A prospective analysis of robotic tip cover accessory failure

The robotic monopolar scissors tip cover accessory (TCA) is an insulation device that prevents current leak from surfaces on the instrument other than the scissors tip. Reports of insulation failure and patient injury have been made but not systematically studied. We investigate the incidence of TCA failure and potential mechanisms that lead to malfunction.

Eighty TCAs (40 first and 40 second generation) were collected after a single urologic or gynecologic surgery at a single academic institution. Each TCA was inspected for damage under a microscope. Current leak was measured in an electrolysis solution, and electrical arcing was tested in a porcine kidney model. Log-rank and Friedman two-way analysis of variance by ranks compared failure at different angulations and power settings. Chi-square analysis compared failure between first and second generation TCAs (f-TCAs and s-TCAs).

Visible insulation defects were detected in 39% of f-TCAs (size range <0.5-2.75 mm). Electrical arcing was observed in 33% of f-TCAs. Arcing increased with greater wrist angulation (P=0.014) and higher power settings (P=0.048). Minor damage was observed in 25% of s-TCAs. No electrical arcing was observed in any of the s-TCAs despite angulation and power strain. s-TCAs demonstrated significantly less failure than f-TCAs (P<0.001).

In this study, 33% of f-TCAs demonstrated insulation failure after a single surgical use. f-TCA failure increased with greater wrist angulation and electrical power. The improved design of s-TCAs demonstrated no current leak or arcing on ex-vivo testing and appears to have significantly decreased failure potential. Centers still using the f-TCA should transition to the s-TCA and be vigilant in reporting device failures to prevent unnecessary patient morbidity.