Destruction of stone extraction basket during an in vitro lithotripsy-A comparison of four lithotripters

Background: Various techniques are available for intracorporeal disintegration of renal and ureteral stones, among them ballistic lithotripsy, ultrasonic lithotripsy and laser lithotripsy. The therapeutic effectiveness of these devices has been sufficiently studied and compared. This does not apply, however, to the risk of destroying the stone basket. Materials and Methods: The time until destruction of the wires of various baskets with use of four different lithotripsy devices (LithoClast, EMS; LithoRapid, Olympus; Calcuson 27610029, Storz; Vera Pulse, Coherent) was measured in a model closely aligned with the clinic. Results: As expected, the direct application of laser pulses (wavelength 2.1 μm) irrespective of thickness and shape led to a melting of all wires of the stone extraction basket in less than 50 seconds (pulse energy: 800 mJ, pulse repetition rate: 8 hertz; fiber diameter: 365 μm). The purely kinetic functioning lithotripters (electrokinetic-ballistic and pneumatic-ballistic) were not able to destroy any wire within the set time limit of one minute. The sonotrode of the ultrasonic device, which is considered to be very tissue-conserving, separated all wires of baskets with a diameter of 1.8F (4 wires), 75% of baskets with a diameter of 2.5F (9 of 12), but only 8.3% of baskets with a diameter of 3.5F (1 of 12). Plaited wires demonstrated a good resistance (0 of 4) in comparison with the sonotrode. Conclusion: Our study consequently shows that in addition to the laser, the ultrasonic probe can also easily destroy nitinol (nickel titanium) baskets.