Increased Efficiency in Spontaneously Passing Kidney Stones Using a Novel Ureteral Double-J Stent

Abstract

Kidney stones are stiff deposit minerals formed in the kidneys. In patients with kidney stones disease, double-J stents are used to increase the openness of the ureter in case of blockage by the kidney stones. The stent surfaces are normally smooth with symmetric friction along the longitudinal axis. In this work, we show that a modified double-J stent with asymmetric friction surface facilitates passage of stone fragments after extracorporeal shock wave lithotripsy or trans ureteral lithoclast. To examine the effect of asymmetric friction on the stone passing efficiency, finite element simulations were conducted. Simulation results revealed that at excitation vibration frequency of 0.15 Hz the stone unidirectionally moves along the stent at an average speed of 0.03 cm/s which is a significant increase compared to the clinical reports. Practically, the asymmetric friction can be made by laser micro-engraving techniques such as the same method in CD writing.