Overview of surgical procedures used in the management of burn injuries

INTRODUCTION — Once the burn patient has been resuscitated and stabilized, restoring anatomy, preserving function, and rehabilitating the patient are the next priorities. To accomplish this, the surgeon must evaluate the extent to which tissue is missing and identify potential donor sites or other solutions to best manage skin and soft tissue defects. The aim is to reconstruct like tissue with like tissue, restoring function first, which supersedes immediate concerns over cosmesis. Appropriate measures are taken to limit scarring in the postoperative period; however, once the patient has progressed through the acute phase of the injury, including acute wound coverage, reassessment of the wounds may necessitate wound revisions to achieve an optimal cosmetic outcome.

An overview of the surgical techniques used for burn reconstruction is reviewed here. The general management of the burn patient and management of burn injuries according to depth of injury are discussed in separate topic reviews. (See "Overview of the management of the severely burned patient" and "Treatment of deep burns" and "Treatment of superficial burns requiring hospital admission".)

GENERAL PRINCIPLES — Burns are a specialized form of trauma, and, as such, they are managed according to recognized protocols of trauma resuscitation. Characteristically, these protocols assess the trauma/burn patient through a primary survey, a secondary survey, and a process of continuous reassessment that ultimately refers the patient to a definitive treatment facility. (See "Emergency care of moderate and severe thermal burns in adults".)

There are two important priorities within the primary survey that are specific and exclusive to the burn patient. These are the assessment of the total body surface area (TBSA) or extent of the burn wound and the assessment of the depth of the burn wound. These are of paramount importance because the assessment of the TBSA determines the level of fluid resuscitation, while the assessment of the depth of the burn wound determines the need for surgical debridement,

Any burn larger than 10 percent TBSA in a child or 15 percent TBSA in an adult requires fluid resuscitation according to specific formulas. We use the Parkland formula, though many others are available and are used according to burn unit preference. These burns are called resuscitation burns.

Assessment and approach by burn depth — The assessment of the burn depth determines the categorization of burns into the following types according to the dermal damage and to clinical parameters mainly related to preservation or destruction of the skin's multiple vascular plexuses (table 1 and figure 1). Burn wound imaging increases the accuracy of predicting wound-healing potential and can aid clinical decision-making in the management of mid- to deep dermal burns. In particular, laser Doppler imaging has strong published evidence of utility in predicting which wounds will heal within the 21-day time frame and which wounds would benefit from surgery [1]. (See "Assessment and classification of burn injury", section on 'Methods of estimation'.)

●Superficial or epidermal burns (ie, first degree) – These burns are characterized by extensive erythema due to hyperemia of the dermal plexus or outpouring of burn inflammatory mediators. They exhibit pain but a lack of blisters and characteristically heal without the need for surgery and with no sequelae such as scars or pigmentation. Superficial burns are not included in percent TBSA determination.

●Partial-thickness or dermal burns (ie, second degree) – These burns involve dermal damage and may or may not require surgery in the acute period depending on the depth of the dermis involved. The pathognomonic feature of partial-thickness burns is the breakdown of the epidermis, with presence of blisters and exposed dermis. These may require reconstructive surgery for resulting scars appearing as a result of delayed healing or deep damage. Partial thickness wounds that heal within 21 days of injury have a much lower risk of developing hypertrophic scarring [2]. Further studies have shown a daily increase in risk of hypertrophic scarring after 14 days, particularly in patients with higher Fitzpatrick skin types (table 2) [3]. Skin grafting undertaken within 14 days improves scar outcome [4].

According to the level of dermis involved, partial thickness burns are subdivided into:

•Superficial partial-thickness or superficial dermal burns – These burns affect partially the papillary dermis. They exhibit pain, brisk capillary refill, blistering, and a moist and pink appearance and may heal without surgery with dressing care only, though characteristically they may require surgery if they are extensive to debride the denuded epidermis and to promote dermal preservation with specialized dermal-preserving materials (eg, Biobrane, Suprathel). These characteristically heal in less than three weeks and do not leave scars that require reconstructive surgery, though pigmentation changes post-burn may appear.

•Mid-dermal partial-thickness burns – These burns affect the papillary dermis and the upper part of the neighboring reticular dermis. These exhibit pain that may be less compared with superficial partial-thickness burns as the deeper damage to the neurovascular supply of the dermis reduces the pain component of the injury. The capillary refill is more sluggish and difficult to ascertain, and the appearance may be drier and paler. These may require surgery in the acute period to debride nonviable dermis and provide dermal preservation coverage. These are more likely to scar and require reconstructive surgery once healed.

•Deep dermal partial-thickness burns – These burns affect deeply the reticular dermis and can be considered a precursor or potential for full-thickness burns. These may not exhibit pain and present with a dry, cherry-red-color appearance. These always require surgery and skin coverage in the acute period and therefore will leave scars that may require reconstruction at a later stage.

●Full-thickness burns (ie, third degree) – Full-thickness burns damage the entire thickness of the dermis and its neurovascular supply. These appear as leathery brown injuries with or without thrombosed vessels and are insensate and without self-healing capacity. They always require debridement and graft coverage in the acute period and always leave scarring that may need reconstructive surgery at a later stage.

BURN WOUND EXCISION — Early burn wound excision is essential in the management of deep burn injuries to eliminate necrotic and potentially infected tissue [5,6]. Best practice dictates that definitive skin coverage should be attempted at the time of debridement, as soon as possible after the burn injury, whenever possible. Management of the burn patient poses several challenges due to the nature and extent of the injury. While burn wound excision and coverage within the first five days is optimal, it is not always possible. The burn-injured patient often suffers extensive skin loss that can occur at multiple anatomic sites, and multiply injured patients may also have other injuries that impact their management (eg, inhalational injury, head injury, extremity trauma). (See 'Burn wound coverage' below and "Overview of inpatient management of the adult trauma patient", section on 'Introduction' and "Treatment of deep burns".)

Early excision of necrotic tissue and coverage of the burn wound has been one of the single greatest advancements in the treatment of patients with severe burns and a mainstay of therapy [7-9]. In an early review evaluating burn wound care in 3561 burn patients over a 14-year period, a significant decrease in length of hospital stay (23 days in 1979 to 14.2 days in 1990) was correlated with a decrease in surgery interval (14.8 days in 1979 to 6.1 days in 1990) [10]. The surgery interval reflected the rapidity with which the surgical team was able to close/cover the burn wound. Mortality also decreased significantly while burn severity indices remained constant. A meta-analysis of six trials showed a significant reduction in mortality for burn-injured patients (with or without inhalation injury) undergoing early excision and grafting compared with dressing changes and delayed skin grafts following eschar separation (relative risk [RR] 0.36, 95% CI 0.20-0.65) [9]. The length of hospital stay was shorter for the early excision group, but there were no differences in the duration of sepsis, wound healing time, or skin graft take between the two groups. Early wound closure is also associated with decreased severity of hypertrophic scarring, joint contractures, and stiffness and promotes faster rehabilitation [11,12]. However, burn wound coverage alone does not eliminate the hypermetabolic response [8]. (See "Hypermetabolic response to moderate-to-severe burn injury and management".)

BURN WOUND COVERAGE — Various reconstructive procedures are used to restore function and cover burn wounds in the acute period and to manage contractures and improve aesthetics of resultant burn scars. As with any patient with soft tissue defects, wound coverage ascends the reconstructive ladder whenever difficulty is encountered, providing restoration of anatomy at lower steps or levels of the ladder when possible. In ascending order of complexity, surgical procedures used in burn wound coverage and reconstruction include the following, which are discussed in more detail below:

●Direct wound closure (see 'Direct wound closure' below)

●Skin grafting (see 'Skin grafting' below and 'Use of skin substitutes' below)

●Coverage with expanded tissue (see 'Tissue expansion' below)

●Tissue transfer – Local flaps, pedicle flaps (see 'Flap reconstruction' below)

The acute burn wound or scar contracture or deformity that may result later is highly variable in terms of size, shape, anatomic location, and level of healing. As such, burn reconstruction often requires the use and combination of several types of procedures in one or more body regions simultaneously, or sequentially over a variable period of time. The aim is to reconstruct like tissue with like tissue. To accomplish this, the surgeon must evaluate the extent to which tissue is missing and identify potential donor sites or other solutions to best manage skin and soft tissue defects.

Coverage of skin defects — Free skin grafts, either split-thickness or full-thickness, are the conventional options for coverage of freshly excised burns, with the exception of the smallest burn wounds, which may be closed directly, and burns exposing bone and tendons devoid of a graftable vascularized layer, which generally require flap coverage [13]. Skin grafts can only be used to cover exposed bone or tendon if there is a vascularized layer of periosteum or if the paratenon (paratendon) is intact. Split-thickness skin grafting is likely to form contractures and to lead to scar deformities. Honest discussion with patients helps to prepare the ground for later revision and to avoid unexpected disappointment.

Coverage with autologous skin grafts is possible only when donor sites that can be safely harvested are available. If autologous skin coverage is not possible due to the environment of the wound (infection, potential for conversion to a deeper pattern of injury), the patient's physiology (deterioration, instability), or paucity of donor sites, then temporary skin coverage must be attempted. (See "Skin autografting", section on 'Skin anatomy'.)

Allografts are characteristically the preferred next choice due to their adhesion, capacity for dermal preservation, and temporary biocompatibility. If they are not available due to financial constraints, personal choice, or unit protocols, xenografts provide another choice for coverage, but of undoubtedly less quality and dermal advantage. At times, temporary wound dressings or other alternatives (eg, skin substitutes) can be used until more definitive reconstruction can be accomplished.

Careful consideration and caution should be exercised by clinicians when using human cadaveric allograft, as there is growing evidence these may compromise future composite tissue allotransplantation [14]. (See "Skin substitutes", section on 'Available products'.)

Coverage of soft tissue defects and deep structures — Complex wounds in which the volume of tissue loss is either too large or exposes deep structures (eg, vessels, nerves, tendons, bone) are unsuitable for skin grafts and require ascending the reconstructive ladder [15]. Flap reconstruction (local/distant flap with or without tissue expansion) is ideal, if tissues are available. A complete evaluation assesses the skin, subcutaneous tissue, fascia, muscle, blood vessels, nerves, cartilage, and bone. (See 'Flap reconstruction' below and "Overview of flaps for soft tissue reconstruction", section on 'Principles of reconstruction'.)

BURN SCAR REVISION AND TIMING — The timing of burn scar revision can be regarded as urgent (immediate), essential (early), and desirable (delayed) [16]. While definitive management of burn scars may be delayed until full maturation of the scars is achieved or to let physiotherapy modulate the surgical behavior, some burn scars require immediate reconstructive attention to restore function or protect vital areas. In one retrospective cohort study, 13 percent of patients underwent reconstructive surgery during the 10-year follow-up period [17]. The most common indication was scar contracture, and the hands and head/neck were the anatomic regions most frequently involved.

Physiotherapy and scar management techniques (eg, stretching, mobilization, exercise, splinting, silicone sheeting, massaging, moisturizing, pressure garments) may alter the scar sufficiently to make it functionally compatible and cosmetically acceptable, or to potentially reduce the complexity, number, or timing of the reconstructive procedures. For hypertrophic burn scars, the use of lasers is rapidly becoming the first-line treatment of choice [18]. (See "Hypertrophic scarring and keloids following burn injuries", section on 'Preventive strategies and their efficacy'.)

Immediate — The priority in immediate (urgent) procedures is to protect anatomically sensitive structures fundamental for full function and optimal quality of life. Immediate procedures are restricted to burns for which there is no other suitable treatment, such as providing coverage of exposed or severely damaged vital structures [16]. Immediate revision should be performed following full healing of the acutely burned areas (in the best scenario, grafts will heal in five days) but as soon as symptoms related to the exposure of vital structures appear. Characteristically, these are performed prior to the period of full scar maturation, in order to preserve function.

Examples include:

●Release of eyelid contracture to protect the cornea to avoid cicatricial ectropion

●Release of microstomia (severe contractures of the mouth)

●Release of compressed neurovascular bundles

●Release of synechial neck contractures that limit neck extension

Early — Early (essential) procedures are performed to improve the burn care rehabilitation and nonvital function [16]. Early procedures are performed for mature burn scar contractures that do not respond to splinting or aggressive physical therapy. Examples of abnormal scarring areas that are amenable to early reconstruction include:

●Nonsynechial neck contractures

●Contractures of major joints (eg, elbow, knee, ankle)

●Contractures of areas that limit mobility (eg, axilla, groin)

●Contractures of the hand

Delayed — Most burn reconstructive procedures are performed as delayed (late/desirable) procedures [16]. These procedures are performed after the scar has matured, typically 18 months to two years after full healing. Delayed procedures address the size and shape of the mature scar as well as abnormalities in color and texture mismatched to the surrounding skin. Functional reconstructive procedures should always be performed with the goal of the best aesthetic result possible, thus providing dual benefits to the burned patient [19]. Examples of late reconstruction include:

●Reconstruction of passive areas (eg, trunk, extremities)

●Aesthetics (eg, face, breast)

DIRECT WOUND CLOSURE — Direct wound closure is the simplest procedure that can be used for small to moderately sized burn scars that are suitable for revision by excision, provided the wound edges can be brought together without tension. Excess tension will lead to stretched, unsightly, and painful scars. Although direct closure is primarily applicable to relatively small wounds, larger wounds can be closed in areas with sufficiently redundant tissue or in areas where the elasticity of the surrounding tissues allows for tension-free closure. As an example, a large lower abdominal burn scar can be excised and closed with an abdominoplasty-type closure providing excellent cosmetic outcomes.

The main advantage of direct closure is a theoretical improvement in aesthetic outcome by transforming a functionally disabling or unsightly scar into a cosmetically acceptable line of closure. This principle needs to be applied judiciously as overambitious and careless planning may lead to large wounds not amenable to direct closure, potential dehiscence, and other problems if the wound edges are close to or occupying joint lines. Small burn wounds or scars that cross joint lines or involve areas close to the eyes, mouth, and nose can be revised using local flap procedures (eg, Z-plasty). (See 'Flap reconstruction' below.)

SKIN GRAFTING

Split-thickness autografting — A split-thickness autograft includes the epidermis and varying amounts of dermis. The split-thickness skin graft is the most frequently used donor tissue and is the workhorse resurfacing technique in the management of acute burn wounds. The primary limitations of skin grafting in the burn-injured patient are the frequent lack of availability of unburned donor sites, the reduced elasticity and pliability of the donor skin, and the tendency for scarring and contraction. The general principles of skin grafting, including the advantages and disadvantages of split-thickness skin grafts, surgical techniques, and general postoperative care, are discussed separately. Our preferences for coverage of burn wounds are provided below. (See "Skin autografting", section on 'Split-thickness skin grafting'.)

When donor sites are limited, expansion of the graft by meshing techniques (picture 1), reharvesting, and combination with allograft techniques (eg, sandwich technique) allows for coverage of larger defects. The quality, elasticity, and pliability of the reconstruction can be improved by combining the split-thickness skin graft with a skin (dermal) substitute. (See 'Use of skin substitutes' below.)

●Characteristically, 1:1 mesh (mini mesh), 2:1 mesh, and 4:1 mesh (with overlying allograft) are used depending on the availability of donor sites. The Meek technique is an alternative technique for expanding autografts. (See "Skin autografting", section on 'Graft meshing'.)

●Sheet grafts (unmeshed) provide optimal coverage for burns of the face and hands and other anatomic sites where cosmesis and function are important, but their use also depends upon the availability of unburned skin (picture 2 and picture 3) [20-22].

●Donor sites are chosen carefully with a mind toward the possibility of repeated harvesting. Convex, easy-to-harvest areas such as the anterior and lateral surfaces of the thigh are preferred split-thickness skin graft donor sites. When donor sites are plentiful, skin can be taken from an inconspicuous location that is easily accessible for wound care. However, for large surface area burns, every available site may need to be used. This may include the scalp and scrotum area [23].

●We do not harvest split-thickness skin grafts thicker than 12/1000 of an inch in the burn-injured patient. Harvesting thicker grafts requires a longer time for donor sites to heal and may preclude that site from repeat harvesting.

The primary dressing (in direct contact with the graft) should be nonadherent (eg, Telfa, Mepitel). This greatly facilitates skin graft inspection and minimizes graft shearing. A secondary dressing with antimicrobial properties (eg, povidone-iodine solution, silver-based topical agents) is placed overlying the primary dressing. Tertiary dressings (bandages) that control exudate and keep the patient's environment clean complete the dressing. Tie-over bolsters are helpful for the fixation and immobility of the grafts. By applying a nonadherent dressing and then tying over the secondary and tertiary dressings, grafts are secured when other options such as simple bandaging may seem less useful. Application of negative pressure wound devices in the immediate post-graft period helps secure graft take and prepares the area for further splinting [24,25]. Grafts in high-range-of-motion areas (and therefore with a great possibility of shear), such as in the axilla, elbow, or popliteal fossa, need to be protected by splinting; however, graft protection and preservation needs to be balanced with preserving the range of motion in joints. (See "Skin autografting", section on 'Graft placement and fixation'.)

Early graft inspection is recommended, especially in cosmetically sensitive areas, though the protocol may vary according to the surgeon's preferences or level of experience. We generally inspect the grafts and change the dressings every 48 hours with removal of staples or other suture material at day 6. The aim of this close surveillance approach is early detection of graft shearing, hematomas, seromas, or any other problem.

Care of the donor site is also fundamental, particularly if reharvesting may be necessary. A wound contact layer dressing (eg, Mepitel) as a primary dressing has been a good option in our practice, but the choice for the burn surgeon is vast. (See "Skin autografting", section on 'Donor site dressings and care'.)

Full-thickness autografting — A full-thickness autograft includes the entire thickness of skin, both epidermis and dermis. The donor site is closed primarily. The general principles of skin grafting, including the advantages and disadvantages of full-thickness skin grafts, surgical techniques, and general postoperative care, are discussed separately. (See "Skin autografting", section on 'Full-thickness skin grafting'.)

Full-thickness skin grafts are used in areas of special anatomic and functional importance (eg, head, eyelids, perioral areas, neck, and hands) [26]. (See "Principles of burn reconstruction: Face, scalp, and neck" and "Primary operative management of hand burns".)

Full-thickness skin grafts provide better-appearing texture, pliability, elasticity, and color match and contract less compared with split-thickness skin grafts [26,27]. However, particularly in burn-injured patients, the availability of sites for harvesting full-thickness skin grafts may be limited. (See "Skin autografting", section on 'Donor site selection'.)

Similar with split-thickness skin grafts, bolstering and tie-over of the grafts may help in protecting the grafted areas, though their usefulness in applying pressure in the interface between recipient and graft area to ensure better take has been questioned [28]. Negative pressure wound therapy is another fixation option in selected patients. The graft is best serviced by an early check to ensure graft take. (See "Skin autografting", section on 'Graft placement and fixation'.)

Use of skin substitutes — The use of skin substitutes (single layer, bilayer) has increased the number of reconstructive options for burn surgeons. In the treatment of burns, skin substitutes are primarily used to treat full-thickness skin defects but can also be used to cover skin defects that may result following release of post-burn contractures [29]. In addition, the quality, elasticity, and pliability of split-skin grafts can be improved by supplementing them with a skin (dermal) substitute, which adds a dermal component to the reconstruction [30]. (See 'Split-thickness autografting' above and "Skin substitutes".)

If there is not enough donor site skin to provide coverage, or if the wound bed is not primed for autologous coverage, then the wound is debrided, and tissue samples and wound swabs are sent for microbiology. If there is no evidence for burn wound infection, the burn wound can be covered with the skin substitute, typically an allograft. Dressings are placed and changed routinely. Adhesion to the wound bed is inspected every 48 hours with removal of staples at the third dressing change (six days after coverage). If the wound environment is not optimized or there is lack of adhesion, excessive incorporation, or rejection, the allograft will need to be removed after 10 to 14 days and substituted by a fresh one. Otherwise, the primed wound bed can be autografted.

In our practice, we have used Integra and Matriderm in the management of burn wounds. Our use of Integra has also included acute coverage of full-thickness burns and coverage of exposed deep structures. In two trials identified in a systematic review, treated burns had a significantly faster time to healing (11 versus 14 days) compared with autografts, other allografts, or xenografts, but a significantly lower proportion of patients with ≥75 percent of wound closure [31]. We have found Integra to be more useful for reconstructive indications rather than coverage in the acute period, primarily because of failure due to infection [32]. As an example, in a prospective multicenter trial that included 216 burn patients, the incidence of superficial wound infection at Integra-treated sites was 13 percent, and invasive infection occurred in 3 percent [33]. Matriderm is a highly porous dermal scaffold that can be used to resurface a burn wound without theoretical loss in pliability and elasticity [34]. However, in a prospective study of 42 paired burn wounds and 44 paired scar reconstructions, in spite of short-term benefits, there was no evidence for long-term clinical effectiveness among burn patients [34,35]. A novel, synthetic polyurethane dermal template (eg, NovoSorb Biodegradable Temporising Matrix) has shown promising results, with robust performance in contaminated wound beds and reduction in cost [36].

TISSUE EXPANSION — Tissue expansion is a technique that gradually stretches an area of pliable skin (taking advantage of the principles of creep and stress relaxation) in preparation for its use as coverage of a burn defect or area of contracture release [37,38]. Tissue expansion techniques are used in the reconstructive stage of scar management when the wounds are fully healed and the scars resulting from the original burn injury need to be addressed.

Tissue expansion provides tissue that best matches the affected skin in terms of function and cosmetic appearance (color, consistency, elasticity, pliability, presence of hair, and sensation) [39,40]. However, suitable tissue neighboring the burned region must be available. Expanded free flaps are another effective option to cover larger wounds [16].

Tissue expansion has been used in multiple anatomic areas and is particularly useful in head and neck reconstruction [39-41]. Indications for tissue expansion include:

●Limited availability of tissue for reconstruction

●Reconstruction of specialized hair-bearing areas (eg, scalp)

●Reconstruction of sensitive cosmetic areas (eg, head and neck, breast)

●Reconstruction of sites requiring skin match for color, thickness, and/or texture

The procedure is performed in stages. The first procedure creates a pocket in a subcutaneous plane (subgaleal in the scalp) in which to insert the expander. Expansion requires repeated injections of saline into the expander's port. A later generation of self-inflating osmotic expanders eliminates the need for repeated injections and may potentially reduce infection and other complications [42]. Expansion is started once the burn wounds are healed and stopped once enough of the expander has achieved the desired volume. Temporary cessation of expansion may be needed it there is excessive pain or blanching of the expanded skin. A second procedure removes the expander and advances, rotates, or transposes the expanded tissue into the defect, and the wounds are closed.

Complications related to tissue expansion include infection, extrusion of the implant, loss of use of the saline port, or expansion flap necrosis (before or after the second stage of the procedure). A 10-year review of tissue expansion procedures used in 82 burn patients identified complications in 22 percent of the procedures [43]. The most frequent complications were expander exposure (50 percent), infection (24 percent), and malfunction of the expander (13 percent). A retrospective analysis of 102 tissue expanders in 57 burn patients reported major and minor complications in 9.8 and 18.6 percent of procedures, respectively [44]. The total failure rate was 7.8 percent (8/102 procedures) and was highest at the head (20 percent) and with higher volumes of expander (400 and 800 mL).

Complications can be minimized with optimal choice of expander and proper surgical and expansion technique [45]. (See "Overview of flaps for soft tissue reconstruction".)

FLAP RECONSTRUCTION — Flaps represent the gold standard of reconstruction by providing like tissue for like tissue in burn wound defects. The types and classification of flaps used for reconstruction are reviewed separately. (See "Overview of flaps for soft tissue reconstruction".)

The obvious limitation to their use in the burn patient is the availability of healthy, pliable, well-vascularized tissue. The selection of a reconstructive option is based on the relative importance of replacing each component of the defect [46]. Careful design of flaps, taking into consideration the frequent presence of scarred tissue around the defect, is fundamental.

Local procedures — Small contractures or defects can be approached with flaps based on the Z principle [47-51] (see "Z-plasty"). These local flap techniques are especially useful in the release of burn contractures that distort anatomic structures (eg, eyelid), functionally important joints (eg, axilla), and web space contractures or other more complicated anatomic sites [50]. Other options for local flap usage include the propeller flap reconstruction (eg, elbow contracture) and bilobed transposition (eg, axilla, neck contracture) [51-53]. When needed, local skin flaps that include previously burned reconstructed skin can be used [54]. In a retrospective review of 238 local skin flaps harvested from previously burned and grafted sites, there was no difference in complication rates compared to 115 sites of unburned donor flaps [54].

Pedicled and free flaps — Burn reconstruction has benefited from the improved understanding of the blood supply of the skin at the angiosome for the creation of pedicled and free flaps. Once a contracture or scar has been released or the defect to be reconstructed has been defined, the flap choice is established based on criteria of availability of tissue, successful and reliable pedicle location, and adequate match in texture and color. The blood supply to the flap must be intact and unaffected by the burn injury. (See "Overview of flaps for soft tissue reconstruction", section on 'Principles of reconstruction'.)

Free flaps require much planning and surgical expertise and are outstanding reconstructive options when successful, but they can also be causes of severe morbidity if vascular complications lead to partial or complete flap necrosis. The patient needs to be optimized to withstand a potentially lengthy surgery. An advantage of perforator flaps (a type of free flap) for burn reconstruction is that a large cutaneous flap can be obtained from the same region of a conventional musculocutaneous flap without the need to include the muscle, which might not be expendable, though it is important to exclude the possibility that the subdermal plexus and/or main perforator has been affected by the burn injury. Appropriate mapping of perforators, selection, and careful dissection helps to prevent complications associated with perforator flaps [55,56].

In our practice, we have found that free flaps have a small but definite role in burn reconstruction. Only approximately 1 percent of surgically treated burns will require a free flap [57]. We use a free flap in the following situations:

●When less complex reconstructive methods (eg, skin grafting) have failed.

●When deep structures (eg, calvarium, frontal sinus, nasal pyramid, tibial crest, neurovascular structures, tendons) are exposed.

●When there is an absolute need to combine reconstruction with cosmetic appearance, such as with the facial structures or the female breast.

●Unsalvageable deep burns.

●Resurfacing following release of scar contractures.

While extensive burns limit tissue availability for accessible donor sites, an area that includes acutely burned donor skin can be harvested successfully as flap coverage for another burned site [58,59]. Further studies to evaluate the survival of free flaps created from burned donor sites should be performed before any definitive statement can be made regarding the safety and efficacy of this procedure.

Despite their complexity, advocates support their use because free flaps help preserve exposed deep structures and are a source of well-vascularized, pliable tissue that can be used to correct contracted burn scars [56]. In a review of 53 free flap reconstruction procedures for otherwise unsalvageable burn injuries or contracted burn scars, 50 patients (94 percent) had a successful outcome with a good aesthetic and functional result [60]. In a retrospective review of 38 free fasciocutaneous flaps used to reconstruct hand burns, all flaps survived at least in part, and three flaps experienced partial skin loss due to infection and were later skin grafted [61]. (See "Overview of flaps for soft tissue reconstruction", section on 'Free tissue transfer'.)

Timing of free flap reconstruction and type of burn injury may be important to the success rate of the free flap. In a review of 75 free flaps in 60 severely burned patients, the overall flap failure rate was 13 percent [62]. Eight of the 10 flap failures occurred in the group that was reconstructed between 5 and 21 days post-burn. None of the free flaps failed when the procedure was performed immediately (within five days) or as a secondary reconstructive procedure six or more weeks post-burn. The free flap survival rate was lower in the electrical high-voltage group (81 percent) compared with the burn injury group (90 percent). However, during the critical time period between 5 and 21 days, the survival rate for the flaps in the high-voltage group was higher (44 percent) compared with the burn injury group (25 percent).

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Care of the patient with burn injury".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Flap surgery (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Burn wounds present many challenges for the reconstructive surgeon. The immediate goal of reconstructive surgery is to restore function. Appropriate measures are taken to limit scarring, but burn wounds may require later revision to achieve an optimal cosmetic outcome. (See 'Introduction' above.)

●Split-thickness skin grafts are versatile and are used to reconstruct large burn wound areas and to provide coverage for donor flap sites. When donor sites are limited, expansion of split-thickness skin grafts using meshing techniques and reharvesting healed donor sites allows for coverage of large surface area burns. Full-thickness skin grafts provide a more satisfactory aesthetic appearance due to their pliability and are used in areas of special anatomic and functional importance. If autologous skin coverage is not possible, temporary skin coverage must be attempted. During recovery, a balance must be achieved between immobilization to allow for skin grafts or tissue flaps to heal and mobilization to restore function. (See 'Coverage of skin defects' above and 'Skin grafting' above.)

●The use of skin substitutes has increased the number of reconstructive options for burn surgeons. In addition, the quality, elasticity, and pliability of split-skin grafts can be improved by supplementing them with a skin (dermal) substitute, which adds a dermal component to the reconstruction. (See 'Use of skin substitutes' above and "Skin autografting".)

●Wounds for which the volume of tissue loss is either too large or exposes deep structures are unsuitable for skin grafts and require more complex reconstruction. Flap reconstruction (local/distant with or without tissue expansion) is ideal, if tissues are available. While extensive burns limit tissue availability of donor sites, an area that includes acutely burned donor skin can be harvested successfully as flap coverage for another burned site. (See 'Tissue expansion' above and 'Flap reconstruction' above.)