Introduction

The literature is replete with descriptions and various classifications of flaps. This ample classification can be confusing. The intent of this chapter is to provide a brief clarification of the systems commonly consulted for classification of skin and muscle flaps. The chapter is not intended to be a treatise on flap physiology or classification but simply to define some of the terms, which will be used in the remainder of the book.

Our understanding and improved success with the use of local and regional flaps is a direct consequence of a better understanding of the physiology of skin perfusion.

The understanding of the arterial supply has been a continuous process that had its foundation in pioneering works from the likes of Manchot,¹ Cormack,² and Salmon³ to Taylor⁴ and most recently Saint-Cyr.⁵ Continued advancements have been made in the entire reconstructive arena based on their work.

In general terms, we can classify flaps based on their vascularity, their composition, or their method of transfer.

Local flaps

Local flaps are flaps that are located adjacent to the defect site. They may be contiguous to the defect or a small amount of tissue may separate the flap from the defect. The surrounding tissue is transferred to repair the defect and therefore the flap tends to be similar in color and texture, and the thickness can often be tailored to the needs of the defect.

Local cutaneous flaps

Local flaps can also be classified based on the method of transfer. Broadly speaking, they can be pivot, advancement, or hinge flaps. The pivot flaps are further subdivided into: rotation, transposition, interpolated, and island flaps.

The rotational flap is a flap that is transferred to the recipient bed by pivoting around the base of the flap. The defect and the base of the flap have to be contiguous. Another form is to transpose a flap. This description entails the use of a flap with a geometric shaped design whereby the local tissue is undermined after elevation of the flap and then the flap is mobilized to fit the defect. At times, the design will include two shapes, as in a bilobed flap, so that the flap is transferred to the defect site and the smaller portion of the flap is transposed to the donor site. The area is closed after wide undermining.

The interpolated flap is where the defect is not intimately connected to the base of the flap. During transfer, the flap needs to cross over the intact portion of skin to reach the defect. There are two options for flap transfer. One is to develop a tunnel between the flap and the defect and then de-epithelialize the portion of the flap that will travel under the skin bridge and transfer the flap. The second and most commonly utilized method is to stage the reconstruction: transfer the flap over the tissue bridge, return after enough collateral blood supply to the flap has developed from the recipient bed, and then section the connecting portion of the flap between the recipient bed and donor site.

In the island flap design, the skin is circumferentially incised and the blood supply to the flap comes from the subcutaneous tissue or through the muscle or septum. A common design of the flap is with the pedicle composed mainly of the vasculature to the flap.

Regional flaps

Regional flaps are located at a significant distance from the donor site. Because of this distance, the flap usually has its own blood supply in the form of a named vessel. There are several potential disadvantages of regional flaps. The first and perhaps the most important is the arc of rotation of the flap. The ability to use a particular regional flap will be dependent on the reach of the flap based on its arc of rotation. The reliability of regional flaps is improved when the flap can reach the defect and the inset is performed without tension. Other/>