Mohs Micrographic Surgery Design and Execution of Advancement Flaps

Surgery of the head and neck results in seemingly countless defects that often require complex closures due to the limited amount of skin laxity or redundancy in these areas. Surgical flaps can facilitate the repair of defects that cannot be closed linearly due to suboptimal function or cosmesis. Advancement flaps offer various closure methods for large defects in a safe, effective, reproducible, and often straightforward way. While there are many subtypes of the advancement flap, there is often an uncomplicated, unidirectional movement of the leading edge of the flap over the defect being repaired. After the leading edge is sutured into place, tissue redundancy manifests along the margins of the flap. These redundancies can be excised, or the rule of halves allows for suture placement so that the redundancies will be equally dispersed along the length of the suture lines. The advancement flap differs from other closures, such as rotation or transposition flaps, because the tension vector of the advancing flap remains parallel to the primary motion of the flap. This limits the ability for wound tension to be redirected to a favorable axis. Caution must be exercised when considering an advancement flap in areas where anatomical distortion is undesirable, as the insertion point of the advancement flap will always have some degree of secondary motion.   Once in place, advancement flaps are initially sustained by dermal and subdermal vascular plexuses. As the flap incorporates into the surrounding tissue, neovascularization provides a permanent arterial supply. Through neovascularization, a new arterial supply will support the flap permanently. Before selecting a flap technique, it is crucial to have confidence that the chosen flap will yield optimal functional results for the patient and achieve the desired cosmetic outcome.