Shan R. Baker

Introduction

Rotation flaps are pivotal flaps with a curvilinear configuration. By necessity they must be designed immediately adjacent to the defect. Thus, a border of the defect becomes the advancing border of the skin flap. Although rotation flaps are useful in many clinical situations, the configuration creates curved incisions that frequently do not lie completely in relaxed skin tension lines (RSTLs). Like all pivotal flaps, rotation flaps develop standing cutaneous deformities at the base of the flap that cannot be easily removed without compromising the vascularity of the flap. Most rotation flaps have a random pattern blood supply; however, depending on the position of the base of the flap, they may on occasion be axial by incorporating the underlying fascia or musculature into the pedicle of the flap. Regardless of whether their blood supply is random or axial, rotation flaps are broad based with a favorable length-to-width ratio, and their vascularity tends to be reliable.

Although rotation flaps are pivotal flaps in their movement, most are also advanced by stretching of the flap. Depending on the degree of stretching, the vector of greatest wound closure tension may be along a line extending from the base to the apex of the distal flap. When no advancement is used in movement of rotation flaps, the greatest wound closure tension is perpendicular across the distal border of the flap, not across the long length of the flap.1,2

Studies by Larrabee and Galt have demonstrated minimal benefit at the defect site of extending the arc of rotation flaps beyond 90° from the axis of the defect.² This is to say, wound closure tension is not reduced at the defect site by increasing the pivotal movement of the flap by more than 90° from the axis of the defect. However, there is often some benefit in extending the incision to accommodate redraping of skin.

The secondary defect created by rotation flaps represents a transformation and a translocation of the primary defect.³ The surface area encompassed by the primary defect is equivalent to the surface area of the secondary defect.³ The geometry of the secondary defect is determined by the size of the flap. The larger the flap, the longer and narrower is the secondary defect. The narrower the width of the secondary defect, the less is the tension required to close the wound and the less is the secondary movement of tissue adjacent to the donor site. Another way of stating this is that the greater the length of the arc and thus the larger the flap, the less is the wound closure tension across the repair of the secondary defect.

Rotation flaps are best suited for repair of defects that are triangular. Design of the classic rotation flap is seen in Figure 7-1. A standing cutaneous deformity will develop at the base of the flap. A Burow triangle can be removed to facilitate repair of the donor site wound. A back cut⁴ at the base of the flap shifts the position of the pivotal point and changes the location of the standing cutaneous deformity.^5–7 When a rotation flap is converted to a two-dimensional form, it appears as in Figure 7-2. As can be seen in the illustration, a problem encountered with rotation flaps is the unequal length of the flap’s border, labeled B in the drawing, compared with the width of the primary and secondary defects, labeled A in the drawing. A common method to equalize this discrepancy is to excise an equalizing Burow triangle at some point along the periphery of the curvilinear incision. The triangle’s base is equal in width to the width of the base of the defect, labeled C in Figure 7-2. Excision of the triangle of skin results in equalizing of the length of the two sides of the incision. An alternative solution to the management of the discrepancy in length of wound margins is to modify the movement of the flap from one that is purely pivotal to one that is both pivotal and advancement. By advancing the flap while at the same time rotating it around its pivotal point, the flap is stretched to equalize the discrepancy (Fig. 7-3). In so doing, the surgeon takes advantage of the distensibility (Fig. 7-4, side B) and the compressibility (Fig. 7-4, side A) of the skin along the wound margins. Repair is then accomplished by use of the principle of halving by suturing on the bias (Fig. 7-4C, D). This is accomplished by placing a suture to appose the two borders of the wound at the halfway point along the length of the flap. Succeeding sutures are placed in a manner that continues to equally divide the remaining distances along the flap’s border. An experienced surgeon will learn to suture on the bias from one end of the flap to the other without resorting to planned halving sutures.

As a general rule, in designing rotation flaps on the face, the length of the flap (Fig. 7-2, side B) should be four times the width of the base of the triangular defect (Fig. 7-2, side C). When this ratio is used, excision of an equalizing Burow triangle is usually not required. Undermining of the base of the flap along with its pivotal point enables advancement of the flap toward the defect during wound closure. Advancement reduces wound closure tension and often necessitates a smaller flap with less movement about its pivotal point than when the flap’s pedicle is not widely undermined and advanced. In addition to reducing the overall size of the flap, undermining limits the development of a standing cutaneous deformity by advancing a portion of the deformity peripherally away from the flap’s base.

Increasing the degree of undermining of the flap without lengthening the border of the flap does not significantly decrease wound closure tension. Likewise, enlarging the flap beyond the length of four times the width of the defect does not significantly decrease wound closure tension.⁸ When a single flap is used for wound repair, the arc of the flap may be adjusted for a number of considerations. For instance, the arc of the flap may be shortened to maintain the incision along or inside hair-bearing tissue. The arc may be extended more than four times the width of the defect when the defect is located in areas of limited skin mobility.

To avoid a standing cutaneous deformity at the base of a rotation flap used to repair a defect, the defect should ideally assume the configuration of an inverted triangle. The triangle should have the height-to-width proportion of 2 : 1 (Fig. 7-5). In addition, if the arc of rotation of the flap is to be a completely symmetric curve, the height of the triangular defect should be 0.5 to 1 times the radius of the curve of the flap (Fig. 7-6). To create the ideal condition for use of a rotation flap, the defect can be enlarged by removing normal tissue and converting the defect into a triangle with a height-to-width ratio of 2 : 1 (Fig. 7-7).⁹

There are several advantages of using rotation flaps. The flap has only two sides; as a result, the surgeon can sometimes position the arced incision in an aesthetic border. The flap is broad based, and therefore its vascularity tends to be reliable. There is great flexibility in design and positioning of the flap.10–12 Design of inferiorly based rotation flaps promotes lymphatic drainage and reduces flap congestion and edema. Similarly, arterial and venous disruptions may be minimized and sensory innervation may be maximized by appropriately positioning the base of the flap.

Rotation flaps should not be selected as a first option in situations in which design of the flap will necessitate placement of incisions that cross RSTLs or aesthetic borders at right angles. This will likely result in an inadequately camouflaged scar along a portion of the donor site. Rotation flaps are not a good choice to repair central upper cheek skin defects in men because hair-bearing skin of the sideburn is moved medially into the non–hair-bearing area of the cheek covering the malar eminence. Except for the dorsal nasal flap, rotation flaps are not often used in repair of nasal defects because donor site scars do not follow the boundaries separating the nasal aesthetic units. The skin of the nasal tip is inelastic, making the use of rotation flaps difficult. Small defects over the dorsum of the nose are best repaired with transposition flaps, such as a bilobe or rhombic flap. Furthermore, rotation flaps transferred from the cheek to the sidewall of the nose usually have an unacceptable result because of the necessary bridging of the flap across the nasofacial sulcus. This partially obliterates this important landmark. Similarly, rotation flaps from the cheek are inappropriate for reconstruction of lateral lip defects because the arc of the flap must extend across the melolabial fold and crease at right angles. The melolabial crease is a prominent aesthetic border, and incisions crossing it perpendicularly often create unsightly scars.

Applications