At the very minimum, any reconstructive technique must maintain a watertight intraoral closure to prevent neck salivary contamination. The main goal of any reconstruction is to maximize both function and form. Reconstruction of function includes restoration of tongue mobility and volume, maintenance of oral competence, preservation of taste, facilitation of masticatory rehabilitation (tissue-borne or osseointegrated implants), reestablishment of intraoral sensation and an adequate respiratory conduit. These factors can help prevent or minimize aspiration. Simultaneously addressing possible trismus with coronoidectomy and/or subperiosteal masticatory muscular detachment can also help improve post-operative function. This is especially important in patients that require bulky maxillary obturators. In addition, coverage of important structures such as bone, large vessels, and brain parenchyma is vital.
Fulfillment of these goals with a minimum of incisions helps reconstruction of form. This also includes maintenance of facial soft tissue proportions, maxillary-mandibular contours, and dental occlusion. Ideally, reconstruction of form involves replacement of like with like. Unfortunately, like tissue does not necessary retain all the function of native tissue, especially in terms of sensation and motor function. The appropriate reconstruction will try to maximize both of these goals concurrently using the technically simplest method possible with the minimal amount of collateral disability at the donor site. This philosophy minimizes the procedure length, technical complexity and post-operative complication potential. This approach is especially important in the current environment of managed and limited health care resources. Fortunately, although each reconstructive challenge must be individualized to each patient, indications for specific reconstructive methods along the reconstruction
Secondary Intention Primary Closure
- Non-Vascularized Grafts -
Regional Pedicled Flaps Microvascular Free Flaps-
spectrum are greatly overlapping (Fig. 1). Also, techniques are often used in combination to maximize the overall reconstructive outcome. Whatever reconstructive technique is implemented, it should not hinder post-operative recovery with multiple surgeries, possibly delaying or preventing necessary timely adjuvant therapy. Single-stage primary reconstructions are best for meeting this goal. Similarly, complications are always possible, and should be dealt with expeditiously.
Using primary closure or healing by secondary intention is the simplest reconstructive method requiring minimal reconstructive expertise and operative time. Often, primary closures under great tension due to size, poor native-tissue healing ability, and mobility considerations become healing by secondary intention. It is the ideal for replacing like with like, although scarred granulation tissue is not functionally equivalent to the native tissue. Also, this scar tissue generally contracts significantly, causing distortion, and has decreased pliability. In addition, aggressive granulation cannot be easily differentiated from early recurrence of carcinoma. This technique is generally limited to small to medium size defects in areas with significant mobility such as the tongue, lip and vestibule. Primary closure of larger defects is also possible, including segmental composite defects, but often with significant effects of post-operative form. Effects on function are variable (33,34).
Local tissue rearrangement techniques or direct random flaps move tissue from a site adjacent or near to the primary defect, maintaining attachment to some form of vascular supply. Generally, small to medium primary defect sites adjacent to areas of increased mobility and/or elasticity are most amenable to closure using these techniques. The uvula, palate, lateral tongue, and buccal mucosa are examples of random flap sources. These techniques also require minimal reconstructive technical expertise and operative time. Frequently this reconstructive method is used in combination with other more advanced techniques described below. Unfortunately, previous radiation therapy and/or surgical incisions can compromise the blood flow to local direct flaps, lowering their success rate and usability. This can potentially leave a larger defect to have to repair or heal. Also, the donor site may also be left with some functional impairment (i.e., tongue, palate).
Oral cavity reconstruction using non-vascularized tissue techniques can be divided into two general categories: soft-tissue coverage and skeletal jaw support. Reconstructions requiring replacement of only one tissue type have been used with success in the oral cavity (35,36). Both autograft and allograft techniques have been described for mucosal reconstruction. In complex reconstructions comprising more than one type of tissue (i.e., soft tissue and bone), these techniques require combination with vascularized techniques due to the need for recipient-bed neovasculariza-tion or protection of the graft from oral or external contamination.
For soft-tissue reconstructions, very large defects can be covered and healed with this technique, which also requires minimal technical expertise and operative time. Soft-tissue reconstructions can provide water-tight closures and are best used in concave intraoral areas that require coverage of a large surface area, but are not suitable for areas requiring replacement with bulk (i.e., floor-of-mouth, vestibule, sulci, and maxillectomy cavities). Large split-thickness skin grafts can be harvested concurrently with the extirpative procedure with minimal donor-site morbidity. Allograft usage is faster and incurs no potential donor-site morbidity. Full-thickness grafts are rarely used intraorally because of the significant mobility and contamination within the oral cavity. Graft success depends mostly on the vascular supply of the recipient bed and maintenance of low-mobility contact between the graft and recipient bed. Neovascularization of these grafts is compromised in areas with poorly vascularized tissues such as cortical bone, cartilage, tendon, fibrotic scar, irradiated or crushed tissue, or defects containing foreign bodies (i.e., reconstruction plates, alloplastic material). Large bolsters are often needed, which can temporarily compromise the airway or deglutition. Thus, this technique is not universally applicable throughout the oral cavity. In addition, there is a significant degree of contraction with split-thickness skin grafts during the healing process in mobile areas. This contraction can cause a significant amount of intraoral tethering, with concurrent loss of mobility or concavity. Allograft incorporation takes significantly longer and requires mucosalization of the surface. Collapse of two opposing raw mucosalizing surfaces of a previously bolstered concavity can cause synechia or collapse, resulting in a suboptimal result.
Non-vascularized skeletal reconstruction usually involves prosthetics or autologous bone grafts in combination with rigid fixation techniques. Both grafts and implants generally need protection from oral or external contamination for incorporation. Unfortunately, this is more troublesome in the setting of primary reconstructions and/or the poorly vascular recipient bed, although not impossible (37-40). This method is generally more successful in the setting of secondary bone reconstructions, allowing isolation of the avascular bone graft site from oral contamination via an established soft-tissue barrier. Reconstruction of composite oral defects with vascularized soft tissue and a mandibular reconstruction plate is possible, but it can have a significant complication rate on a long-term basis (28,29). Radiation dosimetry effects of reconstruction plates have not proven to be a hindrance clinically (41). Use of homograft bone is not widely practiced and use of hydroxyapatite cement or xenograft bone grafts in the jaws is currently not indicated.
The use of prosthetic maxillary obturators for reconstruction of partial maxillary alveolar and hard palate defects has a longstanding and successful history (42). Maintenance of tongue abutment against the reconstructed hard palate is important for speech and bolus preparation and transport. For limited defects, both form and function are well maintained. In addition, the recipient extirpative bed is easily evaluated for disease recurrence without being covered up by a complex reconstruction. Larger maxillary defects are less adequately reconstructed with prosthetic obturators alone due to lack of adequate skeletal support for mastication and prosthesis adherence. In these cases consideration should be given to fasciocutaneous or osteocuta-neous free-tissue reconstruction (43-45). Tissue-born dentures and osseointegrated dental implants are important adjuncts to assist with post-operative mastication. The best time to place osseointegrated implants remains controversial (46). Tissue-borne dentures are best left to well after oncologic therapy is finished. Financial constraints often severely limit widespread availability of these dental restorations. Also, free cable nerve grafts are available to assist reinnervation of both facial and intraoral sensation to maximize post-operative function (37).
In general, larger and/or more complex oral cavity extirpative defects require larger and more complex reconstructions. Replacing like with like frequently requires the use of vascularized tissue reconstructions from outside the oral cavity. Regional pedicled flaps for head and neck reconstruction have been used successfully for greater than 30 years (47-49). These techniques include many different regional donor sites with capabilities to transfer skin, fascia, muscle, and bone in different combinations, although pedicled boney flaps generally have very limited usefulness and reliability in current day reconstructions. Pedicled-flap reconstructions are taught in essentially all head and neck residencies and are easy techniques to learn, but the art of successful and appropriate application requires prolonged experience (50-53). One of the advantages of the use of regional pedicled flaps is the technical ease of harvest of well-vascularized tissue that is usually outside the prior head and neck irradiation field. The reliable vascular supply can be readily identified, and the thick vascular pedicle can provide needed coverage of exposed neck structures with better healing. In contrast to simpler reconstruction techniques, large surface areas can be reconstructed, but survival difficulty can arise if too small of a skin paddle is harvested. Some flaps do require staging procedures to increase size, survivability, and overall cosmetic result. Some require other concurrent procedures at the recipient and/or donor sites such as supplemental skin grafts.
Rough handling, tension, pedicle kinking or compression, or minimization of the pedicled fasciocutaneous paddle can compromise the sometimes tenuous vascular perforators and result in partial or total flap loss. In addition, availability of donor sites is very sensitive to previous surgical incisions, trauma, and neck dissections. Concurrent harvest during the extirpative procedure is often difficult due to the closeness of the recipient and donor sites and differences in patient positioning. Pedicled flaps usually are limited in their reach, malleability, and mobility secondary to the tethering pedicle's arc of rotation. Most have a significant amount of bulk and subsequent difficulty with gravitational settling which can hinder both function and cosmesis (54). With time, this bulk tends to atrophy due to denervation. The effect on donor site cosmesis and function is also significant compared to simpler local reconstructive techniques, especially in the setting of ipsilateral compromise of trapezius function from a neck dissection.
Many challenges associated with the use of the pedicled flap in reconstruction have been minimized with the increased popularity and availability of microvascular free-tissue transfer. The numerous donor sites provide options for not only large and composite defects, but can also provide attractive reconstructions for smaller defects with complex geometry restraints (i.e., posterior-lateral oral cavity, ventral tongue-anterior floor-of-mouth). Replacement of cutaneous lining, mucosa, bone, soft tissue volume, and function (i.e., sensation, secretions, muscular movement) in various combinations are available in a single-stage reconstruction depending on the specific donor site chosen. Unfortunately, reconstructive priorities are frequent determinants of the available options. Free flaps can provide well-vascularized tissue aiding healing in the previously irradiated oral cavity. Many free flaps provide sensory reinnervation capability via transferred intrinsic nerve grafts (55-57). However, even without direct neurography, some level of intraoral flap sensation is possible (58). Frequently, flaps can be harvested concurrently with the oncologic resection to minimize total anesthetic and operative time. In most cases, adequate recipient vessels can be accessed in several places of the extirpative field. This, in combination with frequently long flap pedicles, provides relative freedom of flap placement throughout the head and neck. In addition, free-flap reliability in large centers is equivalent or better than with pedicled tissue transfer (11,59,60).
Free-tissue transfer techniques do demand sub-specialty training and involve a career-long learning process. In addition to the added expertise, microvascular reconstructions require increased health care resources, including time, equipment and personnel. The actual costs of microvascular reconstruction are comparable to other techniques (54,61,62). Free flaps are dependent on the presence of adequate recipient bed vessels for microvascular anastomosis, which may not always be readily available in the multiply operated patient. Donor-site morbidity can range from minimal to inhibiting. These issues must be weighed in balance with their success in terms of restoring oral cavity form and function. The best result often subsequently requires multiple fine-tuning operations after the initial extirpative and reconstructive procedure, taking advantage of aesthetic facial plastic techniques by a facial plastic surgeon.
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