Omental Flaps for Coverage of Sacral or Gluteal Defects: A Useful and Potentially Underused Tool

A 51-year-old man presented with a slowly growing mass arising from his left gluteus maximus muscle that measured 12 cm in its greatest dimension (Fig. 1A). Imaging demonstrated that the mass extended into the dorsal aspect of the sacrum. Preoperative staging of the neoplasm was T2bN0M0. The patient underwent preoperative radiation therapy before undergoing extirpation of the lesion including partial sacrectomy, partial iliac bone resection, and pelvic floor reconstruction. AGore-tex (TM) mesh was used to span the sacral defect and the wound was closed primarily. Unfortunately, a fall three weeks postprocedure resulted in wound dehiscence, exposing the underlying mesh. Negative pressure wound therapy was initially used as a temporizing approach given the performance status of the patient at that time. After improvement in the patient's nutritional and performance status, and the formation of a healthy wound bed, the decision was made for wound de bridement, colonic diversion, and omental flap coverage. The procedure began with the patient prone by incising the remaining intact prior inferolateral incision. The resulting wound was over 15 cm in size tracking inferomedially (Fig. 1A). The wound was debrided to healthy bleeding tissue. The preoperative plan was to pedicle the omental flap through Petit's triangle so as to avoid dissection around the rectum (Fig. 1B). We then dissected a subcutaneous tunnel from the right edge of the wound up to Petit's triangle on the right side (marked out with medial border being marked by the latissimus and inferior border being marked by thepossible immunocompromised conditions such as diabetes, poor nutrition, history of radiation to the affected area, and wound infections. Flap options include local flaps including muscle, fasciocutaneous skin flaps from the gluteal, back, or posterior thigh region. Other options include VRAM flap and pedicled omental flaps. Paraspinal muscles have been used with greater success for flat wounds but omentum is ideal for deep wounds as a result of its ability to be readily contoured. However, the approach taken for this patient is often not considered. In our case, the patient had radiotherapy to the gluteal region; therefore, local flap options were very limited. He also had a history of wound infection and debridement and needed reconstruction with well-vascularized tissue with the ability to overcome resistant bacterial infection. In such patients, transpelvic vertical rectus abdominis muscle flaps have been advocated. 1 The flap is detached from the pubis and the pelvis inset isiliac crest). The patient was then turned supine. The abdomen was opened with the midline incision proceeding to the left of the umbilicus to preserve the possibility of a left vertical rectus abdominis myocutaneous (VRAM) flap. Laparoscopy was also not performed in case a VRAM flap was needed. The omentum was freed from the distal transverse colon and greater curvature of the stomach and the flap was mobilized inferolaterally with vascular supply based on the right gastroepiploic artery. The cecum was mobilized medially to expose the region of Petit's triangle from the abdominal approach. The omentum was placed near the triangle for easy access in second part of the surgery. An end colostomy through the left rectus muscle was created and the abdominal fascia was closed. The patient was then turned prone. A 5-cm counterincision over the previously marked Petit's triangle was made and the omentum was delivered through the previously dissected space. As demonstrated in Figure 2A, complete coverage of the sacral defect was achieved. We then secured the omentum to the sacral wound using polydioxanone suture. The remainder of the omentum was used to fill the void of the left gluteal region. A superiorly oriented incision was then performed from the lateral edge of the initial incision thereby developing a superiorly based rotation advancement fasciocutaneous flap (18 5 cm). The fasciocutaneous flap was then advanced over the omentum and the wound was closed primarily. The patient was seen in clinic postoperatively six weeks after the operation (Fig. 2C). He was ambulating well. At three months, the sacral wound had healed well. The colostomy was reversed. Soft tissue reconstruction of the pelvis with vascularized tissue flaps is becoming an increasingly common procedure. The primary goal of such an operation is to restore form and function, obliterate dead space, and create an environment favorable to wound healing. Resections of tumors from the pelvis and presacral areas often leave deep and extensive defects, which are challenging for the surgeon to reconstruct. Other obstacles that hamper wound healing also include possible immunocompromised conditions such as diabetes, poor nutrition, history of radiation to the affected area, and wound infections. Flap options include local flaps including muscle, fasciocutaneous skin flaps from the gluteal, back, or posterior thigh region. Other options include VRAM flap and pedicled omental flaps. Paraspinal muscles have been used with greater success for flat wounds but omentum is ideal for deep wounds as a result of its ability to be readily contoured. However, the approach taken for this patient is often not considered. In our case, the patient had radiotherapy to the gluteal region; therefore, local flap options were very limited. He also had a history of wound infection and debridement and needed reconstruction with well-vascularized tissue with the ability to overcome resistant bacterial infection. In such patients, transpelvic vertical rectus abdominis muscle flaps have been advocated. (1)The flap is detached from the pubis and the pelvis inset isadvanced into the sacral defect. Because the operative plan included colonic diversion and colostomy creation, this approach was not considered ideal. Another flap that has been widely used in intraperitoneal and extraperitoneal defects because of its generous blood supply, large surface area, and angiogenic potential is an omental flap. It successfully fills dead spaces, induces angiogenesis, and is known to have immunological function. (2)These properties make it an effective option in treating infected, irradiated, or ischemic wounds. Anatomically, the omentum can be divided into greater and lesser omentum, gastrohepatic, and hepatoduodenal ligaments. For an omental pedicle flap, greater omentum is used with the vascular supply being from either the right or left gastroepiploic artery. Omental pedicle flap length can be varied depending on the volume needed at the recipient site. It is dissected from the transverse colon and greater curvatureof the stomach and tunneled laterally along the left or right colic gutter to the pelvic floor. (2)Petit's triangle is formed by the iliac crest, latissimus dorsi, and external oblique muscles. This can be used as a tunnel to bring the omentum posteriorly to cover sacral defects. Contraindications for the use of omental flaps include adhesions, prior surgeries, malignancies with peritoneal metastasis, or other concomitant abdominal disease. (3)The main disadvantage of using the omental flap is the combined anterior and posterior approach, which increases morbidity and creates problems with positioning. (4)Other complications may include small bowel obstruction, herniation, and fluid and electrolyte disturbances. The omental flap has also been used successfully in chest wall, scrotal, and penile reconstruction. Reconstructive options for large sacral defects, which have been previously irradiated and infected, are very limited. The possibilities that have been explored in this report include local flap options like gluteal, thigh, or back flaps as well as vertical rectus abdominis and pedicled omental flaps. When the surgeon cannot use local flaps or free tissue transfers, the omental flap with its rich vascular supply, contourability, and ability to fight infections can be used successfully through the Petit triangle to cover such defects. This is a safe option with good wound closure and healing and provides better results than the use of local flaps. It may be a particularly attractive option when colostomy is also indicated.