Randomised comparison of two skin preparation methods in foot and ankle surgery

Foot and ankle surgery has an increased incidence of post-operative surgical site infections. The aim of this study was to examine the efficacy and efficiency of an alternative method of surgical site preparation for foot and ankle surgery.

Fifty-one volunteers were recruited for this study which compared standard gauze painting using 2% chlorhexidine with 70% alcohol to immersion of the foot and ankle in a non-sterile bag filled with 60mL of the same solution and rubbing all skin surfaces (bag immersion method). Each method was applied to different feet of each volunteer in a randomised order. Commercially available impression agar slides were used to measure bacteria colony-forming-unit (CFU) counts from four areas of each foot after allowing the preparation to dry. Outcomes included CFU count and preparation time.

There was no difference between the methods in terms of CFU count (0 total CFU vs. 1). Preparation time was significantly shorter for the bag immersion method (63.98s vs. 67.98s). Two-side 90% confidence intervals (2.03-6.00) for the difference in means of preparation time demonstrated equivalence using a margin of ±20%.

The bag immersion method is a valid alternative, equivalent in preparation timing and the elimination of transient skin flora when using 2% Chlorhexidine with 70% alcohol.