SHORT COMMUNICATION

Postural mechatronic assistant for laparoscopic training

A. MINOR MARTINEZ1, R. MUNOZ GUERRERO1, J. NIETO1 & R. ORDORICA FLORES2

1Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Ingenierıa Electrica Seccion de Bioelectronica,

Mexico City, Mexico, and 2Hospital Infantil Federico Gomez, Mexico City, Mexico

AbstractIn this article we describe a new concept for manipulating a laparoscope during surgery training. The methodology ofhandling and navigating of the laparoscope suggested depends on the position of the surgeon’s body, assisted by amechatronic system with three degrees of freedom.

Key words: Laparoscopic surgery, mechatronic surgery assistant training, endoscopy, surgery mechatronic assistant

Introduction

Laparoscopic surgery is considered as a technique for

the new millenium and has been established as a useful

alternative to open surgery because it is associated with

less morbidity and shorter hospitalization times.

To acquire the specific psychomotor skills neces-

sary for this procedure a surgeon has to practice

constantly with animal models and human corpses

(1). However, the psychomotor skills could be

trained more effectively if the conditions of the

training experiences were similar to those met with

in real laparoscopic surgery (2,3). In real laparo-

scopic surgery the optical perspectives of objects

frequently change depending on the distance and

closeness within the organs. In daily sessions with

animal models, we normally use a still camera and

only if there is another assistant the pespective can

be modified in real time through changing observa-

tion points. Another alternative is the use of a robot

as a training assistant, but the costs would be higher

(4,5). In this article we propose a new auto-assisted

training system that may be very useful to increase

the psychomotor skills of the laparoscopist.

Material and methods

We used a training box to simulate the surgical

space. To manipulate the laparoscope along with the

visual perception, we propose a mechatronic assis-

tant with three degrees of freedom. This mecha-

tronic device is made of aluminum and weighs

2.5 kg, including laparoscope and camera. This

system consists of a harness that is placed over the

surgeon’s shoulders (Figure 1). The first degree of

freedom is subject to the harness and is the active

part, while the other two degrees are the passive

ones. The end of the whole part is attached both to

the laparoscope and to the camera, with a device

called laparoscope holder; this can be easily removed

manually. To make movements inside the training

box, this mechatronic system uses a supporting point

and movement to the port of entry from the

laparoscope to the training box.

To navigate the laparoscope, we need six

basic movements: Up, down, in, out, to the left,

to the right. To perform any of these movements

inside the space along with the harness, the surgeon

will use the following techniques: For the right and

left movements of the laparoscope, it is advisable to

use lateral body movements along with the last

passive link of the system (Figure 2a). A more

valuable movement can be achieved through a

partial change in the lateral posture of the surgeon’s

torso.

There are two ways to insert or remove the

laparoscope: Either the surgeon moves his/her torso

close to or away from the training box, or he/she uses

Correspondence: A. Minor M., Centro de Investigacion y de Estudios Avanzados del IPN, Av. IPN 2508, C.P. 073000. Mexico City, Mexico. E-mail:

aminor@cinvestav.mx

Minimally Invasive Therapy. 2005; 14:6; 357–359

ISSN 1364-5706 print/ISSN 1365-2931 online # 2005 Taylor & Francis

DOI: 10.1080/13645700500381818

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his/her entire body to perform these movements

(Figure 2b).

The angle of entry or exit of the laparoscope for

the up and down positions inside the box is obtained

with the assistance of the lineal electromechanical

guide and the second passive link along with the near

and far position of the surgeon’s body to the point of

insertion as illustrated in Figure 2c. The active

degree of freedom is moved in both ways using two

pedals that are available at the surgeon’s feet. To

make mixed movements, the surgeon moves his/her

body through visual perception.

Results

The system and its operation was tested in the

training box, carrying out dissection and sutures on

pieces of chicken tissue, using 0˚ optics. To establish

a combined valuation of the system these tests were

carried out separately by two expert surgeons and

two students in the last year of the specialty.

For both students, a lack of coordination was

observed at the beginning between the system and

the hand-eye coordination. After approximately five

minutes, this limitation was overcome. It was also

observed that in both cases the use of the pedal

partially distracted the visual attention and the

concentration during the training. The expert

surgeons, on the other hand, demonstrated an

immediate intuitive sailing and a natural joining

with the system. It was observed, although to a lesser

degree, that the handling of the pedals took away

minimal visual attention. For the four cases, the

laparoscope’s direct command advantages were

observed, first, by showing the availability of the

visual perspective changes in real time and keeping

the hands free to carry out the training. There was

absolutely no tremor in the image. The complete

system produces a working space in form of a

partially overturned cone, facing the surgeon’s body

(Figure 3); due to this, the 0˚ optics adapts naturally

to the training, although it is not limited for any

other optics. The PMAT laparoscope holder holds

but does not immobilize the optics, thus optics other

than 0˚ can be used, but such changes should be

carried out manually.

Discussion

There are some other electromechanical systems

that can be useful for the self-training in this medical

specialty. Active systems such as the AESOP (6)

robot, the Endoassist (6,7), the Tonatiuh (8), and

the Fips (9) describe an overturned cone as a

working space from any surgeon’s point of view.

Thus it is possible to carry out a complete visual

journey for the training from any optics. However,

(a) (b)

Figure 1. Postural Mechatronic Assistant: (a) design, (b) current prototype.

Figure 2. Movements: (a) right and left , (b) in and out, (c) up

and down.

358 A. Minor Martınez et al.

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the costs are limitative, and the temporary delay

during resetting represents another disadvantage.

With another view of a different design, passive

systems such as the Passist (10), the Tiska (11) and

the Endofreeze (12) can be used for the same

purpose, but their resetting has to be done manually;

due to this, they do not have the changes of visual

perspective ‘‘dynamics’’ as those that are part of real

surgeries, and this might partially limit the training

objective. We consider that our new tool of training

could be a good alternative to acquire more surgical

skills in laparoscopic procedures.

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Figure 3. Simulation of the working space of the PMAT using

Visual NastranTM.

Postural mechatronic assistant for laparoscopic training 359

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