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Introduction
CHAPTER 26 Interpolation Flaps
Rachel Redenius Jeremy S. Bordeaux
SUMMARY
Interpolation flaps are very effective for large or deep defects, as their robust
vascular supply allows closure of distant defects.
Most interpolation flaps require at least two stages, and the degree of local care
and functional and cosmetic compromise between stages means that appropriate patient selection is of vital importance.
The paramedian forehead flap is the most frequently used interpolation flap in
dermatologic surgery, though cheek- to-nose, paranasal, postauricular, lip, and eyelid interpolation flaps are used as well.
Beginner Tips
The surgeon should precisely design a template that accounts for the three-dimensional
shape and contour of the nose.
Doppler localization of the underlying axial vessel may not be needed.
It is best to match the thickness and contour as much as possible during the initial inset,
though a delicate balance must be maintained as aggressive thinning in the first stage may increase the risk of ischemia.
Expert Tips
The Abbรฉ flap may result in difficulty with eating or speaking prior to flap division.
This flap may also appear markedly edematous for up to a year postoperatively, and no
revisions should be attempted prior to 6 months to allow this swelling to resolve. Sensory and motor functions are affected during the procedure and it may require a year or more to regain complete neuromuscular function.
The three-stage paramedian forehead flap may provide a superior cosmetic outcome,
though an additional surgical procedure is required.
Donโt Forget!
An oversized flap, or a flap that has not been appropriately thinned, may require a
revision with another surgery, intralesional steroids, dermabrasion, or laser.
Necrosis may be seen more often with the cheek-to-nose flap compared to other
interpolation flaps due to its less robust blood supply.
Pitfalls and Cautions
All patients should be counseled that additional revisions such as dermabrasion or
contouring may be required at a later date.
For the Abbรฉ flap, patients should be appropriately counseled regarding the
anticipated difficulty with eating and speaking prior to pedicle division.
Lymphedema lasting many months is common after eyelid interpolation flaps.
Patient Education Points
From the patientโs perspective, staged interpolation flaps are among the most
challenging closures in dermatologic surgery, as they must care for and endure an unsightly pedicle for several weeks postoperatively.
Paresthesias secondary to transection of the supratrochlear nerve can be permanent,
and patients should be counseled about this prior to surgery.
Billing Pearls
Interpolation flaps on the nose, eyelids, and lips are coded with 15576 at the time of
pedicle formation and 15630 at the time of takedown.
Like all flap codes, there is a 90-day global period associated with these codes.
CHAPTER 26 Interpolation Flaps
INTRODUCTION
A large, complex facial defect may create permanent disfigurement and significant psychological morbidity. While cosmetic expectations differ among patients, all desire to retain a normal-appearing face. Surgeons have many reconstructive options, and their selection is based on the size, location, and depth of the defect.
A properly executed local flap is one of the most reliable options for restoring cosmesis and function. When local random pattern flaps are unable to repair a defect, the surgeon may consider using an interpolation flap, a highly effective technique for large or deep defects. They can be supplied by a named artery (axial pattern flap) or by a rich vascular plexus (random pattern flap), and their robust blood supply allows them to repair distant defects. Interpolation flaps generally require two or more stages for completion, though single-staged variants have been described.1 During the first stage, the surgeon transfers the flap into the defect, leaving the vascular supply attached to its pedicle. During the second stage of the procedure, approximately 3 to 4 weeks later, the pedicle is divided, and the flap is inset. Given the complexity of these repairs, and the need to care for a cosmetically unsightly pedicle until takedown occurs, appropriate patient selection is essential.
An extensive preoperative conversation should take place between the surgeon and the patient when an interpolation flap is anticipated. The surgeon should assess what is required to repair the defect, the limitations of the patientโs anatomy, and whether this type of flap is reasonable for this particular patient. The patient should have a driver present and have someone at home to assist with wound care. Photos of prior repairs can be shown to the patient and caregiver to help them visualize and comprehend the procedure. Some patients may not wish to undergo a multistage procedure, and the surgeon must always balance the complexity of the procedure (and attendant postoperative care) with the desire for a perfect reconstruction. All available alternatives should be discussed with a patient, even if they provide inferior cosmetic and functional outcomes, to allow the patient to make an informed decision. Certain social situations may preclude the use of interpolation flaps, and other reconstructive options should be considered for patients who live alone or for those who suffer from
decreased mental status and may manipulate the repair prior to the second stage.