Mark A. Varvares
INTRODUCTION
The major goals of palatomaxillary reconstruction include both restoration of function and an acceptable cosmetic outcome. The functional considerations include maintenance of a functional oral cavity of appropriate dimensions, the separation of the oral and nasal cavities to prevent nasal regurgitation and hypernasality, a framework to allow masticatory function, and an osseous structure to which to anchor a dental prosthesis and to provide the structural foundation for the nasal base.
Through-and-through defects of the oral cavity to the nasal cavity traditionally have been managed with oromaxillofacial obturators. The advantages of this approach include achievement of acceptable functional outcome without additional surgery, the ability to monitor the cavity for recurrent tumor, and the ability to restore functional dentition mounted on the obturator. Disadvantages include the extreme problems with hypernasality when the obturator is removed for cleaning, the hygienic issues related to obturator and cavity maintenance, and difficulty retaining the prosthesis in the edentulous patient.
The radial forearm free flap (RFFF) is useful as a fasciocutaneous flap for the reconstruction of defects involving the central palate without involvement of the alveolar ridge or for defects involving the central palate and the alveolar ridge posterior to the canine. Such defects are classified using the classification outlined by Okay et al (2001) as class Ia and class Ib defects, respectively (Fig. 20.1) Such defects do not involve loss of premaxillary bone and soft tissue, and therefore, the reconstructive demands related to nasal support and premaxillary projection are avoided. More extensive defects involving a larger area of the hard palate and including the alveolar ridge anterior to the canine and the premaxilla would be difficult to repair using a RFFF unless it contained an osseous component (radial forearm osseofasciocutaneous flap) or other osseous components are included in the reconstruction.
FIGURE 20.1 The Mount Sinai classification of palate defects. Class Ia defects involve any portion of the hard palate but not the tooth-bearing maxillary alveolus. Class Ib defects involve premaxilla or any portion of the maxillary alveolus and dentition posterior to the canines. Class II defects involve any portion of the hard palate and tooth-bearing maxillary alveolus and only one canine. The anterior margin of the defect lies within the premaxilla. This class includes transverse palatectomy defects that involve less than 50% of the hard palate. Class III defects involve any portion of the hard palate and tooth-bearing maxillary alveolus including both canines. This class includes total and transverse palatectomy defects that involve more than 50% of the hard palate. (Redrawn from Okay DJ, Genden E, et al. Prosthodontic guidelines for surgical reconstruction of the maxilla: a classification system of defects. J Prosthet Dent 2001;86:352–363.)
HISTORY
I am careful to ask whether the patient has a history of prior surgery or injury to the forearm donor site since this could compromise the blood supply to the skin paddle. Additionally, I always determine the dominant hand so that I can plan to harvest from the nondominant hand to limit the potential impact on the patient's quality of life.
PHYSICAL EXAMINATION
A physical examination should always include an evaluation of the forearm donor site to establish if there has been injury or prior surgery that may preclude use of this donor site. An Allen test should also be performed to determine if there is an intact vascular palmar arch. The dimensions of the tumor to be excised as well as the anatomic sites to be removed should be recorded. Photographs of the defect should be made to incorporate into the medical record.
INDICATIONS
The RFFF has been the most frequently used flap for head and neck reconstruction since the 1980s. It has been used for nearly every head and neck soft tissue defect that one can encounter. This flap is widely employed due to its ease of harvest, large blood vessels, low donor site morbidity, and potential for simultaneous two-team surgery and for the quality and quantity of tissue available. This donor site has also recently gained popularity as an osseofasciocutaneous flap, useful for reconstruction of composite defects with a small bone component. It has also been previously reported as being useful for reconstruction of subtotal defects of the palate.
Genden et al. (2004) recently described a series of patients with class Ia and Ib defects who were reconstructed using a RFFF. As part of this study, they performed a functional and quality of life comparison with a similarly matched group of patients who used an obturator. They found improved function and quality of life in those patients who had undergone flap reconstruction. The major goal of the soft tissue reconstruction was to provide oral–nasal separation and improve the overall quality of life of the patient. In their series, patients who achieved dental rehabilitation did so by using a dental prosthesis anchored on remaining dentition or osseoin-tegrated implants in the bone of the native palate.
The RFFF is a fasciocutaneous flap best used in the reconstruction of the subtotal palate defect when the defect is classified as class Ia or Ib. In addition, it is possible to use the RFFF as an osseofasciocutaneous flap with the transfer of vascularized bone when the defect requires it. This donor site can also be used in combination with nonvascularized bone grafts. An example of the use of the RFFF as an osseofasciocutaneous flap is in the reconstruction of a premaxillary defect when it is desirable to restore the premaxilla.
CONTRAINDICATIONS
Defects that require extensive bone replacement which is a demand not met by this donor site are contraindications to this technique, as are previous trauma or surgery to the forearm donor site and a negative Allen test.
PREOPERATIVE PLANNING
Prior to harvest of the RFFF, it is important to note that the patient has an intact palmar arch. A clinical Allen test can be done that reliably demonstrates the safety of harvest of the radial artery. It is also possible to obtain a more objective test such as a Doppler Allen test in a vascular laboratory. Typically, this is done only if the clinical Allen test leaves any doubt as to the findings.
SURGICAL TECHNIQUE
The majority of palate reconstructions using a RFFF can be performed using a transoral approach with a neck incision for vascular access for recipient vessel isolation. The pedicle of the RFFF is usually one that easily allows inset of the soft tissue and bony components in the oral cavity with adequate length of the vessels to reach the recipient vessels in the neck.
Prior to harvesting the RFFF, it is important to note that the patient has an intact palmar arch. A clinical Allen test can be done that can reliably show the safety of harvest of the radial artery. It is also possible to obtain a more objective test such as a Doppler Allen test in a vascular laboratory. Typically, this is done only if the clinical Allen test leaves any doubt as to the findings.
The flap is harvested based on the dimensions of the defect of the recipient site. The skin paddle is outlined centered over the radial artery in the distal forearm just proximal to the skin crease of the wrist. The flap can be extended over on to the dorsal surface of the forearm, particularly if one is interested in capturing the distal portion of the cephalic vein in the skin paddle. This ensures that if the caliber of the cephalic vein is adequate proximal in the antecubital fossa, the flap will be adequately drained using the cephalic vein alone (Fig. 20.2).
FIGURE 20.2 Typical outline of the fasciocutaneous RFFF on the left arm, with placement of the paddle laterally to capture the cephalic vein as well as the radial artery.
The arm is exsanguinated using an Ace wrap after the outline of the flap is made in the distal forearm and a curvilinear incision is drawn from the proximal portion of the skin paddle to the anterior cubital fossa. A tourniquet, which has had previously been placed above the elbow, is inflated to 90 mm Hg greater than the patient's resting systolic blood pressure. Skin incisions are then made circumferentially. Dissection starts either medially or laterally depending on the surgeon's preference. If dissection starts laterally, the skin and subcutaneous tissues are dissected off of the brachioradialis muscle and tendon. The cutaneous branch of the radial nerve is identified, as it exits deep to the brachioradialis tendon. Care is taken to mobilize the cephalic vein along with the skin paddle as the flap is mobilized from lateral to medial. Once the brachioradialis tendon is exposed, care is taken to leave paratenon overlying this tendon (and all the tendons in the forearm). The radial artery can be visualized in the groove between the brachioradialis and flexor carpi radialis. The flap is then mobilized medially, and dissection is carried out from medial to lateral, again carefully leaving paratenon overlying the tendons of the flexor carpi ulnaris, palmaris longus, and flexor carpi radialis. Once the flexor carpi radialis muscle tendon is identified and the flap mobilized lateral to this tendon, the radial artery distally in the forearm at the level of the distal portion of the skin paddle can be dissected and ligated using a 2-0 silk suture.
The flap is then mobilized from distal to proximal by mobilizing the radial artery out of the groove between the brachioradialis and flexor carpi radialis tendons. On the deep surface of this plane of dissection, there is a transverse layer of fascia that can be identified reliably and indicates that the dissection is proceeding in the appropriate level. Once the dissection and mobilization reach the proximal portion of the skin paddle, the skin flaps of the forearm proximal to the skin paddle are elevated at a level of dissection above the muscle fascia. Care must be taken to be certain that the cephalic vein is not injured in this elevation of soft tissue from the proximal forearm. Dissection continues along the vascular pedicle proximally by separating the brachioradialis and the flexor carpi radialis muscles and mobilizing the radial artery and its venae comitantes from this space. Dissection continues toward the antecubital fossa until adequate length of the pedicle has been achieved. Of note, it is important not to carry the dissection of the radial artery proximal to the radial recurrent vessel in the proximal forearm. I dissect proximal enough into the antecubital fossa to find the communicating vein between the confluence of the venae comitantes of the radial artery and cephalic vein. This allows a single venous outflow draining both the superficial and deep systems of the flap. It is not essential for this connecting vessel to be mobilized as the flap may be adequately drained using either of the superficial or the deep systems. There may be cases, however, where one of the two systems may not appear as robust. Harvesting the flap vein in this manner may avoid a problem of inadequate venous outflow. Once this stage of the dissection is completed, the tourniquet may be released, the flap and the arm perfused, and hemostasis obtained both on the flap and it's pedicle and the donor site. Once the recipient site is ready for flap inset, the arteries and veins are clamped at their takeoff in the antecubital fossa and the vessels ligated.
When harvesting the radial forearm osseofasciocutaneous free flap, the procedure is modified such that as the dissection is done distally in the forearm from the lateral aspect, the radial artery is not separated from the radius. The distal portion of the radius is identified, and the periosteum is scored using a Bovie cautery. The radius is then measured, and a harvest of approximately one-third of the thickness of the medial aspect of the distal radius is made. A boat-shaped ostectomy is outlined and incised using a sagittal saw (Fig. 20.3). Care is taken to preserve the soft tissue attachments between the radial artery medially and the radius.
FIGURE 20.3 Schematic showing the area of harvest of the distal radius and the relationships to the pronator teres insertion and pronator quadratus.
If an osseofasciocutaneous flap is harvested, the Orthopedic Service is asked to place a heavy fracture plate along the lateral aspect of the distal radius to prevent a pathologic fracture. The donor site is then closed as any other RFFF donor site. A split-thickness skin graft of 0.018 inch is harvested from the thigh. This is used to cover the portion of the defect that corresponds to the skin paddle. The proximal portion of the flap harvest is drained with a closed suction drain, and the skin is closed in multiple layers, usually a subcutaneous layer of absorbable suture followed by a skin layer of either staples or nylon or fast-absorbing chromic sutures.
Prior to flap transfer and inset, recipient vessels must be isolated and a connection must be made between the area of vessel exposure in the neck and the flap inset site. An appropriate vessel in the setting of palate reconstruction is the facial artery and vein with the external jugular vein as a possible recipient vessel as well. If a neck dissection has not been done, an incision consistent with that used for excision of the submandibular gland is made. Excision of the submandibular gland will help to locate the facial artery and vein and create some working room to allow the microvascular anastomosis to be performed. The main trunk of the facial artery can be preserved when excising the submandibular gland if care is taken only to divide the glandular branches of the facial artery and not to be quick to divide the main trunk of the facial artery as is frequently done in excision of the submandibular gland (Fig. 20.4).
FIGURE 20.4 Removal of the submandibular gland with maintenance of the facial artery in continuity to allow a greater vessel length as a recipient vessel for midface and palate reconstruction.
Once the vessels are isolated, a connection is created from the neck to the ablative site. There are two different anatomical levels that can be used. In most cases, I prefer a subcutaneous tunnel. This dissection proceeds from the neck incision used for vascular access by dissecting in a supraplatysmal plane from the neck to the midface. The advantage of this approach is that the supraplatysmal plane protects the marginal mandibular nerve and, as dissection proceeds more cephalad, all of the distal branches of the facial nerve. Once dissection of this tunnel is extended cephalad to be adjacent to the defect, it is connected with the recipient site of the midface. This does require dissection through the superficial musculoaponeurotic system (SMAS) into the oral cavity. This is done bluntly by spreading the tissues in the direction of the branches of the facial nerve. The tunnel must be wide enough to allow the flap to be pulled from the neck into the midface or allow the vessels to be passed from the defect into the neck. Typically, a tunnel three or four fingers breadth wide will be adequate. It is important to obtain meticulous hemostasis during creation of the tunnel to prevent postoperative bleeding that could lead to a hematoma and flap compromise.
The second option for creating the tunnel connecting the neck to the midface is to use a deeper plane of dissection. This would require a subplatysmal dissection extending superiorly directly overlying the periosteum of the mandible and masseter muscle. This is a layer of dissection deep to the branches of the facial nerve, thereby preventing the potential injury to these nerves. An advantage of this plane of dissection is that it brings me right into the appropriate plane of the maxillary defect, usually by passing through the buccal space and its pad of adipose tissue.
Once the vessels are isolated and the tunnel is created, the flap is brought into the inset position. I typically prefer to pull the flap from the neck through the tunnel into the recipient site in the oral cavity. This allows me to know that there is not been any twisting of the vascular pedicle in the tunnel while the flap has been positioned. Retrograde placement of the vessels into the neck from the mouth by floating them through a prepositioned Penrose drain is another useful technique.
Once the flap has been brought through the tunnel into the oral cavity, it is inset into the defect and sewn to the mucosal edges using an absorbable Vicryl suture. This must be a watertight closure. Nasal secretions will be exposed to the deep surface of the flap where the vascular structures are located. This typically is not a problem and has not resulted in a higher risk of flap failure. Once inset is completed, revascularization is performed.
In patients who are undergoing reconstruction with an osseofasciocutaneous flap, the bone component of the forearm flap is plated into position followed by soft tissue inset.
Once the flaps are vascularized, the wound is irrigated and suction drains are placed, and then the wound is closed in layers.
Case report: This patient presents with a premaxillary defect that extends from the second premolar on one side to its corresponding premolar on the other. There was a through-and-through defect into the nasal cavity, with loss of premaxillary support. The patient was not interested in osseointegrated implants into the reconstructed bone and desired not to have an obturator. Nasal and premaxillary projection was achieved by placement of an arch-shaped split calvarial bone graft (Fig. 20.5). This was covered with a RFFF (Fig. 20.6). At 3 months, the reconstruction is well healed intraorally (Fig. 20.7), and the patient has excellent anterior nasal support.
FIGURE 20.5 Defect of anterior palate, premaxilla, and floor of the nose with a calvarial bone graft in place just prior to wrapping the radial forearm free flap to cover the nasal surface, necessary because of the nonvascular nature of the bone graft.
FIGURE 20.6 Radial forearm free flap in position at the end of the procedure.
FIGURE 20.7 Results at 6 weeks, flap well healed in the anterior palate region.
POSTOPERATIVE MANAGEMENT
The RFFF donor site is rather easy to manage postoperatively. The donor site is splinted with the hand slightly extended. The arm is dressed using Xeroform gauze followed by web roll and Kerlix followed by a ventral splint and then ACE wrap. The splint is left in place for 7 days, at which point it is removed and the skin graft evaluated. Therapy is started once the splint is off to help with mobilization of the writs.
COMPLICATIONS
The most significant complication that occurs using a RFFF for palate reconstruction is flap failure. A hematoma in the tunnel leading to flap compromise is a possible cause of flap failure. It is important to secure excellent hemostasis of the tunnel at the time of its development to prevent bleeding postoperatively. In addition, it is extremely important during flap harvest to be certain that all the small vessels off the pedicle are clipped or coagulated so as not to allow bleeding once the flap is revascularized and inset into the recipient site. It would make it very difficult to isolate and locate the bleeding vessels on the pedicle once the flap is inset.
RESULTS
The RFFF has been shown to be a very reliable technique for reconstruction of multiple head and neck defects. In properly selected patients, the RFFF can reliably improve function and quality of life of the patients with subtotal palate defects.
PEARLS
• Proper patient selection is the key to success as in all reconstructive techniques. The reconstructive technique described is best suited to patients with Okay defect class 1a and 1b.
• Patients with large defects involving the premaxillary area are best reconstructed with a flap that has an osseous component. This could include the radial forearm osseofasciocutaneous flap or another donor site such as the fibula or scapula.
• All patients who undergo reconstruction of major defects in the palate who desire eventually to have full dental restoration must be counseled as to the expense and time that is typically invested to be able to achieve this goal.
PITFALLS
• Usually, the dental component of the rehabilitation is not covered by insurance and is an out-of-pocket expense for the patient.
INSTRUMENTS TO HAVE AVAILABLE
• Standard neck dissection tray
• Tourniquet of appropriate circumference
• Midface rigid fixation plating system
SUGGESTED READING
Yang G, Chen B, Gao Y, et al. Forearm free skin flap transplantation. Natl Med J China 1981;61:139.
Okay DJ, Genden E, Buchbinder D, et al. Prosthodontic guidelines for surgical reconstruction of the maxilla: a classification system of defects. J Prosthet Dent 2001;86:352–363.
Genden E, Wallace DI, Okay DJ, et al. Reconstruction of the hard palate using the radial forearm free flap: indications and outcomes. Head Neck 2004;26:808–814.
Kim JH, Rosenthal EL, Ellis T, et al. Radial forearm osteocutaneous free flap in maxillofacial and oromandibular reconstructions. Laryngoscope 2005;115(9):1697–1701.
Karamanoukian R, Gupta R, Evans GR. A novel technique for the prophylactic plating of the osteocutaneous radial forearm flap donor site. Ann Plast Surg 2006;56(2):200–204.