title: Significance of Extraction Forces in Kidney Stone Basketing.
abstract: BACKGROUND
  Ureteroscopic stone extraction devices are effective tools in the management of urolithiasis, but on occasion, their improper use can cause injury to the ureter. Avulsion and perforation of the ureter as a result of excessive forces on the extraction device are some of the more serious complications of this treatment.
  
  
  METHODS
  In this article, avulsion and perforation forces were measured by two different test setups. Eleven clinicians were asked to apply three ranges of forces (safe, cautious, and dangerous).
  
  
  RESULTS
  The output force measurements were recorded and plotted for further analysis. The maximal average perforation forces were 7.13±2.36 N in the benchtop tests and 7.07±2.20 N in the ex-vivo porcine tests (P=0.54). The maximal average avulsion forces were measured to be 10.14±2.01 N in the benchtop tests. Although the average forces were similar in the proximal and distal parts of the ureter (P=0.27), higher values were recorded for the distal part. The operative time was noted to be significantly different in the safe and cautious force regions (P=0.006). The average forces were higher in the benchtop tests compared with the porcine ureter tests. The extraction forces were measured and were noted to be significantly different for attending physicians and residents. The results suggest the need for force feedback training for residents.
  
  
  CONCLUSIONS
  The findings can be used to design a "smart device" that can provide visual force feedback to clinicians while they are operating, leading to improved patient outcome.
authors.affiliation: 1 Department of Biomedical Engineering, The University of Akron , Akron, Ohio.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Najafi
authors.affiliation: 2 Division of Urology, Southern Illinois University School of Medicine , Springfield, Illinois.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tieu
authors.affiliation: 1 Department of Biomedical Engineering, The University of Akron , Akron, Ohio.
authors.forename: Ajay M
authors.initials: AM
authors.lastname: Mahajan
authors.affiliation: 2 Division of Urology, Southern Illinois University School of Medicine , Springfield, Illinois.
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D007396:Internship and Residency; D007669:Kidney Calculi / Q000601:surgery*; D008505:Medical Staff, Hospital; D008953:Models, Anatomic; D061646:Operative Time; D010820:Physicians; D013552:Swine; D014513:Ureter / Q000293:injuries*; D018666:Ureteroscopy / Q000009:adverse effects / Q000193:education / Q000379:methods*; D014572:Urology / Q000193:education*