Reconstruction of the Mandible and Maxilla


Reconstruction of the Mandible and Maxilla

Matthew M. Hanasono

Restoration of the mandible and maxilla are among the most challenging and arduous procedures performed by reconstructive surgeons. Accuracy is paramount to restoring facial appearance and function, including airway maintenance, mastication, swallowing, speech, and, in the case of the maxilla, vision. This chapter focuses on reconstruction of segmental defects of the mandible and maxilla that require grafts and flaps for reconstruction rather than rigid fixation alone. An understanding of the nuances of reconstruction of this region of the body can help the surgeon achieve success in accurate reconstruction and minimize the chances for complications. Because microvascular free flaps play a huge role in contemporary mandibular and maxillary reconstruction, this chapter focuses on avoiding and treating complications related to free tissue transfer in addition to addressing other nonmicrovascular complications that are specific to these structures.

Reconstructive Techniques to Minimize Complications

Mandibular, and occasionally maxillary, reconstruction with a reconstruction plate that spans a segmental bony mandibular defect was a more popular technique before the development of microvascular free bone flaps. Some centers still rely, at least occasionally, on reconstructive plates when a patient is deemed unsuitable for a prolonged operative procedure involving free tissue transfer or when a surgeon with microvascular expertise is not available. However, experience has shown that such reconstructions are at high risk for complications, including plate fracture and exposure, either intraorally or through the skin of the cheek or chin.

To help decrease the rate of exposure, many surgeons have attempted to combine reconstruction plates with a pectoralis major muscle or myocutaneous pedicled flap or a soft tissue free flap. However, Wei et al1 still reported a complication rate of 69% in patients undergoing mandibular reconstruction with a titanium plate and soft tissue free flap in a series of 80 patients. Plate exposure was the most common complication, followed by soft tissue deficiency, deformity of the lateral face, intraoral contracture, trismus, and osteoradionecrosis.

Overall, complication rates associated with a reconstructive plate and soft tissue flap are reported to be between 21 and 87%.2 Anterior defects are associated with a higher rate of plate extrusion than lateral defects, as are defects in patients undergoing radiation treatment or with a history of prior irradiation. In addition, larger defects result in significantly higher failure rates than smaller defects.

Even when patients are reasonable candidates for a free flap, some surgeons advocate plate or plate and soft tissue flap reconstruction in patients with advanced cancers and a limited life expectancy, because the surgery is usually shorter and recovery is usually faster. However, this approach must be carefully considered on a case-by-case basis, because the incidence of plate-related complications is high. In addition, the results are rarely ideal because of persistent contour deformity and malocclusion. Secondary salvage of such complications with vascularized bone flaps can be performed but tends to be more difficult than if it is performed at the time of the surgical resection. Additional difficulties at the secondary surgery include more challenging dissection of recipient vessels and greater difficulty restoring accurate occlusion because of postoperative and radiation therapy–associated scar contracture.

Autologous Bone Grafts

Autologous bone grafts can be used for mandibular and maxillary reconstruction. The bone is revascularized by a process of creeping substitution. Sources of cortical bone graft include iliac crest, split calvarium, and rib. Nonvascularized bone grafts may be used in defects shorter than 5 cm. High failure rates are common in longer segments and in anterior defects. Preoperative or postoperative radiation therapy is usually considered a contraindication for mandibular reconstruction with bone grafts regardless of the size of the defect because of the heavy torque forces on the mandible associated with mastication. Therefore use of nonvascularized bone grafts for mandible reconstruction is usually restricted to patients with benign disease or who require mandibular surgery for posttraumatic or orthognathic rather than oncologic indications. Bone grafts can be used successfully in non–load-bearing parts of the maxilla and midface, such as in orbital reconstruction, but should be supported by well-vascularized tissues, such a pedicled temporalis or free flap, especially in the setting of irradiation.

Microvascular Free Flaps

Microvascular free flaps are the preferred method of reconstruction for most segmental mandibular and maxillary oncologic defects. In particular, bone free flaps allow for restoration of facial contour, provide a stable surface for mastication, and, as long as there is adequate bone height and thickness, accommodate osseointegrated implants for dental restoration. Osteocutaneous free flaps not only replace mandibular or maxillary bone, but also are accompanied by a skin paddle that can be used to close soft tissue defects of the oral cavity and/or of the cheek and neck in the case of through-and-through defects. The most commonly used bony or osteocutaneous free flaps include the fibula, iliac crest (deep circumflex iliac artery), scapula, and radial forearm free flaps. Of these, the fibula osseous–osteocutaneous free flap is probably the most commonly used at most reconstructive centers.

Soft Tissue Free Flap

For specific defects, soft tissue free flap reconstruction alone without a reconstruction plate can give acceptable results for mandibular and maxillary reconstruction. An osteocutaneous free flap is necessary to maintain facial symmetry when there is an anterior defect of the mandible or maxilla.36 When there is an isolated posterior defect of the mandible or maxilla, a soft tissue free flap, such as the anterolateral thigh (ALT) or rectus abdominis myocutaneous (RAM) free flaps, can be used if the patient is not a good candidate for an osteocutaneous free flap (because of poor medical condition or peripheral vascular disease, for example).4,5

For the mandible, posterior defects that encompass the condyle, ramus, and as far anterior as the parasymphysis can be reconstructed with a soft tissue free flap. For such defects, the benefits of osteocutaneous free flap reconstruction are arguably less, because the aesthetic appearance is less affected by loss of bony structure, the muscles of mastication cannot generally be reattached in a functional manner, and there is no perfect substitute for the resected temporomandibular joint.7 There will be a tendency for mandibular de viation toward the side of the defect when reconstructed with a soft tissue flap alone that can be mitigated by slightly overcorrecting the volume of the defect with the flap. There is also a tendency toward flap atrophy, especially after radiation therapy, so a bulky flap can help improve the aesthetic result as well.

Edentulous patients tend to have more deviation of the mandible, because they do not have teeth to guide their mandible into proper occlusion, which is another factor to consider when opting for a soft tissue free flap over an osteocutaneous free flap in posterior mandible reconstruction. In summary, osteocutaneous free flap reconstruction will tend to have better occlusal outcomes, but bulky soft tissue free flap reconstructions may be acceptable for patients who are not good candidates for an osteocutaneous free flap because of poor functional status, donor site unavailability, or limited life expectancy.

For the maxilla, soft tissue free flaps or prosthetic obturators can be considered for defects posterior to the canine tooth.6,810 Defects of the posterior hard palate and alveolus can usually be reconstructed with soft tissue free flaps, such as the ALT or RAM free flaps (or the radial forearm fasciocutaneous free flap for obese individuals) with good functional and aesthetic results. It is important to make sure the flap is inset such that it is not ptotic into the oral cavity, because this makes concurrent use of a prosthetic for dental restoration difficult or impossible. For anterior defects, bony reconstruction is necessary to maintain midfacial height, width, and projection.11

Soft tissue free flaps can be combined with titanium mesh or bone grafts to reconstruct the orbital floor when the maxillary defect includes the orbital floor.6 In a review of orbital floor reconstruction for trauma, Kirby et al12 found that autologous bone reconstructions were more likely to be complicated by orbital dystopia and enophthalmos compared with titanium mesh and porous polyethylene, possibly related to increased difficulty in shaping the reconstructed orbital floor, irregular thickness, and unpredictable resorption. Because accurate reconstruction is very important to prevent these complications, as well as decreased vision or even blindness related to excessive pressure on the globe or the optic nerve, the orbit should be preplated with mesh before making osteotomies whenever possible. This mesh can then be used for the reconstruction or serves as a template for reconstruction with bone grafts. Alternatively, I am increasingly using three-dimensionally printed models to guide titanium mesh or bone graft reconstruction (Fig. 52.1).

If the orbit is exenterated in combination with a superstructure maxillectomy that spares the alveolus and palate, soft tissue free flaps are usually indicated to obliterate the orbital cavity and close the orbito-sino-nasocutaneous wound.13 If the palate is also resected with the orbit and rest of the maxilla, a multipaddled soft tissue free flap is used to close both the intraoral wound and the orbital wound. Rarely, the defect is so extensive that the orbit and the anterior palate and alveolus are both resected. In such cases, our reconstructive algorithm would call for a soft tissue free flap to fill the orbital cavity and an osteocutaneous free flap to reconstruct the palate and alveolar arch to maintain midfacial projection.

Pectoralis Major Myocutaneous Pedicled Flap

In patients who are poor candidates for a microvascular free flap reconstruction, the pectoralis major myocutaneous (PMMC) pedicled flap is sometimes used to reconstruct mandibular and maxillary defects.14 Use of this flap, alone or in combination with a titanium plate as described previously, should be considered a secondary option. Functional and aesthetic results are rarely optimal. Complications associated with using this flap include tethering by the proximal flap and vascular pedicle, restriction of neck movement and pulling of the bulk of the flap downward, an unsightly bulge in the neck, and, if adequate cutaneous perforators are not incorporated into the flap design, partial skin-paddle necrosis that can lead to a fistula (Fig. 52.2).

If the PMMC flap is used, the skin paddle should be designed so that it is centered over the fourth intercostal space to provide adequate reach, and the proximal flap should be debulked as much as possible15 (Fig. 52.3). A long neck and short torso should be considered a potential contraindication for maxillary and even some mandibular reconstructions because of the inadequate reach of this flap.

Postoperative Care

After major head and neck reconstruction, patients are usually kept sedated and on a ventilator overnight; they are weaned off the ventilator the next morning as tolerated, then transferred to a flap-monitoring floor when they are deemed stable. The advantage of having patients sedated overnight is it prevents unnecessary agitation and vomiting, which may result in an increased risk of hematoma or flap compromise. The disadvantage of keeping patients sedated and on a ventilator overnight is the need for high volumes of intravenous fluids because of the sedation and paralysis. Sedation and paralysis often cause hypotension and require intravenous fluid resuscitation, because vasopressors are generally considered contraindicated after free flap surgery. Therefore patients may become fluid overloaded, which can cause significant cardiopulmonary complications in patients with minimal cardiopulmonary reserve. In recent years, we have opted to allow some patients to breathe spontaneously without ventilator support and avoid sedation after surgery in our institution. These patients seem to recover faster and develop less cardiopulmonary complications with a shorter hospital stay. Venous thromboembolism, infection, and delirium tremens prophylaxis are given as indicated.

Patients routinely receive tracheostomy and nasogastric feeding tube placement at the time of surgery. They then receive tube feedings for 2 weeks, while intraoral incisions are allowed to heal. For uncomplicated intraoral defects, a pureed diet is allowed after 2 weeks if all incisions appear to have healed without a fistula. For more complex defects, such those with a concurrent glossectomy, a modified barium swallow study is obtained to assess swallowing and to rule out a leak in areas that are not easily visualized by physical examination. Tracheostomy decannulation can usually be performed early, around postoperative day 5, when the immediate postoperative swelling has subsided. In select cases of maxillary reconstruction where the flap is not bulky and does not obstruct the airway, a tracheostomy is not performed, but the airway is closely monitored postoperatively in case the flap swells more than expected.

Patients who undergo fibula free flap reconstruction are allowed to ambulate as early as postoperative day 2, even in a splint, with weight-bearing as tolerated on the affected limb.16 Early ambulation is important to prevent deep venous thrombosis and pulmonary complications. When not ambulating, the patient is instructed to keep the donor limb elevated at all times, whether in bed or in a chair, to facilitate wound and skin graft healing. We usually allow about 15 to 20 minutes of ambulation or dangling and advance gradually based on the amount of lower extremity swelling observed.

When the orbit has been reconstructed, a forced duction test is performed at the end of surgery to rule out entrapment. Corticosteroids are given during surgery and again postoperatively if there is swelling to prevent pressure on the globe. If possible, the patient is woken up immediately after surgery rather than kept sedated so that the vision can be assessed. Visual checks are performed regularly in the postoperative period. Any decrease in vision is an indication for prompt ophthalmologic evaluation. Traumatic optic neuropathy secondary to traction injury is usually treated with high-dose steroids, and any impingement on the optic nerve or pressure on the globe should be relieved by emergent return to the operating room. Diplopia should be followed with computed tomography (CT) to rule out entrapment or suboptimal positioning of grafts and hardware used to reconstruct the orbit.

Management of Complications Associated with Mandible and Maxilla Reconstruction

Summary Box

Complications Associated with Mandible and Maxilla Reconstruction


• Flap loss

• Pedicle thrombosis

• Venous thromboembolism


• Infection

• Would dehiscence

• Fistula

Donor Site

• Infection

• Wound dehiscence

• Skin graft loss (flap loss)

• Lack of mobility and stability

Management of Microvascular Complications

At our institution, trained nursing staff in a dedicated free flap unit perform hourly flap checks for the initial 48 hours and then every 2 hours for the next 48 hours, and finally every 4 hours until discharge. Any concern for a microvascular complication mandates immediate evaluation by a microsurgeon with a low threshold for operative exploration. The use of prophylactic anticoagulants such as heparin, dextran, aspirin, or low-molecular-weight heparin (i.e., enoxaparin) has not been demonstrated to improve flap survival or decrease pedicle thrombosis, and therefore the use of anticoagulants is not routine at our institution except as prophylaxis against venous thromboembolism.16

Signs of flap compromise such as increased swelling and bruising, change in color, or loss of the Doppler signal should prompt an immediate return to the operating room as long as the patient is medically stable. Early intervention remains the single most significant predictor of flap salvage, and, as such, a low threshold should exist for reoperation even at the slightest suspicion for thrombosis.1719 A negative exploration is far preferable to a lost free flap.

Every effort should be made to diagnose the cause of the flap compromise during reoperation (Fig. 52.4). Making the correct diagnosis is critical for salvage and prevention of future thrombotic events. Causes of flap compromise that can be corrected by clot removal and anastomotic revision performed in a timely manner include pedicle compression, kinking, or twisting; focal pedicle injury (e.g., those resulting from intimal injury near the anastomosis); and anastomotic error. Vein grafts are used as needed to replace sections of damaged pedicle or recipient vessel and relieve excess tension on the pedicle and anastomoses. Hypercoagulable conditions may also result in flap compromise and need to be addressed with anticoagulants after thrombectomy and anastomotic revision. Prolonged vasospasm or hypotension resulting in flap compromise are extremely rare and should be considered diagnoses of exclusion. They can be treated with topical vasodilators and by intravascular volume restoration, respectively. More problematic are thromboses related to purulent infection, traction injuries to the perforator(s) or distal pedicle, poor flap design, or injury to the distal circulation during flap harvest. These usually represent unsalvageable conditions.

Although anticoagulant and antiplatelet medications are not routinely used as prophylactic agents, I do use them in select cases after a pedicle thrombosis not only if hypercoagulability is suspected but also if we are concerned about a residual clot in the distal microcirculation of the flap that could not be extracted during revision surgery. If return to the operating room is delayed or evidence of thrombosis of the distal flap circulation exists, I also use small doses of thrombolytics, such as tissue plasminogen activator (2–6 mg injected into the recipient artery with a 30-gauge needle or into a vessel side branch while the vein is clamped for several minutes to prevent dilution by release into the systemic circulation).16 However, in general, many of these interventions have not been demonstrated to have a significant impact on flap salvage.17

Management of a Flap Loss

In most circumstances, reviving a free flap requires a lengthy operation, potentially additional donor site morbidity for harvest of vein grafts, added blood loss, need for blood transfusions, and a prolonged hospital stay and recovery. In certain circumstances, consideration should be given to abandoning a flap, immediately or after a judicious salvage attempt, and performing a second reconstruction rather than putting the patient through an extensive flap salvage operation, which may ultimately prove futile. We have demonstrated that delayed flap thromboses occurring later than 3 days after reconstruction and late recognition of flap compromise in which both the artery and vein are thrombosed are associated with significantly lower salvage rates. Similarly, compromised muscle-only flaps are also associated with worse salvage outcomes compared with fasciocutaneous and osteocutaneous free flaps. Multiple attempts at salvaging a failing free flap result in the most dismal prognosis and are not recommended.20 Before every attempt at salvaging a failing free flap, I discuss the possibility of abandoning the flap and performing an alternate reconstruction, either in the same setting or after a delay to wait for more optimal conditions in terms of the patient’s medical condition and the freshness of the surgical team.

Ultimately, in the setting of a flap loss, the reconstructive microsurgeon is faced with a dilemma of whether to proceed with another free flap or pursue another option such as a pedicle flap or a prosthetic obturator (in the case of maxillectomy defects).6,21 In my experience, the loss of a free flap does not preclude the patient from another free flap provided that the patient is stable and medically able to undergo another free tissue transfer. For many mandibular and maxillary defects, if a free flap was indicated for the initial reconstruction, a free flap is still the best option in the setting of a flap loss and should be considered as the primary option if there are no definitive contraindications.22,23 Although a pedicled pectoralis major muscle or myocutaneous flap, with or without a titanium plate, represents a potential option in the setting of a free flap loss, at least for mandibular reconstruction, I usually prefer to use a second free flap, which has proven to be equally successful and demonstrates superior aesthetic and functional outcomes.21

Patient management after a flap loss is to some extent dependent on identifying the cause of the flap, if possible, and taking the necessary steps to avoid the same conditions when performing a second flap. For example, if there is a suspicion for a hypercoagulable state, consideration should be given toward a hematology consult.21 The loss of a free flap used to reconstruct the mandible or maxilla because of infection or fistula (see later discussion) results in an inflamed, infected wound that may require antibiotics and serial débridement and washouts before another free flap reconstruction is done. When performing a second free flap, the surgeon and patient should be prepared for the use of alternate recipient vessels such as the transverse cervical vessels, contralateral neck vessels, internal mammary vessels, thoracoacromial vessels, or the cephalic vein and for the use of vein grafts.21,24

Particularly when a patient who is referred for reconstruction has lost a flap performed by another surgeon, I have found it useful to perform preoperative CT angiography of the potential flap vasculature to identify any abnormalities that may have caused the flap loss2528 (Figs. 52.5 and 52.6). CT angiography of the neck may also be helpful in identifying available recipient blood vessels, especially when the prior surgery was performed by a different surgeon. Finally, in the setting of a delayed secondary reconstruction in which the original architecture of the mandible or maxilla is unknown, computer-aided design (CAD) of the reconstruction can be used to produce three-dimensional medical models, and computer-generated cutting guides can be invaluable in performing an accurate restoration27,28 (Figs. 52.752.9). In such cases, the fibula or other bony free flap can be shaped on the computer “virtually” so as to best restore facial shape and dental occlusion. Computer-generated cutting guides help the surgeon to make osteotomies such that the bony segments of the flap have the precise lengths and angles needed to replicate the preoperative plan made on the computer.

Management of Nonmicrovascular Complications

Aside from complications associated with the microvascular anastomosis, patients undergoing free flap reconstruction are potentially at risk for a number of other complications. Often, patients undergoing major resections and reconstructive operations for extensive tumors are malnourished, have had prior radiation and chemotherapy, and have had a history of or may be actively using tobacco products. Consequently, these patients are potentially at risk for infection, wound dehiscence, and fistula formation during the perioperative recovery period.

Although superficial infections can be managed with antibiotics, purulent deep space infections warrant prompt operative intervention. Early, aggressive drainage and irrigation of a neck abscess is critical to minimize the risk of a vascular rupture or flap loss. Infection can cause flap pedicle thrombosis, and, as mentioned previously, such cases of flap compromise are rarely, if ever, salvageable.

Although minor wound separation can be managed conservatively, exposure of blood vessels, bone, or hardware warrants further surgery. In the setting of prior radiation and surgery, preemptive replacement of damaged neck skin with external flap coverage should be considered. Designing a flap with two independent skin paddles based on independent perforating blood vessels, or a chimeric flap with a skin and muscle component in which the muscle can be skin grafted, to separately close intraoral and extraoral defects obviates suturing radiated tissue together and may minimize the risk of wound dehiscence (Fig. 52.10). When this is not possible, a second free flap or a pedicled PMMC can be used for neck coverage (Fig. 52.11).

Late complications include trismus and hardware failure. Trismus may be related to fibrosis of the temporomandibular joint (TMJ) secondary to radiation therapy or to cicatricial contracture of the skin paddle in some cases. TMJ fibrosis is usually treated conservatively with physiotherapy but is unfortunately often recalcitrant and may interfere with eating and dental care and restoration. Early and dedi cated prevention with mouth-opening exercises is critical to maintaining long-term function. Cicatricial trismus is often more easily treated with scar release and intraoral z-plasty or, when severe, an additional cutaneous free flap, such as the radial forearm flap. Hardware failure is very rare because of excellent bony healing of free flap tissues, but radiated bone may necessitate a new free flap (Figs. 52.1252.14). Another promising development is the availability of computer-planned, custom-made titanium plates. Such plates are milled from a solid block of titanium and, because they have never been bent, are much stronger than traditional plates, but they also have a very low profile, which helps prevent plate exposure through radiated skin.

Management of Fistula

The development of an orocutaneous fistula is often a major complication that can potentially lead to flap failure or death if a patient suffers a carotid blowout. A high index of suspicion should be exercised in all patients who have received preoperative radiation, chemotherapy, and surgery. Prolonged swelling, increasing erythema, malodorous or purulent discharge, or changes in drain output should all prompt further evaluation. Patients may or may not exhibit leukocytosis and fever. CT or a barium swallow may be indicated to evaluate for the possibility of a fistula but are not required for an obvious fistula. Early exploration is almost always warranted, because free flap pedicle thrombosis secondary to infection is almost never salvageable. A so-called “herald bleed” should be considered an emergency that warrants urgent exploration to prevent a life-threatening complication. Before neck exploration, irrigation, and débridement, the potential risks for multiple surgeries, prolonged wound care, and a flap loss should be explained to the patient.

Empiric antibiotics are given and wound cultures are obtained at the time of neck exploration. Antibiotics are adjusted as indicated by the results of the wound culture. Based on experience, I manage fistulas with repeated operative or bedside irrigation and débridement procedures until the wound is clean. If the free flap has been lost, a second free flap is performed only when the wound is clean, because performing a free flap in a grossly infected field is associated with an increased risk of failure. Orocutaneous fistula reconstruction is usually performed with a pectoralis major muscle or myocutaneous flap, because attempts to close the fistula in the acute stage when tissues are inflamed are usually unsuccessful. In some cases, small fistulas that do not come in contact with the carotid artery or internal jugular vein, as well as a free flap pedicle or hardware, can be managed conservatively and allowed to heal on their own.

Oct 23, 2018 | Posted by in General Surgery | Comments Off on Reconstruction of the Mandible and Maxilla

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