Which is easier for beginners: supine or prone position percutaneous nephrolithotomy? Assessment of the learning curve in novice urologists through a randomized clinical trial.

Background: Percutaneous nephrolithotomy (PCNL) could be performed in both prone and supine positions. Each position has its own advantages and disadvantages. "Learning curve" is a graph that represents progress of a skill against the time needed to master the technique. We hypothesized that supine PCNL might have a shorter learning curve by novice urologists compared to prone PCNL based on the findings of previous studies assessing the learning curve of both techniques. The aim of this study is to assess the learning curve of prone and supine PCNL among novice urologists to detect which is easier for the beginners.

Methods: One hundred and fifty patients undergoing PCNL for renal stones were included and divided into two groups; Group A included 75 patients undergoing supine PCNL and Group B included 75 patients undergoing prone PCNL. Subsequently, each group was subdivided into three subgroups of 25 patients to allow the evaluation of the learning curve of the two novice surgeons as regards: operative time, fluoroscopy time, stone free rate, and complications.

Results: The mean operative time in group A decreased from of 111.8±13.91 minutes to 84.2±15.86 minutes, and thereafter, decreased to 78.4±12.97 minutes in the three consecutive subgroups. Similarly, in group B, the mean operative time decreased from 122±23.76 minutes to 110.2±17.05 minutes, and thereafter, further decreased to 82±15.34 minutes. The operative time plateau was reached after 25 and 50 cases in groups A and B, respectively. The overall stone free rate, and complications were comparable in both groups.

Conclusions: Both supine and prone PCNL are safe and effective; however, supine PCNL may be associated with significantly shorter learning curve.