Keystone design perforator island flap in facial defect reconstruction

Figure 1 Schematic illustration of traditional classifications and representative modifications of the keystone design perforator island flap. A: Type I keystone design perforator island flap (KDPIF) (skin incision only); B: Type IIA KDPIF (division of the deep fascia along the outer curvilinear line); C: Type IIB KDPIF (division of the deep fascia and skin graft to the secondary defect); D: Type III KDPIF (opposing keystone flaps designed to create a double-keystone flap); E: Type IV KDPIF (keystone flap with undermining of up to 50% of the flap subfascially); F: The Ω-variant KDPIF (defect closure in the fish-mouth fashion). Further undermining of the flap (blue-colored circle) with preserving the central hot spot of perforators (red-colored x marks); G: Sydney melanoma unit modification (maintenance of a skin bridge along the greater arc of the KDPIF). KDPIF: Keystone design perforator island flap; SMU: Sydney melanoma unit.