Evaluation of flexible ureteroscope with an omni-directional bending tip, using a JOYSTICK unit (URF-Y0016): an ex-vivo study



To compare the range of reach of our newly designed omni-directional ureteroscope (URF-Y0016), compared to the commonly used URF-P6, FlexX2s, and LithoVue™ scopes, in the upper, middle, and lower calyces in an ex-vivo pyelocaliceal model.


We fabricated a three-dimensional pyelocaliceal model of the upper, middle, and lower pole calyces using urethane and acrylic resin. The inner surface of the dome of each calyx was engraved with reference lines along eight directions, set at 10° of latitude from the top to the base of the dome, and at angles of 0–90°, to precisely determine the range of reach of each scope. The main feature of the URF-Y0016 scope is the omni-directional bending of the tip of the flexible ureteroscope, with the control of these four directions integrated into a handgun-type control unit with a joystick. The range of reach within each calyx was measured by four expert surgeons.


The URF-Y0016 scope provided a greater range of reach along all directions in the lower pole calyx compared to URF-P6, FlexX2s, and LithoVue™ scopes (p < 0.001), particularly along the anterior–posterior direction in the lower lobe calyx. However, the URF-Y0016 scope did not influence the improvement of reach range in the upper and middle pole calyx compared to URF-P6, FlexX2s, and LithoVue™ scopes (p = 0.08, p = 0.296).


The novel design of the URF-Y0016 could improve treatment outcomes for calyceal stones in the lower pole in practice.

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Extracorporeal shockwave lithotripsy


Percutaneous nephrolithotomy


Retrograde intrarenal surgery


European Association of Urology


Stone-free rate


Infundibulopelvic angle


Infundibular length


Infundibular width


Caliceal pelvic height


Transurethral bladder tumor resection


Transurethral prostate resection


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TI: protocol/project development, data collection, data analysis, manuscript writing. SO: protocol/project development. SH: protocol/project development. HM: data collection. JM: data collection. MT: data collection. HF: protocol/project development. MF: protocol/project development. TM: protocol/project development. KN: protocol/project development.

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Correspondence to T. Inoue.

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Olympus funded, and lent the equipment for this study.

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Inoue, T., Okada, S., Hamamoto, S. et al. Evaluation of flexible ureteroscope with an omni-directional bending tip, using a JOYSTICK unit (URF-Y0016): an ex-vivo study. World J Urol 39, 209–215 (2021). https://doi.org/10.1007/s00345-020-03151-w

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  • New technology of fURS
  • Omni-directional bending
  • Joystick handle
  • Lower pole access