text: Flap classification and survival factors. Current concepts.
  Flap survival variables are different for each type of flap and for each anatomic location. One must have sound knowledge concerning tissue survivability for all types of flaps. Otherwise, a high rate of failure may be experienced. A thorough knowledge of blood flow patterns of the foot and leg is paramount, as well as insight to the basic fundamental concepts concerning flap mechanics. These fundamentals include delay phenomenon, designing flaps, length-to-width ratios, and evaluation of flap vascularity. Successful and appropriate use of flaps in the lower extremity can be rewarding and provide the surgeon with a powerful tool to use in reconstructive procedures. Inappropriate or poorly performed flap procedures often create situations that are more difficult to manage than the original problem. According to Hoopes, "flaps are vicarious, mischievous, and frequently insubordinate reconstructive agents. They demand thorough understanding and meticulous attention for successful employment." Therefore, judicial use of these procedures is recommended.