Definition
At its most basic level, a flap is a portion of tissue that can be dissected, elevated, and inset into a nonanatomic position as a consequence of its vascular supply and outflow. By this definition, flaps may be composed of any combination of skin, fascia, muscle, and bone. Complexity may range from a random pattern skin flap based on a subdermal plexus to a fascio-osteocutaneous free flap supplied by a known arterial perforator.
A systematic approach to choosing the appropriate form of soft tissue coverage for a wound defect, commonly referred to as the “reconstructive ladder,” was popularized by Mathes and Nahai in 1982.
In order of increasing complexity, the “rungs” of the ladder are:
Primary closure
Secondary intention
Skin graft
Tissue expansion
Local flap
Regional flap
Free tissue transfer
Free tissue transfer is defined as the vascular dissection and detachment of an isolated and specific region of the body (eg, skin, fat, muscle, bone) and transfer of said tissue to another region of the body, with anastomosis of the divided artery and vein to a separate artery and vein located at the site of the defect. The latter portion of this procedure ensures the perfusion and drainage, and ultimately the survival, of the flap. This ability to transplant living tissue from one region of the body to another has greatly facilitated the reconstruction of complex defects.
Free tissue transfer has become commonplace in many centers around the world. The numerous advantages of this technique include stable wound coverage, improved aesthetic and functional outcomes, minimal donor site morbidity, and the ability to utilize vascularized tissue from remote parts of the body that are outside the zone of injury (trauma, malignancy, infection, irradiation, etc). Since the introduction of free tissue transfer in the 1960s, the success rate has improved substantially, currently being 95-99% among experienced surgeons. This article provides a framework to facilitate the planning, execution, and monitoring of free flaps.
For more information on various flap procedures, see Flaps.