Although tissue expansion was first introduced by Neumann in 1957,³ Radovan popularized it with its use for breast reconstruction in the late 1970s and early 1980s.⁴ In burn reconstruction, expanded advancement flaps began being used for resurfacing after excision of adjacent burn scars. The idea of expanding normal skin to provide more donor site for burn reconstruction was introduced.⁵ Tissue expanded flaps were found to be more vascularized than normal skin, and flaps were found to survive for greater lengths.^6,⁷ This ultimately led to increased availability of better suited skin for facial reconstruction, expanded free flaps and pre-fabricated flaps.

The 1970s saw the new development of microsurgical techniques allowing further development of autologous tissue transfers (free flaps) from one place on the body to another. Ultimately, this, along with the seminal work of Joseph Murray, a plastic surgeon who performed the first successful human kidney transplant in 1954, which subsequently led to a Nobel Prize in Physiology of Medicine in 1990 for his work on organ and cell transplantation, would lead to the first allotransplantation of the face in 2005.

Currently, new techniques continue to be developed and tested to improve reconstruction after facial burn injury. Stem cell research gives some promise of growing new facial structures.

Basic science

Burn injury primarily consists of damage to the skin and its immediately underlying tissues as a result of physical trauma. The most common physical trauma is thermal in nature. Essentially, the heat energy kills living cells in the tissues and denatures the proteins that make up the tissue that dies. This energy could be from fire and explosions, hot water and steam in the case of scalds, or contact with hot objects. The physical damage can be inflicted through a chemical reaction of some substances such as acids and alkalis with the skin. Electrical energy, converted to heat by the resistance imposed by the skin, and by transmission through the skin can damage the skin and the underlying tissues through which the high voltage electricity passes.

The damage to the skin is a function of the amount of heat energy transferred to the skin. An agent of very high temperature (i.e., energy) can cause the same amount of damage as a much lower temperature agent applied for a longer period of time.

The degree of tissue damage is classified by the depth of the damage to the skin and the underlying tissues (Fig. 21.1). Damage to the epidermal layer alone is described as an epidermal burn scientifically, and a first-degree burn in common usage. An example of a first-degree burn is typical sunburn. An epidermal burn heals by sloughing the dead epidermal cells with immediate regrowth of new cells.

Fig. 21.1 The degree of tissue damage is classified by the depth of the damage to the skin and the underlying tissues. Burns are classified by depth of burn and extent of burn in percent total body surface area (%TBSA). There is a gradation of tissue damage from necrosis to tissue injury to normal tissue seen on the surface of the skin and histologically. This diagram is an attempt to represent what is seen clinically based on the depth of burn.

With greater energy transfer, not only are the epidermal cells lost, but the underlying dermis is damaged to varying depths. This damage consists of the denaturing of the dermal collagen, and thrombosis and destruction of the blood vessels within the dermis. The denatured collagen stays in place, and changes colors from pink to white to black depending on the number of remaining viable capillaries remaining close to the surface of the dermis. A superficial dermal injury consists of the epidermis coming off as a blister leaving a pink collagen surface due to the persistence of patent blood vessels close to the surface. A mid-dermal injury causes the remaining dermis to become increasingly pale, and a deep dermal injury causes the remaining dermis to be white in color.

Corresponding damage to the nerves within the dermis results in progressively less and less sensibility of the surface of the wound. Very superficial dermal burn wounds are very painful to contact because of the nerves at the exposed dermal wound surface. The dermal wound becomes more anesthetic as the depth of injury is greater. Although the dermal surface becomes anesthetic, the burns are still painful because the nerves are still injured at some level within the dermis.

A dermal injury heals by one of two mechanisms. Superficial injuries leave enough epidermal accessory structures such as hair follicles and sweat glands to provide epidermal cells for re-epithelialization of the dermal surface. Superficial injuries will usually re-epithelialize within 2–3 weeks if enough of the epidermal accessory structures are present. Superficial dermal injuries therefore may heal with some change in pigmentation of the new epithelium, but without burn scarring.

With deeper injuries, there are fewer epidermal accessory structures, and the wound heals by development of scar tissue and contraction mediated by fibroblasts and myofibroblasts, respectively. These cells migrate into the burn wound during the 1st week after injury, and proliferate in the granulation tissue that forms if re-epithelialization does not take place. It is, therefore, the deep dermal and deeper burn injuries that heal with burn scarring and burn scar contracture.

When the amount of energy transferred is so great that the full-thickness of the skin is destroyed, the appearance of the dermis can vary from white to cherry-red from capillary thrombosis to black from charring. Left alone, the dead dermis would separate from the underlying wound and it would go on to heal by scar formation and wound contraction.

Scientifically, ‘second-degree’ burns are all dermal injuries, both superficial and deep, and full-thickness burns are technically ‘third-degree’ burns. However, in common usage, ‘second-degree’ refers to the superficial burns that will heal by re-epithelialization within 2–3 weeks, and ‘third-degree’ refers to those deeper burns that will not. For the burn surgeon, the important diagnosis is whether the burn will heal by re-epithelialization and not require excision and grafting to prevent burn scarring and contracture. Therefore, the most useful terminology in diagnose of a burn is either “superficial” or “deep”, which corresponds most closely to the common usage of second-degree and third-degree.

Without intervention, deep facial burns heal by scarring and contraction. If the wound does not epithelialize in 2–3 weeks, fibroblasts and myofibroblasts migrate into the wound and lay down collagen and cause the wound to contract. The excess collagen becomes hypertrophic burn scar: the erythematous, thick, exuberant scar characteristic of any open wound that heals secondarily.

All scars, even primarily closed wound scars, contract. Contracted scars that limit mobility of joints or deform mobile structures, particularly of the face, are called contractures. Contractures of the neck are extrinsic to the face, but the face is affected by pulling forces from the neck transmitted to the mobile facial structures just as and frequently in conjunction with the intrinsic contractures represented by the scars adjacent to and deforming the mobile facial structures.

Diagnosis: determination of depth of burn

The most critical determination that the acute burn surgeon makes is whether the burn is superficial or deep because it determines whether the burn injury requires surgical intervention. A superficial burn will heal with minimal scarring, and a deep burn will heal with scarring and burn scar contracture causing significant facial distortion.

Therefore the diagnosis of burn depth is critical to determine what to do to get the best outcome for the patient’s facial burn injury. Generally, this diagnosis can be made by examination of the wound for color, sensitivity to touch, and other such characteristics. The most difficult diagnosis is that of a mid-dermal injury. This injury may or may not have enough epidermal accessory structures to allow the wound to re-epithelialize within 2–3 weeks. These mid-dermal burns are often termed ‘indeterminate.’ The decision to excise and graft these is frequently deferred hoping that the wound will heal within 3 weeks without scarring, knowing that excision and grafting will cause a definite change in facial appearance.

Cole et al. have proposed that the decision to operate on indeterminate facial dermal burns be made at approximately 10 days, and based on the best clinical judgment, excise if indicated and graft with thick split-thickness skin graft.⁸

Recently the scanning laser Doppler has been shown to help with the diagnosis in indeterminate dermal burns.⁹^–¹¹ This device determines the relative amount of blood flow in the superficial burn wound by reading the change in frequency of laser light caused by the movement of blood cells within the wound as it scans the surface of the wound. The color and numerical flux readings correspond to the likelihood of the burn wound healing within the 2–3 weeks window consistent with healing by re-epithelialization and minimal or no scarring.

Treatment of acute facial burns

Treatment of the acute facial burn injury is based on the diagnosis of the level of burn injury to both the face and the rest of the patient’s body. Severe facial burn injuries frequently occur in the setting of a critically large burn injury to the rest of the patient, and critical care and saving the patient’s life is often the first priority.

Because of the high degree of vascularization of the facial skin, infection of facial burn wounds is less likely than burns in other anatomic areas. This allows for some delay in making critical decisions regarding excision and grafting of facial burns. For management of the nonfacial burn, the idea of early tangential excision of deep dermal and full-thickness burns was championed by Janzekovic in the 1970s and continues to be the standard of care. Controversy still exists among surgeons regarding the early excision and grafting of facial burns. It is currently recommended to first treat a deep burn nonoperatively for 7–10 days with topical ointments, creams and local debridement.^8,¹² Some deep burns are obvious and may be excised and grafted earlier, but the vast majority are initially indeterminate.

A superficial burn injury will heal by re-epithelialization within two to three weeks if the wound heals without complication. Therefore the primary task of caring for a superficial facial burn injury is to prevent infection or any other problems that might interfere with normal re-epithelialization. Generally, superficial wounds epithelialize better in a moist environment. After initial cleansing, a mild antibiotic ointment is applied. The wound is gently cleansed twice-daily and the ointment reapplied. Every effort is made to avoid disrupting the migration of epithelial cells from the epidermal accessory structures across the surface of the wound. Although stronger antibiotic preparations are available, the author usually reserves these for evidence of active infection. I believe that treating the face open is safer than covering the face with an opaque dressing that prevents observation of the wound or allows for covert infection. Also any dressing that adheres to the wound through a dry interface reduces the pace of re-epithelialization as the fibrin bond between the dressing and the wound has to be broken down before the epithelial cells can migrate.

Deep facial burn injuries that will clearly not heal by epithelialization are doomed to heal with hypertrophic scarring and contractures if there is no surgical intervention. The standard surgical intervention is early excision and grafting in facial aesthetic units. This should be done as early as possible to minimize the migration of fibroblasts into the facial burn wound. Engrav recommends that a decision be made to excise and graft by 7–10 days post-injury, and have the face entirely grafted by 21 days. Initial excision of the wound is followed by sheet split-thickness skin allograft for 1 week. After that, the patient is returned to the operating room for closure with thick split-thickness autografts in the range of 0.018–0.021 inches in adults, and 0.008–0.012 inches in children placed in facial aesthetic units (Fig. 21.2).¹²

Fig. 21.2 (A) Aesthetic units. (B) Aesthetic unit markings. (C) Allograft at time of application. (D) Bubble facemask. (E) Mayfield headrest. (F) Allograft at 1 week. (G) Duplicast mold. (H) Plaster reinforcement. (I) Foam. (J) Autograft placement. (K) Bubble and elastomer. (L) Bubble and foam.

(From Cherry GW, Austad E, Pasyk K, et al. Increased survival and vascularity of random-pattern skin flaps elevated in controlled, expanded skin. Plast Reconstr Surg. 1983;72(5):680-687.)

Another consideration is to use the acellular dermal matrix applied immediately after facial burn wound excision in aesthetic units, preferably after preparation with sheet allograft for up to 1 week, as above. When successful, the engrafted acellular dermal matrix is covered with split-thickness autograft which can yield facial skin that is superior to thick split-thickness autograft.

Eyes/eyelid

Generally, it is rare for a thermal injury to involve the globe. In the current literature, the reported incidence of ocular, intraocular, intraorbital foreign bodies (especially in explosions) and periorbital injury due to a burn ranges from 8% to 20% of all burn admissions.¹³ This is most likely due to a significant number of protective mechanisms that include a patient’s reflex protective movements of the head and arms, and more importantly, the blink reflex. It should be noted that one of the most commonly overlooked or missed foreign body is the contact lens.

All facial burns should have an ophthalmological exam on admission, preferably by an ophthalmologist.

Most commonly the problem is globe protection in burns that damage the eyelids. Various ointments, corneal shields, or protective contact lenses help shield the cornea from further injury. A temporary suture tarsorrhaphy may be useful and effective in aiding lid closure, but dehiscence and complications are common, making tarsorrhaphy use controversial.¹⁴ Tarsorrhaphy does not prevent wound contraction, and the basic principles of early excision and grafting, and ectropion release and tissue transplantation are primary.

In the very young patient population, eyelid closure for as little as 3 days places an infant at a high risk for blindness in the affected eye. Prolonged occlusion of the eye due to scar contracture leads to decreased retinal stimulation and subsequently poor neuronal development of the corresponding optic cortex.

Wound nonoperative management of facial burn scars

Once facial burn wounds are healed, there are a number of ways that facial scars can be minimized and maturation of the scars can be encouraged. The two primary mainstays of non-operative facial burn scar therapy are compression and contact with silicone gel. The silicone gel is thought to be effective in reducing scarring and in encouraging scar maturation.^15,¹⁶ Compression tends to keep the hypertrophy of the scars in check.

Modern facial compression masks made with clear plastic with silicone interfaces provide patients with the benefit of both, and allow the patient’s face to be visible. This is an improvement over opaque elastic compression masks. Not only because they allow the patient’s face to be seen, but it allows individual pressure regulation on each of the hypertrophic scars by molding the plastic to the point of blanching of the scars.

Other important modes of nonoperative therapy during the ‘waiting period’ before surgery and in the postoperative period include splints to maintain scars to as optimal length as possible, massage to reduce swelling and help orient new collagen fibers in as normal orientation as possible, and occasionally steroid injections into smaller hypertrophic scars.

The use of pulsed dye laser therapy has been used to reduce the erythema and pruritus, and possibly improve scar remodelling in immature hypertrophic burn scars.^17,¹⁸ Carbon dioxide fractional ablative laser therapy seems to have a positive effect on remodeling of mature burn scars sometimes many years after forming.^19,²⁰

Surgical management of the late effects of face, head and neck burns

Introduction

There are a myriad of techniques described to reconstruct the multiple problems of dysfunction and deformity related to the individual anatomic components located within the face, head and neck. Most of these techniques are well-described elsewhere in these volumes. This section will focus on general principles and an approach to reconstruction of the most common late effects of burn injury primarily of the face, but also the ears, scalp, and neck.

One of the primary aspects of burn reconstruction surgery that sets it apart from other reconstructive surgery is the exceedingly common lack of local normal skin for donor sites. Techniques and solutions specifically for this problem will be addressed.

Specific techniques most commonly used in a burn reconstruction practice are described in more detail with emphasis on important technical considerations that will be of particular benefit to the patients of plastic surgeons less experienced in facial burn reconstruction.

General principles

Importance of allowing total wound healing and scar maturation

Burn reconstruction should virtually never be done in the presence of residual open burn wounds. Bacteria in open wounds risk infection in the reconstructive surgery. The presence of inflammation and active scarring will compromise the result. Incomplete contraction of original wounds will affect the reconstructive outcome within that wound unless the entire burn wound is excised. Typically, one waits about 1 year to begin facial burn reconstruction. The exception to this is reconstruction to protect vital structures or restore critical functions such as eyelid closure and oral competence.

Additionally, the time waiting for reconstruction frequently results in resolution of erythema and hypertrophy of some areas of scar, and, in some cases, improving function through therapy resulting in a reduction of the extent of the scar problem requiring surgical intervention (Fig. 21.3).

Fig. 21.3 The importance of allowing scar maturation. (A) Facial hypertrophic burn scar 4 months after injury. (B) Same scar 16 months after injury.

Reconstruction must be preceded by analysis of the problem and diagnosis of the factors causing it

Usually the most important factor is skin deficiency resulting from destruction of skin by the burn. Excisions of burn scar and contracture releases recreate the original skin deficit. The magnitude of the tissue deficit is often underestimated. Being prepared with this knowledge helps the surgeon determine whether normal donor sites will be adequate and what technique to use.

Do not assume that the entire scar must be treated similarly. Another element in diagnosis is determining whether treating only a portion of the scar will provide the desired improvement while leaving another area of the scar untreated. This is particularly true in determining the tension in a scar. By releasing tension, hypertrophy which is frequently potentiated by the tension is minimized in the rest of the scar.²¹

An overall plan for reconstruction should be developed

Once the problems are analyzed, an overall plan for surgical reconstruction and rehabilitation should be developed. Not only is this exceedingly helpful to the surgeon for planning operations and what donor sites to use, but it provides the patient with an understanding of the process required, adjusting expectations, and providing hope that there is, in fact, a positive outcome in the future.

Restoration of function usually precedes aesthetic reconstruction

This is especially important for protective functions such as the protection of the eyes by the eyelids, and oral competence. Ideally, to a degree, both goals are achieved simultaneously.

Release of contracture usually is the first priority. Extrinsic contractures, contractures of the neck in the case of facial burn scars, need to be released before the true extent of facial intrinsic contractures can be determined (Fig. 21.4). Neck contracture release also allows for safer anesthetic management by allowing neck extension.

Fig. 21.4 Importance of releasing extrinsic contractures before addressing intrinsic contractures. (A) Posture of lower lip with severe neck burn scar contracture. (B) Posture of lower lip after release of severe neck contracture.

Local flaps should be used whenever possible

Local flaps tend to provide ideal color match, skin thickness and texture due to their close proximity to the skin deficit or deformity that is being replaced. Furthermore, flaps do not contract, or change color or other characteristics as skin grafts do unpredictably.

Skin grafts are used because of their thinness when a thicker flap would hide underlying anatomic contours or interfere with function

Skin grafts are less stable in their characteristics. They change color and other characteristics unpredictably, but starting with the best well-matched local skin available gives the best chance of success.²²

All skin grafts contract to a degree and can lead to tightness that restricts facial expression or leads to recurrent contractures. Therefore, when using skin grafts, overcorrection is a general rule.

Box 21.1

Ancillary techniques in facial burn reconstruction

• Corrective cosmetics

• Laser therapy

• Steroid injection

• Prosthetics

• Anatomic parts, e.g., ear, nose

• Hair; hairpieces

• Hair transplantation

• Fat transplantation

• Tattooing.

Follow-up must be diligent

The reconstructive procedure is not an endpoint. A caring doctor–patient relationship must be continued, and the surgeon must remain available, particularly in case of complications. Nonoperative modalities typically used for burn scar management such as silicone gel sheeting, compression therapy, and pulsed dye laser therapy, are frequently reinstituted to treat the new surgical scars.

An algorithmic approach to facial burn in reconstruction

Based on some of the above general principles, a framework (Fig. 21.7) evolved in the author’s practice allows for analyzing burn-related facial deformity and dysfunction, simplifying often complex problems, and guiding reconstructive surgical decisions.^24,²⁵

Fig. 21.7 Algorithm for the reconstruction of large facial deformities.

(From Spence RJ. An agorithm for total and subtotal facial reconstruction us an expanded transposition flap: a 20-year experience. Plast Reconstr Surg. 2008;121(3):795–805.)

This algorithm first divides the facial aesthetic units into two broad categories: the peripheral aesthetic units of the forehead and bilateral cheeks, and the central aesthetic units of the eyelids, nose, upper lip, and the lower lip and chin aesthetic units. The peripheral facial aesthetic units are large units with minimal contour definition or structure and with relatively uniform skin characteristics. The central facial aesthetic units are smaller and have a higher degree of contour definition with intricate infrastructure and variations of skin characteristics.

Second, the algorithm analyzes the donor skin available for addition to or replacement of scarred or contracted facial skin. Specifically it asks the question whether there is donor site available locally in the ‘blush’ areas, the skin that is the most well-matched to replace facial skin. If this is not available, another path is taken in the decision tree.

This algorithm also incorporates all available techniques ranging from the simplest scar revision or excision and closure to complete replacement of the skin of the face. When scarred skin replacement is indicated, the algorithm recommends flap replacement of the peripheral aesthetic units as these areas are best reconstructed with broad, relatively featureless normal skin. However, when the replacement of the central facial aesthetic units is indicated, the infrastructure of the various contours needs to be reconstructed first, if necessary, and covered with a thin skin replacement usually in the form of full-thickness skin graft. As described in the literature, the expanded transposition flap ²⁶ is central in the algorithm when major facial deformities are addressed, as it provides both relatively thin flaps for the peripheral aesthetic units and full-thickness skin grafts for the central aesthetic units (Fig. 21.8).

Fig. 21.8 An example of total facial reconstruction using the algorithmic approach. Bilateral expanded transposition flaps for cheek reconstruction (peripheral), and full-thickness skin graft from expanded flap pedicle for central reconstruction. Forehead was resurfaced with thick split-thickness skin graft.

Specific techniques

Scar replacement with local skin

The simplest example of scar replacement with local skin is simple scar excision with primary closure. This excises the burn scar and replaces it with a surgical scar that is designed to be better and, optimally, much less noticeable. Basic plastic surgery principles critical to obtaining the best results include: (1) performing the excision within relative adjacent tissue excess where possible; and (2) respecting resting skin tension lines (RSTL) in the planning of the new scar (Fig. 21.9).²⁷ This repositions the new scar in a pre-existent anatomic line or contour such as the nasolabial crease, a hairline, or forehead wrinkles. It also imparts the least tension across the new scar minimizing the negative effects of tension on the scar.

Fig. 21.9 Resting skin tension lines lie perpendicular to the action of the underlying facial muscles. Scars placed parallel to these lines are least noticeable.

Generally, there should be careful perpendicular incision through the skin to allow the most accurate re-approximation on closure of the new surgical wound. The optimal quality of the new scar is based on very careful anatomic re-approximation of the dermis and epidermis individually. The dermis is carefully re-approximated with absorbable sutures minimizing tension on surface sutures if they are used. It may make the accurate epidermal closure with surgical adhesive possible. Long-term it reduces the spreading of the new surgical scar.

The epidermis is carefully re-approximated with either surgical adhesive if the dermal sutures have brought the epidermal edges into anatomic alignment, or carefully placed sutures, with just enough tension to bring epidermal edges into anatomic alignment. If the epidermal edges overlap or are inverted, less favorable healing and suboptimal scars will form. The failure to close the epidermis results in a small open wound that will lead to increased scar formation and possible scar hypertrophy.

Serial excision

An extension of simple scar replacement by excision and primary closure is the technique of serial excision. When a scar is too large for excision and primary closure, only that portion of the scar that can be excised is, and the wound closed. The tension resulting from the first wound closure results in stretching of the surrounding skin (mechanical creep) and subsequent growth of the skin in response to the additional tension (biologic creep).²⁸ The increase in the amount of surrounding skin that takes place over at least 3 or 4 months allows reoperation to excise the residual scar and close the resulting wound with the expanded normal surrounding skin. With the advent of tissue expansion to develop new skin adjacent to scars, serial excision is used much less, but should be considered if the serial excision is likely to take only two or, at most, three operations.

W-plasty

A W-plasty is the closure of a wound with multiple sawtooth lines that better approximate the resting skin tension lines (RSTL) of the facial skin (Fig. 21.10).²⁹ The resulting lines more in-line with the RSTL become less noticeable. They also break up the linear nature of the unfavorable scar. A similar effect can occur if multiple small Z-plasties are placed in the linear skin closure. Technically, this technique can be exceedingly tedious. For W-plasty closure to be safe and effective, it needs to have limbs that are millimeters in length not to exceed 1 centimeter.