Midface and Palatomaxillary Reconstruction

Midface reconstruction has undergone numerous advancements. Key among these advances has been the availability of biocompatible, versatile, rigid internal fixation hardware. Further, improvement in osteocutaneous free tissue transfer has allowed surgeons to bring moderate-to-large amounts of well-vascularized composite tissue into the midface for reconstruction. Lastly, the availability of experienced prosthodontists who are able to obturate postsurgical defects continues to provide a robust and scalable adjunct or alternative to nonsurgical closure of palatomaxillary defects.

An image depicting a midface and palatomaxillary defect can be seen below.

Maxillectomy defect demonstrating significant midface bone and palatal soft and hard tissue defect.

Midfacial reconstruction is typically required following extirpative cancer surgery of the palate and sinonasal tumors. Alternatively, panfacial trauma can result in significant amounts of bone and soft tissue loss requiring midface reconstruction. These situations often represent high-energy traumatic injuries resulting in additional trauma to other organ systems. Reconstruction of the midface, regardless of the etiology, is complicated by its central and conspicuous position and its complex contour. Further, the palate and alveolar ridges are crucial for proper mastication, control of deglutition, and velopharyngeal speech control.

Palatomaxillary reconstruction related to oncologic surgery results most commonly after removal of a squamous cell carcinoma of the oral cavity or sinonasal mucosa.[1] However, removal of minor salivary tumors and adenocarcinoma, among others, can also result in defects requiring midface reconstruction. Again, palatomaxillary reconstruction can also be required following high-energy trauma and often is concurrent with reconstruction of other craniofacial injuries.

See Etiology.

Midface reconstruction is required when extirpative defects result in functional impairment, significant bone and soft tissue loss that cannot be reconstituted primarily with local tissue, open communication between the oral and sinonasal cavity, or significant cosmetic deformity. In addition to the above indications, posttraumatic unstable injuries, especially comminuted fractures or those with bone loss, and injuries that are too large or positioned such that nonsurgical obturation is not adequate to reconstitute function can require reconstruction with composite tissue.

The midface is composed of the hard and soft palate, the alveolar ridge, and the maxilla and maxillary sinus, as well as the overlying skin and soft tissue envelope. In addition to the importance in cosmesis, the maxilla plays a crucial role in separation of the oral and sinonasal cavities, speech production, and mastication, acting as a stable platform for dentition. Structures that are critical in preoperative planning include the number of teeth and quality of residual dentition. Firstly, successful obturation requires existing dentition to anchor the prosthesis. Secondly, the presence of dentition and need for dental reconstruction are indications for osteocutaneous free tissue transfer, as the fibula free flap can accommodate osseointegrated implants.

In the patient with cancer, few contraindications to palatomaxillary reconstruction exist, except in those patients with unresectable disease or patients that cannot tolerate the initial extirpative surgery. Markers of unresectable disease include skull base/dura/brain parenchyma or prevertebral fascia involvement, orbital apex involvement, extension into the nasopharynx or clivus, and encasement of the carotid artery. Many patients with small-to-moderate defects who are willing and able to undergo frequent follow-up are good candidates for obturation.

However, obturation can be contraindicated in those patients with large defects, edentulous patients, or those patients with defects that preclude stable anchorage of the prosthesis. Lastly, patients must have an adequate donor site of soft tissue or composite osteocutaneous tissue to be candidates for free tissue transfer reconstruction.

Particularly in the patient with peripheral vascular disease, fibula osteocutaneous flap harvest might be contraindicated because of compromised peripheral vasculature. However, given the diverse donor site options, including fibula osteocutaneous, radial forearm osteocutaneous, fasciocutaneous, and scapula osteocutaneous free tissue transfer, one is usually able to find adequate donor tissue. Lastly, although rare, patients who do not have adequate recipient vessels due to prior trauma or surgery are not good candidates for free tissue transfer. However, given the ability to obtain vessels from the contralateral side, this too is an unusual scenario.

In the patient with multiple traumas, reconstruction is typically contraindicated in the unstable patient or in the patient with multiple severe injuries, such as intracranial trauma, requiring more immediate management.

Most frequently, a CT scan is performed for preoperative evaluation in both the cancer patient (with contrast) and the trauma patient (noncontrast). CT provides the optimal level of detail of bone loss or tumor involvement of bone. When available, direct axial and coronal images can help predict the precise 3-dimensional midface defect that must be reconstructed. Coronal imaging can also be reformatted from fine-cut axial CT data. Further, these data can be used to format 3-dimensional images that precisely outline the anticipated defect. This can also be used to create scale models to assist in operative planning.

Magnetic resonance imaging (MRI) can also be of use to determine soft tissue involvement (in particular, perineural tumor involvement) or concurrent intracranial injury following trauma.

Additional testing should be directed by the patient’s history. Particular attention should be paid to the history and physical examination of the cancer patient to determine whether additional lab or imaging studies should be performed to rule out metastatic disease. At a minimum, this would typically include chest radiographs and contrast-enhanced CT scanning of the neck.

In addition to the above noted imaging and preoperative evaluation, all palatomaxillary tumors require definitive preoperative pathologic confirmation. Further, any suspicious findings in the neck or chest should be pursued to determine the presence and/or extent of metastatic disease.

A complete discussion of the pathologic staging of palatomaxillary tumors is beyond the scope of this article, but a brief discussion follows:

• T0 - No evidence of tumor is found.

• T1 - The tumor is limited to the maxillary sinus mucosa without bone erosion.

• T2 - The tumor causes bone destruction, extends to the middle meatus or hard palate, but does not extend to the posterior wall of the maxillary sinus or pterygoid plates.

• T3 - The tumor invades the posterior wall of the maxillary sinus, pterygoid fossa, ethmoid sinuses, subcutaneous tissue, and floor or medial orbital wall.

• T4a - The tumor invades the cheek skin, orbit, pterygoid plates, infratemporal fossa, cribriform plate, sphenoid, or frontal sinus (resectable).

• T4b - The tumor invades the skull base/dura/brain parenchyma, involves the orbital apex, or extends into the nasopharynx or clivus (unresectable).

For most palatomaxillary defects, surgical therapy involves, at a minimum, split-thickness skin graft coverage of any significantly denuded areas of buccal soft tissue. This reduces contraction and speeds wound healing. Options at that point include intraoperative modification of an obturator by a skilled prosthodontist versus composite reconstruction.[2] In most cases, this includes osteocutaneous free tissue transfer consisting of either fibula, radius, or scapula osteocutaneous free flap placement.[3, 4, 5, 6, 7, 8, 9, 10] The details of these procedures are beyond the scope of this article, but appropriate references can be found in the References section.

Advantages of free tissue transfer include immediate reconstruction, closure of the oncologic defect, and potential to place osseointegrated implants to support dental and/or facial implants. However, the need for postoperative adjuvant radiation therapy often modifies the ability to place osseointegrated implants.

The drawbacks to free tissue transfer include second-site surgery, prolonged operating room time, and a long period of wound healing prior to the resumption of oral intake.

Obturator placement is likely to be more successful in patients with less than 50% hard palate defect.[2] Further, the presence of dentition makes obturator retention much more stable by allowing placement of clasp units to residual dentition. The advantages of obturation include shorter operative time, near immediate resumption of oral intake, no need for second surgical site, ability to remove the prosthesis and directly inspect potential sites of recurrence, patient acceptance of oral prostheses (especially in the denture wearer), and the ability to modify the prosthesis in the clinic. The drawbacks include the need for a skilled prosthodontist, ongoing prosthetic modification, and the need to remove and clean the prosthesis.

A retrospective study by Swendseid et al indicated that in upper facial and midfacial free flap reconstruction, optimizing pedicle orientation often involves strategies such as vascular grafting and using more distal branches of the facial system as recipient vessels for revascularization. Out of 295 such reconstructions, including 108 bony and 187 soft tissue, the ipsilateral neck was reached by the vessels in 82% of cases, allowing them to be anastomosed to traditional target vessels. Two percent of reconstructions required arterial grafts, and 7% required venous grafts. Thirteen percent of cases involved selection of alternate recipient vessels, including the superficial temporal vessels, distal facial branches (accessed through a separate facial incision), and angular vessels. The investigators also found an association between vein grafting and a greater flap failure rate.[11]

In both the patient with trauma and the patient with cancer, the surgeon must adequately assess the anticipated defect and identify sufficient sources of composite tissue for palatomaxillary reconstruction. This requires Allen testing of the nondominant forearm, usually, or duplex ultrasound of the bilateral lower extremities, if fibula free tissue transfer is planned. These tests are both required to identify possible vascular compromise that risks both flap and donor extremity injury.

Many questions currently surround the indications for primary reconstruction versus creation of an obturator. In some cases, both approaches might be indicated. The current considerations that must be addressed prior to deciding on the optimal reconstructive approach include the following:

• General medical condition of the patient

• Margin status and the possible need for postoperative adjuvant therapy

• Patient desires

• Size of the surgical defect

• Status and availability of remaining dentition

• Availability and experience of the microvascular surgeon and/or prosthodontist

Some have argued that obturation allows direct inspection and earlier identification of high-risk recurrent disease.[2] However, this, in and of itself, is not a sufficient reason to use an obturator and to not perform reconstruction. In cases in which the operative site and regions of potential recurrence are not exposed, these patients continue to be followed for signs and symptoms of recurrence, and directed imaging studies (CT scanning or MRI) are effective at identifying potential recurrent disease.

In the patient undergoing obturation, preoperative creation of a dental and palatal mold can help with the intraoperative creation of the obturator. Not only does this provide a template upon which the obturator can be added, but it also allows the preoperative identification of points of dental fixation of the obturator. Thus, the preoperative involvement of an experienced prosthodontist is essential.

The primary intraoperative concern is complete and successful resection of the primary tumor. Reconstruction cannot proceed unless the surgeon is confident in the gross total resection of tumor. Additional intraoperative findings can suggest the indication for postoperative radiotherapy in the case of residual disease or close margins. Following complete tumor resection, the decision to pursue free tissue transfer reconstruction versus obturation depends on the factors noted above (see Preoperative Details).

A team-based approach with both an experienced microvascular surgeon and prosthodontist available at the time of the resection aids in determining the most appropriate next step in management.[12] Free tissue transfer donor sites are chosen based on the size and geometry of the resulting defect. The fibula harvest site can provide significant amounts of bone stock but provides a smaller soft tissue paddle. Further, the ability to create multiple osteotomy sites in the fibula donor bone stock allows contouring of the osteocutaneous site to the corresponding defect.

The radial forearm osteocutaneous site can provide up to 7 cm of bone, but this tends to be less robust and does not accommodate osseointegrated implants. Lastly, the scapula donor site can provide an intermediate amount of bone stock with options for harvesting larger, complex cutaneous donor tissue.

In the case of obturation, the previously created dental appliance can be subsequently molded and shaped to the defect intraoperatively and then reduced in the clinic as the defect contracts. Lastly, once an adequate appliance has been created, the cavity is obliterated with Xeroform gauze or a similar material, and the obturator is secured in place with a single screw through the residual hard palate. Care must be taken to ensure that this screw can be removed in the clinic in an awake patient to prevent unnecessary return to the operating room.

In the case of free tissue transfer, the postoperative management is much more complex than that in patients who have undergone obturation. The authors anticipate a 5-day hospital stay, during which every 4 hours the flaps are checked by the physician team for the initial 48 hours and then twice daily during the following 3 days. The authors use implanted Doppler probes to determine arterial inflow into the flap and determine venous competence based on the gross appearance of the flap and, occasionally, bleeding after puncture of the skin paddle with an 18-gauge needle. Antibiotics that cover oral flora are continued for 48-72 hours. Depending on defect size, oral intake is delayed for 1-2 weeks and, in the interim, nutrition is delivered via nasogastric feeding.

Following placement of a surgical obturator, patients are fed immediately following surgery. The inpatient stay is typically limited to 24 hours unless other indications exist for inpatient management. The patient is usually seen by the prosthodontist within the first 3-4 weeks. The obturator is removed along with any packing material in the clinic, and the obturator is modified. The defect is expected to begin to progressively contract at this point, and the obturator can be reduced in size during this and subsequent visits.

Regardless of the method of defect closure, the immediate postoperative visit must be used to confirm adequate oncologic control and, if indicated, be focused around adjuvant therapy planning for adequate cancer management.

See Postoperative Details.

Flap failure represents the most serious complication of free tissue transfer. This should occur in fewer than 10% of cases, and, in many experienced surgeon’s hands, fewer than 5% of patients experience flap failure. Given the gross violation of both the oral and sinonasal cavities, wound infections occur infrequently. These can be handled in most cases with local wound care or antibiotic treatment.[3]

Controversy currently exists regarding which patients/defects to reconstruct with primary microvascular free tissue transfer versus obturation or a combination of both strategies.[2, 12] At the authors’ institution, patients with large defects (> 50% of the hard palate) generally benefit from free tissue transfer. Patients without residual dentition, elderly patients who have limited life expectancy, or those who prefer obturation over free tissue transfer are reconstructed with an obturator.[13]

Another controversial question that arises is whether or not to place osseointegrated implants in patients requiring adjuvant radiotherapy after fibula free tissue transfer.[2] Further, the timing of osseointegrated implant placement has been debated. At the authors’ institution, we typically delay implant placement at least 12 months after completion of adjuvant radiotherapy. Some authors have advocated concurrent hyperbaric oxygen therapy to reduce the risk of osteoradionecrosis following the placement of osseointegrated implants.