Validation of a novel cost effective easy to produce and durable in vitro model for kidney-puncture and PNL-Simulation.

Introduction: Nephrolithiasis is one of the most common diseases in urology. According to the EAU Guidelines, a percutaneous nephrolitholapaxy (PNL) is recommended when treating a kidney stone >2cm. Nowadays, PNL is performed even for smaller stones (<1cm) using miniaturized instruments. The most challenging part of any PNL is the puncture of the planned site. PNL-novice surgeons need to practice this step in a safe environment with an ideal training model. We developed and evaluated a new, easy to produce, in vitro model for the training of the freehand puncture of the kidney. Materials and Methods: Porcine kidneys with ureters were embedded in ballistic gel. Food coloring and preservative agent were added. We used the standard imaging modalities of X-ray and ultrasound to validate the training model. An additional new technique, the iPAD-guided puncture, was evaluated. Five novices and three experts conducted 12 punctures for each imaging technique. Puncture time, radiation dose, and number of attempts to a successful puncture were measured. Mann-Whitney-U, Kruskal-Wallis, and U-Tests were used for statistical analyses. Results: The sonography-guided puncture is slightly but not significantly faster than the fluoroscopy-guided puncture and the iPAD-assisted puncture. Similarly, the most experienced surgeon's time for a successful puncture was slightly less than that of the residents, and the experienced surgeons needed the least attempts to perform a successful puncture. In terms of radiation exposure, the residents had a significant reduction of radiation exposure compared to the experienced surgeons. Conclusion: The newly developed ballistic gel kidney-puncture model is a good training tool for a variety of kidney-puncture techniques, with good content, construct, and face validity.