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Page 4 of 8 Riaz et al. Mini-invasive Surg 2018;2:28 I http://dx.doi.org/10.20517/2574-1225.2018.41

Laparoscopic grasper
Laparoscopic port, 5 mm
Two-tier shoe rack Neoprene sheet

Electronic weighing scale

Figure 3. Home-made laparoscopic task setup

Mouth of grasper

Piece of raw neoprene

Figure 4. Mouth of grasper was locked to hold the piece of neoprene

Task
Each candidate was required to conduct a pulling action, applying a predetermined target force. The target
force remained consistent in both groups and its numerical value was not disclosed to candidates. They
were allowed to position themselves in their own comfortable standing. They were not in sight of the
electronic weighing scale.

Target force
The electronic weighing scale in this study used measurements up to 40 kg, and poorly detected those
under 0.5 kg. For the purposes of this study, the target force applied was measured in kilograms. Different
human organs have different connective tissue strengths resulting in multiple target forces required to
cause a tear. Although, it was beyond the scope and limitations of this study to check target forces on
human tissue; nevertheless, to have a general idea about the laparoscopic pulling target force, a small-scale
experiment was conducted on a pig’s gall bladder with the same electronic scale. Twenty fresh gall bladders
of adult pigs were acquired to check their wall strength. It was concluded that an average maximum
pulling force beyond a mass of 1.1 kg was the tearing point of the pig’s gall bladder tissue. Hence, the target
force was set at 1kg for all participants, with an upper limit of 1.1 kg and a lower limit of 0.5 kg.

Kinaesthetic training
Each subject went through 5 attempts of kinaesthetic training, with both hands each. It started with the
dominant hand, consisted of conducting five pulling motions with verbal feedback from the observer
to notify when the target force has been reached. It was decided that under-traction of tissue was more
acceptable than over-traction; therefore, if target value was exceeded, participants were notified to
immediately restart the pulling motion.