#AUA14 - Simulating friction-force interaction between endoscopic instrumentation and the ureter - Session Highlights

ORLANDO, FL USA (UroToday.com) - Motor memory, established by proper tissue-tool interaction, is an important component of learning a psychomotor task. The University of Minnesota SimPORTAL kidney ureter models are validated, used widely across courses for ureteroscopic skills training, and are developed to simulate the anatomy and physical appearance of ureteroscopy. The objective of this study was to examine and replicate the friction-forces involved in ureteroscopy and compare the new models with this gold standard.

auaExperiments were completed to objectively quantify frictional interaction between “fresh” ex-vivo human ureters and synthetic material and endoscopic instruments. An access sheath or ureteroscope was placed in a water bath, clamped to a single arm of a biaxial tensile testing system, and pulled through the simulator material or human ureter. This simulated the sliding motion of the endoscope through the urinary tract. Additional force sensors were placed at the point of contact between the instrument and material or human ureter, allowing for calculation of relative coefficient of friction using the force data. Based on this data, the most ideal material formulations were chosen for integration into a new kidney-ureter model. This model was compared with the current gold standard by 4 blinded experts, including 3 attending urologists and 1 chief urology resident.

Luminal material used in the new version of the model had a 3% difference and 83% difference in kinetic coefficient of friction compared to human ureter for the access sheath and ureteroscope, respectively. Luminal material used in the gold standard version had a 76% difference and 127% in kinetic coefficient of friction compared to human ureter for the access sheath and ureteroscope, respectively. The differences in the new version were not statistically significant, but differences in the gold standard were statistically significant. Three out of 4 study participants found that the new version of the model more accurately represented the frictional forces used during actual ureteroscopy. Three out of 4 blinded participants preferred the new version.

The study group designed an improved gold standard model for training of ureteroscopy that accurately represents frictional interactions between endoscopic instruments and simulator model luminal material with evidence provided by quantification of kinetic coefficient of friction and subjective evaluation by subject matter experts.

Presented by Lauren Poniatowski, MD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA

Minneapolis, MN USA

Written by Achim Lusch, MD, University of California (Irvine), and medical writer for UroToday.com