Novel Biocompatible Adhesive to Remove Stone Dust: Usability Trial in a Kidney Model

"Clinically insignificant residual fragments" are an independent predictive factor for recurrence of nephrolithiasis. To improve the stone-free rates (SFR), we tested the viability of a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments <1 mm in a kidney model. All procedures were performed in a standardized setting, including a kidney model (Kidney module right, Samed GmbH, Dresden) in a plastic basin filled with water. We used a Viper URF flexible ureterorenoscope (fURS) (6.6/8F, Richard Wolf, Knittlingen). A mean amount of 138 mg (standard deviation [SD] ±32.2 mg) of sand grains (range, 0.2-0.8 mm) was inserted in renal calices of the kidney model. We assessed the extraction efficacy of fURS using the bioadhesive system. In total, eight different surgeons performed each one trial, respectively. The endoscopic and macroscopic SFR, the level of the surgeons' experience, and the overall time of stone retrieval were evaluated. Additionally, a survey of the participants was conducted, to assess the contentment with this novel system. The extraction of the sand grains was only possible using the bioadhesive system, otherwise they were too small sized to grab with a retrieval basket. The total SFR was 84% (SD ±11.7%). The operation time (p = 0.052) and the percentage of extracted sand grains (p = 0.194) were not significantly different between experienced and less experienced surgeons. All participants stated that it was a promising technique, which they could imagine using on a daily basis. The bioadhesive system improves the SFR with fragments from 0.2 to 0.8 mm (0% vs 84%). Also, the performance of this operation is not dependent on the surgeon's experience level. This method might improve the SFR in difficult anatomic conditions, that is, lower calices or anomalous kidneys.