Prognosis is heavily defined by the grade of the sarcoma as measured by the mitotic activity, in addition to the histological subtype, but long-term survival is next determined by the completeness of the resection (4-9). Treatment is multifactorial but primarily centers on a R0 surgical resection that may require removal of adjacent viscera or portions of the abdominal wall. Local recurrence is directly correlated with the ability to achieve negative margins. Margins of at least 1 cm have been demonstrated especially in retroperitoneal sarcomas to increase the likelihood of local control (2,3,9). Margins that are found to be R0 on the final pathologic specimen but less than 1 cm may be recommended for re-excision and/or radiation therapy depending on the tumor location and grade.
Atlas of Abdominal Wall Reconstruction, 2e free download
The external oblique, internal oblique, and transversus abdominis muscles form the muscular layers of the lateral abdominal wall. The external oblique is the most superficial of the three, and its fibers are oriented with an inferomedial vector. The inferior oblique is in between external oblique and transversus. The internal oblique fibers are oriented superomedially, perpendicular to the external oblique. The transversus is the deepest muscle of the three and has horizontally oriented fibers. Laterally, parietal peritoneum is found immediately deep to the transversus abdominis (10,11).
Component separation is a technique that is used to gain medial advancement of each side of the abdominal wall. Reported distances of 5 cm in the epigastrium, 10 cm at the waistline, and 3 cm in the suprapubic region may be achieved (18). In an anterior separation, external oblique aponeurosis is released 1.5 cm lateral to the linea semilunaris and dissection carried out in the avascular plane between the internal and external oblique muscles from the pubis to the costal margins (19) (Figure 2). This technique could be utilized bilaterally for central defects or only on the contralateral side of the resection to allow for primary closure.
A pedicled omental flap may be used alone or in conjunction with a bridging prosthetic mesh to minimize the risks of mesh complications previously mentioned with this technique. If the omentum is uninvolved by the tumor, it is harvested on either the right or left gastroepiploic pedicle depending on the required arc of rotation for final inset. Reports of using the omentum alone to cover the abdominal wall defect and then either skin grafting or mobilizing local fasciocutaneous flaps for coverage have been made, but this leaves a hernia defect and inherent risk of evisceration (25). More commonly, the omentum is used along with a synthetic mesh and can be used as coverage alone or as a sandwich technique that splits the omentum and provides peritoneal lining in addition to external coverage of the prosthetic that can then be skin grafted (26,27). Omental flaps build upon a simple bridging mesh and preserve other reconstructive options if needed in the future.
The rectus abdominis flap muscle flap is a locoregional flap with a robust blood supply that allows it to be used anywhere on the anterior abdominal wall for full thickness defects (15,28). The deep inferior epigastric artery pedicle allows the flap to provide caudal coverage and the secondary pedicle is the superior epigastric artery that allows for cranial coverage (29). The musculofascial edges can be sutured to the edges of the resection bed. The major concern with rectus abdominis flaps is donor site morbidity and resultant hernia as it requires transferring abdominal wall strength from one location to another via both the rectus abdominis muscle and the anterior rectus sheath (30). The secondary defect may or may not be able to be closed primarily but it is generally recommended to reinforce either closure with a mesh to minimize ventral hernia or abdominal bulge (31,32). This addition of mesh does not affect abdominal wall strength in relation to flexion or rotation activities. Abdominal functional strength has been evaluated extensively in related to post-operative function following bilateral transverse rectus abdominis muscle (TRAM) flaps for breast reconstruction. This would likely correlate with oncologic resections on one side of the abdomen with sacrifice of the contralateral rectus muscle for rotational reconstruction. There is a demonstrable loss of strength in trunk flexion with bilateral TRAMs with some subjective reports of increased difficulty in activities in daily living, but this is mostly seen in activities like getting out of bed, which are directly based off of trunk flexion (33). Partial flap necrosis is an additional potential complication as the arc of rotation requires ligating one of the vascular pedicles, and the remaining one is not the dominant blood supply for the distal portion of the flap (32). Although there are benefits of the versatility of the flap, ease of harvest, and proximity to the resection, the morbidity of the donor site makes it less attractive than other locoregional or distant free tissue transfer options.
The gracilis flap is a lower extremity muscular or myocutaneous flap that is very versatile and used for a wide variety of reconstructive procedures throughout the body. It can be used as both a free or pedicled flap based on the medial circumflex femoral artery, but most commonly described as a pedicled flap for lower abdominal and groin coverage given its origin at the ischiopubic ramus and insertion just distal to the medial condyle of the tibia (36,37). It was traditionally described as a muscle flap alone that could then be covered with a split-thickness skin graft, but may also include the overlying adipocutaneous soft tissue as well (38). In situ, the muscle belly is approximately 2 cm thick, 4 cm wide, and up to 30 cm in length, so its shape and size can be a limiting factor in its ability to cover larger defects. Wounds up to 240 cm2 have been reported for extremity coverage, but these are rectangular in shape and require scoring of the superficial epimysium in order to flatten the cylindrical shape (39). A reinforcing mesh for abdominal wall fascial defects should be utilized. Donor site morbidity is low with no significant functional deficits of the hip and knee and an aesthetically pleasing closure after harvest (40).
Rectus femoris flaps are best used as pedicled turnover or rotational flaps for lower abdominal defects. This can be taken as either a muscular or musculocutaneous flap and is supplied by the descending branch of the lateral circumflex femoral artery. It originates from the ASIS and the upper portion of the acetabulum with both heads joining together to insert into the patellar tendon (41). The distal portion of the flap can be divided at variable lengths proximal to the patellar tendon to preserve the stability of the knee, leaving in place the surrounding quadriceps muscles (vastus lateralis/intermedius/medialis). Strength and range of motion tests have been performed pre and post-operatively on patients who have undergone reconstructions utilizing the rectus femoris and have shown no significant decline in strength or donor site morbidity. These conclusions are made with the assumption that intra-operative technique of linking the vastus lateralis and vastus medialis muscles in the midline and a rigorous postoperative rehabilitation program maintain long-term function (42,43). It also should be used in conjunction with a reinforcing mesh for the abdominal wall fascial defect.
Final post-operative result, demonstrating inset of pedicled right ALT flap to right lower quadrant full thickness abdominal wall defect. Donor site closed with split-thickness skin graft. ALT, anterolateral thigh. 2ff7e9595c
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