Assessment of a New Tipless Nitinol Stone Basket and Comparison with an Existing Flat-Wire Basket

Abstract

Flexible nephroscopes and ureteroscopes make it possible to see calculi in remote calices, but it is often impossible to remove these with existing technology. Flat-wire baskets impede deflection and can traumatize the papilla. This study compares the performance of a new 3.2F tipless nickel-titanium (Nitinol) basket with that of an existing 3.0F flat-wire basket. Specifications were compared using a 15F nephroscope and a 7.5F flexible ureteroscope in a pig kidney model. A calculus was placed in a calix, and the author and two residents were timed while using both baskets to retrieve the stone. To open fully, the flat-wire basket needed to protrude 1.2 cm further than the tipless basket. The tipless basket did not restrict deflection of the nephroscope, whereas the flat-wire basket limited flexion by 24° and extension by 28°. The tipless basket did not restrict extension of the 7.5F ureteroscope but limited flexion by 10°. The flat-wire basket limited flexion by 79° and extension by 72°. Using the pig kidney model, the three operators took a mean of 5.3, 11.8, and 6.4 seconds to catch the stone with the tipless basket. Using the flat-wire basket, the mean times were 15.3, 34.5, and 28.9 seconds (combined data: 8.2 seconds for the tipless basket and 27.8 seconds with the flat-wire basket; P = 0.0001). Only the flat-wire basket was seen to traumatize the papilla. The Nitinol tipless basket has significant advantages over the flat-wire basket.