Transposition Flaps

Excerpt

Flap-based tissue transfer, commonly involving skin or mucosa, is a key method in reconstructive surgery for achieving wound closure. Flaps are especially useful when closure through secondary intention, primary linear closure, or skin grafting is either not feasible or would result in suboptimal functional or aesthetic outcomes.

Flaps are classified primarily by their blood supply. Axial flaps derive their blood supply from a specific, named artery running longitudinally through both the flap and its pedicle. In contrast, random pattern flaps depend on the dermal and subcutaneous vascular plexus for perfusion and venous drainage.

Flaps may also be grouped based on the relationship between the harvest site and the defect. Free flaps involve harvesting tissue from a distant site, transferring it to the wound, and revascularizing it through microsurgical anastomoses. Regional flaps move nonadjacent tissue near the defect into the wound while maintaining a vascular pedicle for perfusion. Local flaps transfer tissue adjacent to the defect to repair the wound. Generally, free and regional flaps are supplied by axial blood vessels, while local flaps are typically perfused through random pattern blood vessels.

Local flaps are further subdivided based on their primary movement. Advancement and rotation flaps, also known as sliding flaps, recruit adjacent tissue and move in a linear or arced motion, respectively, to fill the primary defect. Transposition and interpolation flaps, also referred to as lifting flaps, involve incising and shifting noncontiguous donor tissue to replace intact tissue, thereby closing a wound.

Common transposition flaps in cutaneous surgery include bilobed, rhombic, nasolabial (melolabial) flaps, and Z-plasties. These flaps are particularly useful for defects near the medial and lateral canthi, cheeks, and the lateral upper 2/3 of the nose, but they also have a well-defined role in lateral forehead, temple, perioral, inferior chin, and dorsal hand defects. Interpolation flaps, such as the paramedian forehead flap, involve transferring nonadjacent tissue across or underneath intact tissue that remains undisturbed by the procedure. Due to this topology, interpolation flaps are usually more accurately classified as regional flaps.

Ultimately, the exact nomenclature of a local flap is less important than its topology and physiology. Additionally, many of the same principles applied to the design of local flaps may also be applied to larger, regional flaps with axial blood supplies. Examples include propeller transposition flaps in the extremities, omental transposition flaps in the abdomen, and muscular transposition flaps in the pelvis and breast. Many application-specific, named transposition flaps exist, such as the Estlander lip-switch flap for lip reconstruction, the Furlow double-opposing Z-plasty for cleft palate closure, and the Fricke lid-switch flap for eyelid repair. This article will focus on the more generally applicable types of local transposition flaps as they pertain to facial surgery.