Surg Endosc (2018) 32:183–190
https://doi.org/10.1007/s00464-017-5655-1

and Other Interventional Techniques

Analysis of the posture pattern during robotic simulator tasks
using an optical motion capture system
Kenta Takayasu1 • Kenji Yoshida1 • Takao Mishima1 • Masato Watanabe1 •Tadashi Matsuda1 • Hidefumi Kinoshita1

Received: 8 March 2017 / Accepted: 6 June 2017 / Published online: 29 June 2017
Ó Springer Science+Business Media, LLC 2017

Abstract
Background Surgeons are sometimes forced to maintain
uncomfortable joint positions during robotic surgery
despite the high degree of instrument maneuverability. This
study aimed to use an optical motion capture system toanalyze the differences in posture patterns during robotic
simulator tasks between surgeons at two skill levels.
Methods Ten experienced and ten novice surgeons performed two tasks in a da Vinci Skills Simulator: Suture
Sponge 1 (SP) and Tubes (TU). The participants’ upper
body motion during each task was captured, including thejoint angles (axilla, elbow, and wrist), the percentage oftime when the wrist height was lower than the elbow height(PTW), and the height of the elbow and wrist relative to thearmrest.
Results The novice group showed significantly more
excess extension in both elbow angles and extension([50°) in both wrist angles than did the experienced group.
The novice group had significantly lower PTW than theexperienced group on the right side in both tasks (bothp \ 0.001), and on the left side in SP (p \ 0.001). Compared with the experienced group, the novice group had asignificantly higher elbow relative to the armrest on theright side (SP, TU: p \ 0.05), and a significantly lower
wrist relative to the armrest on the right side (SP, TU:
p \ 0.05).
Conclusions An optical motion capture system can detectthe differences in posture patterns in the positional& Hidefumi Kinoshitakinoshih@hirakata.kmu.ac.jp
1

Department of Urology and Andrology, Graduate School of
Medicine, Kansai Medical University, 2-5-1 Shinmachi,
Hirakata, Osaka 573-1191, Japan

relationship between the elbow and wrist and the joint
angles of the upper limb between two groups of surgeons at
different skill levels during robotic simulator tasks.
Keywords Robotic surgery training  Motion capturesystem  Skill analysis
Robotic surgery has recently become popular in various
surgical fields, due to its stereoscopic visualization, highdegree of freedom regarding instrument movement, minimal
invasiveness, and minimal bleeding in the operative field.
Although the high degree of instrument maneuverability inrobotic surgery reduces surgeon stress and muscle fatigue[1, 2], surgeons are also forced to maintain uncomfortable joint positions intraoperatively. Surgeons performing
robotic surgery have a relatively large degree of physicalsymptoms or discomfort, similarly to those performing
laparoscopic surgery [3–5]. The adoption of unnatural postures while conducting surgery might cause musculoskeletal
complaints and decrease surgical performance.
The science of ergonomics for posture analysis was first
discussed in the 1950s to create a comfortable work environment [6]. Optimal ergonomics to monitor position andinstrument handle design have also been investigated toreduce surgeons’ physical stress [7, 8]. Also, with recent
progress in engineering technology, reports on minimallyinvasive surgery and gastrointestinal endoscopy have analyzed surgeons’ motion using motion capture systems(electromagnetic systems, video-based analysis systems,
inertial systems) during simulated tasks or actual surgery[9–13]. Adopting the proper posture could potentiallyprevent the excessive force that is sometimes accidentally
applied by novice surgeons; therefore, this information isneeded for surgical education.

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There are some reports in robotic surgery on the frequency of musculoskeletal problems and the correlations
between usage of the armrest and learning curves [14, 15].
However, there are no reports investigating the differencein posture patterns between surgeons at different skill
levels. We hypothesized that the position pattern of joint
angles and the positional relationship during robotic surgery differs depending on the skill level of the surgeon
such as expert surgeons operate in a relaxed posture withthe armrest and novice surgeons tend to take an excessive
wrist extension and elbow extended posture. In this pilot
study, we used an optical motion capture system to analyze
the differences in the posture pattern during robotic simulator tasks between surgeons at two skill levels.

Materials and methods
Participants and task
The study protocol was approved by the Ethics Committee,
Kansai Medical University, Osaka, Japan (Protocol Number 922). This study included 20 participants: 10 wereexperienced surgeons who had performed [100 cases ofrobotic surgery and had more than 15 years of surgicalexperience, and 10 were assigned to the novice group(medical students with no robotic surgery experience)(Table 1).
We selected two exercises based on a needle driving
task in a da Vinci Skills Simulator (DVSS, Intuitive Surgical, Inc., Sunnyvale, California, USA): Suture Sponge 1
task (SP) and Tubes task (TU) (Fig. 1). In SP, the needle
had to be passed from one predetermined point to anotherpoint on the suture sponge. First, the participant passed theneedle from the top point to the bottom point with the righthand three times. The exercise was then repeated with theleft hand. The needle was then passed from the bottom
point to the top point with the right hand, and repeated withthe left hand three times. In TU, the needle had to bepassed through eight points that appeared in order in a tube
similar to the intestinal tract. In TU, needle driving was
operated with the right hand. Before performing thesetasks, novice group practiced for 1 week (30 min to 1 h aday) under an instructor’s guidance, while the experienced
surgeons practiced each task several times.

Measurement
The participants’ upper body motion during each simulated
surgical task was captured with the commercially available
optical motion tracking system OptiTrack Flex3 (NaturalPoint, Inc., Corvallis, Oregon, USA), using six infrared
cameras and retroreflective markers of 14 mm spherical
diameter. A sampling frequency of 100 Hz was used tocapture tracking data from each marker. Post-procedural
processing of the kinematic data was analyzed in Motive:Body (NaturalPoint, Inc., Corvallis, Oregon, USA). Fifteen
markers were used to track the head, shoulder, elbow (lateraland medial), wrist (lateral and medial), hand, and hip for
motion capture (Fig. 1). All marker trajectories that vibrated
faster than 6 Hz frequency were smoothed. An opticalmotion capture system can measure three-dimensional
coordinates with an extremely small degree of error.
Although a few meters squared of space is required to install
the camera, it is suitable for analyzing elaborate movements
in a limited space, such as during a surgical procedure.
Outcome measures
We evaluated the automated scoring system of the DVSS,
including the operators’ performances in eight categories
and an overall score (time to complete the exercise,economy of motion, instrument collision, excessive
instrument force, instrument force, instrument out of view,
master workspace range, drops, and missed targets).
According to the surgeons’ point of view, we defined the xaxis as in front and behind, the y axis as up and down, andthe z axis as right and left. The location information wasused to calculate the joint angles [axilla (x–y plane: h1, y–z
plane: h3), elbow (x–y plane: h2), wrist (flexion–extension:h4)], the percentage of time when the wrist height was
lower than the elbow height (PTW), and the height of theelbow/wrist relative to the armrest. The axillary angle wasdefined as the angle formed by the hip, the shoulder, andthe lateral of the elbow marker, while the elbow angle wasdefined as the angle formed by the shoulder, the lateral of
the elbow, and the lateral of the wrist marker. The wrist
angle was defined as the angle formed by two normal
vectors consisting of each of three points (1: hand, medial
wrist, lateral wrist, 2: lateral elbow, lateral wrist, medial
wrist). All angles were calculated using the cosine theorem:

Table 1 Participant characteristics
Group

NumberMale/
femaleHandedness (right/
left)

Career(years)Robotic surgery(number)

Experienced

10

10/0

10/0

16–32

[100

Right 27.4, left 27.1

Novice

10

8/2

10/0

0

0

Right 29.1, left 28.8

123Length of upper arm (cm, average)

Surg Endosc (2018) 32:183–190
Fig. 1 We selected two
exercises based on a needle
driving task in a da Vinci Skills
Simulator. A Suture Sponge 1
task, B tubes task. C Right sidemarkers. Participants were
equipped with fifteen
retroreflective markers

185

A

C

head

shoulderhandlateral wrist

Blateral elbow

medial wrist

medial elbow
hipcosh ¼ AB  AC=jABjjACj:
For each joint angle, we analyzed the average angle andthe average standard deviation of the angle as an indicatorof joint stability during each task. If only the average angle
was compared, then the variation of the angle during eachtask could not be evaluated. Measuring the average standard deviation of the angle enabled us to include the time
factor in the evaluation.
It is important to assess the ability to adjust the positionof the master controller in order to evaluate posture patternduring robotic simulator tasks; hence, we recorded thenumber of times that each participant used the camera
button and the clutch button.
Statistical analysis
Data are expressed as mean ± standard deviation. Statistical analysis was performed by creating SPSS 20.0.0.1(SPSS, Chicago, IL, USA). All parameters were compared
between the two groups using the Mann–Whitney U test. A
p value \0.05 was considered statistically significant.

Results
The DVSS scores are shown in Table 2. There were significant differences between groups in all parameters
except for ‘‘instrument out of view’’ in both tasks and‘‘missed target’’ in TU.
The average joint angles and average standard variability angles are shown in Table 3. There were significant
differences between groups in the joint angle of h2 on theright side in SP and in the joint angles of h1 and h2 on theright side in TU. Therefore, the elbow joint angle on theright side tended to be more extended in the novice groupthan in the experienced group. There were also significant
differences between groups in the angle variability of h1–h4
on the right side, h4 on the left side in SP, in h3 and h4 on
the right side, h1 and h4 on the left side in TU.
With respect to wrist angle, we examined every 10°
separately (from 0° to 50°) because there were significant
differences in the average standard deviation angle
between the two groups on both sides in both tasks (Fig. 2).
Novice group showed significantly more excess extension([50°) in both wrist angles than experienced group in SP
and in the right wrist angle in TU (Fig. 2). There was no
significant difference when comparing wrist angle distribution every 10 degrees.
Figure 3 shows the differences in the PTW, which differed significantly between groups in the SP on the rightside (experienced group: 9.22 ± 11.24, novice group:
66.83 ± 25.28, p \ 0.001) and the left side (experienced
group: 23.11 ± 20.71, novice group: 58.70 ± 36.43,
p \ 0.001), and in TU on the right side (experienced
group: 10.69 ± 12.66, novice group: 68.64 ± 24.96,
p \ 0.001). There was no significant difference between
groups in TU on the left side (experienced group:
19.96 ± 29.37, novice group: 38.35 ± 32.48, p = 0.082).
Table 4 shows the height of the elbow and wrist relative
to the armrest. In SP, the average height of the elbow in thenovice group was significantly higher than in the experienced group on the right side, and the percentage of time
when the elbow rose more than 5 cm from the armrest wasalso significantly higher in novice group versus experienced group on both sides. In TU, the percentage of time
when the elbow rose more than 5 cm from the armrest wassignificantly higher in the novice group compared with the

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Surg Endosc (2018) 32:183–190

Table 2 Skill simulator score including the operators’ performances in eight categories
Task

Suture Sponge 1

Group

Experienced

Tubes
Novicep value

Experienced

Novicep value

Overall score87.9 ± 7.4

62.0 ± 15.1

0.001*

72.4 ± 13.6

56.6 ± 10.9

0.028*

Time to complete expertise

185.9 ± 22.9

283.5 ± 73.8

0.002*

209.0 ± 20.0

264.5 ± 40.6

0.006*

Economy of motion

224.3 ± 26.0

324.9 ± 84.5

0.005*

352.7 ± 35.6475 ± 83.9

0.004*

Instrument collision

1.9 ± 2.3

9.3 ± 6.9

0.001*

3.3 ± 2.45

7.8 ± 2.90.005*

Excessive instrument force

0±0

1.4 ± 2.7

0.030*0±0

1 ± 2.1\0.001*

Instrument out of view

0±0

0±0

–

0.4 ± 0.8

1.3 ± 2.1

ns

Master workspace range
Drops

3.3 ± 0.46
0±0

4 ± 0.7
0.4 ± 0.7

0.015*
0.030*

5.3 ± 2–7.8 ± 1.1–

0.007*–

Missed targets

7.2 ± 3.5

19.9 ± 8.8

0.002*

5.8 ± 6.8

3.2 ± 2.0

ns

Experienced group: surgeons who had performed [100 robotic surgeries and had [15 years of surgical experience (n = 10)
Novice group: medical students with no robotic surgery experience (n = 10)
Values are presented as the mean (SD)* p \ 0.05

experienced group on the right side. The average height of
the wrist in the novice group was significantly lower thanin the experienced group on the right side in both tasks.
There was no significant difference between groups on theleft side, although the novice group tended to have a lower
wrist height than the experienced group.
The total number of times that each participant used thecamera button and the clutch button was significantly lessfor the novice group in both tasks (SP: experienced group
4.5 ± 5.4 times, novice group 0.8 ± 1.0 times, p = 0.003;
TU: experienced group 26.6 ± 12.3 times, novice group
8.8 ± 3.8 times, p \ 0.001).

Discussion
This study analyzed differences in the posture patterns during
robotic simulator tasks between novice and experienced surgeons using an optical motion capture system (OptiTrack).
Our data showed that the PTW was greater in novice group, as
those in the novice group tended to elevate the elbow andperform tasks using the lower portion of the upper limb.
With progress in engineering technology, several studies
have quantified operative maneuvers to assist in acquiring
efficient surgical skills such as the applied force patterns ofsuture techniques, dissection maneuvers [16–19], and forceps tip motion tracking [20, 21]. Regarding posture
analysis, low-cost motion capture systems will continue tobe developed and used for motion analysis. In the field ofsports, motion analysis has been used for instruction andcoaching of golf swing [22]. Kinect (Microsoft, Corp.,
Redmond, WA, USA) is a popular motion analysis systemthat was introduced in 2012. Motion analysis has also beenused for postural analysis during endoscopic procedures

123

such as upper gastrointestinal endoscopy and colonoscopy[9, 10]. The distance between both hands was different
among surgeons of different skill levels, and keeping thehands wider apart kept the colonoscope straight andallowed fine control of the tip of the endoscope. For novice
surgeons, early exposure to tips regarding surgicalmaneuvers would help shorten the learning curve. Advice
on proper posture may also prevent chronic injury and leadto earlier proficiency. In this study, we used the OptiTracksystem, which consistently produces positional error of lessthan at least 0.3 mm [23]. As Kinect cannot quantify theoverlapping parts of the body and record the motion patternof torque steering, such as forearm supination and pronation, it would be difficult to use Kinect to evaluate finemovements such as finger movement.
Recently, the field of ergonomics for preventing musculoskeletal injury in robotic surgery has attracted a lot of
attention. It is generally considered that robotic surgery
systems relatively provide surgeons with a good ergonomic
work environment. Hubert et al. reported that physicalworkload during standard laparoscopies was significantly
greater than during robotic surgery using an objective
assessment sheet (NASA-TLX), and surgeon heart rateduring standard laparoscopy was significantly increased
compared with during robotic surgery [1]. Zhini et al. also
compared the ergonomic differences between robotic andlaparoscopic surgery using surface electromyography, andfound that laparoscopic surgery elevated bicep, tricep, anddeltoid activation compared with robot-assisted surgery[2]. However, another report showed that even in robotassisted laparoscopic prostatectomy, neck and back pain
was present in 23% of urologists [3]. Lee et al. reported
that 236 surgeons (56.1%) practicing robotic surgery
complained of physical symptoms or discomfort; neck

5.98 ± 1.96
ns

ns

8.84 ± 1.81

Tubes
Novice0.023*
7.81 ± 1.72

p value\0.001*
Experienced 4.5 ± 1.82
p value

8.41 ± 2.87

5.3 ± 1.71

Novice5.65 ± 1.19

2.85 ± 1.13

Experienced

0.019*

6.25 ± 2.68

0.004*
3.75 ± 2.22

4.64 ± 1.42

2.54 ± 0.77

16.34 ± 6.43
ns

122.69 ± 13.18\0.001*39.47 ± 8.84
0.041*

Novicep value

18.52 ± 7.53

98.23 ± 5.79

ns

23.36 ± 11.00

24.88 ± 15.99

h3

31.99 ± 5.05

Experienced

119.28 ± 7.53

37.04 ± 10.76
ns

Novicep value0.001*

103.84 ± 7.96

h2

37.28 ± 6.09

Experienced

h1

Right sidex

SutureSponge 1

Tubes

SutureSponge 1

Group

y
z

0.004*

18.95 ± 2.86

0.019*
14.75 ± 1.65

18.60 ± 3.87

13.76 ± 2.55

ns

28.65 ± 7.01

23.30 ± 5.74

ns

22.42 ± 3.87

21.85 ± 2.55

h4

y

θ3

0.049*

9.33 ± 1.83

ns
7.34 ± 2.13

4.88 ± 1.71

4.31 ± 1.75

ns

34.83 ± 6.86

31.96 ± 8.23

ns

31.99 ± 8.29

34.39 ± 6.3

h1

Left side* p \ 0.05

Values are presented as the mean (SD)

Novice group: medical students with no robotic surgery experience (n = 10)

Experienced group: surgeons who had performed [100 robotic surgeries and had [15 years of surgical experience (n = 10)

Average standard
deviation angle (°)

Average angle (°)

Task

Table 3 Joint average angle and average standard deviation angle

θ1

θ2

ns

12.66 ± 1.52

ns
11.36 ± 2.17

7.91 ± 2.84

6.37 ± 1.6

ns107.16 ± 12.67

96.84 ± 11.44

ns

108.66 ± 6.05

107.49 ± 9.47

h2

-90°

ﬂexion

0°

θ4

90°

extensionns

5.92 ± 2.51

ns
5.23 ± 1.63

3.66 ± 2.28

2.89 ± 1.82

ns

25.06 ± 3.59

24.21 ± 5.69

ns

23.88 ± 4.49

26.02 ± 15.34

h3

0.038*

31.49 ± 4.34

0.013*
22.24 ± 3.24

17.72 ± 2.83

15.03 ± 1.90

ns

16.34 ± 6.43

18.52 ± 7.53

ns

23.36 ± 11.00

24.88 ± 15.99

h4

Surg Endosc (2018) 32:183–190
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Surg Endosc (2018) 32:183–190

Expert3.28 㼼 2.99%

4.61 㼼 3.49%

p=0.049ns

12.45 㼼 8.75%

8.24 㼼 5.11%

15.76 㼼 8.34 %14.27 㼼 9.46%

Right sideLe side

Right sideLe side

Suture sponge 1

Tubes

Fig. 2 Percentage time in which the wrist angle was extended
beyond 50°. Experienced group: surgeons who had performed [100robotic surgeries and had [15 years of surgical experience (n = 10);
novice group: medical students with no robotic surgery experience[%]

8.39 㼼 8.11%

p=0.019p=0.006

Novice5.61 㼼 4.23%

p < 0.001*

p < 0.001*(n = 10). Values are presented as the mean (SD). *Mann–Whitney U
test. The black section of the pie chart indicates the percentage time inwhich the wrist angle was extended beyond 50°

[%]

100

100

80

80

60

60

40

40

20

20

p < 0.001*

p = 0.082*

00ExpertNoviceRight side

ExpertNoviceLe side

Suture Sponge 䠍 task

ExpertNoviceExpertRight side

NoviceLe side

Tubes task

Fig. 3 The percentage of time when the wrist height was lower thanthe elbow height (PTW). Expert group: surgeons who had performed[100 robotic surgeries and had [15 years surgical experience(n = 10), novice group: medical students with no robotic experience(n = 10). The PTW significantly differed between groups in the SP
on both sides, and in the TU on the right side. *Mann–Whitney U test

stiffness, and finger and eye fatigue were the most common
symptoms [4]. Megan et al. also reported that of 250 surgeons who currently performed [50% of procedures
robotically (n = 122), laparoscopically (n = 67), or via
open surgery (n = 61), the rate of physical symptoms was
significantly higher in the robotic group (72%) than in thelaparoscopic (57%) or open surgery group (49%). Even inrobotic surgery, unnatural postures can cause musculoskeletal complaints and lower performance during surgical procedures [5].

Generally, surgeons seem to experience less fatigue
during robotic surgery when they hold their joints in
optimal position. Novice surgeons sometimes twist theirhands and extend their elbows while performing operative
maneuvers. In contrast, an experienced surgeon may fix
their elbow on padded armrests in a more relaxed posture.
Advancements in engineering technology have enabled
analysis of surgical maneuvers in various approaches. The
use of an armrest during robotic surgery decreases operator
fatigue because of the reduction of the workload of the123Surg Endosc (2018) 32:183–190

189

Table 4 The height of the elbow and wrist relative to the armrest
Right side

Left side

Elbow
Task
Suture Sponge 1

Tubes

Group

Height (cm)More than 5 cm (%)

Wrist

Elbow

Height (cm)Height (cm)

Wrist
More than 5 cm (%)

HeightExperienced

0.89 ± 0.37

1.36 ± 1.41

4.10 ± 2.53

0.94 ± 0.37

1.17 ± 2.52

2.20 ± 3.01

Novice2.49 ± 1.90

18.90 ± 23.62

0.68 ± 1.80

1.61 ± 1.01

7.38 ± 9.03

0.65 ± 1.85

p value
Experienced

0.034*
1.41 ± 0.76

0.005*
4.29 ± 8.94

0.005*
5.49 ± 2.30

ns
1.99 ± 0.63

0.042*
10.54 ± 8.04

ns
5.64 ± 4.53

Novice2.30 ± 1.23

13.52 ± 16.18-0.85 ± 3.30

2.14 ± 0.95

13.08 ± 10.18

2.84 ± 2.59

p value

0.042*

0.014*\0.001*

ns

ns

ns

Experienced group: surgeons who had performed [100 robotic surgeries and had [15 years of surgical experience (n = 10)
Novice group: medical students with no robotic surgery experience (n = 10)
Values are presented as the mean (SD)* p \ 0.05

forearm [14]. Yang et al. [14, 15] reported the developmentof a pressure surveillance system that alarmed when theoperator’s forearms were not in contact with the armrest.
Group training with the alarm has produced good results
using the da Vinci Trainer robotic simulator. Training withthe alarm was able to improve the proper use of the armrestand help train the novice surgeons to relax during robotic
maneuvers.
Our study compared the upper body motion pattern during
simulated surgical tasks conducted by novice group versus
experienced group. There were significant differences
between groups in the dominant elbow joint angle (h2) in SP
and TU. The average h2 angle of the novice group was larger
by about 15°–20° compared with the experienced group. The
elbow angle of the novice group extended further than 90
degrees, which is a good limb position for the elbow, but may
strain the musculoskeletal system. We also found significant
differences in the average standard deviation angle of h1–h4
on the right side and h1, h4 on the left side (Table 3). This
indicates that although it is not so large range, novice group
have an unstable position and many unnecessary movements. Furthermore, there were significant differences
between groups for the PTW during SP on both sides and for
the PTW during TU on the right side (Fig. 3, Table 4). These
results indicate that novice surgeons tended to extend theirelbows (holding the elbow higher relative to the armrest) andkeep the wrist in a lower position relative to the armrest than
did the experienced group. Lifting the elbow from the armrest reduces operational stability and promotes fatigue of theshoulder, and a low working area leads to extension of theelbow and wrist. The current results regarding the elbow
position supports the previous findings [14, 15]. We foundlittle difference between groups in the overall parameters of
the left side in TU. This may be because the left hand only
played an assisting role, while the needle driving was doneby the right hand. There are two factors that adjust theposition of the master controller to make it easier to operate:
the camera button and the clutch button. In both tasks, theparticipants used the camera button and the clutch button
significantly less in the novice group; this indicates that thenovice group did not take a posture that would make it easierto perform tasks, and tended to work in a relatively low
position and extend their arms.
As for the wrist angle, Yu et al. reported the impact of
three types of laparoscopic tool handle configurations onwrist posture [8]. Generally, excessive wrist flexion andextension more than 15° from neutral poses a risk ofmusculoskeletal strain. The ergonomic risks of musculoskeletal strain could be reduced by using the appropriate
handle angle, with the pistol-type tool handle configuration
recommended as most appropriate. In our study, novice
group tended to experience stronger flexion at angles ofmore than 50° than the experienced group. This indicatesthat the novice group has a greater risk of musculoskeletal
problems (Fig. 2).
The position of the wrist and elbow joints was very
different between the experienced group and the novice
group. This ergonomic information has a possibility tominimize musculoskeletal problems in the novice group.
During a surgeon’s career, musculoskeletal problems could
lead to chronic diseases, decrease in quality of life, andeven absence from work. Hence, surgeons need to undertake training to increase awareness about ergonomics
during endoscopic surgery, and to learn to adopt a relaxed
natural posture that minimizes muscle stress. Tjiam et al.
[24] reported that about 89% of all respondents werewilling to improve ergonomic awareness, preferably byintegrating ergonomics in hands-on training.
Several limitations of our study must be noted. We did
not evaluate the learning curve, and the stages of development of surgical skills still need to be researched. We
also did not evaluate the skills during the actual operative

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procedures but rather just during simulation tasks. Moreover, we did not include experienced surgeons from a highvolume center who had performed [1000 cases of robotic
surgery. The motion capture system is reasonably expensive and requires ample working space for the camera
setting. However, optical tracking systems have a highaccuracy compared with other approaches. In future work,
we plan to evaluate the relevance of surgical posture andfatigue using an assessment sheet (e.g., NASA-TLX,
SURG-TLX) or surface EMG to evaluate the learning
curve for novice surgeons to provide feedback on postureand the role of the hips and legs in controlling the console
movements.
In conclusion, the optical motion capture system
detected the differences in the posture patterns of novice
versus experienced surgeons during robotic simulator
tasks. There were differences between the novice groupand the experienced group in the positional relationshipbetween the elbow and wrist and joint angle of the upper
limb, indicating that the experienced group may have lessposture stress. This information would be helpful for thenovice group in robotic training to understand how to movetheir own posture efficiently, and for the establishment ofergonomic guidelines.

Funding This work was supported by JSPS KAKENHI Grant
Number 16K11074 and 16K20167.
Compliance with ethical standards
Disclosures Drs. Kenta Takayasu, Kenji Yoshida, Takao Mishima,
Masato Watanabe, Tadashi Matsuda, and Hidefumi Kinoshita have noconflicts of interest or financial ties to disclose.

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