57.11 Some of the simpler flaps

If you cannot bring the skin edges of a patient’s wound together, an alternative to grafting it is to use a local skin flap which will wear better and look nicer than a graft. Flaps, even local flaps, are not as easy as split skin grafts, and are for the careful, caring operator who: (1) is unable to refer patients who need them, and (2) has enough time to plan and do them well.

Severe contractures (as from burns), or defects in important areas (such as the head and neck), or pressure sores in paraplegics, are often best managed by a myocutaneous flap. This is a single stage procedure in which a muscle and its overlying skin are moved to fill in the defect. For example, pectoralis major can be used on the face, or biceps femoris for a trochanteric ulcer. These methods are not described here so you will have to refer patients who need them. The most complex flap described here is the groin flap for the back of the hand (75.27).

Local flaps combine the principles of sliding, rotation, and transposition with a little ingenious geometry. The great danger in any flap is that its arterial and venous supply will not be adequate, so that it breaks down—venous obstruction easily kills a flap. As a general rule, never make any flap longer than its base—the 1:1 ratio.

(1) A sliding flap

may be possible if a patient’s skin is fairly elastic. If it is, you may be able to undercut the edges of his wound and slide the skin over it, as in Figures 57-15 and 54-6. This is easier on some parts of the body than on others, for example, it is be easier on the back of the hand than on its front.

(2) A rotation flap

requires that you make the defect into a triangle, and then swing the skin around. It has to rotate on a pivot point, the radius of the arc of rotation being the line of the greatest tension, as in Fig. 57-16. You can only use rotation flaps on skin which has a good blood supply. They are particularly useful on the scalp, as in Figs. 63-13 and 63-15, but are unsuitable below the knee where the blood supply is poor. You can easily overestimate the elasticity of the skin, so make a rotation flap three times bigger than you think will be necessary.

MAKE A ROTATION FLAP THREE TIMES BIGGER THAN YOU THINK IS NECESSARY

(3) A transposition flap

is made by moving a rectangle or square of skin and subcutaneous tissue on a pivot point to cover an immediately adjacent defect, as in Fig. 57-17. Make sure the end of the flap extends beyond the defect, as in this figure, and plan it carefully before you cut.

(4) A single pedicle advancement flap

is done by moving skin as in Fig. 57-18. Excise the triangles as shown to equalize the length of the flaps and the adjacent wound edge.

(5) A double pedicle advancement flap

requires an incision parallel to the long axis of the defect. Undermine the skin between the incision and defect, and advance the skin to cover it, as in Fig. 57-19.

(6) A Y–Y advancement

is useful if there is plenty of elasticity available across an incision, and you want elasticity up and down it. Do it by sewing up a V-shaped incision as a Y. Abundant elasticity across a wound is unusual, and even if it is present, it only provides a moderate amount of extra skin down the length of an incision. So don’t overestimate what you can do.