Classification of Flaps

Authors: Liv Schöllhammer, MD, Christian Kaare Paaskesen, MD, Frederik Gulmark Hansen, med.stud. and Magnus Balslev Avnstorp, MD

Facial flaps can be fundamentally categorized based on three different principles.

Vascular supply

The vascular supply is a key determinant in flap design, as adequate blood flow is essential for survival. Flaps can be classified into:

• Arterial flap: Based on a specific artery, including multiple tissue layers.
  • Axial flap: Supplied by a named artery running in the subcutaneous tissue, e.g., the supratrochlear artery for the paramedian forehead flap.
  • Perforator flap: Supplied by a named artery that perforates a muscle to reach the overlying tissues, e.g., the Deep Inferior Epigastric Perforator (DIEP) flap.
  • Free flap: Involves cutting the artery and vein, moving the flap to another region, and reconnecting vessels microsurgically, e.g., the Anterior Lateral Thigh (ALT) flap frequently used in lower leg reconstruction.

• Random flap: Relies on interconnecting subdermal plexuses from deeper musculocutaneous arteries.

Tissue to be Transferred

A flap can be classified according to the layers of tissue it contains. It may consist of a single type of tissue, such as skin, muscle, or visceral tissue, or multiple types, which are referred to as composite flaps.

• Random skin flap: Composed of skin and a layer of subdermal tissue, with its blood supply depending on random subdermal plexuses, e.g., the nasolabial flap.

• Direct cutaneous arterial flap (Axial flap): Includes skin and subdermal plexuses, and is based on a named subcutaneous artery running parallel to the skin, e.g., the paramedian forehead flap.

• Fasciocutaneous flap: A composite flap that includes skin, subdermal tissue, and fascia. It can be classified as either axial or perforator.

• Musculocutaneous flap: A composite flap composed of skin, subdermal tissue, and muscle. It may be based on one or more perforators, and can be either axial or perforator in classification.

The Geometrical design

Geometrical flap designs include rotation, transposition, and advancement flaps.

To learn more about these designs, their practical applications, and case studies, please proceed to the chapters in the left hand menu.

Acknowledgements

Illustrators: Emma Tubæk Nielsen, med.stud.