Optimal Timing of Preoperative Skin Preparation with Povidone-Iodine for Spine Surgery: A Prospective, Randomized Controlled Study

STUDY DESIGN: A prospective, randomized, controlled study. PURPOSE: The objective of this study was to evaluate the effectiveness of two techniques of skin preparation with povidone-iodine. OVERVIEW OF LITERATURE: Preoperative skin preparation is important for preventing surgical site infection by reducing the bacteria in the surgical area. Povidone-iodine is a commonly used agent for preoperative skin preparation, and further decrease in surgical site infections can be expected by understanding how to apply it more effectively. METHODS: Eighty-nine spine surgery patients were randomly allocated to two groups. In group A, povidone-iodine was applied to the surgical site just before starting the operation; in group B, povidone-iodine was applied several minutes prior to starting the operation and was allowed to dry. We collected samples from the wound edge before suturing, and we compared the rates of positive culture between the two groups. RESULTS: The rate of positive culture was 30.2% (13 out of 43 patients) in group A, and 6.5% (3 out of 46 patients) in group B. This indicates that there was a significant difference in postoperative infection rates between group A and group B. CONCLUSIONS: Because bacteria on the skin appeared significantly reduced by allowing povidone-iodine to dry for several minutes prior to surgery, we recommend this approach to reduce the incidence of postoperative infections.