INTRODUCTION AND FLAP DYNAMICS
Most operative wounds are suitably repaired with local adjacent tissue transfers. When a local flap is not able to achieve an aesthetic closure a staged interpolation flap may be utilized. Interpolation flaps are delayed pedicle flap reconstructions in which a flap of tissue is elevated at one location and transposed over intervening skin to an operative wound. The flap is left in place for a defined period of time in order to vascularize from the recipient bed, and then the pedicle is severed. Interpolated pedicle flaps allow for the reconstruction of challenging operative wounds, in particular wounds of the nose, ear, and lip.
The history of pedicle flaps dates to ancient India and has been artfully reviewed. The most well-known pedicle flap is the paramedian forehead flap, which is based on the rich vasculature of the supratrochlear region.1–4 The great benefit of a forehead flap or cheek interpolation flap is the ability to tap into a reservoir of suitable tissue at a substantial distance away from its intended target defect. Other than the mastoid pedicle flap, all of the flaps discussed herein have a robust, predictable vascular supply, allowing them to have a narrow and highly mobile base. The paramedian forehead flap carries within it the supratrochlear artery and vein or branches thereof. The cheek-to-nose pedicle flap is supplied by large perforating vessels from the angular artery. The Abbe–Estlander flap contains the labial artery. The inclusion of a single larger caliber vessel in such pedicles increases the blood supply to the flap by a factor of 625, and it is usual for a very long, narrow pedicle flap to have arterial bleeding from its distal tip after complete elevation.
Pedicle flaps require a substantial knowledge and understanding of anatomy, surgical planning, and surgical skill. Properly designed interpolation flaps can recreate a distal nose so well that it appears to be a native nose at a conversational distance. This, however, requires a precise plan, meticulous operative technique, and an attention to detail both at the initial flap creation and at the flap takedown. While failure of a local flap is problematic, complete failure of a pedicle flap can be devastating. The recipient site for a pedicle flap must be deep enough to receive a full-thickness operative repair, and must have the appropriate support structure to shape the flap and recreate a native aesthetic contour. In some instances, particularly on the distal nose, this may entail the need for mucosal repair and/or cartilage graft placement.
Pedicle flaps with appropriate planning have an excellent arterial blood supply, even when the pedicle is narrow. A wider or deeper pedicle may be needed in order to assure adequate venous drainage. While the portion of the flap placed in the operative wound may have very little subcutaneous tissue, the same cannot be true of the nourishing stalk or pedicle. Also, pedicle flaps are designed ...