Background

An interpolation flap is a 2-stage tissue flap in which the base of the flap is not immediately adjacent to the recipient site. These flaps are used when insufficient tissue or mobility in nearby skin prevents coverage of a surgical defect with primary closure or an adjacent flap. Interpolation flaps are similar to transposition flaps in that the flap is lifted over an area of normal skin to reach the defect. While the base of a transposition flap is adjacent to the defect, the base of the interpolation flap is located a distance away from the area to be repaired. This arrangement results in a bridge of tissue, or pedicle, between the flap base and the surgical defect that typically must be removed in a second stage after vascularity is established between the wound and the flap.^[1]

The following 3 interpolation flaps are used most commonly in dermatologic surgery:

Forehead flap
Cheek interpolation flap
Postauricular flap

The forehead flap uses tissue from the forehead to repair the nose.^[2]The cheek interpolation flap takes advantage of the loose skin of the cheek to repair small but somewhat deep defects in the nose, and the postauricular flap uses skin from the posterior part of the ear and the retroauricular aspect of the scalp to repair defects in the helix and anterior surface of the ear.

Also see Forehead Anatomy, Forehead and Temple Reconstruction, and Cheek Reconstruction.

History of the Procedure

The forehead flap is believed to have been used in India as early as 700 BCE. Antonio Bronca of Italy performed the procedure in the 15th century. The first reports of the midline forehead flap in the English-language literature appeared in 1793. Since the 1960s, many advances have been made, including Menick's use of the paramedian forehead flap, which is based on a narrow vascular pedicle supplied by the supratrochlear artery.^[3]This modification allows easier closure of the forehead defect, as well as greater flap mobility, and it is currently the most commonly used forehead interpolation flap.

The cheek interpolation flap is believed to have been used since 600 BC, when it was first used in India. In contrast, the 2-stage postauricular helical flap is a relatively recent technique, which Lewin described in 1950.^[4]

Indications

The forehead flap is used to repair more extensive defects on the nasal tip and ala for which simpler techniques cannot provide adequate coverage. It is sometimes used to provide nasal lining as well. In very extensive defects, the forehead can be used in combination with other techniques such as microvascular free flaps, cartilage or bone grafts, and mucosal flaps to achieve satisfactory function and appearance.^{[5, 6]}

Select small-to-medium, deeper defects on the nasal ala and nasal tip can be repaired by using the cheek interpolation flap.

The postauricular helical flap provides good coverage and cosmesis in medium-to-large defects on the helix and adjacent antihelix, with or without the loss of small amounts of cartilage.^[7]

The described interpolation flaps are most commonly used to repair surgical defects resulting from tumor excision, but they can also be used to repair traumatic wounds.

Relevant Anatomy

The paramedian forehead flap is an axial flap based on the supratrochlear artery. Cadaver studies show that the supratrochlear artery exits the orbit 1.7-2.2 cm from the midline, passing deep to the orbicularis oculi muscle and ascending superficial to the corrugator supercilii muscle. It then passes medial to the eyebrow and through the frontalis muscle ascending superiorly in the subcutaneous tissue, 1.5-2 cm from the midline. The angular and supraorbital arteries also contribute to the vascularity of this flap through a rich periorbital plexus of anastomoses.^[8]

The cheek interpolation flap is a random flap, but it receives an ample blood supply from the perforating branches of the angular, nasal, and superior labial arteries.

The postauricular scalp has a rich vascular supply from branches of the posterior auricular, superficial temporal, and occipital arteries. Therefore, the postauricular helical flap, which is a random flap, is rarely affected by vascular necrosis.

Also see Anatomy in Cutaneous Surgery.

Contraindications

The use of pedicle flaps is contraindicated in patients who are unwilling or unable to tolerate multiple-staged surgical procedures. Likewise, these procedures should be avoided in patients who cannot leave their surgical sites undisturbed, or special measures must be taken to protect the sites in these patients.

Actively infected skin should never be covered with a flap or used to form a flap. With a forehead with a low vertical height, a variation of the forehead flap or another repair method may be required.

Smoking is a relative contraindication to the use of staged island pedicle flaps because it increases the risk of flap necrosis. However, procedures with these flaps can usually be performed safely if fat is not thinned from the undersurface of the flap. In addition, avoiding the use of previously radiated skin or a previous surgical site is generally best, unless no better repair options are available.

Interpolation flaps should be performed with great care in patients who are receiving anticoagulant therapy or in patients with bleeding disorders. Consultation with the physician who prescribed the medication is prudent before discontinuing any anticoagulant therapy. The author rarely discontinues warfarin prior skin surgery. Similarly, the author only stops aspirin usage initiated by the patient and not when prescribed by a physician. Contacting consulting physicians is appropriate before operating on individuals with bleeding dyscrasias.

Workup

Ramsey ML, Ellison CA, Al Aboud AM. Interpolated Flaps. StatPearls. 2021 Jan. [QxMD MEDLINE Link]. [Full Text].
Ramsey ML, Brooks J, Zito PM. Forehead Flaps. StatPearls. 2021 Jan. [QxMD MEDLINE Link]. [Full Text].
Menick FJ. Aesthetic refinements in use of forehead for nasal reconstruction: the paramedian forehead flap. Clin Plast Surg. 1990 Oct. 17(4):607-22. [QxMD MEDLINE Link].
Lewin ML. Formation of the helix with a postauricular flap. Plast Reconstr Surg (1946). 1950 May. 5(5):432-40. [QxMD MEDLINE Link].
Burget GC, Walton RL. Optimal use of microvascular free flaps, cartilage grafts, and a paramedian forehead flap for aesthetic reconstruction of the nose and adjacent facial units. Plast Reconstr Surg. 2007 Oct. 120(5):1171-207; discussion 1208-16. [QxMD MEDLINE Link].
Monarca C, Rizzo MI, Palmieri A, Chiummariello S, Fino P, Scuderi N. Comparative Analysis between Nasolabial and Island Pedicle Flaps in the Ala Nose Reconstruction. Prospective Study. In Vivo. 2012 Jan. 26(1):93-8. [QxMD MEDLINE Link].
Cochran JH Jr, Shinn JB. The postauricular flap in helical injuries. Laryngoscope. 1979 Aug. 89(8):1347-50. [QxMD MEDLINE Link].
Reece EM, Schaverien M, Rohrich RJ. The paramedian forehead flap: a dynamic anatomical vascular study verifying safety and clinical implications. Plast Reconstr Surg. 2008 Jun. 121(6):1956-63. [QxMD MEDLINE Link].
Stigall LE, Bramlette TB, Zitelli JA, Brodland DG. The Paramidline Forehead Flap: A Clinical and Microanatomic Study. Dermatol Surg. 2016 Jun. 42 (6):764-71. [QxMD MEDLINE Link].
Angobaldo J, Marks M. Refinements in nasal reconstruction: the cross-paramedian forehead flap. Plast Reconstr Surg. 2009 Jan. 123(1):87-93; discussion 94-7. [QxMD MEDLINE Link].
Christenson LJ, Otley CC, Roenigk RK. Oxidized regenerated cellulose gauze for hemostasis of a two-stage interpolation flap pedicle. Dermatol Surg. 2004 Dec. 30(12 Pt 2):1593-4. [QxMD MEDLINE Link].
Blazquez-Sanchez N, Fernandez-Canedo I, Repiso-Jimenez JB, Rivas-Ruiz F, Martin MT. Usefulness of the Paramedian Forehead Flap in Nasal Reconstructive Surgery: A Retrospective Series of 41 Patients. Actas Dermosifiliogr. 2015 Nov 10. [QxMD MEDLINE Link].
Sanniec K, Malafa M, Thornton JF. Simplifying the Forehead Flap for Nasal Reconstruction: A Review of 420 Consecutive Cases. Plast Reconstr Surg. 2017 Aug. 140 (2):371-80. [QxMD MEDLINE Link].
Fisher GH, Cook JW. The interpolated paranasal flap: a novel and advantageous option for nasal-alar reconstruction. Dermatol Surg. 2009 Apr. 35(4):656-61. [QxMD MEDLINE Link].
Selcuk CT, Durgun M, Bozkurt M, Kinis V, Ozbay M, Bakir S. The reconstruction of full-thickness ear defects including the helix using the superior pedicle postauricular chondrocutaneous flap. Ann Plast Surg. 2014 Feb. 72 (2):159-63. [QxMD MEDLINE Link].
Wright TI, Baddour LM, Berbari EF, et al. Antibiotic prophylaxis in dermatologic surgery: advisory statement 2008. J Am Acad Dermatol. 2008 Sep. 59(3):464-73. [QxMD MEDLINE Link].
[Guideline] Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation. 2007 Oct 9. 116(15):1736-54. [QxMD MEDLINE Link].
Robinson JK. Laser and Light Treatment of Acquired and Congenital Vascular Lesions. Surgery of the Skin. Philadelphia, Pa: Mosby; 2005. 625-44.
Baker SR. Interpolated paramedian forehead flaps. Local Flaps in Facial Reconstruction. Philadelphia, Pa: Mosby; 2007. 265-312.
Gourishetti SC, Chen JH, Isaiah A, Vakharia K. Predictors of Postoperative Complications After Paramedian Forehead Flaps. Facial Plast Surg Aesthet Med. 2021 Apr 13. [QxMD MEDLINE Link].
Farber N, Haik J, Weissman O, Israeli H, Winkler E, Zilinsky I. Delay techniques for local flaps in dermatologic surgery. J Drugs Dermatol. 2012 Sep. 11(9):1108-10. [QxMD MEDLINE Link].
Newlove T, Cook J. Safety of Staged Interpolation Flaps After Mohs Micrographic Surgery in an Outpatient Setting: A Single-Center Experience. Dermatol Surg. 2013 Oct 17. [QxMD MEDLINE Link].
Kenerson MC, Hughes JD, Sanchez AE, DePerrior S, Rubinstein BJ, Dobratz EJ. Outcomes of Two-Stage Interpolated Flaps Versus Single-Stage Techniques for Reconstruction of Intermediate Nasal Defects. Facial Plast Surg Aesthet Med. 2020 Dec 28. [QxMD MEDLINE Link].

Media Gallery

Nasal defect after Mohs surgery. The boundaries of the nasal tip are outlined for excision to allow replacement of the entire anatomic subunit.
Surgical defect.
Diagram shows a nasal defect due to tumor removal and the remnants of significantly involved anatomic subunits.
Doppler ultrasonography is used to identify the course of the supratrochlear artery prior to flap surgery.
The course of the supratrochlear artery is identified by using Doppler ultrasonography and marked on the skin.
Gauze or other flexible material is used to measure the necessary length of the flap, and a mark is made at the most distal portion.
The gauze is rotated and placed over the course of the supratrochlear artery, and the distal end of the planned flap is marked on the forehead skin.
A foil template of the surgical defect is placed with its most distal aspect touching the mark representing the distal end of the flap. The template is outlined with a surgical marker.
Template of nasal tip subunit is drawn on the forehead after the length of tissue flap needed to reach the defect is carefully measured.
A 1- to 1.5-cm-wide pedicle is drawn over the course of the supratrochlear artery from its origin to the outline of the template.
Planned nasal subunit excision and flap incisions are drawn with a surgical marker.
Forehead flap is elevated and ready for placement.
Flap affixed to nasal wound with planned closure of forehead donor defect.
Paramedian forehead flap in place. Although a full-thickness skin graft was later placed in this patient, the widest portion of the forehead donor site is usually allowed to granulate.
The forehead flap is incised, elevated, and sutured into the nasal defect. The forehead defect is repaired as completely as possible, and any remaining defect on the forehead is allowed to heal secondarily.
Appearance 2 weeks after flap surgery, immediately after division and inset of the pedicle flap. A delayed full-thickness skin graft has been placed in the donor defect on the forehead.
The pedicle is severed in 2-3 weeks, and the flap is inset in the proximal portion of the wound. The proximal stalk can be excised and inset in an inverted V shape, as shown in the diagram.
The proximal pedicle can be excised in a fusiform fashion, and the defect can be closed primarily. This is the preferred method in the author's experience.
Forehead flap at 3 weeks, at the time of suture removal.
Nasal defect prior to cheek interpolation flap repair.
Nasal defect.
Template of nasal defect. This may be expanded to include entire anatomic subunit.
Template is rotated and placed on medial cheek.
Nasal defect with planned cheek interpolation flap. The needed flap length was previously measured with a rolled gauze, and a template of the defect is used to mark the necessary width of the flap.
Cheek flap sutured in place.
Cheek interpolation flap is elevated and trimmed to fit into the nasal defect after the cheek donor defect is closed.
Appearance after division and inset of cheek interpolation flap. The proximal pedicle will be excised and the resulting defect will be closed primarily.
Appearance of the cheek interpolation flap after division and inset. The proximal stump of the pedicle has been excised as an ellipse, and the cheek defect has been closed primarily.
Cheek interpolation flap after division and inset.
Postoperative result of cheek interpolation flap before dermabrasion.
Alternately, skin can be incised and a subcutaneous pedicle may be used.
Subcutaneous pedicle flap in place.
Finished repair.
Helical rim defect after Mohs surgery.
Surgical defect on the helix of the ear.
Planned incision for a postauricular flap.
Planned postauricular flap is marked on the skin. The flap should be of sufficient size to cover the defect without significant tension in any direction. Burow triangles are planned to allow advancement of the skin.
Postauricular flap sutured in place.
A postauricular flap is sutured in place. One or 2 temporary retention sutures can be placed between the ear and the postauricular skin to decrease tension, if necessary.
Mohs surgery defect anterior to the helix.
Postauricular flap in place.
Postauricular flap after division and inset.

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Author

Michael L Ramsey, MD Director, Micrographic Surgery and Dermatologic Oncology Fellowship, Department of Dermatology, Geisinger Medical Center

Michael L Ramsey, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery

Disclosure: Nothing to disclose.

Coauthor(s)

Faith Miller Whalen, MD Procedural Dermatology Fellow, Department of Dermatology, Geisinger Medical Center

Faith Miller Whalen, MD is a member of the following medical societies: American Academy of Dermatology, American Society for Dermatologic Surgery

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

John G Albertini, MD Private Practice, The Skin Surgery Center; Clinical Associate Professor (Volunteer), Department of Plastic and Reconstructive Surgery, Wake Forest University School of Medicine; Past President, American College of Mohs Surgery

John G Albertini, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: QualDerm Partners; Novascan<br/>Have a 5% or greater equity interest in: QualDerm Partners - North Carolina.

Chief Editor

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

Desiree Ratner, MD Clinical Professor of Dermatology, NYU Langone Health

Desiree Ratner, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery, American Dermatological Association, American Medical Association, American Society for Dermatologic Surgery, New York Dermatological Society, Phi Beta Kappa

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Regeneron; Genentech; Canfield, Castle Biosciences<br/>Serve(d) as a speaker or a member of a speakers bureau for: Genentech; Castle Biosciences<br/>Received income in an amount equal to or greater than $250 from: Regeneron; Genentech; Canfield.

Acknowledgements

Heidi Kozic, MD Mohs Fellow, Department of Dermatology, Geisinger Medical Center

Heidi Kozic, MD is a member of the following medical societies: American Academy of Dermatology, American Society for Dermatologic Surgery, and Women's Dermatologic Society

Disclosure: Nothing to disclose.