Defect on the right nasal supratip is too large to close in a side-to-side fashion without causing significant distortion to nearby structures (Fig. 5.1A). A rhombic transposition flap is a good choice for filling the surgical defect and avoiding unnecessary tension on the nasal tip or ala (Fig. 5.1B). Most of the adjacent loose tissue is located superior to the surgical defect. As a transposition flap, first sutures are used to close the secondary defect, effectively causing the flap to transpose over the intervening tissue and “fall” into place. After the secondary defect is closed and the flap is transposed into place, a small tricone or standing cone develops. This tricone is excised from the point of rotation, angling away from the pedicle and avoiding transection of blood vessels within it (Figs. 5.1C and D).

The second surgical defect is located on the right nasal dorsum and sidewall (Fig. 5.1E). Although the defect in the second patient in Section 5.2 is similar, a rhombic transposition flap was selected for repair of this defect, whereas a bilateral advancement flap was selected for the repair in Section 5.2. The key is to evaluate each situation individually and choose what works best for that particular case. When evaluating as to what is missing and where the loose tissue is, the answer for both defects is the same: the loose skin is on the proximal nose or on the lateral nose and medial cheek. In this case, the surgical defect is a little larger; a bilateral advancement flap would have been a bit more difficult, and the patient has had previous surgeries in this location with the repair recruiting tissue from the nasal sidewall (see vertical scar on nasal dorsum above current surgical defect). As a result, there is relatively less loose tissue from which to borrow on the nasal sidewall and cheek in comparison to what is available on the more proximal nose (i.e., superior nasal dorsum and nasal root). A rhombic transposition flap reconstructed the surgical defect with the closure of the secondary defect falling close to the junction of the nasal dorsum and sidewall and avoiding excessive pull on the medial canthus or lower eyelid (Figs. 5.1F and G).

Finally, the third example contrasts nicely with the first example. Both defects are similar in size and located on the nasal supratip; however, one is repaired with a lateral-based rhombic transposition flap (Figs. 5.1A, B, C, D) and the other, a medial-based rhombic transposition flap (Figs. 5.1H, I, J). Choice of a medial versus lateral pedicle is illustrated well by the idiom “the devil is in the details.” The defect in the first example is slightly more anterior than the defect in the third example. As a result, in the first example, a lateral-based rhombic transposition flap can transpose into the surgical defect without affecting the alar crease (and underlying internal nasal valve). On the other hand, a lateral-based flap in the third example could cause excessive tissue to develop at the pivot point located in proximity to the internal nasal valve. A better choice for the slightly more posterior defect in the third example would be a medial-based rhombic transposition flap, which would allow the flap to transpose into the surgical defect without affecting the internal nasal valve. Remember, first, what is missing has to be decided; second, the location of the loose tissue from which to borrow has to be determined; and third, the method in which the tissue has to be moved to the surgical defect while hiding scars and avoiding secondary problems has to be chosen (e.g., margin or landmark deviation, or in this case potential impact upon the internal nasal valve). In this third case, we designed a medial-based flap to successfully reconstruct the defect and avoid secondary complications.

Although transposition flaps are good on the lateral aspect of the nose, bilateral advancement or bilateral rotation flaps may work best for defects located more centrally. The rationale behind this is that transposition flaps borrow from one side of the nose, whereas bilateral advancement or bilateral rotation flaps borrow from both sides. As a result, transposition flaps may cause some asymmetry when the patient is viewed head-on. This is because tissue is recruited on one side of the nose only. In bilateral advancement or bilateral rotation flaps, tissue is recruited from both sides (i.e., donor sites are bilateral), thereby helping to maintain nasal symmetry.

The first surgical defect measures approximately 1.8 × 1.5 cm and is located on the midnasal dorsum (Fig. 5.2A). A bilateral advancement flap was designed, recruiting tissue bilaterally from the nasal sidewalls. Two incisions were made from the inferior aspect of the surgical wound bilaterally onto the nasal sidewalls. The flaps were undermined by blunt dissection to the junction of the nose and cheek in order to facilitate advancement of the flaps (Fig. 5.2B). Tricones were excised from the distal (i.e., lateral) aspect of the two incisions to help mobilize the flaps centrally (Fig. 5.2C). By advancing the flaps centrally, absorbable buried vertical mattress sutures were used to secure the flaps into place, and a nonabsorbable, half-buried horizontal mattress suture (i.e., “tip” suture) was used to secure the two tips of the flap to the inferior incision line. Several other absorbable, buried vertical mattress sutures were placed to
approximate wound edges and remove tension from the closure. Once the flaps were advanced and sutured into place, a tricone or standing cone was excised from the superior aspect of the surgical wound (Figs. 5.2D and E).

The second case illustrates a similar example in a young woman with a 1.5 × 1.3 cm defect on the right nasal dorsum after Mohs micrographic surgery for a basal cell carcinoma (Fig. 5.2F). A bilateral advancement flap was performed, and the healed result demonstrates the appearance 3 months after surgery (Figs. 5.2G and H). In review, a significant amount of tissue can be recruited bilaterally from the nasal sidewalls (carry undermining to the cheek to recruit the greatest loose tissue), and by “sharing” from where tissue is recruited, symmetry of the nose may be better maintained.

Available adjacent loose tissue for this first surgical defect would include the medial cheek as well as the area superior to the surgical defect on the nasal root and glabella (Fig. 5.3A). An island advancement flap was chosen to reconstruct this surgical defect, recruiting tissue from the convex nasomelal cheek or nasomelal fold (Fig. 5.3B). When using island advancement flaps, it is preferable to place at least one of the long sides of the triangle within a rhytid or boundary between cosmetic units or subunits. In addition, because of the central pedicle and lack of cutaneous attachment, these island flaps may develop some mild trapdooring or pincushioning. On a convex surface such as the nasomelal cheek, that is not generally a problem; however, in other locations, use of absorbable buried vertical mattress sutures around the periphery of the island flap will help to minimize trapdooring by maintaining tension around the periphery of the flap.

After the triangular flap is incised, the flap is mobilized by careful blunt and sharp dissection, starting at the leading and trailing edges. Undermining continues along the sides of the flap so that a healthy vascular pedicle is maintained in the central body of the flap while being mobilized adequately to advance into the surgical defect with minimal tension. At this point, the leading edge is secured to the superior-medial aspect of the surgical defect with absorbable buried vertical mattress sutures (e.g., 4-0 polyglactin 910). The secondary defect is closed and the long sides of the triangle similarly secured with buried absorbable sutures. The epidermis is approximated and everted with a nonabsorbable running percutaneous suture (e.g., 6-0 polypropylene).

An important point when using these types of advancement flaps for surgical defects near the medial canthus, eyelid, or any free margin is to make sure the advancement of the flap and subsequent secondary tension vectors do not pull back or distort the free margin of the eyelid or medial canthus. In both of these examples, the flap was directed toward the medial aspect of the defect to avoid secondary tension vectors on the medial canthus of the eye (Figs. 5.3C and D).

In the second example, the surgical defect measures 2.3 × 1.6 cm in diameter following Mohs surgical excision of a basal cell carcinoma (Fig. 5.3E). The defect sits at the junction between the nose and the cheek. As in the first example, one of the long sides of the triangular island advancement flap extends into the nasomelal furrow and avoids blunting of the junction between the cheek, nose, and lip (i.e., alar sill). The flap is advanced superiorly and medially, and avoids secondary tension vectors on the medial canthus or lower eyelid (Fig. 5.3F). The patient underwent scarabrasion with a hand engine and coarse pear-shaped diamond fraise at 2 months following surgery to soften the transition between the scar and surrounding sebaceous skin. Mild trapdooring or pincushioning developed, which was treated with intralesional triamcinolone (10 mg/cc) each month for 3 months. The final healed view at 6 months demonstrates how well the flap has reconstructed this area and the benefit of considering ancillary treatments, such as intralesional steroids or dermabrasion, in the postoperative period for select cases (Fig. 5.3G).

A surgical defect like this one on the nasal sidewall and supratip is well suited for a transposition flap repair such as a bilobed transposition flap (Fig. 5.4A). Rhombic flaps are useful for nasal defects of up to about 1.0 cm in diameter, but the upper limit size may be lesser for defects located within the distal one-third of the nose (e.g., nasal tip and ala). Bilobed transposition flaps are useful for defects of up to about 1.5 cm in diameter in this region. A surgical defect of this size and location repaired by a rhombic flap requires that a larger area be recruited immediately adjacent to the surgical defect. Recruiting a larger share of tissue immediately adjacent to the distal one-third of the nose may cause some depression on the nasal sidewall or nasal asymmetry. A better option may be to use a bilobed transposition flap and “walk” the tissue downward from the more proximal portion of the nose, where there is a greater abundancy of recruitable tissue.

In this case, as the defect is relatively anterior on the nose (i.e., closer to the midline than the cheek), a lateral-based pedicle was used, and the flap was designed so that the excised tricone would sit just above the alar crease (Figs. 5.4B, C, D). For defects more posterior on the nose, a medial-based pedicle would be considered (see Section 5.9).

Most present-day bilobed transposition flaps are based on the article by Zitelli (The bilobed flap for nasal reconstruction. Arch Dermatol, 1989;125(7):957-959), which described his modification of the bilobed transposition flap originally designed by Esser. Zitelli’s modification included two similar-sized lobes with a maximum angle of 45 to 50 degrees between each lobe and the excision of a tricone at the point of rotation.

The bilobed transposition flap has been referred to as a “workhorse” for nasal reconstruction. At the same time, it seems to be one of the more intimidating and easily bungled flaps for nasal repair. Although no facial repair is as simple as a cookbook recipe, there are specific design elements and techniques that help to ensure success. The author’s preference for design and completion of a bilobed transposition flap can be simplified as follows, which should make the flap less frightening and more straightforward (Fig. 5.4B).