Flap Based Reconstruction for the Defects of Fournier's Gangrene.
In the treatment of Fournier's gangrene serial debridement, copious irrigation, and broad-spectrum IV antibiotic remain mainstay treatments for the eradication of infection. After resolution of the infection, an open wound of varying depth and size frequently requires reconstruction. Based on the extent of the wound and the tissue planes of the perineum requiring reconstruction, there are different reconstructive approaches. Common goal is to achieve acceptable functional and aesthetic results. For small and superficial defects of the perineogenital region, wound care, primary closure, and skin grafts may be sufficient. However, exposure to vital structures and large defects require flap-based reconstruction [Table 1].  Moreover, skin graft is not as resistant as flap to moisture from urination and to the sheering of the undergarments and may lead to maceration and graft breakdown.  As Fournier's gangrene is more common in males (20 to 1), numerous reconstructive options for the scrotum have also been described. [3,4] An algorithm-based approach can help surgeons to decide among different flap options [Table 2].
MATERIALS AND METHODS
A systematic review of the literature was conducted using "PubMed" and "Google Scholar" in June 2017. Different searches were performed using keywords "Fournier's gangrene" "plastic surgery," "reconstruction," and "flap." The search was limited to the studies published in English and French. The reference list of each retrieved article was manually searched to find other potentially relevant articles.
Local flaps are comprised healthy, vascularized tissues harvested adjacent to the perineal defect. They may be rotation, advancement, or transposition flaps and their utility is limited to small defects that are adjacent to healthy tissue. They are technically straightforward to perform and provide the most aesthetical reconstruction with "like" tissue. Because they rely on a random pattern of perfusion, their length is limited to twice the width of their base. In addition, care must be taken to ensure that their blood supply has not been compromised by previous debridement or radiotherapy.
These are flaps derived from tissue not directly adjacent to the defect that are perfused by named, reliable vessels. The internal pudendal artery supplies two main pudendal flaps: The Singapore and lotus petal flaps. These fasciocutaneous flaps are perfused by perforators coming between the medial edge of the gluteus maximus and the posterior border of the scrotum or vulva. Pudendal flaps are reliable, easy to harvest, and cause minimal donor site morbidity. However, their small size dictates bilateral flaps to provide sufficient tissue in most cases. On occasion, even bilateral pudendal flaps will not provide sufficient coverage to cover both testicles.
Wee and Joseph described the pudendal thigh fasciocutanoeus flap (Singapore flap) and designed it lateral to the labia majora with a posterior pedicle that was transposed medially.  It is an axial flap based on the terminal branches of the superficial perineal artery. It may be tunneled medially to cover the skin defect of the scrotum and perineal area. This flap is easier to raise and less bulky than the gracilis muscle flap. Chen et al. used this flap in four patients to cover a mean area of 69 cm2 on the scrotum and did not report any complications.  Yii and Niranjan described lotus petal flaps for vulvovaginal reconstruction.  This flap, which resembles a lotus flower, can be designed in a different orientation to optimize its versatility [Figure 1].
Scrotal musculocutaneous or advancement flaps provides good quality and elastic skin with reliable blood supply derived from anterior scrotal branches of the deep external pudendal artery. This flap can be used to cover small defects of the scrotum or the penis. It has sensation and is elastic; properties that make it advantageous over a skin graft. Tiwari et al. used this flap to resurface dorsal proximal penile defects after burn contracture release.  All of their six flaps healed successfully. Ferreira et al. used this flap on 10 patients, four of whom had penile reconstructions. 
Anterolateral thigh flap
The anterolateral thigh (ALT) flap is supplied by the descending branch of the lateral circumflex femoral artery. The design of the ALT flap is very straightforward. First, a line is drawn between the anterior superior iliac spine and the superolateral aspect of the patella. The midpoint of this line is identified and approximately 90% of the perforators can be detected within a radius of 3 cm around this landmark [Figure 2]. After arterial signals are confirmed with a Doppler probe, a flap is centered over these perforators. In 2% of the cases, there are no skin perforators. Fascial, fasciocutaneous, or musculocutaneous flap can be raised in the subfascial or suprafascial plane. The ALT flap can provide a large skin paddle up to 35 cm long and 25 cm wide on a single dominant perforator. However, limiting the width to 8.10 cm allows the primary closure of the donor area  whereas larger donor sites are normally closed with a split.thickness skin graft.
Fournier's gangrene involves the upper medial thigh to varying degrees. The surviving tissue may not be available to provide a flap for an early reconstruction, and in some cases, it may Fournier's gangrene involves the upper medial thigh to varying degrees. The surviving tissue may not be available to provide a flap for an early reconstruction, and in some cases, it may need multiple stages. However, ALT flaps can be transferred immediately after the infection is resolved because neither its pedicle nor the skin paddle is involved in Fournier's gangrene. It can also be transferred as a sensate flap by including lateral femoral cutaneous nerve proximally with the flap. In addition, the flap can be further thinned to resemble original scrotal tissue. This flap can also be used for lower abdomen reconstruction, and fascia lata can be included to reconstruct the abdominal wall.
Yu et al. performed pedicled ALT flap for perineal reconstruction. They noted minor skin breakdown that healed with wound care in four patients. 
Hsu et al. used pedicled ALT flap to cover ischial, trochanteric, perineogenital, lower abdominal, and knee defects in 33 patients. Among those patients, one experienced total and another partial flap necrosis. They stated that an islandized ALT flap provided them with large, reliable, thin, and pliable fasciocutaneous coverage. 
Gracilis muscle and musculocutaneous flap
The gracilis muscle is located in the medial thigh and works as a thigh adductor and knee flexor. However, its absence does not cause any functional deficit to the patient. The dominant vascular pedicle is normally the terminal branch of the medial femoral circumflex artery, but on occasion it may arise directly from the profunda femoris artery. The medial circumflex femoral artery traverses between the adductor magnus and the adductor longus muscles and enters the deep surface of the gracilis muscle approximately 6-10 cm inferior to the pubic tubercle [Figure 3]. A branch of the obturator nerve, the medial cutaneous nerve of the thigh, innervates the proximal medial thigh skin overlying the gracilis muscle. It can be found under the adductor longus muscle and can be included in the flap. The gracilis muscle can also be harvested as a functional muscle flap. It is innervated by the anterior branch of the obturator nerve that enters the muscle 1-2 cm superior to the vascular pedicle. Patients undergoing this flap are typically marked with the thigh abducted where the gracilis muscle can be palpated under the adductor longus muscle. When required, the skin paddle is marked on the proximal half of the thigh since distal half is unreliable. The longitudinal skin paddle size should be two.thirds the length of the underlying muscle with a width limited to 4.6 cm to enable primary closure.  Some authors advocate that a proximally located transverse skin island has more reliable perfusion, and a scar following primary
closure that can be concealed closer to the inner thigh crease. 
In the literature related to Fournier's gangrene, gracilis muscle or musculocutaneous flap is used to fill large and deep perineal defects. [3,4] Chen et al. preferred using gracilis muscle flaps because of their reliable blood supply to reconstruct perineogenital defects in their four patient series.  Hsu et al. reconstructed perineal defects ranged from 12 cm x 7 cm to 30 cm x 15 cm with unilateral gracilis V.Y musculocutaneous advancement flap on eight patients. All of their flaps survived without complication, but one case had hematoma that required surgery. 
Medial circumflex femoral artery perforator flap
The medial circumflex femoral artery is the dominant pedicle to the gracilis muscle. The dominant pedicle enters the muscle 6-10 cm below the pubic tubercle. The perforators are typically located within a radius of 6 cm from the entrance of the pedicle to the muscle. Usually, just opposite to the medial circumflex femoral artery, one or two perforators supply the overlying skin.  This flap can be designed parallel or perpendicular to the groin crease. Coskunfirat et al. used this flap (with a dimension of 10 cm x 6 cm -17 x 7 cm) to cover scrotal defects in seven patients [Figure 4]. No major complication happened, but wound dehiscence occurred in two patients.  This flap is thin enough to define the contours of the testicles. Moreover, it has good mobility and allows the primary closure of the donor site.
Superomedial thigh flap
This flap was first reported by Hirshowitz et al. for scrotal and vulval repair.  It is designed on the proximal superomedial part of the thigh. It is perfused by three different sources: The deep external pudendal artery, the anterior branch of the obturator artery and the medial femoral circumflex artery. This flap provides sensate coverage of the perineum due to genital branch of the genitofemoral and ilioinguinal nerve. Ferreira et al. harvested 43 superomedial thigh flaps in 26 patients and did not experience any perfusion problem. However, in five patients, partial dehiscence was recognized and primarily repaired.  They emphasized that the transverse dimension of the flap was not sufficient to cover both testicles, so bilateral flaps were needed in most of the cases.
The groin flap is based on the superficial circumflex iliac artery (SCIA) and has an unpredictable origin, direction, and size. The SCIA takes off from superficial femoral artery or from a common trunk with the superficial inferior epigastric artery and runs superolateral toward the anterior superior iliac spine. Its superficial branch runs above the deep fascia of the Sartorius muscle and distally in the fat. The deep branch runs through the inguinal ligament and under the deep fascia of the sartorius muscle. It can also be designed over the superficial inferior epigastric artery if the SCIA cannot be found or is of inadequate size. This flap is normally insensate, but the inclusion of the lateral cutaneous nerve of the intercostal nerve of T12 can provide sensation. This flap can provide a skin island up to 12 cm x 30 cm and can be used for abdominal or perineal defects. This flap is harvested from lateral to medial, deep to the sartorius muscle fascia. It should be transferred to the defect without tunneling.  Due to its limited arc of rotation and reach, it has limited use in genital reconstruction and is considered as a "Plan B" flap.
It can also be raised as a superficial circumflex iliac perforator flap. Instead of using the whole length of SCIA, this flap is only based on the distal perforator artery. In addition, it can be harvested thinner and can be transferred in a propeller fashion. 
Vertical rectus abdominis muscle flap
The rectus abdominis is supplied by two main sources: The superior epigastric artery (SEA) and the deep inferior epigastric artery (DIEA). Secondary sources such as posterior intercostal arteries, subcostal artery, and lumbar arteries provide blood supply. The SEA runs inferiorly deep to the rectus abdominis and superficial to the posterior rectus sheath. It runs 2.5-4 cm from the midline before arborizing to form multiple anastomoses with the DIEA. The DIEA arises from the external iliac artery above the inguinal ligament. It ascends obliquely and pierces the transversalis fascia within the vicinity of the anterior superior iliac spine. Then it continues between the rectus abdominis and posterior rectus sheath. The rectus muscle is segmentally innervated by the terminal branches of T7-T12 which are located between the transversus abdominis and the internal oblique muscles. Patients with previous abdominal surgery or cesarean section should be further evaluated because the pedicle might have been damaged.
The rectus abdominis flap was modified by Shukla and Hughes as a vertical or oblique skin paddle and inferior pedicle for the closure of perineal defects.  The skin paddle can be as large as 10 cm x 20 cm [Figure 5]. This flap has the advantages of having plentiful volume, long, and reliable pedicle with a wide arc of rotation, ease of dissection, and low risk of necrosis. However, removal or denervation of the rectus abdominis muscle may result in weakened flexion of the trunk, reduced core strength, and abdominal hernias or pseudohernias. 
A free flap is a flap whose blood supply is divided and then microvascularly anastomosed to recipient vessels within or near the defect to be reconstructed. Free flaps are rarely required for perineal reconstruction as numerous local options are usually available. However, if the defect is too large for a pedicled flap or if there are multiple defects that have already used regional or distant flap options, then free flaps become a more reasonable option. However, free-flap surgeries last longer and need microsurgical expertise and special instruments. Moreover, they are associated with higher costs and longer hospitalizations.
Thin perforator flaps such as the ALT, the latissimus dorsi perforator and SCIA perforator flap can be used. Although, if more bulk is needed the free latissimus dorsi muscle, DIEP, or gluteal muscle or perforator flap may be considered. Free radial forearm or free fibula flaps are the most popular flaps for penile reconstruction.
Free latissimus dorsi muscular or musculocutanoeus flap is the most popular flaps in the reconstruction of large defects. The latissimus dorsi muscle derives dual blood supply from the thoracodorsal branch of the subscapular artery and the posterior paraspinous perforators. Despite the absence of the large latissimus dorsi muscle, functional deficit of the shoulder and the arm are reported in only 7% of patients who have received this flap. If all the other muscles of the shoulder girdle are intact, loss of the latissimus muscle does not substantively affect daily activities. This flap can be designed deliberately according to the differential needs for skin or muscle. If more skin than muscle is required, the skin paddle should be placed on the anterior edge of the muscle where skin perforators are concentrated. 
Ahn et al. reported their experience on the reconstruction of perineogenital defects in 20 patients. Three of these patients received free latissimus dorsi perforator flap, ranging from 13 cm x 16 cm to 10 cm x 18 cm, for suprapubic and perineal defects. The only complication was a hematoma that occurred in the donor region. 
The future of perineal reconstruction is in tissue engineering and the alteration of molecular pathways that regulate wound healing. Acellular dermal matrices (ADMs), which are derived from deepithelialized, decellularized, and processed cadaveric or porcine dermis, may be placed on a suitable wound bed to promote revascularization and facilitate coverage.  Zhang et al. investigated the effect of the porcine ADM in the preparation of a wound bed following irradication of the Fournier's gangrene. In their case.control study of 36 patients, they showed that ADM was better and faster at promoting the growth of granulation tissue compared with dressings made with hydrogen peroxide and sodium hypochlorite solution.  Oberwalder et al. reported a patient who had an extensive resection that was successfully reconstructed with porcine ADM.  Kim et al. reconstructed a ventral urethral defect with vascularized dermal flaps created from human ADM.  Said et al. successfully reconstructed the pelvic floor and perineum with human ADM and bilateral thigh flaps in a 75-year-old woman after radical debridement. 
Eradication of the infection and supportive patient care are the most important initial steps in the treatment of the Fournier's gangrene patient. This is followed by functional and aesthetic reconstruction of the resultant defect. The reconstructive ladder, from simple wound care to free-flap surgery, guides the reconstructive decision-making process.
The author would like to thank Nihal Sulkalar Dolen for anatomic illustrations.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Utku Can Dolen
Division of Plastic and Reconstructive Surgery, Washington University in St. Louis, Saint Louis, MO, USA
Address for correspondence: Dr. Utku Can Dolen, Division of Plastic and Reconstructive Surgery, Washington University in St. Louis, Saint Louis, MO, USA.
How to cite this article: Dolen UC. Flap based reconstruction for the defects of Fournier's gangrene. Turk J Plast Surg 2019;27:56-61.
Table 1: Pedicled flap options for the defects of Fournier's gangrene Flaps Vascular Defect Composition supply Superomedial Deep external Perineum, scrotum Fasciocutaneous thigh pudendal a, anterior branch of obturator a, medial femoral circumflex a Medial circumflex Medial femoral Perineum, scrotum Fasciocutaneous femoral artery circumflex a perforator flap Anterolateral thigh flap Descending Perineum, scrotum, Fasciocutaneous, branch of groin, abdomen, musculocutaneous lateral suprapubic region femoral a Perineum, scrotum Gracilis flap Medial femoral Perineum, scrotum Muscle, circumflex a musculocutaneous Groin flap Superficial Abdomen, Fasciocutaneous circumflex a suprapubic region Vertical rectus Deep inferior Groin, suprapubic Muscle, abdominis muscle epigastric a region musculocutaneous flap Flaps Ease of pedicle Contour Surface dissection of the flap Superomedial Moderate-difficult Moderately Moderate thigh thin Medial circumflex Difficult Moderately Moderate femoral artery thin perforator flap Anterolateral thigh flap Moderate Usually Large bulky Gracilis flap Easy Moderate Moderate Groin flap Difficult Usually Large bulky Vertical rectus Easy Bulky Large abdominis muscle flap Flaps Vascular pedicle Reliability length Superomedial Short Very good thigh Medial circumflex Short Very good femoral artery perforator flap Anterolateral thigh flap Long Good (muscle) good (skin paddle) Gracilis flap Medium Very good (muscle) moderate (skin paddle) Groin flap Variable Unpredictable Vertical rectus Long Good (muscle) abdominis muscle very good flap (skin paddle)
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|Title Annotation:||Original Article|
|Author:||Dolen, Utku Can|
|Publication:||Turkish Journal of Plastic Surgery|
|Date:||Apr 1, 2019|
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