Evaluation of Novel Ball-Tip Holmium Laser Fiber: Impact on Ureteroscope Performance and Fragmentation Efficiency

Abstract

A novel ball tip (BT) holmium laser fiber has recently been developed, which features a modified rounded tip. The modification is purported to aid in insertion and minimize damage to the ureteroscope working channel. We evaluated this laser fiber with regard to stone comminution, tip degradation, insertional force into the ureteroscope, and impact on ureteroscope deflection. A 242 μm BT fiber and a standard flat tip (SF) fiber were compared. Four kilojoules was delivered to a BegoStone over a constant surface area using settings of 0.2/50, 0.6/6, 0.8/8, and 1 J/10 Hz. Fiber tip degradation was measured at 1 and 4 kJ. Ureteroscope deflection was measured with the Olympus URF-P5, URF-P6, and URF-V. Insertion force into a 270° angled ureteroscope sheath model was measured. A sample size of five fibers was used for each comminution energy setting. Comminution increased with pulse energy without significant difference between fibers. No significant differences in tip degradation were observed. Both fibers reduced deflection (10°-30°) in all ureteroscopes without significant differences between fibers. Four new fibers paired with new sheath models were used to test insertion force. The BT insertion forces were approximately one-third of the SF. One SF fiber caused significant damage to the sheath and could not be advanced completely. The BT fiber has comparable comminution, tip degradation, and ureteroscope deflection performance compared with the SF fiber while exhibiting reduced insertion force within an aggressively deflected working sheath. The new tip design is likely protective of the working channel without loss of performance.