RESUMEN
We evaluated the rate of postoperative wound infection following the use of one or two knives for incision. The infection rate in 277 patients who were operated on with one knife was 3.6%, in 309 patients who were operated on with two knives the rate was 5.5%. This difference was not statistically significant. The limit of a one-sided confidence interval bound from the estimated difference of infection rates in the two groups of patients was 0.94% at a confidence level of 0.95. Thus, if there was any difference at all in favor of two knives with respect to infection, it was probably less than 1%. The present results indicate that the old surgical practice of discarding the skin knife and using a separate scalpel for the deep incision can be abandoned without increasing the risk of wound infection.