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Friction dynamics of trocars
J J van den Dobbelsteen1, A Schooleman, J Dankelman
1Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, NL-2628, CD, Delft, The Netherlands. j.j.vandendobbelsteen@tudelft.nl
Surgical Endoscopy
|December 14, 2006
Summary
Friction in surgical trocars varies with type and movement. Reducing friction by altering sealing caps or lubrication can improve surgical precision.
Area of Science:
- Surgical Engineering
- Biomechanical Engineering
- Minimally Invasive Surgery
Background:
- Friction in surgical trocars affects force feedback during tissue manipulation.
- The influence of different trocar sealing mechanisms on friction forces remains unclear.
Purpose of the Study:
- Investigate dynamic friction changes in various trocars at different instrument velocities.
- Determine how trocar sealing mechanisms impact friction forces.
Main Methods:
- Measured friction forces using a force sensor on a 5-mm grasper moving through six common trocar types.
- Controlled instrument velocity and direction with a servomotor.
- Assessed the effect of shaft moistening on friction reduction.
Main Results:
- Friction varied from 0.25 to 3.0 N, depending on trocar type, velocity, and direction.
- Narrow or thick sealing caps generated higher friction.
- Moistening reduced friction by 15-45%; significant force fluctuations occurred during movement initiation and reversals (0.2-2.5 N).
Conclusions:
- Trocars can generate friction comparable to instrument-tissue interaction forces.
- Friction fluctuations at movement reversals, due to sealing mechanism deformation, can impair surgical performance.
- Modifying sealing cap properties or lubricating instruments can reduce friction magnitude and variance.
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