James S. Brown
INTRODUCTION
There is a reluctance to use the iliac crest donor site for free tissue transfer because of the perceived donor site morbidity, although the site remains popular for nonvascularized grafts. There are publications, however, that have compared this site to the fibula, and both can cause problems. Reconstruction of the maxilla, including the maxillary alveolus, hard palate, maxillary buttress, orbital floor, or orbit itself, results in a varied defect that has been classified (Fig. 22.1), and this is regularly referred to in this chapter.
FIGURE 22.1 Classification of palatal, maxillary, and midface defects.
Low maxillectomy defects not resulting in loss of alar support can be adequately reconstructed with a fibula flap which has been well described, or adequately obturated especially with implant-retained prostheses. If the resection involves the orbital floor (Class III) or the removal of the eye (Class IV), then obturation can give poor results especially after radiotherapy, and reconstruction of the defect is generally preferred. The main methods of free tissue transfer described involve the iliac crest (deep circumflex iliac artery [DCIA]), fibula (peroneal artery), and scapula (circumflex scapula or thoracodorsal angular artery [TDAA]). This chapter describes the use of the DCIA with internal oblique for the reconstruction of Class II-IVb-d defects.
HISTORY
A history of prior surgery or injury in the area of the donor site should be sought. When considering the DCIA flap for maxillary reconstruction, it is important to determine if the patient has a history of gait disturbance or deep vein thrombosis.
PHYSICAL EXAMINATION
The physical examination should focus on identifying evidence of prior surgery or injury in the area of the donor site. Not uncommonly, male patients may have undergone repair of an inguinal hernia. Prior surgery or injury to this region may compromise the reliability of the flap, and an alternate donor site should be considered.
INDICATIONS
The DCIA with internal oblique can provide a high-quality reconstruction of the maxillary bone for all the defects (Class I-IV), and the internal oblique muscle provides an ideal lining for the oral cavity and nasal passage. This flap is superior to the others, especially in the Class III defect when the orbital floor is removed but the orbit retained. The flap can be harvested as a tripartite perforator flap with a vascularized bone graft, muscle flap, and skin paddle.
CONTRAINDICATIONS
The vascular pedicle is short, and the flap harvest requires care, making use of the flap less popular. The advantage of the flap is the size of the bone and ability to shape it to the defect (nasal and orbital), as well as the use of muscle to line the nasal cavity and sinus and provide a very natural result for palatal reconstruction. However, when the neck is depleted of vessels, an alternative donor site with a longer vascular pedicle should be considered, or vein grafts should be prepared.
PREOPERATIVE PLANNING
Preparing the Recipient Site
The principle of selective neck dissection and postoperative radiotherapy in controlling regional recurrence is well established, and as a result, the facial artery and vein can be retained in continuity when preparing recipient vessels in the neck. In general, the pedicle will not reach below the inferior border of the mandible, and so the anastomoses are usually performed above the inferior border being careful to protect the mandibular branch of the facial nerve. I have used superficial temporal vessels occasionally, but it is sometimes possible to divide the retromandibular vein and bring that forward for the venous anastomosis. For either of these options, it is essential to preserve the facial vein to allow drainage through the internal jugular vein. In my experience, the majority of vein grafts have been used for inadequate arterial flow through the facial artery. Papaverine can be used to treat vessel spasm, and if this is not successful, the arterial anastomosis is redone and then an IV bolus of 5,000 units of heparin is given just prior to the release of clamps, after completion of the redo anastomosis. Using these measures has negated the need for vein grafts in the arterial system for the last 5 years.
SURGICAL TECHNIQUE
The skin markings include the pubic tubercle medially, the iliac vessels, anterior superior iliac spine (ASIS), iliac crest, costal margin, proposed osteotomies and internal oblique muscle, and the incision (Fig. 22.2). It is possible to place the anterior osteotomy as much as 40 mm posterior to the ASIS for a Class II-IVb defect as the length of the bone is not a factor. This may not be possible for Class II-IVd defects crossing the midline as the reconstruction needs to span from the zygomatic buttress to the premolar region controlaterally. If raising a skin perforator flap, then the perforators are situated 74 mm (range 50 to 105) posteriorly from the ASIS and 8 mm (range 1 to 35) above the iliac crest and can be identified with a handheld Doppler. It is perfectly reasonable to raise skin or adipose tissue as a perforator component to the internal oblique muscle and the iliac crest to replace loss of facial skin. The incision runs about 20 mm above the line of the iliac crest from the iliacs to posterior to the planned posterior osteotomy. As with all incisions, this can be extended if better exposure is required. If including a perforator skin island, then plan this island around the likely perforator following Doppler identification.
FIGURE 22.2 Exposure of the vascular pedicle can be accomplished with an incision along the iliac crest axis.
Incise the skin, and if raising a perforator flap, identify the perforator before exposing the external oblique muscle with its fibers running in a line from the costal margin to the pubic tubercle. At this point, dissect out the perforator vessel to where it should enter the DCIA and vein just anterior to the ASIS. Next incise the external oblique muscle about 20 mm above the iliac crest from the iliacs to the posterior osteotomy. This plane between the external and internal oblique is easy to separate as there is only a thin layer of adipose tissue. It is best to have access to the internal oblique muscle as far as the costal margin posterosuperiorly and the rectus sheath anteriorly. Next, outline the muscle to be harvested (Fig. 22.3) and begin to incise the fibers of the internal oblique muscle running in the opposite direction to the external oblique muscle where the muscle is thickest about 40 mm above the iliac crest posteriorly. This dissection is best done sharply with a scalpel to avoid damage to the ascending branch of the DCIA that lies in the fascia between the muscles. For this reason, it is essential to keep the fascia with the internal oblique muscle to leave fresh-looking muscle, which is the transversalis (fibers running horizontally) exposed. In most cases, it is easy to see the ascending branch on the undersurface of the internal oblique muscle. The posterior incision goes all the way to the iliac crest, but the anterior incision stops about 20 mm above the ASIS and can then be continued toward the iliac vessels. The DCI vessels lie in the transversalis fascia between the ASIS and the iliacs, but it is best to follow the ascending branch that takes you to the DCIA. It is not necessary to disrupt the attachments to the ASIS or the inguinal ligament as the vessels are accessed from the abdominal side. The pedicle dissection to the iliacus can now be completed, noting that the DCIV often descends just as it enters the iliac vein, before going back to the iliac crest and incising transversalis to reveal iliacus lying more inferiorly.
FIGURE 22.3 The DCIA and ascending branch shown lie under the internal oblique but can be easily dissected once the muscle has been incised as shown.
The anterior osteotomy has to be done from the lateral side of the iliac crest. It is better to pass an instrument down the abdominal side of the iliac crest to ensure protection of the pedicle prior to this anterior vertical osteotomy. Then make the posterior osteotomy to the depth required. At this point, the iliacus muscle can be incised at the planned depth of the osteotomy from the abdominal side. It is often easier to make the osteotomy from the abdominal side especially for longer bone spans such as reconstructing the mandible. Make sure you can see the anterior and posterior osteotomies at their depth prior to making the osteotomy to release the bone toward the abdomen and the side of the pedicle. At this point, the flap is raised and can be left on the pedicle prior to transfer to the head and neck (Fig. 22.4).
FIGURE 22.4 Once raised, the flap can be left pedicled until the time of inset.
The ipsilateral iliac crest is raised so that the pedicle lies posteriorly and the lateral side of the bone is also lateral in the reconstructive site. This ensures that the crest of the ridge replaces the alveolus and the deeper part of the iliac bone can be fashioned to reconstruct the piriform aperture of the nose, lateral nasal bones, and the orbital floor to articulate with the buttress of the zygoma. The muscle then lies in the region of the hard palate, and there is sufficient bulk to obturate the sinus defect, form a neopalate, and reline the nasal cavity (Fig. 22.5). Horizontal placement of the bone means there is insufficient bone to support the alar region and there is little room for the muscle that is best used to reform the palate and obturate the dead space. A miniplate placed at the maxillary alveolus and the zygomatic buttress will provide sufficient fixation. If there is a need for reconstruction of the nasal bones or orbital floor, then nonvascularized bone can be used from the donor site although titanium mesh is often preferred for the orbital floor.
FIGURE 22.5 Vertical orientation of the graft for defects of the vertical maxilla.
In complex defects, it is an advantage to prepare a sterolithographic model so that templates can be prepared to help especially with reconstruction of the orbit. The microvascular anastomoses can be carried out at this point. Some surgeons are concerned that the vessels pass on the lateral surface of the mandible and therefore potentially can be compressed against the bone. In our experience, this has not been a problem. The last two failures with this flap for maxillary reconstruction were in April and June 2004 both for vein grafts, which were inadequate in size for the vein in one case and a severe kink in the arterial system in the other.
In the management of these patients, it is essential to involve the prosthodontist who will be advising the patient on both dental and facial rehabilitation. Patients will wish to know whether it is possible to have their dentition restored and in Class IV cases, the chance of an orbital prosthesis. The composite flap options of fibula, scapula, and iliac crest are well known, and in Table 22.1, I have tried to indicate the various defects and how they can best be reconstructed.
TABLE 22.1 Comparison of Suitability for Composite Free Flaps to Reconstruct and Provide Rehabilitation for Maxillary Defects
The DCIA is still not a first choice in many units even for the Class IIIb,d type defects for which I think it is ideal. The morbidity of the donor site is often stated as a reason not to consider this option, but it is probably because the flap harvest is not straightforward, and the reconstructive surgeon may not be familiar with this option. In Europe, the DCIA has been used extensively for reconstruction of the mandible, and so adapting the technique for the maxilla is less of a problem. I routinely incorporate the internal oblique muscle in the reconstruction to ensure a dual blood supply of the graft and to use the muscle as a marker in case of flap compromise. If the aim of the reconstruction is to restore form and function, then this donor site provides the best bone option in terms of height and width. The ability to raise the internal oblique muscle and use the skin as a perforator flap adds to the versatility of the flap.
In my own unit, we generally keep the DCIA option for those cases in which dental rehabilitation is a primary aim and for Class III defects when we think it is the best option for orbital support, as well as easy articulation with the nasal region and the zygomatic buttress. The muscle is ideally placed to obturate the sinus region, line the nasal cavity, and provide a very natural healed hard palate. There are reports of using the TDAA scapula tip option, but the bone is thin, and although the face and orbit can be addressed, there is little chance of implant-retained dental rehabilitation. The main reason for the popularity of this option is the long pedicle, which makes the flap easier to insert and potentially more reliable. I have lost two bone elements of the flap, which is supplied both by the angular branch of the thoracodorsal as well as by the circumflex scapula arteries. Extending the bone harvest beyond the area of angular artery supply indicated by Senerivatne may be risky, and similarly, osteotomies to shape the bone may compromise the blood supply. Rodriguez has described an ingenious method of insetting the fibula for this defect, but this requires favorable perforators to plan the skin islands and considerable ability with this flap.
Closure of the donor site is an essential part of the operation and, in my view, poor closure is the main reason for excess donor site morbidity if the attachments of the ASIS have been kept intact. Using PDS, suture the transversalis muscle to the iliacus, being careful not to pierce the peritoneum. There is then a defect of the internal oblique muscle that must be reinforced with mersilene mesh and secured with Prolene (Fig 22.6). Small holes are prepared in the cut region of the iliac crest, and the mesh sutured securely to the bone and residual muscle to close the defect. A suction drain can be placed over the mesh prior to closing the internal oblique and then the skin in a four-layered closure.
FIGURE 22.6 Typically mesh is not required; however if necessary it can be used to aid the closure.
POSTOPERATIVE MANAGEMENT
There are no special measures to take postoperatively, but as the muscle can be difficult to monitor, I often use an implantable Doppler to aid flap surveillance. It is important to make sure that bowel sounds return after a short ileus and that there is a soft abdomen on palpation.
COMPLICATIONS
Complications are related to the reconstruction itself or the donor site. The short pedicle is responsible for most complications because revascularization of the flap in the vessel-depleted neck can be a challenge. Whenever we use this donor site for maxillary reconstruction, a heightened sense of vigilance and awareness is required because of the technical challenges related to placing the bone graft into position, orienting the muscle flap, and ensuring that the vascular pedicle is in an appropriate position to allow for revascularization.
RESULTS
The bone graft stock is excellent for accommodating osseointegrated implants, and the extensive bone graft will also serve to reconstruct extensive maxillary defects that involve the orbit, zygoma, and/or the alveolus. There has been no comparative data to other options of reconstruction, and so no claims can be made with robust data. The claims in this article are based on opinion, but if the technique is used successfully, the results will not disappoint.
PEARLS
• Ipsilateral iliac crest to the defect for an ideal curvature of the bone and the best part of the bone (crest) for replacement of the alveolus
• DCIA with internal oblique muscle is probably the best option for Class IIIb,d defects requiring dental rehabilitation.
• The use of muscle to line the nasal cavity and restore the hard palate is ideal for a natural-looking palate and implant–bone interface.
• Retain the facial vessels in continuity when preparing the recipient site.
• The anterior osteotomy can be made 40 cm posterior to the ASIS to ensure a longer pedicle without compromising the vascularity of the flap and the muscle quality.
• Close cooperation with a maxillofacial prosthodontist is essential.
• This surgery is very complex and specialist units with multiple reconstructive options and experience would best serve such cases.
PITFALLS
• Vein grafting of the arterial system may be required if the flap cannot be perfused with pharmacologic assistance.
• Donor site morbidity will be increased if the attachments of the ASIS are disrupted and there is poor attention to detail and failure to reinforce the internal oblique muscle on closure.
• Attention to hemostasis is even more important than in standard surgery, and so take your time and maintain a dry field while harvesting the flap.
INSTRUMENTS TO HAVE AVAILABLE
• Standard head and neck surgical set
• Reciprocating saw
• Miniplating system
• Marlex mesh
SUGGESTED READING
Triana RJ, Uglesic V, Virag M, et al. Microvascular free flap reconstruction in patients with partial and total maxillectomy defects. Arch Facial Plast Surg 2000;2:91–101.
Brown JS, Jones DC, Summerwill A, et al. Vascularised iliac crest with internal oblique muscle for immediate reconstruction after maxillectomy. Br J Oral Maxillofac Surg 2002;40:183–190.
Rodriguez ED, Martin M, Bluebond-Langner R, et al. Microsurgical reconstruction of post-traumatic high-energy maxillary defects: establishing the effectiveness of early reconstruction. Plast Reconstr Surg 2007;120:103s–117s.
Clark JR, Vesely M, Gilbert R. Scapula angle osteomyogenous flap in postmaxillectomy reconstruction: defect, reconstruction, shoulder function, and harvest technique. Head Neck 2008;30:10–20.
Brown JS, Shaw RJ. Reconstruction of the maxilla and midface: introducing a new classification. Lancet Oncol 2010;11:1001–1008.