The Free-style Gluteal Perforator Flap in the Thinning and Delay Process for Perineal Reconstruction After Necrotizing Fasciitis

Perineal wounds present a special challenge for reconstructive surgeons. The vacuum-assisted closure device is useful as a temporizing measure or for wounds too large or contaminated for immediate reconstruction. Compared to traditional myocutaneous flaps, perforator flaps provide thinner fasciocutaneous flaps for perineal reconstruction with favorable results and fewer donor site morbidities.The upper and lower gluteal regions are rich in perforators, which allow for more versatile flap design according to the defect. The authors combined the principles of free-style perforator flaps, flap delay, and thinning of perforator flaps to restore perineal function and aesthetics. The procedure was undertaken in a 72-year-old female who was obese with the diagnosis of necrotizing fasciitis secondary to perineal abscess. After 3 months, the flap achieved adequate and durable reconstruction with acceptable aesthetic contour and patient satisfaction; there was no loss of function at donor sites. Clinical applications and technical refinements of freestyle pedicled perforator flaps can be extended to the perineal region. Because of its many advantages and its versatility, freestyle pedicled perforator flaps constitute a valued reconstructive option and, when indicated, an alternative to pedicled axial flaps or even free flaps, in addition to vacuum therapy, to simplify the reconstructive procedure.

Necrotizing fasciitis (NF) is a serious soft-tissue infection and mainly invades the subcutaneous soft tissue of the fascial layer, resulting in progressive purulent necrosis of the skin and subcutaneous fascial tissues. If perianal abscesses do not receive immediate and proper treatment, a significant number of patients will experience a progressive worsening of their condition; the infection will quickly spread along fascial tissues in the perianal space and eventually develop into acute perianal NF. Regarding microbiology, NF can be a mono- or polymicrobial infection, and the classification system by Sarani et al^1,2 is commonly used. Necrotizing fasciitis can be classified into 4 types. Type 1 is most common, defined as polymicrobial NF, accounting for 70% to 90% of cases. Gram-positive cocci, gram-negative rods, and anaerobes are frequently found in patients with diabetes mellitus or peripheral vascular disease, who are susceptible to NF affecting the abdominal wall, trunk, and perianal areas. Type 2, referred to as monomicrobial, is usually caused by group A Streptococcus and Staphylococcus aureus (including the community-acquired methicillin-resistant type) in patients with no comorbidity. It is far less common than type 1, and the outcome is unfavorable with the increasing risk of toxic shock syndrome. Typically, type 1 infection occurs in the extremity of a surgical incision trauma. Type 3 is caused by gram-negative bacteria like Clostridium spp and Vibrio spp and is related to minor injuries from a fish sting, shellfish injuries, or exposure to sea water (most commonly seen in coastal communities). Patients can deteriorate fast and multiorgan failure might occur within 24 hours of injury. Lastly, type 4 often results from fungal infection, especially in patients with immunological diseases, usually after trauma. However, this classification does not seem as critical in making therapeutic plans and prognoses, except for antibiotics use.

The absorption of a large amount of toxins may lead to systematic toxic symptoms or septic shock, so early diagnosis and treatment are extremely important. If surgery is performed within 24 hours of disease onset, then the mortality rate nears zero, whereas it can reach 30% to 50% if surgery is performed after 6 days.³

Perineal wounds present a special challenge for reconstructive surgeons. The vacuum-assisted closure (VAC) device is useful as a temporizing measure or for wounds too large or contaminated for immediate reconstruction.⁴ It accelerates wound contraction and granulation tissue formation. Local tissue perfusion is increased and edema fluid is removed with harmful exudates and cytokines.⁵ The VAC device allows earlier wound closure, early skin grafting (with improved graft adherence), earlier hospital discharge, and earlier return to baseline functional status. Its use in the perineum presents a challenge, but with proper application even the most complex perineal wounds can be healed.

For the reconstruction of larger defects, several flaps have been described, such as vertical rectus abdominis myocutaneous flap, anterolateral thigh flap, gluteal fold flap, and gracilis or pudendal thigh flaps. These types of flaps allow one-stage reconstruction of deep wounds, while providing well-vascularized, non-irradiated tissue to fill the dead space.^6-8 However, they may lead to donor-site morbidity and are problematic in obese patients, with loss of mobility and difficulty complying with position changes.^9-11 For perianal defects and more posteriorly located defects in the sacral area, the gluteus maximus myocutaneous flap is a good option, as a wide rotation flap or as a V-Y transposition flap. When considering donor-site morbidity after harvesting the gluteus maximus muscle, muscle-sparing techniques are the procedure of choice. Flaps in the gluteal area can be harvested based on perforators of the superior gluteal artery perforation or inferior gluteal artery perforation (IGAP) gluteal vascular pedicle. Because of an advantageous arc of rotation, the IGAP-based flap can be used to address large sacral and perineal defects.¹²

Pedicle perforator flaps are believed to be a less invasive option with better cosmesis.¹³ Advances in perforator flap techniques now make it possible to repair lower back defects using a gluteal perforator flap based on the free-style flap design, which provides a safe, effective, and relatively easy option for lower back defect reconstruction.¹⁴ Free-style, local perforator flaps can be harvested from any region of the body where an appropriate and detectable perforator vessel is present.¹⁵ Their use allows the surgeon to perform a “like with like” reconstruction by mobilizing surrounding tissues on a consistent vascular source.

Surgical delay is aimed at increasing blood flow to adjacent angiosomes by opening choke vessels to obtain larger and more reliable flaps. Angiosome and choke vessels are plastic surgery specific terms. An angiosome is an anatomic unit of tissue (consisting of skin, subcutaneous tissue, fascia, muscle, and bone) fed by a source artery and drained by specific veins. The entire body can be divided into 40 angiosomes. Choke vessels are reduced-caliber vessels that link adjacent vascular territories throughout the body. Staged elevation (delay) from distal to proximal, in addition to the preservation of the perforator artery near the base, may improve survival.¹⁶

The authors report their experience with a V-Y free-style perforator flap in thinning and delay process for perineal reconstruction after necrotizing fasciitis.

The procedure was undertaken in a 72-year-old female who was obese, with the diagnosis of NF secondary to perineal abscess. She underwent surgical treatment immediately after the confirmation of diagnosis which involved debridement of the necrotic tissue and drainage of the abscess from the deep fascia; the mean defect size was 9 cm × 5 cm × 3 cm (Figure 1). A temporary colostomy was performed to facilitate wound care. Initially, the VAC device was used because the wound was too deep and contaminated for immediate reconstruction, then it was used to accelerate wound contraction and granulation tissue formation. The defect was further reconstructed with a 2-stage procedure. In the first stage, a right V-Y advancement gluteal perforator flap was raised in a free-style fashion (Figure 2). The flap was based on 3 perforators; perforators were detected at the upper gluteal area, and the flap design was drawn on the skin of the upper gluteal region. Increased flap mobility could be achieved through extended perforator dissection, but the flap was just advanced and placed in proximity with the defect margins. After a delay of 3 weeks, during which VAC therapy was continued to improve the wound, the flap was thinned on the medial aspect by removing the deep subcutaneous fat and the deep fat lobules of the superficial fat layer. The subdermal plexus was not violated, and a thin layer of fat was left intact. The flap dissection then proceeded from medial to lateral, stopping 2 cm distal to the main perforator, which was centralized on the skin paddle. Afterwards, the distal (medial) one-third of the flap was infolded, slid downward, and adapted to the external anal sphincter and rectal walls (Figure 3). The flap remained perfused, and active bleeding was visualized. A small skin graft was placed inside the inner surface of the left buttock since favorable wound contraction was observed at this side. No significant postoperative complications were seen, although a small 2-cm dehiscence was observed in the peri-sphincteric margin, which was left to heal by secondary intention. 

After 3 months, the flap achieved adequate and durable reconstruction with acceptable aesthetic contour and patient satisfaction (Figure 4). There was no loss of function at donor sites. The patient was able to ambulate without restrictions 3 months after reconstruction and physical rehabilitation therapy. Colonic transit was reestablished after 6 months, and the patient maintained internal anal sphincter contraction and bowel control. 

Necrotizing fasciitis is a very serious infection with an unpredictable course. Surgery is usually used in debridement and soft tissue reconstruction. Adequate surgical debridement is a life-saving necessity; however, there are no quantifiable measurements to determine the extent of removing tissue and adequate debridement. Since the infection spreads along the superficial tissue, it is very difficult to distinguish the infected fascia boundary in patients with extensive edema; and normal tissue will be lost during debridement. Some authors found the temporizing surgical strategy, with early simple incisions and drainage followed by complete debridement 24 hours later, more effective and reasonable for those patients complicated with septic shock by comparison with the radical surgical debridement strategy.^17,18 Ge et al¹⁹ also reported a successful case of a severe patient with NF, where surgical debridement was not carried out in 24 hours while strong life support and antibiotics were provided. 

Vacuum-assisted closure therapy has proved to be useful in improving wound bed preparation and can be used to improve acute and chronic wound healing. When used in the treatment of NF, it can diminish toxin absorbance and decrease daily dressing changes, resulting in less pain and reduced narcotic use. It is necessary to control infection as an adjunctive method.^20,21 Moreover, VAC is useful to preserve residual tissue and facilitate the formation of a healthy wound bed, which is essential for further reconstruction. Suture, skin grafting, and flap coverage are usually necessary, because massive tissue is removed during the process. Therefore, flap reconstruction is more often used in repairing the wound. As VAC is applied widely in treating the disease, the quality of healing improves and flaps are not as necessary. Earlier and simpler flaps/reconstructions can be used as described in this report.

Perineal reconstruction often involves conventional myocutaneous flaps, but it may be complicated with donor-site problems, especially in older obese patients with a colostomy, who have difficulty or lack of control of position changes.

The free-style concept applied to perforator flaps allows flap harvesting in any anatomical region where an audible Doppler signal of a perforator is detected.²² The concept of free-style local perforator flaps represents a safe, versatile, and reliable surgical procedure. It not only offers a greater freedom in flap selection but also provides good aesthetic results. Some classifications were proposed according to the number of perforator vessels preserved and to the type of flap movement.²³ One perforator-based flap offered the widest arc of rotation serving as propeller flaps. If more than one perforator vessel is preserved, flap mobility is limited, but still allows sufficient flap movement either as a rotation or advancement flap or as a combination of both.

Staged elevation is an effective method of delay in both axial and random flaps. When this is combined with preserving the perforator artery, survival rates are further enhanced. Some studies have investigated the perfusion of free-style single perforator flaps with an eccentrically located main perforator by combined laser Doppler spectrophotometry, which is an effective method for objective evaluation of flap perfusion.²⁴ Although distal flap perfusion was diminished initially, the majority of perforator flaps with eccentrically located perforators survived completely, and flap perfusion improved between days 1 and 14. This clinical finding may be explained by reorganization of the vascular system with the opening of so-called connecting or choke vessels. This knowledge may influence decision making in perforator flap surgery.

Perforator flaps for perineal reconstruction have increased in use with advantages, such as sparing of the underlying muscle with resultant decreased donor-site morbidity and the possibility of improving aesthetic outcomes.^7,8 Theoretically, a flap can be based on any perforator, whether free or pedicled, based on the perforasome theory. Complications can include partial flap necrosis and total flap failures, mainly in high-risk patients. Multiple studies have shown the deep fat layer could be safely removed to obtain a thin yet viable perforator flap.^25-28 Some clinical series^25,26  have reported outcomes with an average thickness reduction of 37.91% ± 7.15%. This evidence suggests the macroscopic flap-thinning technique can achieve thin flaps.

Other authors have highlighted some differences between thinning a free perforator flap versus a propeller perforator flap.²⁷ The problem is completely different regarding thinning (or defatting) a flap in which the perforators are generally central or when the perforators are lateralized. Indeed, free perforator flaps are most frequently harvested with centralized perforating vessels on the skin paddle, unlike propeller perforator flaps in which the perforators are lateralized, because of the necessity of rotation. Thinning of free perforator flaps is often achieved without necrosis or any skin suffering. However, thinning of propeller flaps is often more hazardous and sometimes results in extensive unexplained skin problems.

Perforator flaps can still be bulky, especially to resurface the skin defect; Hong et al²⁸ hypothesized that elevation from the superficial fascial plane could obtain a thin and viable flap. In their retrospective study,²⁸ 304 consecutive perforator flaps were elevated at the superficial fascial plane — 196 superficial circumflex iliac perforator flaps, 81 anterolateral thigh flaps, and 27 gluteal artery perforator flaps. Complete survival was noted in 282 flaps, partial loss of flaps requiring secondary procedures in 6 cases, partial loss healing secondarily in 8 cases, and total loss in 9 cases; secondary debulking procedures were required in 6 flaps. Suprafascial flap elevation is reliable, provides viable tissue, and is able to obtain a thin flap achieving good functional and esthetic outcomes.

Chaput et al²⁷ compared 5 tibial posterior perforator flaps harvested with suprafascial dissection, including distal two-thirds thinning (in the subcutaneous plane) of the flap and 5 harvested with subfascial dissection without thinning. The size and rotation (twist between 120° and 180°) were similar. The authors of that article noted almost no distal suffering in the subfascial group versus distal problems of 10% to 20% for 3 flaps in the suprafascial group; all of the flaps harvested in the suprafascial plane and thinned had an initial venous congestion phase greater and more worrying than did the flaps harvested with subfascial dissection. Hong et al²⁸ explained that thinning does little to alter the arterial vasculature because the dermal plexus is respected, but it could reduce venous back flow. Then, perhaps the main problem with thinning is not an impaired arterial supply but venous back flow, since the subdermal plexus is preserved. If it appears less risky for free perforator flaps or when the perforators are centered on the skin paddle, thinning can be harmful when the perforators are lateralized. For the lower limb, it seems best to avoid thinning propeller perforator flaps, because it is clear venous problems are much more common in the limbs — especially the legs — than in the trunk.

In the present clinical case, the principles of free-style perforator flaps, flap delay, and thinning of perforator flaps were used to harvest a gluteal V-Y pedicled flap, and complete flap survival was obtained. No donor site morbidity was seen. Clinical applications and technical refinements of the free-style pedicled perforator flaps can be extended to the perineal region. Because of its many advantages and its versatility, the authors believe it will find its place as a valued reconstructive option and when indicated a simpler alternative to pedicled axial flaps or even free flaps, especially in older patients who are obese, and in addition to vacuum therapy, to simplify the reconstructive procedure.

Compared to traditional myocutaneous flaps, perforator flaps provide thinner fasciocutaneous flaps for perineal reconstruction with favorable results and fewer donor site morbidities. The upper or lower gluteal region is rich in perforators, which allows for more versatile flap design according to the defect. Free-style “thinned” and “delayed” local perforator flaps advanced in V-Y fashion proved to be a valid and reliable solution to restore function and aesthetics of the operated site after NF.

From the Department of Plastic, Reconstructive and Maxillo-Facial Surgery, and Burn Unity, Centro Hospitalar de São João, Porto, Portugal

Address correspondence to:
Ricardo Horta, MD, PhD 
Department of Plastic, Reconstructive and Maxillo-Facial Surgery, and Burn Unity,
Centro Hospitalar de São João
Faculty of Medicine
Porto, Portugal
ricardojmhorta@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.