Pedicle or Interpolation Flaps: An Overview

What Is an Interpolated Flap?

An interpolated or pedicle flap is a two-stage procedure in which the base of the flap is not adjacent to the recipient defect. These flaps are employed when inadequate tissue or skin prevents the complete coverage of a surgical site with primary closure or a surrounding adjacent flap. Using an interpolated flap results in a tissue bridge between the flap base and the surgical defect. In the second stage, this tissue bridge must be removed after establishing vascularity between the surgical site (wound) and the flap tissue. Interpolated flaps deliver an approach to repairing surgical defects that otherwise would be difficult, or not impossible, to repair with other reconstructive methods. A surgical assistant commonly performs interpolation flaps to help manage bleeding and cut sutures. Examples of interpolated flaps include the paramedian forehead, melolabial, postauricular, deltopectoral, and waltzing flaps.

What Are the Commonly Used Interpolated Flaps?

Interpolated flaps are usually based on a named vascular supply but often include a more random blood supply at the distal edges. The commonly used interpolated flaps are:

1. Paramedian Flap - It is an axial flap based on the supratrochlear arterial blood supply. However, some experts have reported that the abundant anastomoses in the forehead can be done as a random flap. Although uncommon, this flap can also be based on the supraorbital vessels.

2. Mesolabial Flap - The melolabial flap is a random flap, but it gets an abundant blood supply from the perforating branches of the nasal, angular, and superior labial arteries.

3. Postauricular Flap - This random flap with a broad pedicle is supplied by posterior auricular branches and superficial temporal and occipital arteries.

4. Deltapectoral Flap - This is an axial flap that relies on dominant arteries from the intercostal vessels (mostly the first three), though it becomes a random flap if it is elevated past the deltopectoral groove. This flap is rarely called for in facilities with microsurgical capabilities.

5. Waltzing Flaps - They can be either axial or random, depending on the location. This flap is rarely called for in facilities with microsurgical capabilities.

What Are the Indications of Interpolated Flaps?

The indications of interpolated flaps include:

• These flaps are employed when inadequate tissue or skin prevents the complete coverage of a surgical site wound with primary closure or a surrounding adjacent flap.

• The forehead flaps are particularly helpful on larger surgical defects that are full-thickness or deep and located on the distal nose.

• On the distal third of the nose, cheek interpolation flaps are helpful, especially lateral, in situations where adjacent tissue transfer or full-thickness grafts are impractical.

• The postauricular interpolation flap is employed for medium to large surgical defects affecting the helix and the nearby antihelix. This technique can be used whether there is cartilage loss or not, particularly when single-stage flaps do not provide adequate coverage.

• Deltopectoral flaps are typically used for large wounds of the face, neck, or head where there are no other technically feasible options.

• Waltzing flaps may be used anywhere in the body, though more often in the head, neck, and upper extremities, where microsurgical techniques are impossible.

What Are the Contraindications of Interpolated Flaps?

The interpolated flaps are contraindicated in the following conditions:

• People are unwilling or unable to tolerate multi-staged surgical techniques.

• These procedures should be avoided in people who cannot leave their surgical sites undisturbed, or measures should be taken beforehand to protect the sites of these people.

• Actively infected skin should be avoided to cover with a flap or to form a flap.

• In an individual with a forehead of low vertical height, when doing a paramedian forehead flap, a variation of the forehead flap or another repair procedure may be required to avoid transferring hair-bearing skin to the nose. In addition, the person must be counseled that subsequent hair removal will be required through electrolysis or laser.

• Smoking is also one of the contraindications to staged island pedicle flaps because of the associated risk of flap necrosis.

• Interpolated flaps should be done with proper care in people receiving anticoagulant therapy or in those with bleeding disorders.

• Consulting the physician who prescribed the medication is critical before discontinuing any anticoagulant therapy. In addition, physicians should be contacted before operating on people with bleeding dyscrasias.

What Are the Equipment Required for Interpolated Flaps?

Equipment needed for interpolation flaps is commonly the same for other local or regional flap surgery, with some possible additions. Listed below are the types of equipment used commonly:

Pre-Operation:

• Local anesthetic.

• Surgical scrub or preparation solution.

• Material for creating a template or pattern for the flap, such as non-stick dressing material, surgical cottonoid, foil suture wrapper, or other suitable options, can be utilized in a sterile environment within the surgical field.

Intra-Operation:

• A scalpel with a 15-number blade.

• Toothed forceps.

• Shea or other fine dissecting scissors.

• Skin hooks.

• Curved iris scissors, preferably serrated.

• Non-absorbable suture (silk thread for stitching closing flap).

• Coagulation device (electrocoagulation)

• For larger flaps like the deltopectoral flap, it may be required to use a conventional soft tissue or flap tray.

• Doppler ultrasound to identify perforators or pedicles.

Post-Operation:

• A dressing made of gauze ribbon soaked in non-adherent petrolatum is applied to the exposed surface of the pedicle.

• Adhesive dressing material or tape with elasticity.

• Fluffed gauze or other absorbent material for post-operated bulky dressing.

What Are the Potential Complications of Interpolated Flaps?

Potential complications common to interpolated flaps include:

• Infection.

• Scarring.

• Bleeding.

• Shrinking or alteration in flap size.

• Pedicle necrosis can occur on rare occasions.

Conclusion

A pedicle or interpolated flap is a versatile two-stage tissue flap used when inadequate tissue or surrounding skin mobility prevents the complete coverage of a surgical wound with primary closure or a surrounding adjacent flap. Interpolated flap examples include the paramedian forehead, melolabial, postauricular, deltopectoral, and waltzing flaps. Interpolated flaps are contraindicated in various conditions, such as potential complications common to interpolated flaps, including infection, scarring, bleeding, and disfigurement.