Gracilis Flap for Perineal and Vaginal Reconstruction

Ajani G. Nugent

Yasmina Zoghbi

Christopher J. Salgado

DEFINITION

Perineal defects reconstructed with gracilis flaps are applied after vulvovaginal resections or more extensive pelvic exenterations with considerable soft tissue loss, dead space, and distortion of the introitus.¹
Vaginal defects indicated for gracilis flap reconstruction are applied for partial or total circumferential full-thickness portions of the vaginal canal including mucosa and muscle layers.¹^,²
The gracilis flap is a highly vascularized muscle or myocutaneous flap that provides regional tissue that has its own independent blood supply, fills in pelvic dead space, and separates abdominal contents from the perineal wound. The gracilis flap is often not in the potential radiation field.¹^,³

ANATOMY

The gracilis muscle—one of the adductors of the leg—is found in the more superficial plane of the medial thigh muscles.
Derived from the Latin word gracile, which means slender, the muscle is thin and straplike, measuring roughly 25 cm in length and tapering from superior to inferior from about 6 to 4 cm.⁴
It takes origin from the ischiopubic ramus and inserts distally via the pes anserinus into the medial tibia inferior to the condyle. The muscle inserts posteromedially to the adductor longus and, along with its tendinous insertion, can be palpated with ease in thinner patients.
The gracilis axis can be defined by drawing a line from the ischium to the medial condyle of the knee. Alternately, by palpating the adductor longus with the thigh abducted, the gracilis axis can be outlined 2 to 3 fingerbreadths posterior to the adductor longus.
The gracilis flap is a type II muscle flap according to the classification of Mathes and Nahai. It has a dominant vascular pedicle from the medial femoral circumflex artery, a branch of the deep femoral system. Two secondary pedicles to the gracilis muscle can be found segmentally proximal and distal to the pedicle.⁵
The neurovascular pedicle of the gracilis free flap is made up of a single arterial branch arising from the medial femoral circumflex artery, two vena comitantes, and the anterior branch of the obturator nerve.⁶
On average, the vessel measures 1.6 mm in diameter and passes deep to the adductor longus and superficial to the adductor magnus to enter the proximal third of the gracilis.⁵
The entry point of the vascular pedicle is typically found 8 to 10 cm inferior to the pubic tubercle.⁶ The proximal attachment of the muscle is often not palpable, and the distal insertion is often used to aid in its identification.
The anterior branch of the obturator nerve can measure up to 12 cm in length and is found approximately 6 cm from the pubic tubercle.⁵
The muscle can be divided into two functioning units, owing to its motor nerve dividing into branches innervating the superior and inferior muscle separately.⁷
Careful attention should be paid to the saphenous vein so that it is not injured during the dissection.

PATHOGENESIS

Perineal defects
- Perineal defects necessitating gracilis flap reconstruction are most often the result of extirpative oncologic surgeries but can be the result of infectious processes as well as trauma.¹
- Perineal malignancies most often occur in the colorectum or cervix and less commonly in the vagina, urinary tract, or anus.¹
- Total pelvic exenteration for recurrent or locally advanced carcinomas provides a potential oncologic cure that leaves a large pelvic defect.⁸
Vaginal defects
- Total circumferential acquired vaginal defects usually arise from perineal malignancies that require pelvic exenterations.¹

NATURAL HISTORY

Perineal defects
- Management of perineal malignancies through resection or pelvic exenteration results in pelvic dead space.
- Patients following pelvic exenteration often benefit from muscle or myocutaneous flap reconstruction to obliterate dead space and provide antibiotic delivery to these often large defects with high metabolic demands.¹
- With loss of perineal support, abdominal viscera may fall into the pelvic basin, leading to adhesions, obstructions, fistulas, or perineal hernias.³ Gracilis flap reconstruction aids to decrease the risk of these sequelae.
- Attempts of closing large perineal wounds, especially those previously irradiated, by primary or secondary intention, are at high risk of dehiscence and breakdown.
- Perineal wounds that remain unhealed for over 6 months after surgery are predisposed to developing chronically draining perineal sinuses³ and should be reconstructed with preferably locoregional flaps such as the gracilis flap, if available.
Vaginal defects
- Total vaginal resection without flap repair leads to prolonged healing, increased risk for complications, abnormal vaginal anatomy, and inadequate function.⁹

PATIENT HISTORY AND PHYSICAL FINDINGS

Wound size
- Evaluation of the defect size and shape is critical in determining if the wound should be managed through primary or secondary intention, debridement and packing, skin grafting, or flap utilization.³
Radiation
- Areas that have been previously radiated must be noted as they compromise the surgical site and occasionally may compromise the vascularity of potential flaps.
Scars
- Thorough preoperative examination includes evaluation for lower extremity scars, as prior surgery or trauma can influence flap selection.
Femoral artery
- With intentions of using the gracilis myocutaneous flap for perineal or vaginal repair, vascular status must be evaluated.
- Physical exam should include palpation of the femoral, popliteal, posterior tibial, dorsalis pedis, and anterior tibial arteries.
- Additional evaluations are capillary refill, skin color and turgor, and Doppler examination if pulses are not detected. Computed tomography angiography (CTA), magnetic resonance angiography, or even angiogram is necessary to ensure patency of arterial inflow. A venous phase with the CTA may be obtained to evaluate the venous outflow as well.
Expectations
- Typically, younger, sexually active women desire an anatomically similar, functioning reconstruction of the vagina to both be aesthetically pleasing and permit sexual activity after surgery.¹
- Conversely, much older patients who may be unlikely to resume intercourse after reconstruction may benefit from a more conservative approach with less risk of complications. Flap obliteration of the perineum without reconstruction of the vagina may yield a quicker and less complicated recovery for the patient.¹ Patients, however, often will request reconstruction of their vaginal canal.