Temporal bone surgery requires thorough knowledge of middle-ear anatomy and great surgical precision. Novice surgeons typically obtain anatomical knowledge by means of anatomical boards, yet these do not offer them a good three-dimensional (3D) visual representation of the middle-ear’s structures. In addition, until recently, the only way for beginners to acquire otologic skills was to train on cadaveric models due to the absence of any adequate animal model. However, obstacles imposed by legislative and ethical issues, as well as costs, seriously limited access to human temporal bones [
Virtual reality (VR) is of growing interest in medical education, especially in surgery [
Before it can be used in a training program, a simulator must fulfill several criteria. The principles of validating surgical simulators are based on two aspects [
The Voxel-Man TempoSurg simulator was the first commercially available temporal bone simulator and has already been evaluated a number of times in the literature [
74 ear, nose, and throat (ENT) surgeons took part in this experiment (Table
Demographic characteristics of participants.
All participants | Novice group | Expert group | |
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Mean age (years) |
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Gender, |
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Male | 38 (52%) | 27 (47%) | 11 (73%) |
Female | 35 (48%) | 31 (53%) | 4 (27%) |
Dominant hand, |
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Right-handed | 63 (86%) | 48 (83%) | 15 (100%) |
Left-handed | 10 (14%) | 10 (17%) | 0 (0%) |
All testing was performed on a Voxel-Man TempoSurg simulator (Voxel-Man, Hamburg, Germany) at the Nancy School of Surgery, France. The participants were seated at a table in front of a 3D monitor, which was used to display a virtual environment that simulated a right-ear surgery (Figures
(a) Experimental design, (b) first-person view, and (c) automatic performance metrics generated by the Voxel-Man TempoSurg simulator.
The novice surgeons were provided with a standardized anatomic description and basic surgical skills by a confirmed surgeon. Both groups were then presented with a standardized description of the simulator, including its composition and working mode. Before starting the evaluation, each participant performed a simple 5-minute drilling task, writing their names, in order to familiarize themselves with the simulator. Once the familiarization phase was completed, each participant performed only once the following four temporal bone dissection tasks in standardized conditions (i.e., normal right ear): opening the cortical bone, exposure of the sigmoid sinus, exposure of the short process of the incus, and exposure of the horizontal semicircular canal. These four tasks were selected from the list offered by the simulator for their educational value. The participants were instructed to perform each task as fast as possible without damaging the neighboring anatomic structures. Once all the dissection tasks were completed, the realism and training effectiveness of the simulator were assessed by the expert group using qualitative surveys rated on a five-point Likert-type scale, in which 1 represented not true/realistic/useful and 5 represented very true/realistic/useful. A score of 3 was considered neutral.
Illustration of the experimental protocol.
The outcome measures for each participant in each dissection task were global score, bone volume removed, time taken, efficiency (i.e., bone volume removed per second), and number of structure injuries obtained from the Voxel-Man simulator. The groups’ performances were compared to assess the construct validity of the simulator. Data from the survey was collected to assess face and content validity.
The Statistical Package for the Social Sciences (SPSS) Version 20.0 (SPSS, Inc., an IBM Company, Chicago, Illinois) was used for analyses. All data was examined for normality using the Shapiro-Wilk test. Due to the nonnormal distribution of data, a nonparametric Mann-Whitney
When we consider all of the four tasks, our results demonstrated that the experts globally scored better than the novices
(a) Median global score, (b) time, (c) bone volume removed, and (d) the ratio of bone volume removed per second for the novice group (white bar) and expert group (grey bar).
Injuries of structures at risk.
Novice group | Expert group | |
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Total injuries | 894 | 125 |
9 (5.25–15.75) | 6 (4.5–11) | |
Injury of the dura | 175 | 45 |
1.5 (1–3.75) | 3 (1.5–4) | |
Injury of the sigmoid sinus | 81 | 30 |
0.5 (0–2) | 1 (0–2.5) | |
Injury to the brain | 20 | 9 |
0 (0-0) | 0 (0-1) | |
Injury of the auditory ossicles | 218 | 37 |
2.5 (1–5.75) | 2 (1–3.5) | |
Injury of the vestibular labyrinth | 65 | 2 |
0 (0-1) | 0 (0-0) | |
Injury of the chorda tympani | 2 | 0 |
0 (0-0) | 0 (0-0) | |
Injury of the facial nerve | 8 | 0 |
0 (0-0) | 0 (0-0) | |
Injury of the posterior wall of the outer ear canal |
325 | 2 |
1 (0–3) | 0 (0-0) |
Results represent occurrence and median (interquartile range).
The realism of the simulator was assessed across several items: the appearance of the drill and anatomical structures, evaluation of the drill-handling characteristics, and quality of the graphics (Table
Face validity.
Expert group | |
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Global assessment |
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Appearance of anatomical structures |
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Appearance of anatomical rapports |
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Appearance of drill |
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Controlling of drill |
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Haptic feedback |
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Performance of drill |
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Ergonomics |
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Data is presented mean
The degree to which the simulator represented the fundamental problem of a temporal bone dissection was assessed across the following items: surgical anatomy and planning, drill navigation and technique, hand-eye coordination, and overall usefulness as a training tool (Table
Content validity.
Expert group | |
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Global assessment |
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Teaching anatomy |
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Teaching surgical planning |
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Training hand-eye coordination |
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Curriculum |
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Transfer to operating room |
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Data is presented as mean
In this study, we sought to assess whether the Voxel-Man simulator can distinguish between experienced and novice surgeons. To meet this objective, we selected four temporal bone dissection tasks considered as the first fundamental steps in most middle- and inner-ear surgeries. Our results demonstrate that experienced surgeons obtained better overall scores than novices. In addition, the experts completed the tasks faster while removing the same volume of bone. These results support the construct validity of the Voxel-Man TempoSurg VR simulator. Previous studies have supported the construct validity of the Voxel-Man TempoSurg simulator for a specific task [
Previous studies have identified the time taken and number of injuries as key factors in differentiating surgeons of differing levels of expertise [
Other variables could also be added for greater assessment of expertise. For instance, Khemani et al. [
The simulator obtained an overall good appreciation for face and content validity. All the experts particularly appreciated the anatomical disposition of the structures and drill running. Most of the experienced surgeons (93.7%) said they would recommend the Voxel-Man simulator for teaching ear anatomy and thought that this simulator could be integrated into surgical training courses. These results are in line with previous studies assessing the face and content validity of the Voxel-Man [
Real-life surgery training consists of the teaching and supervision of a more or less inexperienced surgeon by an experienced ear surgeon. However, the presence of an expert does not reduce the risk of medical error to zero. Moreover, the operational time tends to be increased by the instructions and advice given by the mentor to his student. Longer operation times can induce more postoperative complications for patients and increase costs for hospitals. These issues underline the need to develop alternative methods of learning outside the operating room. Training using a virtual temporal bone offers many significant advantages, including the possibility of training on normal or pathological ears and of repeating the procedure an infinite number of times in reproducible conditions. Simulators are accessible, allowing students to self-correct their errors by starting over, providing the possibility of self-assessment, and reducing the consumption of cadaveric material. Temporal bone surgery is complex, with small errors in judgment resulting in potentially dramatic consequences [
The Voxel-Man TempoSurg Virtual Reality simulator constitutes an interesting complementary tool to traditional teaching methods for training in otologic surgery. Although some features require improvements, this simulator allows trainees to acquire a good 3D visualization of ear structures and to learn complex surgical skills. The simulator’s ability to distinguish between different levels of expertise largely depends on the tasks submitted to participants. Thus, by selecting appropriate exercise, this simulator could also be used as a certification tool, constituting a prior condition for performing real-life surgery.
Cécile Parietti-Winkler takes responsibility for the integrity of the work as a whole, from inception to published article. This work has been presented at the “10th International Conference on Cholesteatoma and Ear Surgery.”
The authors declare that there are no conflicts of interest regarding the publication of this paper.
M. Varoquier, C. P. Hoffman, and C. Parietti-Winkler wrote the paper, M. Varoquier collected the data, C. P. Hoffman analyzed the data, and C. Perrenot, N. Tran, and C. Parietti-Winkler contributed to the design of the study. All authors approved the final version of the manuscript.
This work has been supported within the framework of Project “Hôpital Virtuel de Lorraine.”