This article describes the challenges of facial reconstruction and the role of facial transplantation in certain facial defects and injuries. This information is of value to surgeons assessing facial injuries with massive soft tissue loss or injury.
Key points
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The difficulty of facial reconstruction is in the complexity of the facial structures and functions.
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Conventional microsurgical reconstruction alone cannot effectively provide a neuromuscular reconstruction of significant facial defects, because there is currently no method to connect these reconstructions to the patient’s motor cortex.
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Facial transplantation allows a composite transfer of skin, soft tissue, and bone that replaces the lost tissue with an exact anatomic and functional match.
Introduction
Facial reconstruction has made considerable progress over the last century. Injuries and defects that were once considered impossible to reconstruct have become amenable to modern techniques that are now considered standard of care. The evolution has seen an advance from the early developments of local soft tissue flaps and rigid fixation in reconstruction to the advent of microsurgical free tissue transfer. Complex three-dimensional facial defects can now be repaired using these free flaps. This development has allowed clinicians to not only coapt the residual tissue but also effectively replace significant amounts of tissue that is missing. From the early reports of free flaps in the 1980s to the complex reconstructions of the present day, flaps have undergone their own evolution. Time has made the extraordinary become ordinary. Flaps can be molded, prelaminated, and modified extensively to allow better reconstructions in this patient population. Despite all of these advances, there are certain defects and injuries that are encountered in clinical practice that still remain difficult challenges.
Introduction
Facial reconstruction has made considerable progress over the last century. Injuries and defects that were once considered impossible to reconstruct have become amenable to modern techniques that are now considered standard of care. The evolution has seen an advance from the early developments of local soft tissue flaps and rigid fixation in reconstruction to the advent of microsurgical free tissue transfer. Complex three-dimensional facial defects can now be repaired using these free flaps. This development has allowed clinicians to not only coapt the residual tissue but also effectively replace significant amounts of tissue that is missing. From the early reports of free flaps in the 1980s to the complex reconstructions of the present day, flaps have undergone their own evolution. Time has made the extraordinary become ordinary. Flaps can be molded, prelaminated, and modified extensively to allow better reconstructions in this patient population. Despite all of these advances, there are certain defects and injuries that are encountered in clinical practice that still remain difficult challenges.
Limitations of conventional reconstruction
The difficulty of facial reconstruction is in the intrinsic complexity of the face both in form and function. The face is composed of unique three-dimensional structures consisting of a wide variety of tissue types. The variation sometimes makes identification and transfer of appropriate donor tissue to this area challenging. The unique skin color, texture, and consistency of facial skin are often best reconstructed from adjacent areas within the face. Skin from distal extremities, although effectively transferred through microvascular techniques, is often not appropriately color matched to the face and becomes easily noticeable in the patient. The face also has unique structures that bear no similar homologues in other parts of the body, such as eyelashes and eyelids. The complex spatial relationships and varied tissue types of facial components, such as the nasal base to the upper lip and the junction of the red and white lip at the vermilion, create reconstructive challenges that are not easily overcome. Microvascular reconstruction of the face with the best outcomes is usually seen in cases of complex subcutaneous and bony reconstruction in which the skin and superficial musculoaponeurotic system envelope of the face is unaffected by the injury or surgical resection. When the neuromotor components of the face or facial skin are missing, the reconstruction of these areas becomes more difficult using conventional techniques, because harvest sites do not exist. Flap modification and revision can allow a progressive molding of the tissue to better approximate the desired end points, but there are limitations to this approach.
The difficulties in achieving the form of the face given its complexity, although daunting, are not the most significant limitation to conventional reconstruction. Repair of function is a bigger obstacle. Free flaps (with few exceptions) are static structural tissue transfers. Any motor function is caused by residual muscle function in the face. An example is a mandibular reconstruction with a fibula flap that relies on native function of the muscle of mastication to work. The face moves under complex discrete neuromuscular orders directing all of its activity: smiling, laughing, eating, speaking, and blinking. The ability to communicate emotions with the facial functions has no substitute. Any successful reconstruction of the face from a functional standpoint can not be limited to a replication of form but also needs to make this essential connection to the brain. It is this movement of the central face that is the critical component of all of its functional roles. Almost every facet of human communication and socialization relies on this. At a more esoteric level, but probably as important, the central face is the window to human emotion. People express anger, joy, grief, and love through the subtle and delicates movements of this part of the face. Injuries to this area not only affect the individual who experiences them but affects all of those around them. However, although surgeons have become adept at moving bone, skin, and soft tissue from one region of the body to another, they are still limited in their ability to establish a functional neuromuscular reconstruction. The only widely used clinical application of a neuromuscular flap in the face is the gracilis muscle for smile reconstruction. Although the results are excellent for this indication, the limitations of this procedure are obvious. The gracilis muscle is used primarily to reconstruct only the muscular component of the face and requires the remaining soft tissues and other structures to be intact and uninjured to achieve optimal results. The procedure is in principle solely the replacement of the critical zygomaticus major and minor complex. However, other significant reconstructive challenges remain. How do surgeons reconstruct facial defects when the other facial muscles (orbicularis oculi and oris) are missing? What are the options when facial skin and soft tissue are also missing?
These challenging questions arise when the face is injured by ballistic trauma. The restoration of bony landmarks and closure of soft tissue wounds is often not possible because of the loss of viable soft tissue and bone. In addition, the inherently poor vascularity of the severely traumatized tissues that remain and the associated evolving tissue necrosis and infection makes a challenging situation worse. Primary repair of the injured tissues is rarely feasible because adequate viable tissue is no longer present locally. The paradigm must shift from the classic conceptions of injury repair to rebuilding. Successful restoration of form and function can only be achieved by recruiting tissues to rebuild the deficient structures of the face.
The treatment approach for extensive traumatic head and neck injuries has shifted away from delayed repair to early repair with local tissue and free tissue transfer reconstructions. Staged early definitive reconstruction allows fewer surgeries and shorter hospitalizations. The initial repair may involve some elements of healing with secondary intention or primary closure but usually requires early recruitment of healthy tissue into the face via local tissue rearrangement, pedicled regional flap, or free tissue transfer (anterolateral thigh flap, osteocutaneous fibula flap). Local tissue advancement with a cervicofacial flap can be used to reduce the soft tissue deficit and provide skin coverage. Although this flap brings healthier adjacent tissue into the defect, it is a randomly based flap and susceptible to vascular compromise and distal flap necrosis. Pedicled regional flaps (paramedian forehead flap, deltopectoral flap, latissimus dorsi flap) are supplied by a vascular pedicle allowing greater tissue viability and versatility. The paramedian forehead flap can be used for nasal reconstruction. The deltopectoral flap and latissimus dorsi flap can be used to reconstruct large skin defects of the neck, lateral face, and scalp.
The evolving success and reliability of microvascular surgery has led to the early use of healthy vascularized free tissue transfer for trauma reconstruction. The advantages of recruiting nontraumatized naive tissue for the reconstruction include a more physiologic restoration of function and a reduction in scar contracture. Free tissue transfer also allows the reconstruction of varying tissue defects (mucosa, bone, skin, soft tissue) with comparable vascularized tissue. The anterolateral thigh flap can be used to reconstruct large skin and soft tissue defects. The osteocutaneous fibula flap can be used to reconstruct orbitomaxillary and mandibular defects. Many of these cases are discussed elsewhere in this issue.
Although the results are excellent, a few important points must be emphasized. All of the cases shown do not have significant neuromuscular losses of the central face. As discussed, conventional microsurgical reconstruction alone cannot effectively provide a neuromuscular reconstruction of significant facial defects. The face can be thought of as having 2 distinct physiologic regions. Most of the face and neck is composed of fasciocutaneous structures that are easily amenable to microsurgical and conventional reconstruction. However, the central face has significant neuromuscular functions and uniquely complex structures that are distinct. This relationship is shown in Fig. 1 . Here the traditional techniques are grossly inadequate.
The importance of the central face
The consequences of the limitations in facial reconstruction of the central face are magnified by the importance this area has for quality of life. The functional significance of the area is obvious. Much of human communication depends on the function of the lips and mouth. Labial sounds such as B and P are common in almost all languages and they cannot be articulated without lip function. The function of the orbicularis oris is critical for eating and drinking. Nasal function and form are important to establish a safe and appropriate airway. Eyelid function is critical for maintaining the ability to see. These functions represent just a few of the myriad vital functions that human faces play in daily life.
There are other reasons why midfacial injuries are so serious. The central face is also the key to people’s physical identity. People are recognized more by the interplay of the structural relationship between the eyes, nose, and lips than any other part of the body. Within this small region, which is less than 5% of the body surface area, is the foundation of personal identity. This concept is illustrated in Fig. 2 .
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