Stephen S. Park and Stewart Little

Introduction

Today’s standards for aesthetic and functional results after reconstruction of facial defects are high, requiring meticulous planning and execution to achieve outcomes that are acceptable to both surgeon and patient. Since the advent of Mohs’ micrographic surgery for the treatment of cutaneous malignant neoplasms, complex surgical defects of the head and neck have become increasingly challenging to repair with an acceptable functional and aesthetic result.¹ Primary wound closure for many skin defects is impossible and recruitment of adjacent tissue is required for repair. Over the years, careful study and practice have yielded a wealth of techniques and methods to aid the reconstructive surgeon with the repair of facial cutaneous defects. The use of local and regional cutaneous flaps to achieve wound closure with minimal distortion of surrounding facial landmarks is a hallmark of a well-trained plastic surgeon.

Cutaneous defects that are too large for primary wound closure must be addressed with grafts or flaps. In most instances, flaps are preferred to grafts because of their superior color and texture match with the surrounding skin. With proper planning, local flaps usually provide the preferred method of repair with the best aesthetic results and with minimal distortion of surrounding structures.² A variety of classification schemes for local flaps have been proposed on the basis of blood supply, flap configuration, location, and method of transfer.² A transposition flap typically has a linear configuration and pivots toward the defect over an incomplete bridge of skin. The base of transposition flaps is always adjacent to the defect. The rhombic flap is one type of transposition flap (Fig. 11-1).

A thorough understanding of vascular anatomy and skin physiology and adherence to the principles of facial aesthetic regions are critical to the successful implementation of any local flap. The microcirculatory system of the superficial, dermal, subdermal, and musculocutaneous vascular plexuses provides a rich, redundant source of nourishment to local flaps.² Flap survival hinges on two factors: the blood supplied through the base of the flap and the growth of new vascular channels between the flap and the recipient wound bed. Inosculation and neovascularization typically occur 3 to 7 days after flap transfer. Before this time, the flap is supplied by the perfusion pressure provided from the base of the flap and imbibition of nutrients from the wound bed itself.³

The evaluation of a defect begins in a systematic way, which will often aid the surgeon in the appropriate flap selection and design. Four specific factors should be addressed before bringing knife to skin. First, mobile structures such as the eyelid, lip, and melolabial fold must be accounted for in planning the flap and care taken to avoid distortion of these structures due to unfavorable vectors of tension. Second, an area of skin must be identified with adequate tissue laxity that is best suited for construction of a flap. Third, a careful evaluation of relaxed skin tension lines (RSTLs), lines of maximal extensibility (LME), and aesthetic boundaries must be made to plan incisions that will maximize scar camouflage and minimize wound closure tension.¹ Fourth, scars and all vectors of tension after transfer of a flap must be anticipated, and these are the determining factors for flap selection and orientation. By use of this systematic approach to the analysis of cutaneous defects, the optimal flap may be chosen for reconstruction that will result in the least functional detriment and facial distortion.¹

No single skin flap will provide the best wound repair for every defect. A thorough understanding of the wide array of local flaps available for reconstruction remains essential. A rhombic flap has long been considered a workhorse in the armamentarium of the reconstructive surgeon. This is in large part due to the simplicity of the flap design and the reliability with which it may be used to reconstruct cutaneous defects. The scars from flap transfer are predictable and typically cause minimal distortion of surrounding structures. Proper execution of a rhombic flap requires careful presurgical planning, a thorough understanding of the geometry of the flap, and an understanding of how the flap will affect surrounding tissues. When it is properly used, a rhombic flap can provide excellent aesthetic results.

The first rhombic transposition flap was initially described by Alexander A. Limberg in 1946 and was later published in 1963. On the basis of extensive work with paper models, Limberg described the use of a rhombic transposition flap with internal angles of 60° and 120° to fill a rhombus-shaped surgical defect with similar internal angles.⁴ If the cutaneous defect did not have the configuration of a 60°-120° rhombus, additional skin was removed to create the rhombus. A rhombus-shaped transposition flap with internal angles of 60° and 120° is often referred to as a Limberg flap. By working with paper models, the geometry of the Limberg flap can be appreciated as having a precise and exacting design.⁵ Paper lacks the distensibility of normal tissue, and therefore the standing cutaneous deformities produced from Limberg’s paper models are less forgiving than those in clinical practice (Fig. 11-2).

The use of the flap described by Limberg had some limitations, which gave rise to a number of variations, including those designed by Dufourmentel, Becker, and Webster.6–8 These modifications addressed issues of wound closure tension, the need to discard skin to create a rhombus-shaped defect, and standing cutaneous deformities. In 1962, Dufourmentel expanded on Limberg’s model and described a method to close any acute-angled rhombus-shaped defect. In 1977, Webster published another significant modification of the Limberg flap. He used a narrower 30° angled flap coupled with a W-plasty at the flap’s base to facilitate wound closure. This design required less excision of normal tissue to achieve repair of a defect. It also created less wound closure tension on the flap donor site.

The rhombic flap is a cutaneous, random vascular patterned flap that is transferred primarily by transposition with some limited advancement movement. The flap is dependent on its dermal and subdermal plexuses for survival.⁹ As with any random flap, care must be taken when undermining and transferring the flap to ensure that the dermal and subdermal plexuses are not injured.

Limberg Flap

When a Limberg flap is planned, the defect is modified to create a rhombus-shaped defect with internal angles of 60° and 120°. The 60°-120° rhombus may be thought of as two 60° equilateral triangles aligned base to base. Thus all sides of the defect are of equal lengths, which are in turn equal to the short diagonal of the defect.⁵ To design a Limberg flap, the line of the short diagonal of the defect is extended, bisecting one of the internal 120° angles. The line is extended a length equal to the short diagonal. This creates the first side of the flap (Fig. 11-1). The second side of the flap is designed by marking a second line of the same length as the first, parallel to the adjacent side of the rhombic defect, creating a 60° angle at the flap’s apex. The designed flap is equal in size to the defect. Four possible rhombic flaps can be designed for any rhombus-shaped defect. After transfer of a Limberg flap, the greatest wound closure tension is at the donor site.¹⁰ The tension vector runs roughly parallel to the original border of the defect adjacent to the flap. There is minimal tension across the other portions of the wound (Fig. 11-3).¹ This is an important consideration when distortion of surrounding tissues must be avoided. Therefore, it is the axis of the maximal wound closure tension vector in relationship to LME that is the greatest determinant of flap selection. The scar that results from the Limberg flap is highly predictable and consists of straight, precise lines, not all of which run parallel to RSTLs. The surgeon can easily visualize the anticipated scar configuration and approximate vector of maximum wound closure tension by drawing the flap and then covering the two parallel sides of the flap with his or her fingers.

The Limberg flap has been used to repair defects of the cheek, temple, eyelids, nose, lip, chin, and neck (Fig. 11-4).⁹ The horizontal parallel furrows of the forehead make this region of the face particularly unsuitable for use of rhombic flaps. Disadvantages of the Limberg flap include the formation of a standing cutaneous deformity and the need to discard normal skin to convert the defect into a rhombus if the defect does not already have the configuration of a 60°-120° rhombus. In addition, a portion of the scar resulting from the flap does not lie in RSTLs, and thus scar camouflage is not as good as when certain alternative flaps are used.

Dufourmentel Flap

The Dufourmentel modification of the Limberg flap was introduced as a method of broadening the application of the rhombic flap. Dufourmentel flaps enable the repair of rhombus-shaped defects with any combination of internal angles, in contrast to those with angles limited to 60° and 120°.⁷ In addition, for defects that are more “square,” less normal tissue is sacrificed when this flap design is used. Like the Limberg flap, the Dufourmentel flap can be used to repair only skin defects in which all sides of the defect are equal. However, the length of the short diagonal will vary on the basis of the acuteness of the internal angles of the defect.⁵ To design the flap, two lines are created. The first line is an extension of the short diagonal of the defect, and the second is an extension of one side of the defect. The angle created by these two lines is bisected by a third line to create the first side of the flap, which is equal in length to the sides of the defect. The second side of the flap is drawn parallel to the long diagonal of the defect and is also of equal length to the defect’s sides (Fig. 11-5). The Dufourmentel flap has the advantage of a lesser arc of pivot, thus creating a smaller standing cutaneous deformity than is observed with the Limberg flap. Like the Limberg flap, the Dufourmentel flap must be oriented with respect to LME. The flap covers the defect completely, thus minimizing tension and distortion of tissue surrounding the defect. A limited standing cutaneous deformity must be excised, so some normal skin is discarded in the process of reconstructing the defect. As with the Limberg flap, not all lines of the resultant scar will fall within RSTLs (Fig. 11-5).

Webster 30° Flap

The Webster 30° flap uses two modifications in an attempt to decrease wound closure tension at the donor site and to reduce the size of the standing cutaneous deformity that forms from pivoting the flap. First, the excision of the standing cutaneous deformity is performed as a W-plasty to limit the length of the excision of the deformity. Second, the apex of the flap is designed with an angle of 30° (Fig. 11-6). This design creates a narrow-angled donor site that facilitates closure with minimal wound closure tension. The Webster 30° flap, also known as the 30° rhombic flap, is designed by approximately halving an equilateral triangle. The height of the triangle is designed with a height equal to the length of a side of the defect. The angle of the apex of the transposition flap is 30°. The width of the base of the flap is half the greatest width of the defect. The Webster 30° transposition flap allows a more even distribution of wound closure tension but is more likely to distort neighboring structures.⁸ This is because the surface area of the flap is less than the surface area of the defect that the flap is designed to repair. Thus secondary tissue movement is necessary to assist the flap with closure of the primary defect. Furthermore, care must be taken to ensure that the angle created between the flap and the adjacent side of the defect is at least 110°.⁵ A lesser angle may result in vascular compromise of the repair. The Webster modification results in an irregular closure line because of the W-plasty but does so at the expense of an additional limb of scar (Fig. 11-6B).

Variations of Flap Design

In 1987, Quaba and Sommerlad described a modification of the rhombic flap that used a flap smaller than the surface area of the defect and without conversion of the defect into a rhombus.¹¹ Their design could be used to repair circular defects with an angular flap. This “square peg into a round hole” technique was introduced in an effort to spare skin wasted in an attempt to create a defect with a rhombic configuration and to minimize the size of the flap. Their modification of the rhombic flap is similar to the note flap described in Chapter 8. The flap is designed by selecting a diameter of the defect based on the area of greatest tissue laxity and the desired location for placement of flap donor site scars. To create the first side of the flap, the line of the diameter is extended beyond the defect for a distance approximately two-thirds of the length of the diameter. The second limb of the flap, of equal length to the first, is drawn from the end of the first line, creating a 60° angle. The line follows the curve of the adjacent border of the defect (Fig. 11-7). Care is taken to avoid narrowing the flap’s base as the line parallels the curved border of the defect. After dissection of the flap and appropriate undermining of adjacent skin, the flap is transferred to the defect and key sutures are placed to distribute wound closure tension. The scar resulting from flap transfer tends to look remarkably like that occurring after use of a Limberg flap (Fig. 11-8). Examples of the use of this modification of the Limberg flap are shown in Figures 11-9 and 11-10. The authors note three distinct advantages of this cutaneous flap design: (1) depending on the location of the defect, the flap may be designed anywhere along the circumference of the circular defect; (2) this enables a relatively unlimited choice of donor sites about the defect, allowing scars to be positioned as inconspicuously as possible; and (3) there is limited sacrifice of normal tissue because the configuration of the defect is not modified and only a standing cutaneous deformity is excised.

There are some disadvantages with the method described by Quaba and Sommerlad.¹¹ The surface area of the flap is less than the defect; therefore, more wound closure tension is on the tissues surrounding the defect when the flap is transferred than when a Limberg flap is used. This may lead to distortion of critical facial landmarks and must be considered before flap design. Furthermore, standing cutaneous deformities were noted in 22% of their series of 175 patients treated by use of this flap.¹¹ By creation of a flap smaller in surface area than the defect, the flap’s donor site wound closure is subjected to less tension and therefore closes more easily than when the Limberg or Dufourmentel flap is used. Thus this modification of flap design allows greater versatility at the expense of additional tension placed on tissues surrounding the defect for which the flap repair is designed.

Bilateral Rhombic Flaps

Johnson and colleagues describe the use of bilateral rhombic flaps to facilitate closure of larger cutaneous defects (Fig. 11-11).¹² By visualization of the defect as two adjacent rhombuses, two separate rhombic flaps are designed to fill a single defect. The principles of rhombic flap geometry and design are the same as for a single flap. Use of two rhombic flaps enables the surgeon to use redundant skin at two different locations about the defect. Because two flaps are used, each flap is required to cover only half of the defect, so each flap can be designed smaller than if a single flap were selected for repair. This method of wound closure results in additional scar limbs, albeit in an irregular line, that may be more aesthetically undesirable.

Desciak and Eliezri have proposed the use of bilateral rhombic flaps to close large defects of the nasal dorsum and tip.¹³ They describe visualizing the defect as two overlapping, equally sized rhombuses, each representing approximately half the total surface area of the defect. The rhombuses overlap in the center of the defect. By design of the flaps superiorly and symmetrically positioned on either side of the nose, the resulting wound closure tension vectors are identical. This prevents asymmetric distortion of the nasal base (Fig. 11-12). Furthermore, the tip is often elevated by the wound closure, which can be functionally advantageous in patients with tip ptosis. Superior and inferior midline Burow triangles are removed to facilitate wound closure. The medial corners of the flaps will overlap in the midline and are trimmed. The resultant scar line is irregular and well suited to the nasal dorsum. Bilateral rhombic nasal flaps allow reconstruction of larger (2 cm) midline nasal defects with local skin that possesses maximum color and texture match for the repair. Bilateral rhombic flaps that are based in opposite directions can also be used to repair skin defects of the nasal dorsum. Each flap is responsible for repair of half of the defect, and each pivots in opposite (clockwise and counterclockwise) directions.

Turan and associates have described the use of four 60° rhombic flaps to close large wounds of the trunk and extremities that would normally require a skin graft.¹⁴ Four Limberg flaps are designed an equal distance around a central defect, so that the two opposing flaps pivot in opposite directions, one clockwise and the other counterclockwise.¹⁴ Care is taken during flap design to prevent one flap from restricting the base of another. By use of this design, wound closure tension is distributed in four directions rather than in one, and the orientation of the flaps can be designed to use LME and available tissue reserves. The technique produces additional scars, compared with a single flap, but may be a better alternative to skin grafts. This technique may be used with defects of moderate size of the cheek and scalp.

Other examples of the use of multiple rhombic flaps are described in the medical literature. Limberg himself described the use of three rhombic flaps to close defects of the forehead and scalp.⁴ A similar technique has been used to remove crown alopecia.⁵ The triple rhombic flap technique is based on the visualization of a circular defect as a hexagon with equal sides. The sides of the flaps are designed so that their length equals the radius of the defect. The flaps are created at alternating corners of the hexagon (Fig. 11-13). This design prevents the flaps from sharing a common side. In this manner, the tension of the wound closure is divided equally by the three flaps. All three flaps are pivoted in the same direction, which may lead to distortion of surrounding tissue when this method of reconstruction is used.

Some modifications of the Limberg flap aim to extend the clinical applicability of rhombic flaps. An example is the use of Z-plasties to expand the base of the rhombic flap for larger cutaneous defects.¹⁵ Johnson and Bennett describe the use of multiple Z-plasties at the base of rhombic flaps (Fig. 11-14).¹⁵ This modification allows greater mobility of the flap at the expense of an additional length of the scar. The technique has been shown to be both reliable and predictable when one encounters restriction in tissue movement during initial flap transfer.

Case Reports

Summary

Since Limberg’s initial description of the rhombic flap in 1946, many advances in our understanding of wound healing, wound tension vectors, and aesthetic facial boundaries have been made.¹ Despite these advances, the rhombic flap and its derivatives remain useful for the plastic surgeon. The geometry and reliability of the rhombic flap allow the surgeon to proceed with an accurate knowledge of the expected scar lines and the effects of wound closure on surrounding structures. When it is planned properly, this technique can provide excellent results with minimal distortion of surrounding facial features and predictable scar lines.

When contemplating the repair of a cutaneous defect, the surgeon must guard against an overzealous procedure. If a simple primary closure will suffice, it will often produce the most acceptable result. Untoward outcomes are usually related to poor flap design or surgical techniques rather than an inherent failing of the flap used for repair. With proper surgical judgment and appropriate case selection, the rhombic flap and its derivatives represent a versatile tool for cutaneous reconstruction.

References