title: The Learning Curve for Flank Percutaneous Nephrolithotomy for Kidney Calculi: A Single Surgeon's Experience.
abstract: OBJECTIVE
  Percutaneous nephrolithotomy (PCNL) is conventionally conducted in the prone position. However, the prone position increases anesthesia-related morbidity and position changes lengthen the operation time. We report perioperative outcomes and the learning curve for flank PCNL on the basis of a single surgeon's experience.
  
  
  METHODS
  This study investigated 53 cases of flank PCNL performed for renal stones at our institution from April 2008 to September 2010. We compared mean operative time, stone-free rate, drop in hemoglobin level, length of hospital stay, complications, and need for additional procedures after the surgery. The 53 cases were divided into three groups by case number to compare therapeutic effect, stability, and the learning curve for flank position PCNL.
  
  
  RESULTS
  The mean operation time for the 53 patients was 97.3±43.1 minutes. The mean operation time gradually decreased as the surgeon accumulated experience. From the 36th case, the mean operation time showed a statistically significant decrease to 72.2±24.1 minutes (p=0.003). The overall stone-free rate was 64.2% for all procedures (range, 61.1-76.5%). There were no significant differences in the drop in hemoglobin level, stone-free rate, re-treatment, hospital stay, or complication rate. There was no injury to the bowel or renal vessels, and no other major complications occurred.
  
  
  CONCLUSIONS
  Flank PCNL can be used to remove renal stones effectively while overcoming the disadvantages of the existing prone position PCNL. After 36 cases, the learning curve showed acquisition of surgical competence. The clinical experience reported here suggests that flank PCNL is a safe and feasible technique.
authors.affiliation: Department of Urology, Urological Science Institute, Yonsei University Health System, Seoul, Korea.
authors.forename: Won Sik
authors.initials: WS
authors.lastname: Jang
authors.forename: Kyung Hwa
authors.initials: KH
authors.lastname: Choi
authors.forename: Seung Choul
authors.initials: SC
authors.lastname: Yang
authors.forename: Woong Kyu
authors.initials: WK
authors.lastname: Han