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Rotational and Free Flap Closure of the Abdominal Wall
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Preoperative Considerations
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Risk Stratification
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Smoking, uncontrolled diabetes, chronic obstructive pulmonary disease, morbid obesity, immunosuppression, long-term use of steroids, advanced age, and malnutrition (serum albumin <2.0 g/dL) increase the risk for surgical site infections and can compromise abdominal wall reconstruction.
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Congenital or acquired disorders leading to a hypercoagulable state can put any pedicled or free flap reconstruction at risk and need to be considered preoperatively.
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Bleeding disorders or medically induced coagulopathy need to be addressed before abdominal wall reconstruction.
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Patient Evaluation and Optimization
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The patient history comprises a detailed medical history including comorbidities that can affect reconstructive efforts, surgical history including details pertaining to the abdominal wall defect (dates of previous surgeries and acquisition of surgical reports describing techniques employed and materials implanted), and social history including smoking and illicit drug use.
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On examination of the abdominal wall defect, the physician should note the location, dimensions, thickness of abdominal wall involved, and previous scars limiting the subdermal blood supply in the area.
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An acute or chronic wound associated with the abdominal wall defect needs to be assessed for active infection, and the possibility of an enterocutaneous fistula needs to be considered and investigated further with a fistulogram.
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The location and function of ostomies need to be noted, also assessing for parastomal hernias on examination or imaging.
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A complete preoperative evaluation with laboratory work-up should focus on nutritional status (albumin and prealbumin) and electrolyte imbalances (enterocutaneous fistula, high-output ostomy).
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Imaging should be considered to delineate anatomy better and assist in operative planning.
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Patient optimization includes control of diabetes, smoking cessation, weight loss, and improved nutritional status.
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Controlling Wound in Preparation for Reconstruction and Timing of Reconstructive Procedure
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Any infection needs to be controlled, and attempts should be made to remove all foreign material before definitive reconstruction.
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Serial débridements should be considered for contaminated or infected wounds.
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Patients who are unable to undergo prolonged operative procedures can benefit from staged repairs.
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Selection of Appropriate Flap
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The size of the defect needs to be considered as well as missing components of the abdominal wall. The need for prosthetic material and the need for functional muscle coverage are additional considerations.
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When reconstruction with a pedicled flap is planned, the arc of rotation, pedicle length, and reach for a tension-free closure need to be considered.
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When free flap reconstruction is planned, considerations include the size of flap vessels and match with recipient vessels, adequacy of pedicle reach to the recipient vessels, and the possible need for an interposition vein graft.
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In patients with a history of multiple previous operations, the possibility of vessel compromise if planning for a pedicled flap or recipient vessel damage if planning for free tissue transfer must always be considered.
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Postoperative Management
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Close observation of pedicled or free flaps is of paramount importance for early recognition and management of complications.
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Frequent clinical assessment (ie, capillary refill, temperature, color) is the gold standard for monitoring, although other modalities can also be used for free flaps (eg, Doppler probe, surface temperature measurement, surface oxygen tension measurement).
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Close flap monitoring for at least 72 hours postoperatively is the standard of care for free flap reconstruction.
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Surgical drains placed intraoperatively should remain in place until daily output is less than 30 mL.
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The judicious use of abdominal wall binders on ambulation should be considered for patient comfort, while being mindful of the location of the vascular pedicle, as a tight-fitting binder can potentially result in flap compromise.
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Flaps Used for Reconstruction of the Abdominal Wall ( 
)
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Abdomen-Based Flaps for Abdominal Wall Reconstruction
External Oblique Flap
Clinical anatomy
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The external oblique muscle extends from the lateral eight ribs laterally to the anterior portion of the iliac crest and inguinal ligament. The medial aponeurosis fuses with the aponeurosis of the internal oblique muscle to form the anterior sheath of the rectus muscle extending to the linea alba at the midline. The external oblique functions as a stabilizer of the abdominal core and aids in trunk torsion.
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The external oblique is innervated by the 7th through 12th intercostal nerves.
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The external oblique is supplied by segmental lateral cutaneous branches of the posterior intercostal arteries (dominant pedicle); the inferior portion of the muscle is also supplied by the ascending branch of the deep circumflex iliac artery.
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The arterial supply is accompanied by venae comitantes draining to the azygos and hemiazygos vein systems.
Flap design
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This flap is used extensively for central abdominal wall defects as part of a component separation technique to help medialize the rectus muscle.
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It can be used as a rotation advancement flap with the skin island extending over the rectus muscle to the midline ( Fig. 17.1 ).
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The flap can be designed as a V-Y advancement flap to increase cephalad reach with extension of the skin incision caudally and subsequent closure of the donor defect in a V-Y fashion after a posteriorly oriented back cut.
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To increase the available fascia for closure of an abdominal wall defect at the midline, the insertion of a tissue expander between the external and internal oblique muscles through a remote incision has been described.
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Based on the intercostal segmental perforator blood supply and after division of the insertions to the costal margin and anterior iliac crest, the external oblique muscle can be reversed posteriorly as a muscle-only flap for coverage of flank and lateral back defects.
Operative steps for elevation of the external oblique flap
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The patient is positioned supine with additional support under the ipsilateral back to better expose the lateral abdominal wall.
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The skin incision is a semicircular line extending from the costal margin to the midline and then curving laterally again toward the iliac crest (see Fig. 17.1 ).
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Flap elevation is performed in a medial-to-lateral orientation. After the skin incision, the dissection is carried down to the anterior rectus sheath and then proceeds laterally until identification of the linea semilunaris.
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At the linea semilunaris, the fibers of the external oblique aponeurosis are separated, and the plane of dissection moves between the external oblique and internal oblique muscles so that the external oblique is elevated with the overlying skin island.
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As the muscle is elevated off the internal oblique, the fibers of insertion on the superior portion of the iliac crest are divided. Similarly, to allow for flap rotation, the insertion of the muscle to the costal margin is also divided.
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After flap elevation, the flap can be rotated to help in coverage of an upper or lower central abdominal wall defect.
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