The keystone flap: expanding the dermatologic surgeon's armamentarium.

First described in 2003, the keystone flap has become an established plastic and reconstructive surgery technique for the closure of soft tissue defects following the excision of skin tumors. Complex reconstruction procedures may thus be avoided [3]. In dermatosurgery, however, the keystone flap remains largely unknown.Compared to subcutaneous pedicle flaps, the keystone flap technique warrants better vascular supply by additional-ly preserving musculocutaneous and fasciocutaneous perforator vessels [4]. Moreover, the flap is hyperemic compared to the surrounding skin [5]. Adequate perfusion and its specific design result in high safety of the flap. According to both published data and the authors’ experience, the keystone flap technique is associated with a low complication rate [1, 6].In summary, the keystone flap method yields good aesthetic and functional results by preserving shape and cont-our, avoiding differences in skin coloration and preserving sensitivity (Figure 1b). The flap is particularly well suited for deep defects with exposed bones or tendons, especially on the extremities or the trunk. Alternative closing options such as secondary intention healing, primary closure, or local flaps appear less adequate in these cases. In addition, skin grafting without long-term wound conditioning–for example negative pressure wound therapy–or expensive der-mal replacement products are not very promising. Thus, the keystone flap provides the dermatosurgeon with an effective alternative to reconstruction techniques.