Tipless Nitinol Stone Baskets: Comparison of Penetration Force, Radial Dilation Force, Opening Dynamics, and Deflection

Abstract

Objective: To evaluate 5 commercially available tipless nitinol baskets (2.2F) in 4 performance factors: penetration force, radial dilation force, opening dynamics, and deflection limitation.

Materials and methods: The 2.2F Coloplast Dormia No-Tip, 1.5F Sacred Heart Medical Halo, 2.2F Cook NCircle Nitinol Tipless Stone Extractor, 1.9F Bard SkyLite Tipless Nitinol Basket, and 1.9F Boston Scientific Zero Tip Nitinol Stone Retrieval Basket were tested for penetration force (safety metric), radial dilation force (functional metric for ureteral calculi), and opening or closing dynamics. Limitation of deflection (functional metric) was tested by measuring the difference in maximal upward and downward angle of deflection of a ureteroscope with and without a basket in place.

Results: The Sacred Heart Medical Halo 1.5F basket had the highest mean force required to perforate the foil at 0.676N ± 0.117 (P < .0001). The Sacred Heart Medical Halo 1.5F basket also had the highest mean radial dilation force at 3.04 g ± 0.15 (P < .0001). The Cook NCircle Nitinol Tipless Stone Extractor 2.2F had the most linear pattern of opening, whereas the Coloplast Dormia No-Tip 2.2F and the Sacred Heart Medical Halo 1.5F exhibited exponential opening dynamics. The Cook NCircle Nitinol Tipless Stone Extractor 2.2F limited scope deflection the most with a decrease in 4° downward and 10° upward. The Sacred Heart Medical Halo 1.5F had the least influence on deflection with a decrease in 3° downward and 5° upward.

Conclusion: The penetration force, radial dilation force, opening dynamics, and resistance to deflection varied between 5 commonly available tipless nitinol stone baskets. A small diameter 1.5F basket is capable of providing optimal performance while sacrificing linear opening.