Flap surgery is a plastic surgical technique which is used for treatment of skin cancers where a simple ellipse would not suffice.
The reasons for performing a flap include but are not limited to:
- the wound is too large to close using an elipse
- closing the wound with an elipse would compromise adjacent structures like the eyes, nostrils, ears or result in an asymmetry of the face that could be avoided by using a flap
- closing the wound with an elipse would result in the scar being placed in a direction that is against ideal lines of excision eg at right angles to the lines running around the neck.
Flap surgery involves moving the skin in a variety of directions depending on the technique in order to minimise tension across the wound, to minimise redundant skin removal (tissue conservation) and reposition scars to maximise the cosmetic outcome for the patient. The types of flaps used include, but are not limited to rotation flaps, advancement flaps, transposition flaps and island pedicle flaps. A knowledge of all of these types of flaps is necessary to give the best possible outcome for patients.
Rotation flaps involve moving skin through a curving arc. They are used in areas where there are natural curving lines on the skin, such as the edges of the hairline or the outer parts of the cheek. They involve cutting out the cancer in a wedge shape, like the shape of a wedge of cake, and then moving the skin in an arc to close the defect left by the skin cancer removal. They can be unilateral or bilateral.
Advancement flaps use the natural stretch present in skin to mobilise and stretch skin to cover the defect caused by removal of a skin cancer. They usually have straight lines to achieve this, and thus are used in areas where the natural skin lines are straight, such as the forehead. They can be unilateral or bilateral.
Transposition flaps include rhombic flaps, banner flaps and bilobed flaps. They involve the movement of skin over an intervening section of normal skin. Rhombic flaps use a rhomboidal shaped flap which is often trimmed to fit the defect created by the removal of a skin cancer, prior to suturing in place. Banner flaps are longer rhomboidal shaped flaps and include the nasolabial transposition flap, where skin from the nasolabial fold adjacent to the edge of the lip is used to repair defects on the side of the nose or around the nostril. Bilobed flaps involve the use of two adjacent transposition flaps, which are curved rather than rhomboidal, and are usually used to repair defects of the nasal tip.
A special form of flap is the myocutanous flap. This flap utilises the excellent blood supply to a muscle to ensure that the skin attached to the muscle remains viable when it is moved to a new location. An example of this is the myocunatous flap utilsing the nasalis muscle running along the side of the nose. Defects created by skin cancer removal on the nasal bridge or tip can be repaired using a flap with a specially created pedicle comprising the nasalis muscle, often giving excellent cosmetic repairs to the nasal bridge and tip.