Practical Comparison of Four Nitinol Stone Baskets

Abstract

The use of stone baskets for repositioning of stones or removal of fragment in conjunction with ureterorenoscopy has become widespread. We tested the performance of the ACMI Sur-Catch NT, Bard Dimension, Boston Scientific Zero-tip, and Cook N-Circle in a pig kidney model of flexible ureterorenoscopy. Opening characteristics of the basket were measured with mechanical calipers at 1-mm increments and compared with published reports to ensure the tested baskets were representative. Pig kidneys were placed in a basin and the ureters secured with a suture to a weight for stability. Flexible renoscopy was performed using a 16F flexible cystonephroscope. An 8-mm calculus was placed in the lower pole. Using each of four designs, the time necessary to grasp the stone, time to release the stone, and total time to move a stone from the lower-pole calix to the upper-pole were recorded. Total time experiments were repeated six times with each basket by three surgeons for a total of 18 attempts, and catch-and-release experiments were repeated six times by four surgeons for a total of 24 attempts per basket. The Sur-Catch was significantly slower for catch and release (P < 0.001) and total time; P < 0.05) compared with all other baskets. There were no differences between the other baskets in either catch, release, or total times. There was no difference between surgeons (P < 0.0634) or between attempts one through six (P = 0.538). Baskets with added complexity of the wire configurations (Sur-Catch) or a deflectable-wire mechanism (Dimension) offer no advantages and may slow capture and release of stones.