NAPLES, FLA. Muscular flaps that supply soft tissue volume and a good vascular supply can provide some of the best cosmetic results in the reconstruction of Mohs surgery facial defects that penetrate to bone or cartilage, speakers said at the annual meeting of the American College of Mohs Surgery.
▸ Muscular hinge flaps. These flaps are useful for replacing soft-tissue volume in deep defects that may extend to bone or cartilage and require coverage with a full-thickness skin graft for practical or functional reasons, said Dr. Neil J. Mortimer, a Mohs surgery fellow at the Skin Centre in Tauranga, New Zealand.
"These are generally defects where you'd want to choose a full-thickness skin graft repair over other reconstructive options," Dr. Mortimer pointed out.
Since reconstruction of the vermilion of the lower lip with a simple mucosal flap would leave a substantial loss of volume, Dr. Mortimer recommended the use of orbicularis oris hinge flaps. A flap from the underlying orbicularis muscle is dissected out laterally and is then turned back or hinged into the defect.
"We've found from experience that if the surgical defect is deeper than a millimeter or so, it's useful to dissect these flaps from both sides and overlap them in the defect," Dr. Mortimer said.
Deep defects on the nose can be reconstructed with flaps derived from the superficial nasalis musculoaponeurotic system without causing a functional compromise. The flap can be dissected by separating it from its superior and inferior attachments to work as a simple hinge. These flaps can be unilateral or bilateral.
Frontalis hinge flaps can resurface exposed bone on the forehead. Postauricular defects with exposed partial-thickness cartilage can be repaired with an auricularis posterior hinge flap, which carries a good vascular supply from the auricular branch of the posterior auricular artery, he said.
▸ Galeal hinge flap. "This is a reconstruction that we found particularly useful for repairing defects of the scalp, extending to bone, as a single-stage procedure," said Dr. Matthew Halpern, a fellow in procedural dermatology at Columbia University, New York.
The galea aponeurotica is a strong, inelastic fibrous sheath situated between subcutaneous and loose areolar tissue that covers the calvaria and represents the tendinous connection between the frontalis muscle anteriorly and the occipitalis muscle posteriorly.
In constructing the flap, the galea is lightly scored so that it can be advanced and hinged over the top of the exposed periosteum. A galeal hinge flap is different from a muscular hinge flap because the galea is relatively inelastic, so defects often require bilateral flaps for coverage of the exposed bone. The galea also is thin and will not make an overall change in wound depth.
Dr. Halpern places full-thickness skin grafts on top of the galeal hinge flap to close the rest of the wound. He uses local anesthesia for the whole procedure.
▸ Nasalis myocutaneous island pedicle flap. This flap can be used to repair defects that cover two anatomic units on the nosethe ala and sidewallwith the alar groove as an anatomic boundary line. It can be used in place of a full-thickness skin graft, an island pedicle flap from the side, or a medially based cheek-to-nose transposition flap, said Dr. Robert J. Willard, a Mohs surgery fellow at Brown University, Providence, R.I.
The flap is made superior to the defect, with wide undermining to provide mobility and avoid pin cushioning. The first key sutures are made by stitching the lateral and medial aspects of the leading edge of the flap anteriorly and posteriorly to the origin of the alar groove. The leading edge of the flap is aligned with the alar groove, which recreates the anatomic boundary. No sutures are placed at the inferior portion of the defect since this would create a vertical tension vector and risk alar elevation.
Placement of a guiding suture roughly parallel to the alar rim in the residual alar portion redirects the tension vector to avoid alar elevation while the residual alar defect heals by second intention, he said.