Iliac Crest Tissue Transfer

The composite tissues available for free-tissue transfer reconstruction of bone-containing defects of the head and neck are from the fibula, iliac crest, scapula, radius, and metatarsal. This article describes the iliac crest flap, which is based on the deep circumflex iliac artery (DCIA). ^[1] This flap has many of the desirable qualities of an ideal flap for reconstruction of composite defects of the maxilla and mandible. The flap can be harvested simultaneously with resection or preparation of the recipient bed. The anatomy is predictable, and the bone stock can reliably support dental rehabilitation. The vessels are of appropriate caliber, and the pedicle is usually of sufficient length. ^[2]

The image below depicts iliac crest tissue transfer.

Iliac crest tissue transfer. Exposure of the external oblique fascia. Note the planned incision 2.5 cm medial to the iliac crest.

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The reconstruction of composite bone-containing defects of the head and neck has always posed a major challenge to head and neck surgeons. Free-tissue transfer has brought valuable additional tools to the armamentarium of the reconstructive surgeon. The mandible often is the focus of head and neck reconstruction because of its proximity to the most common locations for the development of intraoral carcinoma (ie, floor of mouth, tongue, retromolar trigone area). Advanced tumors of the oral cavity require adjuvant radiotherapy and complete surgical resection to achieve appropriate rates of disease control.

Chemotherapy may also be necessary, depending on the extent of the lesion. When these advanced tumors encroach upon or invade the mandible, mandibulectomy is required. Reconstruction of the mandible is often necessary to facilitate airway protection, tracheostomy decannulation, oral nutrition, dental rehabilitation, and the establishment of acceptable facial contour. ^[3]

From the viewpoints of cost and rehabilitation time, primary reconstruction has proven to be the most appropriate method of therapy. Mandibular reconstruction using free bone grafts has unacceptable rates of infection. Reconstruction using only a bone plate is associated with significant complication rates (eg, plate dehiscence, plate fracture) and fails to meet the requirements of rehabilitation. The surgeon performing mandibular reconstruction secondarily often has the added difficulty of working within an irradiated field.

The free groin flap was one of the first revascularized free-tissue transfers described. Following its description, numerous attempts were made to include the ilium in the flap; however, these efforts proved to be unreliable. No doubt, interest in such a flap for mandibular reconstruction was based on Manchester's description of the anatomic and structural similarities between the anterior ilium and the mandible.

Taylor et al and Sanders and Mayou were the first to recognize the deep circumflex iliac vessels as the dominant blood supply to the anterior ilium. Dye studies demonstrated that the deep circumflex iliac vessels provided perfusion to the ilium through endosteal and periosteal mechanisms. ^{[4, 5]} The same year, another study described perforators through the multiple muscular layers of the abdominal wall from the DCIA and the deep circumflex iliac vein (DCIV) to the skin that overlies the anterior ilium. Subsequent work showed that the ascending branch of the deep circumflex vessels was responsible for blood supply to the internal oblique muscle. ^[6]

The indications, utility, advantages, and disadvantages of the DCIA flap in oromandibular reconstruction were nicely outlined in a couple of articles. ^{[7, 8]} One specific indication reported for this flap (as well as a major advantage) is for reconstruction of through-and-through defects of the oral cavity, mandible, and skin. At the same time, one of the most significant problems is the thickness of the soft tissue component and the relative immobility of the skin element in relationship to the bone. Where possible, the internal oblique muscle is used for intraoral lining to circumvent this problem.

Brown contributed to the DCIA flap literature by describing use of the flap for maxillary reconstruction; he demonstrated the adaptability of the flap through various alterations in its orientation to the myriad defects that are encountered in immediate maxillary reconstruction. ^[9]

The deep circumflex iliac artery (DCIA) flap may be used for mandibular reconstruction, especially in patients with full dentition ^{[10, 11, 12, 13]} .

The DCIA flap is indicated for the reconstruction of composite bone-containing defects of the maxilla and mandible. Insufficient bone is contained in the flap to reconstruct an entire mandible. The ability to simultaneously transfer bone, muscle, and skin allows for the reconstruction of complex and large deformities. In current practice, ablative surgeries for neoplastic conditions of the oral cavity, trauma, inflammation, osteoradionecrosis, and congenital deformities are the most common indications for DCIA flaps. ^[14]

DCIA flaps remain the flap of choice for dentate patients. The fibula free flap, on the other hand, is more useful in edentulous patients or those patients with significant mandibular defects. ^[15]

Publications describing the use of the iliac crest are limited in number, compared with other options. These other options include the osteocutaneous radial forearm free flap (for small lateral defects) and the fibula and scapular free flaps (larger, through-and-through defects).

The DCIA originates on the lateral aspect of the external iliac artery. The diameter of the DCIA at its branching from the iliac artery is 2-3 mm. The DCIA gives off an ascending branch that supplies the internal oblique muscle. This branch typically arises at or about the anterior superior iliac spine (ASIS). The artery provides blood supply to the ilium through periosteal and endosteal branches. Musculocutaneous perforators provide arterial blood supply to the skin overlying the iliac crest. Rarely, the ascending branch and the DCIA have separate origins from the iliac vessel.

The DCIV follows a similar course to the artery. It is slightly longer because the iliac vein is more medial. A small branch always joins the vein just before its origin from the iliac vein. The vein diameter is 3-5 mm.

The vascular pedicle is found in a prominent groove medial to the iliac crest. It is encased within the fascia of the iliacus and transversalis muscles. The vascular pedicle is not seen directly, and a full-thickness muscle cuff must be harvested (approximately 2.5 cm) on the medial aspect of the iliac crest to avoid injury to the pedicle.

The vessel size and length is substantially shorter compared with other microvascular flaps (osteocutaneous radial forearm, fibula, scapula) available for reconstruction to the maxilla and mandible.

The lateral femoral cutaneous nerve has a variable relationship to the vascular pedicle; alternately, it can lie deep or superficial to the vascular pedicle, or it can lie between the vascular pedicles.

Besides prior surgery with injury to the vascular pedicle, chronic cough and steroid use are considered the only contraindications to using the DCIA flap. These situations increase the risk of hernia formation to an unacceptable degree.

In patients who have preexisting impaired mobility due to lower extremity problems, harvesting the flap from the most functional extremity should be discouraged because the recovery process can be protracted.