The bilobed flap is another form of a transposition flap; in fact, it is a double transposition flap and can also be used as a triple transposition flap. The flap dates back to 1918 when Esser1 described its use for the repair of nasal defects. In that description, Esser used two flaps of equal size at 90 and 180 degrees from the axis of the defect. Since this time, the bilobed flap has remained a staple in the reconstructive arena, especially for its versatility in the reconstruction of defects in the facial region.
The use of the flap as described by Esser results in the formation of a dog-ear at the base of the flap. Zitelli modified the flap design by decreasing the angle of the flaps to about 45 degrees and from 90 to 110 degrees for the second flap with an elongation of the second.2 This modification significantly improved the cosmesis of the flap.
The bilobed flap is extremely useful in the reconstruction of various head and neck defects, and is often used for small defects encountered by the surgeon, particularly in the nasal region, the forehead, or the cheek area. Note that the concept of the bilobed flap allows its use in larger defects, where the design of the flap is still the same.
The concept behind this flap is the successive transfer of a smaller quantity of tissue from the donor site into the defect site along a short arc of rotation.
The advantage of the bilobed flap is that it allows for the reconstruction of defects in the head and neck region with tissues that are immediately surrounding the defect site. Thus, the reconstruction is carried out with tissue of similar color, texture, and thickness to the missing tissue. The transposition of the flap allows for minimal donor site visibility and excellent cosmesis of both donor and recipient sites. Additionally, the bilobed flap can be performed with minimal time commitment and with few resource needs.
The main disadvantage of the bilobed flap is that the need to make additional incisions in the facial region may at times be less desirable.
The bilobed flap is a random pattern, single-stage flap that lacks a large caliber vessel at its base. A bilobed flap uses two adjacent lobes or flaps that are rotated around a pivot point. The primary lobe, usually the same size as the defect, is used to restore the defect. The secondary lobe is used to repair the donor site of the primary lobe. The donor site of the secondary lobe is closed primarily.3
As this is not an axial flap but rather a random-based flap, the most important decision will be the design and placement of the flap. The goal will be to minimize disturbance to the surrounding region, that is, not to alter the esthetics of the area while still moving an adequate amount of tissue to repair the defect.
- The area of the defect site should be assessed to determine the size, depth, and contour of the defect.
- If the borders of the defect are not well defined and or the shape is too irregular, this should be addressed and the defect made into a well-contoured circular shape whenever possible.
- The surrounding tissues should be evaluated for tissue quality, texture, and pliability to design the flap in the most ideal location.
- The area should also be evaluated for esthetic zones that should not be altered; these zones would include the eyebrow, the hairline, etc.
- The radius of the defect should be measured and transferred to a point inferior to the base of the defect.
- A line from both the lateral and medial aspect of the defect should be traced to the previously marked point.
- The resulting V-shaped tracing is the area of skin that will need to be excised to allow for rotation of the flap.
- Using the base of the new defect, two arcs should be drawn, one from the center of the defect and the other from the top of the defect.
- The smaller arc will correspond to the base of both of the two lobes to be transferred.
- Next, a line should be drawn from the center of the defect to the pivot point at the base. Another line, perpendicular to this should then be drawn.
- The perpendicular line represents the center of the second lobe while a line bisecting the 90 degree (i.e., 45 degrees) will be the center of the first lobe (Figure 3.1).
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