Reconstruction of the Vulva With Gracilis Myocutaneous Flaps

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Reconstruction of the Vulva
With Gracilis Myocutaneous Flaps

The gracilis myocutaneous flap is useful in those cases of large denudated defects in the perineum following radical vulvectomy or perineal surgery in which primary closure would likely result in postoperative dehiscence of the wound incision. It is not substitute for the simpler Z-plasty pedicle flap that gives adequate results except when an extended area must be covered.

The principle of a myocutaneous flap is the creation of an island flap that depends on the underlying muscle for its vascular supply. Of course, the blood supply to the muscle underneath the flap must remain intact and viable, or the graft will not survive.

The purpose of the operation is to cover the vulvar defect with a cutaneous structure having its own non-irradiated or traumatized blood supply that can produce a healed wound per primam with a normal functioning vulva.

Physiologic Changes. The predominant physiologic change is the production of a vulva that is healed per primam without scarring or contracture.

Points of Caution. Care must be taken to accurately identify the gracilis muscle and not mistake it for the sartorius muscle. This is facilitated by extending the knee of the patient while abducting the hip 30°. With the patient in this position, the gracilis muscle is generally palpable.

Care must be taken to determine the size of flap needed prior to making the skin incision over the gracilis muscle. One of the most important points in the operation is to ensure that the neurovascular bundle of the gracilis muscle is preserved.

Technique

This patient has had a radical vulvectomy necessitating extensive removal of pelvic tissue. The patient is in a modified lithotomy position in which the hips are slightly flexed and the knee is extended but elevated approximately 30° off the operating table. The legs are abducted approximately 30° at the hip joint to give adequate exposure to the perineum and the skin of the inner thigh.

The area of the defect is measured in centimeters to determine the size of graft needed. With the legs in this position, the gracilis muscle stands out. Its origin is on the ischial rami, and its insertion is at the knee.

The anatomy of the inner thigh and vulva is shown, and the important anatomic landmarks are noted. The gracilis muscle is shown with its insertion on the ischial rami, with a cross section of the leg demonstrating the location of the essential neurovascular bundle that enters at the upper third of the gracilis muscle and exits between the adductor longus and adductor magnus muscles. Because of this consistent anatomic arrangement, the gracilis muscle is an ideal structure for the myocutaneous flap.

After the measurements taken in Step 2 are recorded, a line is drawn on the skin down the middle of the gracilis muscle. A skin flap matching the dimensions of the defect is outlined on the inner thigh. The maximum flap that can survive from the neurovascular bundle feeding the gracilis muscle is approximately 24 x 8 cm. Such a large flap, however, is rarely required for gynecologic purposes. As demonstrated in Step 2, the defect in this case measures 19 cm in length and 6 cm in width. Therefore, a flap 21 cm long is drawn, leaving 2 cm of "overage."

An incision is made full thickness through the skin and subcutaneous fat down to the muscular bundles.

The gracilis muscle (G) must be identified after the distal skin incisions are made, prior to extension of the skin incision proximal to the vulvar defect. Otherwise, skin may be included in the flap that is not supplied by the gracilis muscle.

The gracilis muscle (G) is isolated with an umbilical tape. The adductor longus (Al) and adductor magnus (Am) muscles are identified.

The gracilis muscle is transected.

The gracilis muscle is sutured to the overlying subcutaneous flap by interrupted 4-0 synthetic absorbable sutures.

The vulvar defect is seen on the left, and the full-thickness flap is dissected off the underlying muscle with small Metzenbaum scissors. Extreme care is taken as the area of the neurovascular bundle is approached.

Locating the neurovascular bundle of the gracilis muscle is vital to success of the procedure. Identification is facilitated by incising the fascia over the adductor magnus muscle and dissecting this fascia medially with a blunt instrument.

Assistance can be obtained from a small ultrasound Doppler that can probe each possible pedicle for the exact location of the gracilis artery and vein. The proximal portion of the gracilis muscle is transected from the ischial rami and sutured to the subcutaneous tissue of the graft. At this point, the gracilis muscle is totally isolated and completely dependent on its vascular supply that enters from the border of the adductor longus and adductor magnus muscles.

After the flap on the opposite thigh has been developed, the patient is given 1 g of fluorescein dye intravenously. After 3-5 minutes, the operating room is darkened, a Wood's lamp is focused on the myocutaneous flap, and the viable area of the flap will fluoresce with a brilliant yellow color. Nonviable areas are rendered as dark purple and should be excised at this time, as shown in Figure 14.

The flap is completely isolated. The neurovascular bundle is identified. A closed suction drain is placed in the space previously occupied by the gracilis muscle and is brought out at the distal end of the leg incision.

The flap may be rotated clockwise or counterclockwise, at the discretion of the surgeon, to provide the best coverage for the vulvar defect.

The flap is rotated into place, and a subcutaneous 3-0 synthetic absorbable suture is placed between the flap and the edge of the defect. Fine skin sutures of 4-0 Prolene are placed between the skin and the vulvar defect. Some surgeons prefer a subcuticular suture of 4-0 Dexon, finding it less compromising to the vasculature of the flap edge.

The defect in the leg is closed in layers with a synthetic absorbable suture. The drain is brought out through the distal end of the incision. The proximal end of the drain is placed under the flap. The medial border of the flap is sutured to the edge of the vagina.

The remaining portion of the inguinal lymph node dissection has been closed primarily. The flap on the opposite side has now been drawn on the skin, and the same procedure is performed from Figures 2 through 18.

A drain is placed in the space previously occupied by the gracilis muscle on this side, and this flap is rotated into position.

Closure of the vulvar defect is completed. The leg opening on the opposite side is closed. The closed suction drains are removed the eighth and twelfth postoperative days. Sutures are also removed during this time, depending on the condition of the edges of the flap.