they teach hand–eye coordination, the use
of laparoscopic instruments and the force required for laparoscopy before the first
patient contact [9 ]
[17 ]
[18 ]
[19 ]
[20 ].
There is already evidence from small randomized studies that a structured laparoscopy
training program with institutionalization improved learning outcomes [21 ] and that the success of the box training lasts for several months [22 ]. The effectiveness of different training methods for acquiring laparoscopic surgical
skills remains a vital topic of the investigation. The particular advantage of box
trainers is often seen in the possibility that novices can train independently and
autonomously for a personalized training tailored to their needs [11 ]. However, laparoscopy training programs are not adopted due to a lack of time in
daily work routines [23 ]
[24 ].
The aim of this study is to analyze the enhancement of laparoscopic surgical skills
in laparoscopy box trainers in a systematically guided training program compared to
self-directed training.
Methods
Participants
A total of 40 students with over 3500 training sessions divided in two groups were
observed and evaluated during 04/2021 to 01/2023. The observational study was conducted
in an ecological study design. After a joint introductory event in which students
were introduced to the use of the box trainers (FORCE SENSE, Medishield) and to consent
to participate in the study, the groups were divided into the self-directed and systematically
guided learning groups. The first group consisted of 3rd–5th year medical students
who attended the course voluntarily and completed a 14-weeks training. The second
group consisted of last year’s students who were on their gynecology elective.
The elective course for medical undergraduate students was established in accordance
with the German and European training curricula for MIS. The students completed laparoscopy
courses every week in tandem with a peer tutor under the intermittent supervision
of an experienced surgeon. The experienced surgeon observed the students and gave
feedback if any flaws were noticed. Questions about surgical techniques could be asked
at any time.
The second group was at the site for a total of 4 months and were able to go to the
box trainers at any time during this period to complete the training. In a weekly
seminar, they had the opportunity to discuss technical or content-related issues.
Training
The recommended order of the parcourse, analogous to the training concept of the German
training curriculum for MIS [13 ], is Post and Sleeve (1), Loops and Wire (2), Zig-Zag-Loop (3), Flap Task (4), Wire
Chaser two hands (5), Wire chaser one hand (6), Intracorporeal Knot-Tying (7) and
Needle Track (8).
At the beginning of each session, the participants repeated the parcourse they had
already completed. It was recommended to save the best results of the parcourse each
day. Both groups were free to choose which results to save.
The instructions for the course are provided with an example written and in pictures
by the box trainers program. The training sessions are recorded on video. The program
determines a star rating (score) based on the parameters of distance covered with
both hands (path length), speed (time) and required force (compare [Table 1 ]). Both groups received the same instructions and feedback from the box trainers.
Table 1
In this table the parameters measured in the ForceSense box training system are explained.
The score showed in stars is a combination of the quantitatively measured parameters
time, force, and path length.
Parameter
Description
Time in seconds
Time from start of the parcourse until its completion
Force in Newton
Highest absolute force measured on the plate of the parcourse
Path length in mm
Total distance of both instruments during the parcourse
Score in stars 1–5
Combination of the results above for a quick comparison for the participants (global
rating)
The outcomes included comparisons of distance covered with both hands (path length),
required force, speed (time), and an overall score for both groups across the training
sessions.
The study was approved by the ethics committee of the medical faculty of Heinrich-Heine-University
Düsseldorf (reference: 2021‑1473). Participation had no influence on study outcomes
or grades. To assess the progression of time, linear regressions with session as independent
and the score as dependent variables were calculated. The analyses were conducted
on an alpha = 0.05 level, and run with SPSS version 29.0.0.0 (IBM Corp., Armonk, New
York) and the graphs were drawn with R version 4.1.0 (R Development Core Team, 2015).
Results
Participant demographics and data overview
A total of 3652 measurements were carried out on 40 students. The structured cohort
consisted of 21 students (53%) from the 3rd–5th year of study and the self-directed
cohort consisted of 19 last year students in their elective (47%). Only measurements
for which time, force and path length were recorded were included in the analysis.
This resulted in a total of 962 measurements with 702 measurements (73%) in the structured
and 260 measurements (27%) in the self-directed group (see [Table 2 ]). The completion was monitored through the recording of the training sessions and
the global star rating.
Table 2
Summary of Performance Results for Structured and Self-Directed Training Groups in
Laparoscopic Exercises. This table presents the comparative results of the structured
(Struct) and self-directed (Selfdir) training groups in five laparoscopic exercises
(Post & Sleeve, Loops & Wire, Flap Task, Wire Chaser, One Hand, and Intracorporeal
Knot Tying). Only training sessions that were independently logged by participants
and where performance values did not significantly deviate from the average are included.
The table compares the mean scores, force exertion, and path length, along with standard
deviations (SD) and 95% confidence intervals (CI), to assess differences in performance
consistency between the two groups. Statistically significant differences (p < 0.05)
are indicated where applicable.
Parcourse
Post & Sleeve
Loops & Wire
Flap Task
Wire Chaser One Hand
Intracorporeal Knot Tying
Struct
(n = 276)
Selfdir
(n = 86)
Struct
(n = 236)
Selfdir
(n = 82)
Struct
(n = 123)
Selfdir
(n = 41)
Struct
(n = 54)
Selfdir
(n = 41)
Struct
(n = 3)
Selfdir
(n = 3)
Abbreviations: CI = Confidence Interval; LB = Lower Bound; n.a. = not applied due
to small sample size; SD = Standard Deviation; Selfdir = Self-directed Training; Struct
= Structured Training; UB = Upper Bound; p value
*= significant result
Score
Mean
3.23
3.16
3.33
3.32
3.85
3.59
3.43
2.59
0.83
0.68
SD
0.96
0.98
0.92
0.76
0.85
0.85
1.03
0.98
0.33
0.27
95% CI
3.12; 3.45
2.85; 3.37
3.22; 3.45
3.16; 3.49
3.70; 4.00
3.33; 3.86
3.15; 3.71
2.28; 2.89
0.01; 1.65
−0.02; 1.34
p value
0.557
0.930
0.092
< 0.001*
n.a.
Force
Mean
0.24
0.40
20.16
18.85
3.67
0.73
10494
13275
34.02
89.40
SD
0.08
0.62
8.18
7.20
6.10
0.19
3139
3463
10.31
91.84
95% CI
0.23; 0.25
0.26; 0.53
19.11; 21.21
17.27; 20.43
2.58; 4.76
0.66; 0.79
9637; 11351
12183; 14370
8.41; 59.63
138.75; 317.55
p value
0.003*
0.171
< 0.001*
< 0.001*
n.a.
Path length
Mean
7465
7885
0.33
0.41
1001
6.34
5331
7554
244.50
273.57
SD
2371
3035
1.54
2.88
1989
15.86
1697
2413
55.49
45.97
95% CI
7184; 7746
7234; 8536
0.13; 0.53
–0.22; 1.05
645; 1356
1.33; 11.35
4868; 5794
6792; 8316
106.7; 382.3
159.38; 387.79
p value
0.156
0.722
< 0.001*
< 0.001*
n.a.
[Table 2 ] provides the data on score, force, and path length for participants in five training
exercises, divided into two groups: structured training and self-directed training.
The table distinguishes the overall score, force and the path length. Each row represents
a different task (Post & Sleeve, Loops & Wire, Flap Task, Wire Chaser, and Intracorporeal
Knot Tying) with corresponding sample sizes, mean values, standard deviations (SD),
and 95% confidence intervals (CI) for each metric (score, force, and path length)
in both training groups. Additionally, the p values for the t-tests comparing the
structured and self-directed groups are provided to indicate statistical significance.
In [Table 2 ], it is noticeable that few events were included in the calculation, particularly
for the intracorporeal knot tying parcourse. Only data for which force,
time and path length were saved were included in the calculation. The students only
saved their best result for each training session and the courses they started with
were repeated. Therefore, intracorporeal knot tying was practiced less frequently
and often practiced first and then recorded once per training session.
Comparison of performance scores and consistency
The statistical analysis involved conducting independent t-tests to compare the mean
scores, force, and path lengths between the structured and self-directed training
cohorts across six different tasks. The p values obtained from these tests indicate
whether the differences between the two groups were statistically significant.
Considering the score, the structured participants achieved higher results on average
with a lower standard deviation, which indicates a better consistency of performance.
This applies to the parcourse Post and Sleeve (p = 0.557), Wire Chaser (p ≤ 0.001)
and Flap Task (p = 0.092). Only in the task Wire Chaser the difference was significant.
Force application and variability
Self-directed participants exerted more force with much higher variability in the
parcourse Post and Sleeve (p = 0.003) and Wire Chaser (p ≤ 0.001). In comparison the
structured group exerted significantly more force, with higher variability in the
parcourse Flap Task (p ≤ 0.001) and Loops and Wire (p = 0.171). For the path length
measurement, the self-directed group had longer path lengths with higher variability
in the parcourse Post and Sleeve (p = 0.156), Loops and Wire (p = 0.722) and Wire
Chaser (p ≤ 0.001). Structured training participants were significantly more efficient
in their movements for the task Wire Chaser.
Overall, the structured training group appears to have better performance in terms
of scores and consistency, while the self-directed group exhibits higher force application
and motion variability.
In a first step, it was tested whether the score corresponds to the measured results.
[Fig. 1 ] shows the linear correlation between the overall score and the individual measurement
parameters time, force and path length. Since the score is linearly related to the
measured parameters, the score was used for an overall comparison in the linear regression
(compare [Fig. 2 ]).
Fig. 1
This figure presents the parameters of time, force, and path length to illustrate
their relationship within the overall star scoring system. The data demonstrate how
these raw performance metrics contribute to the final scores and highlight the linear
correlation between the individual parameters and the overall performance ratings.
Fig. 2
Visualization of the Training Progress and Consistency over the Completed Training
Sessions Demonstrated with the Parameter Speed and Global Rating Score. The development
of the parameters overall score (upper part) and time (lower part) in relation to
the completed training sessions on the left side for the structured group and on the
right side for the self-directed group is demonstrated. This figure shows that the
structured group shows a more consistent outcome in overall performance with fewer
training sessions.
Progression over time
In the structured cohort, the number of 10 training sessions was predetermined. Compared
to the structured cohort, the self-directed cohort trained more frequently on average
(compare [Fig. 2 ] with average of 15 sessions in self-directed cohort vs. 10 sessions in structured
cohort).
The results of the groups were also observed over the entire period of their training
session, with equally high variability in the results of the self-directed group as
shown in [Table 2 ] divided for each parcourse.
The structured cohort showed a continuous improvement over time. The self-directed
cohort showed no sustained improvement over the training sessions (see [Fig. 2 ]). In the global rating score, which is determined from the parameters of time, force
exerted and path length, the structured group showed a continuous improvement on average,
F(1,700) = 75.457, p < 0.001, R2 = 0.109, compared to the self-directed cohort, in which no continuity could be seen
even with more training sessions, F(1,258) = 0.098, p = 0.755, R2 = −0.003 (see [Fig. 2 ]).
Discussion
This study investigates the enhancement of laparoscopic surgical skills in laparoscopy
box trainers in a systematically guided training program compared to self-directed
training.
Multiple studies have already shown that box trainers help to improve skills and increase
the learning curve, but often studies have only been carried out selectively with
young surgeons over a few days or weeks and little attention has been paid to the
external conditions when designing the training [2 ]
[3 ]
[4 ]
[6 ]
[9 ]
[10 ]
[11 ]
[22 ].
In contrast, this study was able to show the improvement in the skills of medical
students in preparation for MIS and thus promotes the implementation of the teaching
of practical surgical skills during medical school.
To allow continuous measurement, the ForceSense system from Medishield in accordance
with the guidelines of the German Endoscopy Working Group of MIS was used for the
box training in this study. This allows a deeper insight into the learning effects
of the students and enables a better understanding of the learning curve. The ForceSense
system is the first system to objectively assess laparoscopic skills. In the study
by Hardon et al., after an introduction, the box trainers were taken home for three
weeks to train at least four times a week for at least 15 minutes. The results of
this study show an improvement in all first-year surgeons [10 ].
It is extensively discussed that trainee surgeons can use the time in hospital in
the operating room and can train flexibly outside of working hours with home-based
programs. The high flexibility of the novice training and the reduced personnel costs
for the program to maintain a skills lab are cited as particularly advantageous.
In the study by Hardon et al., it is noticeable that there is a group of poor performers
that differ from the rest. The group has a significantly less steep learning curve,
still improves over the three weeks and reaches the expected exam target, but performs
worse than its peers [11 ]. Compared to the available data from the present study, these students could benefit
from structured or institutionalized training. There are currently no known characteristics
to identify members of this group beforehand.
The present study provides evidence for the hypothesis that structured and guided
laparoscopic simulation training programs are more effective than unstructured training.
Based on our results it could be concluded that the implementation of practical surgical
training must be didactically embedded in the educational program and that mere availability
of training sites does not exploit the potential of laparoscopic box trainers.
The Dutch study group led by Hardon et al. also published a multicenter study by Rahimi
et al., in which the individual learning curve could be predicted after three initial
training sessions [5 ]. This is only possible with a measurement system that can objectively measure force,
time and path length. Here, individual skill training is primarily related to the
number of repetitions required. The available data in the present study suggest that
supervision and collaborative work also have an influence on the success of the objectively
measured results.
In case of poor results, Hardon et al. suggests investigating psychomotor reasons
in novices and considering whether novices are prepared to work independently in the
operating room [10 ]. Alternatively, the low-performing novices could also benefit from a more institutionalized
training curriculum and could develop better under structured conditions, analogous
to the data presented here.
In a Canadian study, gynecology residents were asked about their use of laparoscopy
trainers. The rate of simulator use was found to be less than 10 hours in the last
12 months. Reasons given for this were lack of time, lack of supervised training and
difficult accessibility [23 ]. These results indicate a desire for more structured training and suggest that residents
would also welcome institutionalization in laparoscopic training [24 ].
Surgical simulation training results in a high stress level in inexperienced surgeons
[25 ]. Structured training with peers could help to comfort novices with their stress
levels. Further studies should be initiated.
Limitations
The two groups in the study received different amounts of guidance, so that 75% of
the measurements fall on the structured training group, although the structured training
group had fewer training sessions. The self-directed cohort was not told how long
a training session should be and how many training repetitions they should perform.
It was not checked whether they repeated the previous training sessions. The training
sessions were performed at their own discretion in addition to the four-month-elective
in the department. The participants were allowed to decide which training results
they wanted to save. It was recommended to save the best score from each training
session. In the self-directed cohort, the saving of sessions was not monitored. It
is not possible to draw conclusions from the data collected as to how long the students
spent using the box trainer per training session, as they did not have to save every
training. These could be possible reasons for the relative
difference in the number of measurements in the two groups. The self-directed group
had one year more clinical experience and more contact with surgeries and procedures
in the operating theater, so better training results could be expected. Despite more
clinical experience and high motivation, the results during the training sessions
were inferior to those of the structured group. It can therefore be concluded that
self-directed training is less efficient.
In the structured approach, a continuous improvement in performance was observed in
fewer training sessions. In further research work, the students should initially be
assessed to build equal groups to avoid a selective bias.
According to a literature review, this study is the largest sample and longest observed
time period of a laparoscopy training in medical students.
Conclusion
Setting up a box trainer alone without a suitable curriculum, does not reach the full
potential of the training intervention. Based on the available data, it can be assumed
that institutionalized training with a structured time constraint and a training partner
will show an improved outcome compared to unsupervised training.
The intervention of giving inexperienced novices a training opportunity does improve
their practical skills in all available studies. However, this study was able to show
that institutionalizing the teaching unit with little additional effort on the part
of the training center clearly stabilizes and strengthens the continuity of learning
success.
It remains unanswered which factors are ultimately decisive for the improved outcome
of the structured group in this study and should be assessed in more detail in further
studies nor can this study answer whether the results can be transferred to young
surgeons. However, it is encouraged that when creating a curriculum either for young
surgeons or medical students a fixed training time slot and a collaborative approach
should be chosen.
