Rhombic Flaps

In 1946, Limberg first described a technique for closing a 60° rhombus-shaped defect with a transposition flap. Dufourmentel modified this technique in 1962 to close defects with any acute angle. Webster published a third significant modification in 1978.[7] The Webster, or 30° flap, uses a 30° angulation of the distal flap end along with an M-plasty closure at the defect base.

Rhomboid flaps are full-thickness local flaps with a random blood supply. Rather than depend on an axial blood vessel for nourishment, rhomboid flaps rely upon the dermal-subdermal plexus of blood vessels.

Pedicle width controls the amount of circulation within the dermal-subdermal plexus to some extent. The blood supply to the head and neck is so vigorous that this variable is frequently considered to be of minor importance. Generally, the accepted safe maximum length-to-width ratio of the pedicle in the head and neck is 2-4:1, whereas in some other parts of the body with poorer circulation this ratio might fall to 1:1.

The surgeon must not violate the dermis when undermining this or any other random flap because the chances for partial or complete flap necrosis increases.

Heavy smokers or patients with insulin-dependent diabetes mellitus have a higher complication rate with all flaps.

If a carcinoma has been excised, use frozen sections to confirm that the margins are free of disease before any local flap is used to cover the area.

Rhomboid flaps rotate neighboring tissue to close the primary surgical defect, whereas the donor site is closed by primary closure. Do not consider these flaps for extremely large lesions or in instances where the resulting vector of tension distorts neighboring fixed landmarks such as the nasal ala, eyelid margin, or the lip.

The natural, parallel, horizontal wrinkles of the central forehead prevent good aesthetic result with this closure; therefore, rhomboid flaps are generally avoided in this area.

Take preoperative photographs in the standard fashion for aesthetic surgery of the face.

Preoperative and postoperative photos are below.

The Limberg flap is conceptually the easiest of the three flaps to construct. The Limberg flap is a series of communicating equilateral triangles. All angles are 60°, which means that every side of both the defect and the flap is equal in length. This orientation creates a flap that is the same size as the defect to be excised. Any flap angle other than 60° theoretically involves either widening or compression of the flap. An elliptical defect at the donor site remains after the flap is rotated to fill the rhomboid defect. This defect can be closed primarily with appropriate undermining of the surrounding tissue.

The Dufourmentel flap is more versatile than the Limberg flap. The Dufourmentel flap can be used to close a rhomboid with any acute angle from 60-90°; however, it is slightly more complicated to construct. With rhomboid defect angles of less than 60°, the Dufourmentel flap is narrower than a Limberg flap. This makes donor site closure much easier.

The Webster, or 30° flap, improves upon some of the limitations inherent to Limberg and Dufourmentel flaps. This technique combines a 30° rotation flap with an M-plasty at the defect base, thereby minimizing chances of creating a standing cone at the turning point of the flap and also reducing the tension associated with closure. Tension is more evenly distributed along the length of the flap.

Closure of an ellipse with 60° angles often produces unsightly dog ears, especially in young patients or individuals with thick skin. Webster observed that 30° angulations could be closed in all patients without creating a standing cone. Extending the base of a rhomboid to produce a more acute angle lengthens the resulting scar and unnecessarily removes healthy tissue.

In a retrospective study of patients who underwent Mohs micrographic surgery, Cressey and Jellinek found inferiorly based rhomboid flaps to be effective in the reconstruction of small to medium-sized operative defects of the medial canthus. Defects ranged from 0.6-2.1 cm in diameter, with postoperative complications reported to be infrequent and minor.[8]

When planning a reconstruction, every rhombus can be closed with 1 of 4 distinct flaps (see the image below). Outcome depends on the appropriate positioning of the defect's base and on proper flap choice.

Three important aesthetic and/or functional considerations must be balanced in the flap design: (1) using relaxed skin tension lines, (2) preserving the integrity of neighboring landmarks, and (3) observing aesthetic subunits.

The flap and surrounding tissue are undermined in the subdermal plane after creating the rhombus defect. When possible, take skin from a donor site where it will have the greatest relative laxity. Lines of maximal extensibility lie perpendicular to skin creases.

Tension is greatest at the closure point of the donor defect (see the image below).

The tension vector here has been described as 20-90° from the short diagonal of the rhomboid defect. The size and degree of undermining do not change the relative tensions of closure. Place the line of maximal flap tension, also called the line of closure of the donor site, in a line of maximum extensibility of the face. Primary tension of closure must never displace a neighboring structure. Flap planning should avoid distortion of prominent landmarks like the eyelid, lip margin, or the nasal ala. Respect boundaries of aesthetic units when designing a flap. When possible, match the skin color, thickness, and presence/absence of hair.

Limberg flap

First, a parallelogram with angles of 60° and 120° is drawn around the lesion to be excised (see the image below).

Next, a line (equal in length to the short diagonal of the parallelogram) is extended from the parallelogram as a continuation of the short diagonal (see the image below). This becomes the superior-medial side of the rotation flap.

Drawing a second line from the distal end of the first line forms the apex of the rotation flap. This second line must be equal in length and parallel to one of the adjacent defect sides (see the image below).

Dufourmentel flap

Beginning with such a parallelogram, extend imaginary lines from the short diagonal and from one adjacent defect side.

Bisect the angle formed by these lines with a line equal in length to one of the sides of the defect.

Draw a line parallel to the long diagonal of the defect equal in length to a defect side (see the image below).

A study by Sebastian et al reported that the Dufourmentel flap is superior to the Limberg flap in repair of pilonidal disease lesions, since the former can be used on rhombus-shaped defects possessing any mixture of internal angles, while the Limberg flap is restricted to 60° and 120° angles. The Dufourmentel flap has also been found to be associated with a low recurrence rate.[9]

Webster flap

Incorporating an M-plasty into the lengthened base defect spares tissue and shares the arc of rotation between the 2 30° angles rather than one 60° angle. Tension distribution upon closure is improved, resulting in less distortion of surrounding tissue and less scar widening in specific areas of closure.

Webster flaps also incorporate a 30° angle at the apex of the rotation flap. Reducing the flap angle from 60° to 30° makes the angle significantly narrower. This, in turn, creates a smaller donor site to be closed and reduces the tension required to close the defect.

Flap failure is uncommon. Nevertheless, partial necrosis of the distal tip of the flap can occur if the angle is too acute. More commonly, imperfections such as standing cones or widened scars result from transposition of such a flap. Standing cones are created when the rotation point of a rhomboid flap approaches 60°, especially in young people or in individuals with dense or thick skin.

All rhomboid flaps are closed under some degree of tension, and this tension is characteristically unevenly distributed along the flap's length.

Areas of maximal tension are subject to preferential widening and depression along the line of tension. Pin-cushioning or trap-door deformities may develop and may be related to inadequate incision of wound edges, incomplete undermining, or postoperative scar thickening.

A study by Kang and Kang indicated that when rhomboid flap procedures are performed by an experienced surgeon, long-term patient satisfaction with the resulting scar tends to be excellent. Using the Patient Scar Assessment Questionnaire (PSAQ) at least 1 year after the completion of flap surgery, the investigators found that 90% of patients perceived the scar as having a very well-matched appearance to the surrounding skin, while 10% reported the appearance to be well matched. Scores for the PSAQ’s Satisfaction with Appearance subscale revealed 90% of patients to be very satisfied with the scar’s appearance and 10% of patients to be satisfied. It was also found that appearance outcomes were not significantly associated with patient age or gender or with the size of the defect.[10]

A thickened scar may be managed with intralesional corticosteroid injections (triamcinolone acetate 10 mg/mL) in the early postoperative period, or by secondary revision surgery. A poorly planned flap will distort anatomical landmarks and leave a poorly oriented scar.

Dermabrasion is routinely offered to all patients undergoing facial transposition flap surgery. The authors believe it offers subtle, but definite, improvement even to the best scars and can be performed simply and quickly in the office. Ideally, dermabrasion can be performed 6 weeks after flap transposition but can also be offered to patients at any time after this interval.

A study by Hernot et al suggested that in patients who undergo fistulectomy for tracheocutaneous fistula (a product of long-term tracheostomy), with subsequent closure in layers, final closure of the defect is better accomplished with a rhomboid flap than with Z-plasty. The investigators found that in the Z-plasty group, 8 out of 20 patients (40%) experienced unsuccessful results, while all procedures in the rhomboid flap group succeeded.[11]