Article

The trade-off between flexibility and maneuverability: Task performance with articulating laparoscopic instruments

Minimally Invasive Surgery Program, Legacy Health System, 1040 NW 22nd Avenue, Suite 560, Portland, OR 97210, USA.
Surgical Endoscopy (Impact Factor: 3.26). 04/2009; 23(12):2697-701. DOI: 10.1007/s00464-009-0462-y
Source: PubMed

ABSTRACT

Laparoscopic instruments are rigid and thus cannot provide the degrees of freedom (DOF) needed by a surgeon in certain situations. A new generation of laparoscopic instruments with the ability to articulate their end effectors is available. Although these instruments offer the flexibility needed to perform complex tasks in a constricted surgical site, their control may be hampered by their increased complexity.
This study compared the task performance between articulating and conventional laparoscopic instruments. Surgeons with extensive laparoscopic experience (8 experts) and staff with no surgical experience (8 novices) were recruited for the test. Both groups were required to perform three standardized tasks (peg transfer, left-to-right suturing, and up-and-down suturing) in a bench top model using conventional and articulating instruments. Performance was scored using a standardized 100-point scale based on movement speed and accuracy. After the initial trials with conventional and articulating instruments, each participant was given a short orientation on how to use the articulating instrument advantageously. The participant then was retested with the articulating instrument.
As expected, the expert group scored significantly better than the novice group (p < 0.001). The combined data from both groups showed better performance with the conventional instruments than with the articulating instruments (p = 0.074). The experts maintained their proficient laparoscopic performance using conventional instruments in their first attempts with the articulating instruments (91 vs. 84), whereas the novices had greater difficulty with the articulating instruments than with the conventional instruments (46 vs. 59). After a short orientation, however, the novices outscored the expert group in terms of net improvement in performance with the articulating instrument (27 vs. 1% improvement).
Experienced surgeons are readily able to transfer their skills from conventional to articulating laparoscopic instruments. To speed the learning process, the use of articulating instruments can be started at an early stage of surgical training.

Full-text

Available from: Bin Zheng, Mar 31, 2014
The trade-off between flexibility and maneuverability: task
performance with articulating laparoscopic instruments
Danny V. Martinec Æ Prakash Gatta Æ
Bin Zheng Æ Peter M. Denk Æ Lee L. Swanstro
¨
m
Received: 5 September 2008 / Accepted: 11 February 2009 / Published online: 3 April 2009
Ó Springer Science+Business Media, LLC 2009
Abstract
Background Laparoscopic instruments are rigid and thus
cannot provide the degrees of freedom (DOF) needed by a
surgeon in certain situations. A new generation of laparo-
scopic instruments with the ability to articulate their end
effectors is available. Although these instruments offer the
flexibility needed to perform complex tasks in a constricted
surgical site, their control may be hampered by their
increased complexity.
Methods This study compared the task performance
between articulating and conventional laparoscopic instru-
ments. Surgeons with extensive laparoscopic experience (8
experts) and staff with no surgical experience (8 novices)
were recruited for the test. Both groups were required to
perform three standardized tasks (peg transfer, left-to-right
suturing, and up-and-down suturing) in a bench top model
using conventional and articulating instruments. Perfor-
mance was scored using a standardized 100-point scale
based on movement speed and accuracy. After the initial
trials with conventional and articulating instruments, each
participant was given a short orientation on how to use the
articulating instrument advantageously. The participant
then was retested with the articulating instrument.
Results As expected, the expert group scored significantly
better than the novice group (p \ 0.001). The combined
data from both groups showed better performance with
the conventional instruments than with the articulating
instruments (p = 0.074). The experts maintained their
proficient laparoscopic performance using conventional
instruments in their first attempts with the articulating
instruments (91 vs. 84), whereas the novices had greater
difficulty with the articulating instruments than with the
conventional instruments (46 vs. 59). After a short orienta-
tion, however, the novices outscored the expert group in
terms of net improvement in performance with the articu-
lating instrument (27 vs. 1% improvement).
Conclusion Experienced surgeons are readily able to
transfer their skills from conventional to articulating lap-
aroscopic instruments. To speed the learning process, the
use of articulating instruments can be started at an early
stage of surgical training.
Keywords Articulating Assessment
Laparoscopic instrument Simulation Skill acquisition
Surgical training
Over the past two decades, minimally invasive surgery has
evolved from a surgical novelty to a mainstream approach
for surgery [1, 2]. The concept of minimally invasive
requires the completion of entire surgical procedures with
small incisions. In general surgery, minimally invasive
procedures, often called laparoscopic procedures, are per-
formed using long-shafted rigid instruments placed through
a number of key holes in the abdominal wall. Limited by
the mechanical properties of the instrument, most of the
early laparoscopic instruments did not include an articu-
lation at their end portion. This made it difficult to perform
certain complex surgical tasks such as making an intra-
corporeal suture or tying a knot [3].
The introduction of the Da Vinci Surgical Robot (Intu-
itive Surgical, Inc., Sunnyvale, CA, USA) in 1999 brought
D. V. Martinec B. Zheng (&) P. M. Denk L. L. Swanstro
¨
m
Minimally Invasive Surgery Program, Legacy Health System,
1040 NW 22nd Avenue, Suite 560, Portland, OR 97210, USA
e-mail: bzhengbc@hotmail.com
P. Gatta
Department of Surgery, University of Cincinnat, 231 Albert
Sabin Way, SRU Suite 1466, Cincinnati, OH 45267-0558, USA
123
Surg Endosc (2009) 23:2697–2701
DOI 10.1007/s00464-009-0462-y
Page 1
laparoscopic surgery into a new phase with the use of
robotic articulating instruments [2, 4, 5]. The robotic arms
theoretically provided degrees of freedom (DOF) for the
human hand equal to that of conventional surgery [5].
Improved hand–robot interfaces may allow for greater
flexibility and better surgical performance than conven-
tional surgical instruments. However, with the robot come
significant issues of setup time, use of operating room
resources, and cost. Given these factors, the development
of handheld articulating instruments with the ability to
reproduce the extra DOF of a robotic tool has been a pri-
ority for the next generation of laparoscopic instruments.
Such instruments have many potential clinical appli-
cations, including various single-port and laparoscopic
procedures. Articulation at the end effector of a needle-
driver may make manipulation easier by providing the
extra DOF desperately needed by a surgeon. For example,
articulating instruments would facilitate intracorporeal
suturing, especially in difficult positions such as the
anterior abdominal wall of the deep pelvis. However, such
potential advantages may be offset by the increased
complexity of the instrument, which may make it harder
to predict the movement outcome and more difficult to
build movement coordination between the hand and the
tool [6].
To investigate the relative merits of these instruments,
we studied one such articulating instrument called the
Autonomy Laparo-Angle laparoscopic instrument (Cam-
bridge Endoscopic Devices, Inc. Framington, MA, USA).
We tested its usability and compared it with conventional
laparoscopic instruments in a series of previously validated
simulated laparoscopic tasks. We hypothesized that artic-
ulating instruments would offer advantages of tool
flexibility but would be more demanding to manipulate and
control than a conventional instrument. We predicted that
instrument complexity might offset task performance in the
first attempt at using the articulating instruments compared
with using a conventional instrument.
A secondary goal was to investigate the impact of sur-
gical experience on task performance with these more
complex instruments by comparing groups with distinct
skill levels. We hypothesized that experienced surgeons
would develop a strategy to deal with the added complexity
of additional DOF presented by the articulating instruments
and therefore perform better than novices.
Finally, we evaluated the impact of a brief orientation
course on short-term improvement in skill using the artic-
ulating instrument. We hypothesized that the improvement
in performance would be more pronounced in the expert
group than in the novice group.
Methods
Participants and study groups
For this study, 16 volunteers were divided into two groups
based on prior experience with the use of laparoscopic
instruments. The expert group consisted of eight laparo-
scopic surgeons including four attending surgeons, two
laparoscopic fellows, and two senior residents doing a
laparoscopic surgery rotation. The novice group consisted
of eight nonmedical personnel including premed students,
administrative staff, and research assistants. This group had
no experience with surgical instruments whatsoever.
Simulated tasks and the scoring system
Task selection was based on universality, reproducibility,
and validity. Three tasks were chosen on this basis: peg
transfer, intracorporeal suturing up to down, and intracor-
poreal suturing right to left (Fig. 1). Simulated tasks were
modified based on tasks included in the Fundamentals of
Laparoscopic Surgery (FLS) program [79]. The FLS
program represents a well-validated educational and
training tool with broad training applications for both res-
idents and surgeons. The FLS manual skills component has
five basic drills. Because the availability of articulating
instruments was limited, only the peg transfer and intra-
corporeal suturing tasks were selected for this study.
Although intracorporeal up-to-down suturing is not a
standard FLS task, this task was chosen because it presents
a known difficulty suturing with standard laparoscopic
instruments and potentially could be facilitated by the
articulating device.
The FLS scoring has undergone strict validation and
reliability measurements [8]. Task performance in this
study was scored using the same FLS criteria of movement
speed and accuracy. Performance was reported as a nor-
malized score on a scale of 100 points. Briefly, fast
Fig. 1 Three simulated tasks
included in the study. A Peg
transfer. B Suture (left to right).
C Suture (up to down)
2698 Surg Endosc (2009) 23:2697–2701
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movement (shorter movement time) and high movement
accuracy (fewer movement mistakes) yielded higher per-
formance scores. For the peg transfer task, a penalty score
was given for every peg dropped during the trial. The
penalty score for the suture tasks was applied when the
suturing was conducted inaccurately (measured by devia-
tion from predetermined dot positions) or the knot quality
was low (measured by knot tightness and gap between
tissue).
Conventional and articulating laparoscopic instruments
The conventional instruments used for the peg transfer task
were a pair of Maryland graspers (Karl Storz Endoscope,
Inc., Tuttlingen, Germany). Suturing was performed using
a pair of needledrivers (Jarit Instruments, Tuttlingen,
Germany). The articulating grasper was a 5-mm instrument
with a locking ratchet (Fig. 2). This grasper achieves
articulation at the wrist of the instrument by four wires
hidden along its shaft manipulated using a second joint
controlled by the surgeon’s hand. In addition, the tip of the
grasper can be rotated 3608 without changing the degree of
flexion at the wrist of the instrument.
When we conducted this study, only one articulating
needledriver was available. Therefore, the study tasks were
performed using one articulating instrument in the dominant
hand and a conventional instrument in the nondominant
hand.
Procedure
Instructions on how to perform the three tasks were given
to all the participants via a short demonstration. The par-
ticipants performed the initial trial tasks using conventional
and articulating instruments alternatively. The order of the
instruments was selected randomly for each participant.
After the initial round of attempts, each participant was
then given a 20-min orientation on how to use the articu-
lating instrument to its full potential. Each participant then
was retested to observe any improvement in the scores for
the articulating instrument. Comparison of the pre- and
postorientation data between the different groups also gave
us the opportunity to investigate the ability of different
users to learn a new instrument.
Data analysis
Data analyses were conducted in two steps. First, a 2 9 2
multivariance analysis (two-way analysis of variance
[ANOVA]) was run to test the performance difference
between the two groups of participants and between two
different instrument conditions. Second, another 2 9 2
ANOVA was run to test the impact of training on mastery
of the articulating instruments by the two groups of sub-
jects. A p value less than 0.05 was considered significant.
The results are reported as mean ± standard deviation
unless otherwise stated.
Results
Initial response to the articulating instrument
In the initial trials, the experienced surgeons performed
significantly better than the novices in all three tasks
averaged over the tasks performed using conventional and
articulating instruments (p \ 0.001 for all measures)
(Fig. 3).
Averaged over the two experience groups, the differ-
ences in task performance between use of the conventional
and articulating instruments were detectable but not dra-
matic (Fig. 4). Use of the articulating instrument to suture
left-to-right and up-to-down was slightly worse than use of
conventional instruments for the same tasks. The only
significant difference was in the peg transfer task, in which
use of the articulating instrument resulted in a significantly
lower score (65 ± 25) than use of the conventional grasper
(79 ± 20; p = 0.039). The difference in total scores for
Fig. 2 Articulating laparoscopic instrument
Fig. 3 Experienced surgeons showing significantly better perfor-
mance than novices in all three tasks regardless of the type of
instruments. * p \0.05
Surg Endosc (2009) 23:2697–2701 2699
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performance between the two instruments was not signifi-
cant (sum score of 75 ± 22 for the conventional vs.
64 ± 24 for the articulating instruments; p = 0.074).
When investigating surgical experience and its impact on
task performance, we found that the expert group was at a
clear advantage with their prior experience using conven-
tional instruments (Fig. 5). In the net sum of all the tasks, the
experts maintained their performance using conventional
(91 ± 5) and articulating (84 ± 7) instruments. In contrast,
the novices dropped to a larger degree in their performance
from using the conventional (59 ± 21) to using the articu-
lating (46 ± 22) instruments. However, the performance
difference in the use of the two instrument types was not
significant between the novice and expert groups due to the
large variability in the performances (p = 0.855).
Impact of short-term training on task performance using
the articulating instruments
By going through a short orientation, the participants in
both the expert and novice groups improved their
performance using the articulating laparoscopic instrument.
However, the degree of improvement was modest. The
total score before orientation was 64 ± 24) compared with
69 ± 17 after orientation (p = 0.166). The most obser-
vable improvement was in the peg transfer task (65 ± 25
before vs. 75 ± 12 after orientation, a 15% increase;
p = 0.067).
The two groups responded differently to the orientation
session (Fig. 6). The experts maintained their task perfor-
mance with hardly visible improvement (total score of
81 ± 7 before vs. 80 ± 9 after orientation, a 1%
improvement). In contrast, the novices made significant
improvement with the training session (total score of
47 ± 22 before vs. 59 ± 18 after orientation, a 27%
improvement).
Discussion
The reported data generate some interesting points. Our
first hypothesis was confirmed by the data. Adding flexi-
bility to a laparoscopic tool had some advantages in terms
of manipulations, but these advantages were at least par-
tially offset by instrument complexity. Our observation of
the initial response with the use of the articulating instru-
ment suggested that surgeons could adapt quicker to the
new instrument than a novice, which supports our second
hypothesis. We conclude that a surgical instrument with
extra DOF can be used effectively by an experienced sur-
geon. Once mastery is achieved, laparoscopic instruments
with the capability of articulating at the end effector may
even provide clinical advantages.
Operators with minimal laparoscopic experience did
have difficulty manipulating complex surgical instruments.
However, a short orientation significantly improved their
performance. The 27% improvement in scores after the
brief orientation session shows good ability of junior res-
idents and medical students to learn the use of this new
Fig. 4 Articulating instruments showing slightly worse performance
than conventional instruments. The differences, however, were not
significant except in the peg transfer task
Fig. 5 The high performance level of experts maintained between the
use of conventional and articulating instruments. The novices
performed worse with the articulating instrument than with the
conventional instrument
Fig. 6 No discernable effect of brief training with the articulating
instrument on experienced surgeons’ performance compared with
27% improvement for novices
2700 Surg Endosc (2009) 23:2697–2701
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instrument. Although this contradicts our third hypothesis,
it suggests that training in use of the articulating instrument
can be started at an early stage of surgical education. A
lack of surgical experience does not affect the acquisition
of new surgical skills for using the articulating instrument.
Further study is needed to determine the learning curve
for achieving proficiency in using the articulating instru-
ment for both the novices and experts. It will be especially
interesting to observe whether, once the learning phase is
mastered, the new devices will enable surgeons to dem-
onstrate a new level of manual skills proficiency. Another
intriguing follow-up study should compare the perfor-
mance of this flexible instrument with that of the surgical
robot in the complex and real surgical context.
The current study had some limitations. First, the tasks
included in the study were highly simulated and thus may
not represent clinical situations in which articulating
instruments are desperately needed. A good solution to this
problem is to repeat our tasks in confined spaces, such as in
a cadaver model or with a high-fidelity mannequin model.
Recently, we have observed a number of transanal endo-
scopic microsurgery (TEM) procedures performed in our
institution. The benefit of using articulating instruments
was observed when surgeons were able to make sutures in
the constrained spaces of lower rectal areas, which was
nearly impossible using the conventional rigid instruments.
Second, the short orientation served well as an introduc-
tion to the use of articulating instruments but certainly did
not confer expertise to either the experts or the novices. Our
data are insufficient for making any sound conclusion on the
learning curve for the use of articulating instruments.
Conclusion
A new generation of laparoscopic instrumentation is avail-
able that has more degrees of freedom than the conventional
rigid instruments. Although the new instruments increase the
capabilities of surgeons, their performance may be hampered
due to the complexity of the instruments. In this study,
experienced laparoscopic surgeons could quickly adapt to
the new complex instrument, but novices required extra
training to show practical improvement with the new device.
Acknowledgment We thank Cambridge Endoscopic Devices, Inc.
for supporting the device in the data collection of this study.
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  • Source
    • "Moreover, it is difficult to perform technically demanding maneuvers, e.g., intracorporeal suturing and knot tying [3, 4]. To overcome the restriction in movements, various steerable instruments (also known as deflectable, rotatable, or articulated instruments) have been developed [5–9]. The advantage of these instruments compared with the conventional ones is that they provide sideways rotations of the tip. "
    [Show abstract] [Hide abstract] ABSTRACT: Various steerable instruments with flexible distal tip have been developed for laparoscopic surgery. The problem of steering such instruments, however, remains a challenge, because no study investigated which control method is the most suitable. This study was designed to examine whether thumb (joystick) or wrist control method is designated for prototypes of steerable instruments by means of motion analysis. Five experts and 12 novices participated. Each participant performed a needle-driving task in three directions (right → left, up → down, and down → up) with two prototypes (wrist and thumb) and a conventional instrument. Novices performed the tasks in three sessions, whereas experts performed one session only. The order of performing the tasks was determined by Latin squares design. Assessment of performance was done by means of five motion analysis parameters, a newly developed matrix for assigning penalty points, and a questionnaire. The thumb-controlled prototype outperformed the wrist-controlled prototype. Comparison of the results obtained in each task showed that regarding penalty points, the up → down task was the most difficult to perform. The thumb control is more suitable for steerable instruments than the wrist control. To avoid uncontrolled movements and difficulties with applying forces to the tissue while keeping the tip of the instrument at the constant angle, adding a "locking" feature is necessary. It is advisable not to perform the needle driving task in the up → down direction.
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    • "Taking the single port access surgery for an example, surgical treatment is fulfilled through a single trans-umbilical port. Special surgical instruments are made for this type of surgery by incorporating several articulations or curvatures along its long length shaft to avoid conflictions between hands of surgeons (Martinec, Gatta, Zheng, Denk, & Swanstrom, 2009; Swanstrom, Whiteford, & Khajanchee, 2008). Surgeons learn to use these tools with a long practice phase. "
    [Show abstract] [Hide abstract] ABSTRACT: Tool use brings challenges to human movement control. Mental calibrations are constantly needed to incorporate tool properties into the movement system. This project examines the accuracy of mental calibrations and studies the impact of tool use on the movement control. Eight university students were instructed to perform a matching task using a hand-held grasper. The grasper had a changeable hinge that alters the length ratios of the tool for different trials. Throughout the matching, visual feedback regarding the hand position and tool was not available. The matching accuracy was significantly reduced when using the grasper compared to using the hand directly. This indicates that the mental calibration is not as accurate as visual or proprioception for guiding movement. No significant matching difference was observed as a function of length ratios of the grasper, suggesting similar steps were involved in the mental calibration process for one kind of tool property.
    Full-text · Article · Oct 2009 · Human Factors and Ergonomics Society Annual Meeting Proceedings
  • [Show abstract] [Hide abstract] ABSTRACT: Controlling surgical task speed and maintaining accuracy are vital components of robotic surgical skills. This study was designed to investigate the relationship between accuracy and speed for robot-assisted surgical skills. Ten participants were asked to alternately touch two circular targets with various dimensions and distances between two targets, using the da Vinci Surgical System. The design of this study was based on Fitt's law. Statistical correlations between the index of difficulty (ID) and the movement time (MT), as well as the ID and the smoothness of the movement, were analysed. A significant linear correlation between MT and ID was shown. Speed was reduced to maintain accuracy as the level of task difficulty increased. There was no significant correlation between the smoothness of the movement and ID. The trade-off between speed and accuracy plays an important role in robot-assisted surgical proficiency.
    No preview · Article · Sep 2010 · International Journal of Medical Robotics and Computer Assisted Surgery
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