Reconstruction of the Pelvis: Muscle Transfer
Martin I. Newman
Indications/ContraindicationsMuscle flap reconstruction of the perineum may be necessary following radical ablative procedures, such as abdominoperineal reconstruction. The indications to proceed with reconstruction may include the inability to close the pelvic floor and/or perineum following resection at the time of the initial procedure or the anticipated inability of the wound to heal normally secondary to active infection, previous surgery, or irradiation. In addition, radical surgery for malignant colorectal neoplasms may also involve resection of a portion of the vagina or labia as is often seen when malignancies extend to and invade these structures. In these cases a single well designed and inset pedicle muscle or myocutaneous flap may be used to reconstruct the vagina as well as the perineum. In other cases, a combination of flaps may help the reconstructive surgeon to achieve the desired goal.
Several pedicled muscle and myocutaneous flap options exist for pelvic reconstruction and include, but are not limited to, the right or left rectus abdominus and/or the right and left gracilis. Such flaps offer excellent options for reconstruction following the ablation of primary, recurrent, or persistent lower gastrointestinal tumors. In individuals in whom these donor options are not available, alternatives do exist in the form of pedicled or free muscle, myocutaneous and fasciocutaneous flaps. Additional options such as these are described in a variety of texts and journals dedicated to the reconstructive surgeon. This chapter will focus primarily on the vertical rectus abdominus myocutaneous (VRAM) flap, which is our preferred option.
There are few if any contraindications to proceeding with flap reconstruction of pelvic defects in this context. However, hemodynamic instability at operation may be an indication for the surgeon to defer reconstruction, as it is with most reconstructive procedures. Few defects cannot be temporized with dressings or negative pressure devices while patients regain stability. In contrast, certain situations such as congenital anomalies, previous surgeries, and/or trauma have implications in the design of the reconstruction. A previous ostomy that has been placed through the rectus muscle may compromise the perfusion to the distal portion of rectus abdominus based flap and may stimulate the
reconstructive surgeon to seek alternative options. Previous cosmetic procedures, too, may have implications. In these cases a VRAM flap would not be possible. However, it is not a contraindication to perform a muscle only flap that may serve to achieve all or part of the desired reconstructive goals. Notwithstanding, previous ligation or obliteration of the deep inferior epigastric pedicle is a contraindication to the utilization of that particular rectus muscle, although it does not preclude the use of the contralateral rectus muscle if its vascular pedicle is intact. Similarly, previous surgeries or traumas that have ablated the cutaneous perforators overlying the gracilis muscle or previous obliteration or ligation of the major vascular pedicle to the muscle itself may impose limits on this potential donor site as an option. Congenital anomalies of these structures are rare, but should also be considered in surgical planning. Previous irradiation is also a factor for consideration. Previous irradiation of a donor muscle and skin, as opposed to irradiation of the recipient site, should stimulate the surgeon to consider other options. Although flaps may be irradiated following transposition and inset with satisfactory results, a previously irradiated flap as a donor can be problematic. Potential issues with this approach include difficulty raising the flap in the altered bed, viability of the flap following harvest, closure and healing of the donor site, and performance of the flap following transposition and inset.
reconstructive surgeon to seek alternative options. Previous cosmetic procedures, too, may have implications. In these cases a VRAM flap would not be possible. However, it is not a contraindication to perform a muscle only flap that may serve to achieve all or part of the desired reconstructive goals. Notwithstanding, previous ligation or obliteration of the deep inferior epigastric pedicle is a contraindication to the utilization of that particular rectus muscle, although it does not preclude the use of the contralateral rectus muscle if its vascular pedicle is intact. Similarly, previous surgeries or traumas that have ablated the cutaneous perforators overlying the gracilis muscle or previous obliteration or ligation of the major vascular pedicle to the muscle itself may impose limits on this potential donor site as an option. Congenital anomalies of these structures are rare, but should also be considered in surgical planning. Previous irradiation is also a factor for consideration. Previous irradiation of a donor muscle and skin, as opposed to irradiation of the recipient site, should stimulate the surgeon to consider other options. Although flaps may be irradiated following transposition and inset with satisfactory results, a previously irradiated flap as a donor can be problematic. Potential issues with this approach include difficulty raising the flap in the altered bed, viability of the flap following harvest, closure and healing of the donor site, and performance of the flap following transposition and inset.
Relative contraindication such as obesity, poor nutritional status, history of smoking, or steroid and antimetabolic medications (among others) are well appreciated by the reconstructive surgeon. However, in major ablative colorectal ablative procedures for active malignant neoplasms, surgeons may not have the luxury of deferring intervention until these factors can be adequately corrected. Thus, patient specific characteristics such as those described serve more so as indicators of potential postoperative complications rather than contraindication to reconstruction.
Surgery—VramInitial Intraoperative Evaluation & Positioning
The most common indication for muscle flap reconstruction of the perineum as described above in our practice is an abdominoperineal resection (APR) in a previously irradiated patient. The typical scenario is a patient who has a persistent or recurrent neoplasm following chemotherapy and radiation. The radical nature of the APR often leaves patients with an appreciable defect of the pelvic floor and the surrounding perineal skin. In our practice, in most patients, optimum results are achieved using a right VRAM flap that is based on the right deep inferior epigastric pedicle. Thus, this flap will be the focus of this chapter. The right muscle is preferred as it preserves the left rectus muscle for the intended colostomy. Of course, situations such as those described above including previous ligation of the right deep inferior epigastric vascular pedicle should stimulate the reconstructive surgeon to consider the left rectus abdominus muscle or the gracilis muscles as excellent alternatives.
Assuming normal anatomy, the operation begins at the conclusion of the oncologic resection. The distal descending colon is left stapled closed and the midline incision is left open (if incomplete, it should be extended to the xiphoid process). The umbilicus should be preserved on the left side of the abdominal incision. The patient is already positioned in lithotomy, with the medial thighs prepped and draped in case a gracilis muscle is required. The defect is evaluated by the plastic surgery team. To raise the right rectus flap, the surgeon is positioned on the patient’s left; a headlight is helpful.
Elevation of the VRAM Flap
We begin the procedure with evaluation of the deep inferior epigastric pedicle on the right. Assuming that the native vasculature is intact, we proceed with the design of the myocutaneous flap. This process begins with a semilunar incision parallel and to the right of the midline incision made on the skin overlying the right rectus muscle extending from
the pubis to the xiphoid process. At its widest point, the semilunar incision should be between 8–10 cm lateral to the midline. Dissection continues through the soft tissue straight down to the anterior rectus fascia, which is preserved. Within this crescent of skin overlying the rectus muscle, at the most superior third, an ellipse is designed with the intention of preserving the skin, the underlying subcutaneous tissue, and the associated cutaneous perforators that arise from the underlying rectus muscle. The balance of the skin and subcutaneous tissue within the crescent is débrided. The purpose of designing the flap as a crescent and débriding the skin and subcutaneous tissue not to be included in the transposition is to provide the patient with a well-balanced skin edge for closure later in the case. Irregularly shaped incisions leave patients with an undesirable abdominal contour deformity following complete healing.
the pubis to the xiphoid process. At its widest point, the semilunar incision should be between 8–10 cm lateral to the midline. Dissection continues through the soft tissue straight down to the anterior rectus fascia, which is preserved. Within this crescent of skin overlying the rectus muscle, at the most superior third, an ellipse is designed with the intention of preserving the skin, the underlying subcutaneous tissue, and the associated cutaneous perforators that arise from the underlying rectus muscle. The balance of the skin and subcutaneous tissue within the crescent is débrided. The purpose of designing the flap as a crescent and débriding the skin and subcutaneous tissue not to be included in the transposition is to provide the patient with a well-balanced skin edge for closure later in the case. Irregularly shaped incisions leave patients with an undesirable abdominal contour deformity following complete healing.
Following the debridement of nonessential skin and subcutaneous tissue the remaining skin paddle to be preserved is secured to the anterior rectus muscular fascia with approximately eight 2-0 Vicryl sutures at the points of the compass. The purpose of this maneuver is to reduce the risk of perforator avulsion during transposition and has proven extremely helpful in our experience. Bites are taken through the skin paddle and the underlying anterior rectus fascia, taking care not to strangulate the muscle’s blood supply. The tails of these sutures are left long and will be removed following transposition. The skin and subcutaneous tissue overlying the right external oblique is then dissected away from the anterior abdominal wall fascia along that plane, in a medial-to-lateral fashion, to the level of the anterior axillary line. The purpose of raising this flap is to correct for the loss of skin and subcutaneous tissue over the rectus. At closure, later in the case, this dissection will facilitate advancement of the flap in a lateral-to-medial direction and a tension free closure at the midline. During elevation of this flap, care is taken to control the numerous perforators encountered to reduce the risk of postoperative hematoma. Smaller perforating vessels may be controlled with simple electrocautery. However, larger perforators, as are often seen in obese patients, may respond better to medium vascular clips.
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