Answer:
The Limberg and Dufourmentel flaps are illustrated below:
Ideally, the flap is designed so that the flap donor defect can be repaired with minimal tension. The rhombic defect is then oriented around the flap. In many cases, however, the orientation of the rhombic defect is dictated by anatomical restrictions, and the flap must be modified to accommodate it. A correct Limberg flap is oriented such that the lines of maximal extensibility form its base. This is true in the Dufourmentel flap as well. For any rhombic defect, an infinite number of equilateral flaps can be generated to correspond to the line of maximal extensibility.
Burow devised a method of excising triangles to remove redundant skin folds and permit the advancement or rotation of a skin flap.
The Crane principle was described by Millard in 1969. The idea is to “lift, transport and deposit subcutaneous tissue as a cover for bare bone, joints, tendons, and other vital structures.” A pedicled flap is applied to the defect, left in place for 7 days, shaved off leaving a thin layer of subcutaneous tissue and returning the bulk of the flap to the donor site. After 5 days, the wound granulates sufficiently to receive a skin graft.
An advancement flap moves directly forward into a defect without any lateral movement (e.g V-Y advancement flap). Transposition and rotation flaps have a pivot point at the base of the flap and an arc of rotation whose radius is under the greatest tension. The transposition flap is usually rectangular or square and located immediately adjacent to the defect (e.g. Limberg). A rotation flap is a semicircular flap, often with a circumference 5-8 times the width of the defect. An interpolation flap is taken from a nearby, but not immediately adjacent, donor site and moved either above or below the intervening skin to the defect (e.g. median forehead flap).