Various designs of musculocutaneous flaps may be transferred as free flaps based on the rectus abdominis muscle, supplied by the deep inferior epigastric artery and vein and the periumbilical perforators69 (Figure 18-28). The rectus abdominis muscle is flat and thin, with a large skin island over the muscle that may be oriented in a vertical transverse or oblique fashion. In addition, one or more cutaneous paddles may be used to cover multiple surfaces of complex multidimensional defects in the head and neck.70 In obese patients, however, the flap may be too bulky and therefore it is preferable to transfer the muscle alone, covered with a split-thickness skin graft.
The deep inferior epigastric artery and vein are vessels with a large caliber (2 to 3 mm) and length (8 to 10 cm). If required, the length of the vascular pedicle may be extended to up to 18 cm by dissecting the lateral branch of these vessels within the muscle.71
Another advantage of the rectus abdominis flap for head and neck reconstruction is the possibility of harvesting the flap at the same time the ablative procedure is being performed, without needing to change the position of the patient.
Figure 18-26. A, Defect after total rhinectomy and anterior maxillec-tomy. B, Design of osseocutaneous radial forearm flap. C, Flap inset so that osseous component bridges maxillectomy defect; two skin islands are used to resurface floor of nasal cavity and roof of mouth.
The rectus abdominis free flap is without question the first choice for defects that require a large amount of skin coverage and soft tissue. Such requirements are usually observed after wide excision of scalp or skull base tumors,71,72 total maxillectomy and midfacial defects,38 orbitomaxillectomy, and composite resections of mandible and soft tissue73,74 (Figure 18-29).
The latissimus dorsi may be used as a free muscle or musculocutaneous flap for head and neck reconstruction. Anatomic details of the latissimus dorsi muscle were described in the pedicle flap section. In this section, it is important to emphasize that the vascular anatomy of this flap is extremely consistent and reliable for performing microvascular anastomoses with neck vessels or the superficial temporal artery and vein. The latissimus dorsi is a broad and flat
muscle that is very useful to reconstruct extensive scalp defects, especially following resection of large tumors or debridement of calvaria for osteoradionecrosis75,76 (Figure 18-30). The muscle is covered with a split-thickness skin graft, and once it atrophies a very stable wound is achieved. As a musculocutaneous flap the latissimus dorsi free flap is used for reconstruction of extensive orbitomaxillary or skull base defects that require minor soft-tissue fill and a cutaneous surface.77 For more complex defects of the midface that require two epithelial surfaces, the latissimus dorsi may be harvested with two skin paddles; the intervening bridge of skin is de-epithe-lized and the muscle folded to repair the inner mucosal lining and the overlying skin.78
One of the few shortcomings of the latissimus dorsi free flap for head and neck reconstruction is the impossibility of harvesting the flap at the same time the ablative procedure is taking place. Unfortunately, the
patient needs to be repositioned several times during surgery, thus significantly increasing the surgical time.
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