Ureteral avulsion is the most dreaded situation for any urologist to be faced with. Although uncommon, with rates of ureteroscopy on the increase, the potential for this serious complication should also be recognised. To avoid such serious complications, smart devices could play a significant role in preventing problems. A suitable device is one, which transmits feedback from the tip of the instrument, through the surgical tool and back to the surgeon. The engineering department at the Univeristy of Akron, Ohio, measured extraction and injury forces during ureteroscopy and stone basketing in benchtop and ex vivo porcine ureters performed by two experienced surgeons and nine trainees. Results were measured using a miniature load cell and recorded by an automated data acquisition system to establish the forces required to cause injury and perforation. The results suggested that maximal average perforation forces were 7.13N in the benchtop tests and 7.07N in the porcine model. The maximal average avulsion forces were measured to be 9.98N in the benchtop tests. Interestingly, lower forces are required to cause injury in the proximal ureter implying a natural vulnerability to the proximal ureter. Future developments could involve advancements in simulation and in vivo ureteroscopy devices with ‘smart technology’ to provide visual force feedback to clinicians while they are operating. 

Significance of extraction forces in kidney stone basketing.
Najafi Z, Tieu T, Mahajan A, et al
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Hamid Abboudi

Imperial College Healthcare NHS Trust.

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