Marita S. Teng
INTRODUCTION
The hemimaxillectomy defect arises most frequently from ablative surgery for malignant tumors, although severe facial trauma is another etiology. This type of defect is very complex, as a large oronasal and oromaxillary fistula is present, along with loss of bone support for the lip, orbit, and cheek. Midface projection and dentition are also sacrificed, resulting in significant impairments in speech and swallowing.
In general, reconstruction of the maxillectomy defect has multiple important goals, including the following:
• Separate the nasal and sinus cavities from the oral cavity to restore normal speech and swallowing
• Provide projection for the midface and palatal arch
• Reestablish functional occlusion
• Support the orbit or fill the defect in the case of orbital exenteration
• Maintain a patent nasal airway
Traditionally, these defects were lined with a split-thickness skin graft and a prosthetic obturator placed. Though this technique achieves separation of the nasal and oral cavities, maintenance of the prosthesis can be challenging, especially for older patients and particularly those who are edentulous. Furthermore, simple tasks such as swallowing and speaking are impossible without the obturator in place.
Free tissue transfer has become a very useful modality for single-stage reconstruction of these complex defects. Free flaps with bone include the fibula, iliac crest, and scapula osteocutaneous free flaps. The fibula free flap is an excellent choice for reconstruction of the hemimaxillectomy defect because of its ability to achieve all of the above reconstructive goals, while being relatively simple to harvest, and having minimal to no donor site morbidity. This flap has the additional advantages of having a long enough pedicle to reach the ipsilateral neck without requiring vein grafting, as well as suitable bone stock for osseointegrated implants.
HISTORY
As with any reconstructive surgery, midfacial reconstruction may be performed primarily (at the time of ablative surgery) or secondarily. History-taking will obviously differ depending on which situation is applicable, but in general, probably the most important aspect to assess is the patients’ preoperative ability to eat and their postoperative expectations. For example, if a patient is restricted to a liquid diet preoperatively and has neither the desire nor the capability of eating a regular solid diet postoperatively, then one might reconsider the indications for reconstruction with bone. Other factors that should be assessed are the patient’s age and medical comorbidities, as well as the importance that they place on the cosmetic result. For the fibula free flap, it is also critical to evaluate for a history of peripheral vascular disease or lower extremity trauma or gait disorders that could eliminate the fibula as a potential donor site.
PHYSICAL EXAMINATION
From a reconstructive standpoint, examination of the head and neck region should be focused on the anticipated defect. It is useful to think of the potential defect in terms of hard and soft tissue elements, as well as horizontal and vertical components. The most widely used classification for maxillectomy defects is Brown’s classification, which divides the vertical component of the defect into classes 1 to 4 and the transverse extent of the defect into subtypes a-c (Fig. 25.1) (see Chapter 22). By assessing the anticipated defect in this manner, the surgeon can prioritize the most critical elements of the reconstruction and design the flap accordingly.
FIGURE 25.1 Brown’s classification of maxillectomy defects, including vertical and horizontal components. This classification system provides a reconstructive algorithm to guide the reconstructive surgeon, which is useful in the decision-making process. (Redrawn from Brown JS, Shaw RJ. Reconstruction of the maxilla and midface: introducing a new classification. Lancet Oncol 2010;11(10):1001–1008. doi: 10.1016/S1470-2045(10)70113-3.)
It is also important to assess the suitability of various free flap donor sites. Specifically for the fibula free flap, the legs should be examined for any evidence of arterial insufficiency, venous stasis, or previous scars from trauma or surgery. The AAI (ankle–arm index) can be used as a rough screen of lower extremity vascular perfusion, with an AAI of less than 1.0 being an indication of likely peripheral vascular occlusion.
INDICATIONS
The indications for fibular free flap reconstruction includes defects in the infrastructure or alveolus of the maxilla. The nature of the bone graft is such that it cannot be used to address vertical defect involving the orbital rim and/or lateral aspect of the zygoma. Vertical defects are best managed with a scapular or iliac graft. In contrast, the fibula free flap is ideally suited for the reconstruction of infrastructure defects. The bone stock is hearty and will accommodate osseointegrated implants.
CONTRAINDICATIONS
The most obvious and important contraindication to the use of the fibula free flap is vascular insufficiency, either to the flap (peroneal artery) or to the distal leg and foot after flap harvest (anterior and posterior tibial arteries). Rarely, the fibula bone may be absent or severely diminished in size, or even replaced by a fibrous band.
Relative contraindications include severe edema or venous stasis, as well as bulky overlying soft tissue in the lateral lower leg. Finally, though the fibula is a non–weight-bearing bone, careful consideration must be given to harvesting from a patient’s only remaining leg or only remaining weight-bearing leg.
The fibula flap has limitations in terms of the arc of soft tissue rotation, as well as lack of bulk of soft tissue. Thus, when a large volume soft tissue defect exists, an alternative reconstructive method should be considered. In particular, defects that involve the orbital rim and/or lateral aspect of the zygoma require the vertical bone height that can only be achieved with an iliac or vertically oriented scapular bone flap (Fig. 25.2).
FIGURE 25.2 A maxillary defect with a vertical component that involves the orbital rim is difficult to manage with a fibular graft because there is no support for the orbital rim.
PREOPERATIVE PLANNING
As mentioned above, it is essential to plan out the structure and layout of the flap reconstruction based on the anticipated surgical defect. The fibula free flap contains ample length but limited caliber of bone; furthermore, the skin paddle is typically well vascularized but with limitations in terms of amount and arc of rotation. These characteristics make the fibula flap ideal for defects in the inferior maxilla, those which do not require extensive bone stock for reconstruction of the orbital floor or soft tissue (e.g., orbital exenteration) reconstruction.
Imaging Studies
Imaging studies of the head and neck must be obtained and are critical in planning ablative surgery. In addition, some form of imaging is imperative to evaluate the blood flow in the lower extremity and determine the suitability of fibula free flap harvest. It is imperative to confirm that the tibioperoneal trunk gives adequate runoff to the foot via the anterior and posterior tibial arteries and the peroneal artery. Patency of the peroneal artery is also critical to the viability of the free flap. If three-vessel runoff is identified, fibula harvest can easily be performed with no risk to the vascularity of the foot. If only two-vessel runoff is identified, then harvest of the peroneal artery will leave only one artery to supply the foot, which is very tenuous, and use of the fibula flap should be carefully reconsidered.
Many surgeons advocate the use of magnetic resonance angiography to obtain detailed anatomic information about the tibioperoneal anatomy, as well as to possibly localize perforator vessels on the peroneal artery and their course in the posterolateral intermuscular septum. Others have traditionally advocated color flow Doppler as a less costly and invasive method of imaging the lower extremity. In an experienced ultrasonographer’s hands, this technique can also identify septocutaneous perforators from the peroneal artery, thus aiding in the design of the skin paddle.
SURGICAL TECHNIQUE
In conceptualizing the fibula flap for reconstruction of a hemimaxillectomy defect, it is important to remember that the vascular pedicle should come off the posterior neomaxilla, creating a natural drape of the vessels into the ipsilateral neck for anastomosis. As such, the most distal end of the fibula will be inset into the anterior aspect of the defect, and the palatal soft tissue defect will best be reconstructed with a distally situated skin paddle. With these geometric considerations, it is preferable to use the ipsilateral leg as a donor site, as the skin paddle will naturally fall onto the intraoral/palatal surface when the pedicle is oriented posteriorly (Fig. 25.3A).
FIGURE 25.3 A. Axial view of the contents harvested with a left fibula free flap. B. Depiction of the plating surface of the fibula flap and how it is oriented into an ipsilateral maxillectomy defect. In this case, a left fibula flap is being inset into a left maxillectomy defect. The skin paddle naturally sits in an orientation to fill the palatal defect.
Landmarks for harvest of the fibula free flap are the fibular head proximally and the lateral epicondyle of the ankle distally. A line between these two points denotes the fibula bone itself. The posterior intermuscular septum, in which the septocutaneous perforators run, is located in a plane angled slightly posteriorly from the fibula bone (Fig. 25.3B). Furthermore, the dominant perforators are generally located more distally in the leg, so a skin paddle is centered over the middle and distal third of the bone. As mentioned above, consideration should be given to the desired location of the skin paddle relative to the bone once it is inset.
Six to seven centimeters of bone should be preserved at both the knee and ankle in order to maintain joint integrity. A thigh tourniquet is inflated to 350 mm Hg, and the anterior skin incision is performed first and carried subfascially. This incision exposes the peroneus longus and brevis muscles, which are retracted anteriorly to expose the fibula. The skin paddle is gently retracted posteriorly, and perforating vessels are identified in this manner. The bone is then skeletonized with cautery, taking care to avoid injury to the perforators by maintaining a small cuff of peroneus muscle around the visible perforators (Fig. 25.4). The dissection then proceeds anteriorly around the fibula, through the extensor muscles and to the interosseous septum. The interosseous septum is then incised along the length of the fibula, preserving several millimeters to protect periosteal vessels. It is sometimes necessary, especially in younger patients with less tissue laxity, to perform the osteotomies prior to incising the septum. Also, the posterior skin incision can be made, taking care to incorporate the perforators in the skin paddle (Fig. 25.5). Once the bone has been cut, it is distracted laterally to reveal the posterior compartment muscles. The peroneal vessels are then identified distally in the ankle, ligated, and divided. The tibialis posterior and flexor hallucis longus muscles are divided with cautery. A cuff of the flexor hallucis muscle, as well as of the soleus muscle, is preserved in order to maintain the integrity of any musculocutaneous perforators to the skin.
FIGURE 25.4 The bone can be skeletonized with cautery, taking care to avoid injury to the perforators by maintaining a small cuff of peroneus muscle around the visible perforators. This will lengthen the vascular pedicle.
FIGURE 25.5 The axis of the posterior intermuscular septum is angled and posterior to the axis of the fibula bone. This fact is important to recognize when designing the skin paddle. The majority of skin perforators are generally located distally.
The bone is then shaped with closing osteotomies in order to create a shape that resembles a “minimandible” in order to restore the midface contour while recreating the palatal arch (Fig. 25.6). Miniplates are used to fixate the bone to the anterior palate as well as the remaining zygoma. The skin paddle is oriented to fill the palatal mucosal defect.
FIGURE 25.6 The fibula flap is fashioned into a “mini-mandible,“ secured to the remaining native palatal bone and root of the zygoma.
Closure of the donor site over a suction drain may be performed primarily or with a split-thickness skin graft. The decision about whether to use a skin graft is made not only based on the size of the harvested skin paddle but also by the laxity of the patient’s skin and tissue.
POSTOPERATIVE MANAGEMENT
Immediately postoperatively, the patient should have neurovascular checks of the lower extremity at each flap check, which is performed every 4 to 6 hours. The donor leg should be elevated and immobilized in a neutral splint. On postoperative day (POD) 2, patients may begin ambulating with the aid of a walker and with the assistance of a nurse or a physical therapist. After POD 5, patients may weight-bear as tolerated, but throughout the first 2 to 3 weeks after surgery, the leg should be elevated while supine or seated. The splint is removed on POD 7 and the incision and/or skin graft examined, and the splint is replaced for protection of the leg for the second postoperative week before it is completely removed.
Postoperative care of the free flap itself is standard, with vigilant flap checks over the first 72 hours, in order to identify any microvascular issues early. Because the skin paddle may be quite edematous in the first week, the paddle is at risk for excessive pressure or trauma from the mandibular teeth. Patients should be cautioned against biting on the skin paddle.
COMPLICATIONS
Minor complications to the donor extremity include cold intolerance or edema of the lower leg. When the muscles scar or branches of the peroneal nerve are injured, patients may experience weakness in dorsiflexion of the big toe. Other uncommon complications include hematoma of the donor site or of course, flap failure. As usual, patients must be vigilantly followed for early recognition of problems with the donor site or with flap compromise.
Wound complications range from some simple skin breakdown to sensory or motor deficits resulting from tight closure that can cause a pseudocompartment syndrome. Shindo et al. determined that though multiple factors contribute to donor site wound complications after fibula harvest, if tension is present at the suture line, a skin graft should be strongly considered to minimize the risk of complications.
Extreme tension on the closure, which, due to tissue edema, can worsen after the closure is completed, may result in a very damaging pseudocompartment syndrome. In such a circumstance, the leg muscles can necrose, and both sensory and motor nerves may be impaired. If unrecognized, nerve damage can be permanent. Excessive pain at the donor site is usually the first sign of pseudocompartment syndrome and should immediately be examined by removing the dressing and splint and doing a full neurovascular examination.
RESULTS
Many series have reported successful functional and cosmetic results with fibula free flap reconstruction for hemimaxillectomy defects. In a 2002 case series by Futran, 27 patients underwent fibula reconstruction for this type of defect, with all of them achieving a regular or soft diet, 18 maintaining osseointegrated implants, and 22 being judged by themselves, their significant others, and the physician as having an “excellent” or “good” cosmetic outcome. Recently, Sun et al expanded the use of the fibula flap in their 2011 series of 20 patients undergoing reconstruction of high maxillectomy defects. Because of the increased complexity of reconstruction due to defects of the orbital floor, nasal wall, and/or zygoma, they employed titanium mesh to help support the anterior maxilla. In four cases, either a second flap or a zygomatic implant was used to further augment the defect. Nineteen of these twenty patients achieved bony union and closure of the oronasal cavities, as well as intelligible speech. Both Futran and Sun admit that exposure or infection of titanium mesh is not uncommon, and its use should be employed cautiously in patients requiring or having a history of radiation therapy.
PEARLS
• The ipsilateral leg donor site orients the skin paddle in the most favorable position to restore the palatal defect.
• The posterior crural septum is often visible, especially in older patients with more tissue laxity. This plane is most noticeable when the soleus and gastrocnemius muscles are manipulated while the leg is relaxed, flexed at the knee. Marking out this septum facilitates design of the anterior skin incision to help incorporate the septocutaneous perforators.
• The skin paddle must be designed carefully, not only to incorporate the most likely dominant perforators but also to be placed in a favorable location relative to the bone in order to seal the palatal defect.
• When a long skin paddle is harvested, a portion may be used to reline the lateral nasal wall if necessary. The intervening skin between the neopalate and nasal wall can be deepithelialized to facilitate this.
• The vascular pedicle must be brought off the posterior (and superior) aspect of the maxillectomy defect, such that the vessels may be tunneled into the neck for anastomosis.
• Generally, the soft tissue tunnel into the neck is most easily created on the medial surface of the mandible. The technique creates the least angulation in the vessels and obviates the risk to branches of the facial nerve, which are at risk if a lateral tunnel is created.
PITFALLS
• Excessive traction on the common peroneal nerve during harvest can result in an equinovarus deformity, as well as numbness to the lateral leg and dorsum of the foot.
• Joint instability can occur if a proper (6 to 7 cm) length of fibular bone is not preserved at the knee and ankle joints.
INSTRUMENTS TO HAVE AVAILABLE
• Standard head and neck surgical set
• 2.0 locking plating set
• Reciprocating saw
SUGGESTED READING
Futran ND, Stack BC, Zaccardi MJ. Preoperative color flow Doppler imaging for fibula free tissue transfers. Ann Vasc Surg 1998;12(5):445–450.
Brown JS, Jones DC, Summerwill A, et al. Vascularized iliac crest with internal oblique muscle for immediate reconstruction after maxillectomy. Br J Oral Maxillofac Surg 2002;40:183–190.
Chang DW, Langstein HN. Use of the free fibula flap for restoration of orbital support and midfacial projection following maxillectomy. J Reconstr Microsurg 2003;19(3):147–152.
Genden EM, Okay D, Stepp MT, et al. Comparison of functional and quality-of-life outcomes in patients with and without palatomaxillary reconstruction: a preliminary report. Arch Otolaryngol Head Neck Surg 2003;129(7):775–780.
Futran ND, Mendez E. Developments in reconstruction of midface and maxilla. Lancet Oncol 2006;7:249–258.
Dalgorf D, Higgins K. Reconstruction of the midface and maxilla. Curr Opin Otolaryngol Head Neck Surg 2008;16:303–311.