Principles of burn reconstruction: Extremities and regional nodal basins

INTRODUCTION — The goals of reconstructive surgery for the burn patient are first to restore function and then to restore aesthetic appearances, ideally combining both approaches. Following resuscitation and stabilization, management of the burn wounds becomes the next priority. The later effects of burns, which are related to loss of normal tissue and scarring, include limitation of movement, pain, disfigurement, and social embarrassment [1].

The principles of burn reconstruction of the upper and lower extremities, including the axilla and inguinal lymph node basins, are reviewed. Management of the severely injured burn patient, burn wound management, and the general principles of reconstruction are discussed elsewhere. (See "Overview of the management of the severely burned patient" and "Treatment of superficial burns requiring hospital admission" and "Treatment of deep burns" and "Overview of surgical procedures used in the management of burn injuries".)

INITIAL MANAGEMENT — Following resuscitation and stabilization, initial management of burns to the extremities focuses on ensuring the function and neurovascular integrity of the limb, and dermal preservation to reduce pathological scarring and early contracture. The presence of circumferential burns, deep-patterned burns, and, potentially, acute compartment syndrome should be assessed and escharotomy (picture 1 and picture 2) and/or fasciotomy (figure 1) performed in a timely fashion, as needed, considering also the possibility of decompression using enzymatic debridement [2]. (See "Emergency care of moderate and severe thermal burns in adults", section on 'Escharotomy' and "Acute compartment syndrome of the extremities" and "Lower extremity fasciotomy techniques" and "Upper extremity fasciotomy techniques".)

Extremity and nodal basin burns are cleansed and debrided of devitalized tissue, then dressed. For deep burns, early burn wound excision and grafting procedures are generally performed within five days of the burn injury, if possible, to reduce the presence of necrotic and infected tissue, avoid conversion of a zone of stasis to zone of necrosis, and attenuate the hypermetabolic response to the burn injury. An approach using enzymatic debridement as the primary technique has gained popularity, specifically in sensitive approaches to debridement in the complex burned hand [3] (See "Treatment of superficial burns requiring hospital admission" and "Treatment of deep burns".)

New approaches to scar management: the role of laser techniques — Traditional approaches to managing burn-related scarring include physiotherapy and scar management techniques (eg, stretching, mobilization, exercise, splinting, silicone sheeting, massaging, moisturizing, pressure garments) and reconstructive procedures, if needed. (See "Overview of surgical procedures used in the management of burn injuries", section on 'Burn scar revision and timing'.)

Energy delivery techniques for scar management have dramatically revolutionized the management of abnormal burn scarring [4]. The combined use of carbon dioxide (CO₂) laser to resurface hypertrophic scar and pulse-dye laser (PDL) to control early scar hypervascularity as soon as wound healing is achieved has dramatically reduced the need to perform standard reconstruction in our practice. Studies showed that fractional CO₂ laser therapy has improved both the signs and symptoms of burn scars [5,6]. (See "Overview of lasers in burns and burn reconstruction".)

Thus far, the authors have performed more than 3000 patient-episodes combining these techniques with laser-assisted substance delivery (mainly steroid) prior to standard reconstruction. We have found that performing these procedures according to patient response and satisfaction up to five times separated by six to eight weeks softens scars, facilitates functional recovery, and improves scar appearance. Results have been validated by our therapists using recognized methods of scar assessment such as Patient And Observer Scar Assessment Scale (POSAS) [7]. We believe that laser is likely to become a pivotal method of treatment to modulate and treat scars, either complementing surgery and in certain situations reducing its frequency. We postulate that laser will be an important part of the armamentarium of scar management options in any burn department performing scar management and reconstruction [8,9].

UPPER EXTREMITY BURN RECONSTRUCTION — The primary goal of reconstruction of the upper extremity following severe burn wounds is to restore function, preserve joint mobility, and minimize the cosmetic effect of scarring and presence of disabling contractures. Burns to the upper extremity cause deformities following scar contracture and limit function, thus affecting all activities of daily living. They also greatly disrupt the cosmetic appearance of normal upper limb anatomy. This is particularly damaging when the fine movements of the hand are affected. Numerous methods have been described to release dynamic (early-phase) and static (late-phase) complex scar contracture [10]. Scars cause tendon adhesions, contractures, deep adipose tissue stiffness, and limitation of major joint range of motion [11].

Free flap reconstruction offers the advantages of early mobilization of the upper extremity, excellent functional results, and less concern about limited donor skin availability [11]. Local and regional flaps based on random or recognized vascular pedicles are also used. (See "Surgical reconstruction of the upper extremity".)

If not available, the most common procedure to release scar contractures and reconstruct burned upper extremities is scar excision and coverage with split-thickness skin grafts (STSGs) with or without combination with dermal substitutes or dermal regeneration templates, or full-thickness skin grafts (FTSGs) [12]. There are many disadvantages with skin grafts, the most important of which include a recurrence of the contracture, prolonged immobilization, and possible limitations on donor tissue [13]. The introduction of new options of dermal scaffolding has introduced a valuable tool to improve the quality of reconstruction after burn scarring [14]. (See "Skin substitutes".)

Axilla — Reconstruction of the axillary contractures is performed to restore full shoulder joint mobility once scar maturation is complete and after physical therapy options have been exhausted. Low-grade contractures can usually be managed with range of motion exercises, splint fixation, and pressure treatment with garments and silicone gel sheets. For severe contractures that limit range of motion, these conservative measures are not effective.

Five general types and subtypes of axillary contractures have been described [15]:

●Type I: Small, thin flat contractures, adipose layer is conserved

●Type IIa: Band contracture of the anterior axillary line

●Type IIb: Band contracture of the posterior axillary line

●Type IIIa: Contractures on both the anterior and posterior line with no contractures between the lines

●Type IIIb: Contractures on both the anterior and posterior line with contractures between the lines

●Type IVa: Contractures extending to both the chest and upper arm with no contractures on the back

●Type IVb: Contractures extending to both the back and upper arm with no contractures on the chest

●Type IVc: Contractures extending to both chest and back with no contractures on the upper arm

●Type V: Extensive contractures greater than Type IV

The reconstruction procedure selected should be based on the type of contracture to be released and the size, depth, location, and shape of the area to be covered [15]. Reconstruction should be performed with pliable, unburned tissue, if possible, to reduce the risk of recurrence of contractures [16]. The optimal reconstructive procedure is based on the severity and limitations of the burn wound (table 1).

Reconstruction options include [15,17]:

●Split-thickness or full-thickness skin grafting with or without combination with dermal substitutes and dermal regeneration templates

●Z-plasty and related alphanumeric advancement and transposition flaps

●Local tissue flap transfers

●Regional tissue flap transfers, including perforator flaps and island flaps

●Free microvascular flap transfers

●Any combination of flaps and grafts

●Laser resurfacing techniques with or without delivery of adjuvant scar-modulating substances

Split-thickness skin grafts are reserved for the repair of minor contractions or in instances when no other reconstructive option exists. The lack of pliability of skin grafts results in secondary contractures and limitations of mobility in the axilla. Local and regional flaps either by advance or transposition and free flaps are preferred for reconstructing severe axillary contractures and areas that require large amount of tissue coverage. (See "Skin autografting".)

In our experience, results are improved if a dermal regeneration template is used in combination with an STSG, topical negative pressure is applied, and the arm is immediately splinted in abduction. The next best option includes the use of full-thickness grafts. However, a large defect is created when axillary contractures are released, and availability of unburned full-thickness skin may be insufficient to cover the large defects in the axilla.

Limited axillary contractures can be satisfactorily managed with the use of the Z-plasty advancement flap or any variations such as the Y-V-plasty (picture 3) [17]. The indications for using a Z-plasty for release of contractures include (see "Z-plasty"):

●Increasing scar length

●Transforming a straight-line scar into a less obvious irregular line

●Realigning a scar to minimize contour deformity

The degree of elongation of the scar that can be achieved depends on the angle of the transposing flaps. For every 15 degrees of increase in the angle of the transposing flaps, a theoretical 25 percent in elongation can be achieved. For example:

●A 30° angle achieves 25 percent elongation

●A 45° angle achieves 50 percent elongation

●A 60° angle achieves 75 percent elongation

The limitations of the use of the Z-plasty in burn scar revision are related to this theoretic increase in elongation. The percent of elongation is dependent upon the elasticity of the tissues and the wound closure tension [18]. Unburned surrounding skin and pliable tissues provide for the greatest likelihood of a successful flap transposition without risk of flap tissue loss.

The indications and limitations of the V-Y-plasty are similar to those of the Z-plasty for burn scar reconstruction; however, the success of the V-Y-plasty is more dependent upon the need for unburned surrounding skin. A double reverse V-Y-plasty has been successfully used to restore axillary function when skin tension across the contracture is too great for a local flap and when superficial scarring is localized in the contracture site [19]. While necrosis is a risk of flap procedures, there was no distal flap necrosis in 19 burn patients treated with this procedure.

Additional options for release of axillary scar bands include the alphanumeric transposition flaps (eg, five-flap plasty, seven-flap plasty) [20-22] or a combination of circular excision combined with Z-plasty reorientation of the scar for resolution of large axillary contractures [23]. A prospective trial found that the immediate postoperative percentage mean length gained in the axilla for seven-flap interdigitating plasty was 103 percent (n = 14) and compared favorably to an average of 121 percent for all other anatomic regions evaluated [21].

Local flaps from adjacent tissues are used to treat mild scar contractures and resurface release defects in the axilla and antecubital fossa [24]. Providing that healthy skin is available, subcutaneous pedicled flaps can be used to restore function and improve aesthetics. The tissues adjacent to the axilla provide a rich vascular network to allow regional fasciocutaneous flap options based on pedicles such as the circumflex scapular artery for a bilobed flap [25], intercostal perforator options [26], or options based on ad-hoc or unnamed perforators (picture 4) [27].

In a review of seven children with burn contractures of the axilla, functional release was achieved in all patients using a local flap (n = 4), Integra dermal regeneration template (n = 2), or an anterolateral free flap from the thigh (n = 1) [28]. Excellent results as measured by restoration of 75 to 100 percent of range of motion were reported for 3/4 local flaps, 1/2 Integra templates, and the free flap reconstruction. A skin substitute was used when local tissue was not available for reconstruction. An innovative technique, the free medial thigh perforator flap, was used to reconstruct the burned and scarred axilla in three adults with no complications or recurrence of the contracture at 12 months following surgery [11].

There are also nonbiologic dermal template options that increase the pliability of the reconstruction while reducing the risk of infection of the surgical technique [29]. These are two-stage procedures with a surgical strategy consisting in an initial cover with the template of the defect requiring reconstruction after release of the contracture. The template is checked for appropriate vascularity weekly and delamination of the template and cover with a thin skin graft follows. Preliminary observation of our results at one month and three months show promising pliability and quality of the reconstruction.

Antecubital fossa and elbow — Antecubital fossa burn scars are a complicated challenge, and release of the contractures results in a secondary defect that requires tissue coverage. The principles of reconstruction of burn scar deformities in the antecubital fossa and elbow are to restore normal anatomy and function, eliminate flexion deformities, and preserve cosmesis. Reconstruction is performed after the scars are mature and conservative measures such as physical therapy, occupational therapy, and splinting have been exhausted. We start resurfacing with CO₂ laser any contractures in which there is no immediate need to reintroduce additional tissue cover to introduce pliability and improve function. If the deformity is severe, early surgical intervention can preserve function. A 50 percent reduction of the range of motion of the elbow can reduce the function of the upper extremity by approximately 80 percent [30].

Surgical options include excision of the scar and split-thickness (with or without combination with dermal substitutes or dermal regeneration templates) or full-thickness skin graft coverage; realignment of the scar flaps based on the Z-plasty principle; and resurfacing the area with local, regional, or free flaps after partial or total excision of the scar.

●Skin grafting is the most efficient means of coverage but is associated with prolonged splinting and immobilization, incomplete graft take, and a high risk of contracture recurrence [31].

●Reconstruction of burn scar contractures with a free flap or local flap in five pediatric elbows resulted in an excellent functional result in three children, while the two elbows reconstructed with Integra resulted in no change in function [28].

●In a prospective trial evaluating a technique of a bipedicle flap created from scar tissue with skin grafting of the proximal and distal parts of this bipedicle flap, no early recurrence of contracture was identified and an acceptable appearance was seen in all 12 patients with a burn scar in the antecubital fossa [32].

●Additional local flaps have been described to release an antecubital contracture and include a propeller flap [33], rhomboid rotation flap [34], proximal and distal Z-plasties [35], and V-Y plasties [19]. Limitations to the local flap procedures include less than optimal cosmetic appearances when using previously burned skin.

●Resurfacing of the defect can be combined with the use of dermal regeneration templates that add pliability to the grafted area [36,37]. The benefits of using a dermal regeneration template include improved skin quality and rapid re-epithelialization. One-stage options facilitate quick addition of pliability to the reconstruction in a single surgical procedure. The disadvantages include the occasional necessity of a two-staged procedure to complete the resurfacing, and the need for meticulous wound care. (See "Skin substitutes".)

●Regional pedicle options include the use of medial and lateral arm flaps.

•A retrospective review of 12 reverse medial flaps based on the recurrent ulnar artery found a better color match, more elasticity, improved durability, easier postoperative care, and no further contractures compared with a skin graft [38]. The disadvantages of the reverse medial flap include a large donor defect, the need for unburned and healthy medial skin, a reduction in arm circumference, inconsistent blood supply, and the possibility of ulnar nerve compression and cutaneous nerve injury.

•The reverse lateral arm flap is a regional septocutaneous flap based on the posterior radial collateral artery (PRCA). A retrospective review of 11 elbow contractures treated with a reverse lateral flap found functional improvements in all cases [39]. The advantages of this flap include a one-stage procedure, no need to sacrifice a major artery or muscle, consistency of the vascular pedicle, relative ease of dissection, primary closure of donor site, and shorter immobilization of the elbow compared with other options for reconstruction of elbow postburn defects.

The use of tissue expansion techniques has clearly expanded the potential use of tissue transfer to the upper burn extremity [40].

Wrist — Reconstruction techniques to release contractures or improve deformities of the wrist are similar to those for the antecubital fossa. The reconstruction technique selected is adapted to the tissue deficit, the functional impairment, and the deformity [41].

Prevention of contractures and deformities of the wrist should be the priority. To reduce the risk of edema, contracture, and resulting deformities, the hand and wrist are positioned in a thermoplastic splint in an intrinsic-plus position with 20 to 30 degrees of wrist flexion, 80 degrees of metacarpophalangeal (MCP) joint flexion, fully extended interphalangeal (IP) joints, and thumb abduction. This is called the position of safe immobilization (ie, POSI). Immobilization and rehabilitation are as important to reducing the risk of contractures and functional limitations as timing of surgery and type of wound coverage [42]. While there are no high-quality data from prospective trials regarding splinting of the hand and wrist unit, general practice supports the efficacy of splints and physical therapy [41-43].

A prospective study of 985 patients with burns to the hand and wrist found that 23 percent had developed a contracture, and the most common were contractures limiting wrist extension and wrist flexion (22 percent) [43]. Challenges to adequate splinting and physical therapy included multiple surgeries, dressing changes, concomitant medical problems, and skin grafts.

Wrist contractures and deformities respond well to incision and grafting providing that no deep structures, such as tendons or neurovascular bundles, are exposed. A dermal regeneration template may be used if additional pliability is needed and can be provided by combination with an STSG or FTSG alone [44]. Linear contractures can be repaired using Z-plasty techniques. The complexity of reconstruction is increased when deep structures are exposed, requiring regional or free flap reconstruction (table 1).

Flaps are reserved for coverage of exposed deep structures or when a greater degree of pliability is needed and cannot be provided with a skin graft or plasty. The availability of regional unburned skin and intact vascular pedicles are the limiting factors for use of regional, distant, or free flaps. In a retrospective review of seven children with wrist contracture release and reconstruction, three of five reconstructed with Integra had an excellent functional result while the other two had no change in function, and both treated with a free flap had an excellent functional result [28].

The use of local, regional, and distant flap techniques is a useful adjunct to the reconstruction of the burned wrist when pliable tissue is required to cover deep exposed structures [45,46].

Hand — Burns to the hands have a tremendous impact on activities of daily living. Effective treatment of hand burns requires a multifaceted and interdisciplinary approach that includes burn surgeons, plastic surgeons, rehabilitation physicians, and physical therapists.

Burn deformities occur following skin loss, but secondary changes often occur involving muscles, tendons, ligaments, and joints. Assessment of the deformity is essential to its correction, with each tissue component requiring evaluation to formulate a treatment plan. In particular, the evaluation of extrinsic versus intrinsic joint changes is important in burn scar contracture involving joints. Secondary changes to joints are often the limiting factors for correction of deformity and improvement in function. Approaches and algorithms have been described to aid assessment and planning of treatment for burn scar deformity of the hand [47,48].

Primary operative treatment — The initial operative management of burns to the hand, including evaluation and management, primary and secondary assessment, primary operative procedures, and postoperative care, are discussed in detail in another topic. (See "Primary operative management of hand burns".)

In our experience, we judiciously debride the necrotic tissue with either a Goulian knife or the Hydrosurgery System, Versajet [49,50], while avoiding unnecessary damage to deep structures, specifically tendons, joints, and neurovascular bundles. When debriding interphalangeal joints, exposure of the extensor tendon or joints should be avoided. When the joints are exposed, they are pinned with Kirschner wires (K-wires) in position of function and treated with topical antibiotics and dressings to avoid further desiccation until definitive coverage is performed. Enzymatic debridement for this very sensitive anatomic area is also gaining popularity as a useful operative tool.

Secondary reconstruction — For secondary or delayed reconstruction, we have identified five key injuries that require priority treatment. They include adduction deformities, flexion deformities, extension deformities, exposed joints, and missing digits.

Adduction deformities — Mild-to-moderate adduction deformities of the thumb in the form of linear contractures can be addressed with Z-plasty-type realignments. For more severe contractures in which a larger amount of scarring is present, full resurfacing with a split-thickness graft with or without a dermal template addition or a full-thickness graft is our preferred option. Flap coverage, either local or regional, may be necessary for more complex or fibrotic cases.

Flexion deformities — The surgical management of finger flexion deformities attempts to correct function and range of motion and includes physical therapy and splintage. The principles of management can range from simple realignment of the scar by Z-plasties or alphanumeric transposition flaps to excision and full-thickness skin grafting. Deep burns may result in a skin contracture adhering to the bone or joint, causing a secondary functional deficit of the joint apparatus consistent with a tenodesis or arthrodesis. A combined teno-arthrolysis, release of the tendon and joint apparatus in conjunction with the collateral ligaments and volar plates, may be required to restore joint function [51]. In these cases, the use of flap as a reconstructive option becomes mandatory.

Extension deformities — Extension deformities may be managed in a similar fashion to flexion deformities, with either scar realignment, full scar release and grafting, or the use of pliable thin regional tissue to cover deep structures [52]. Discreet areas of scarring can be realigned with Z-plasties. Posterior interosseus flaps, radial forearm flaps, or groin flaps are options for reconstruction of large defects with exposed extensor tendons.

Exposed joints — Exposed joints represent a serious reconstructive challenge, and, in the acute setting, careful debridement and avoidance of infection, immobilization with K-wires, and consideration of early arthrodesis are options [52]. If healthy granulation develops, skin grafting, together with a skin substitute, is an option. Thin flaps may need to be used as coverage options.

Amputated digits — When digits are irreparably damaged or amputated, preservation of the opposition function of the thumb-fingers is fundamental, and all reconstructive maneuvers are directed to the creation or preservation of this function, either by pollicization (thumb is created from an existing finger), distraction osteogenesis (bone lengthening), first web space deepening Z-plasties, dorsal rotation flaps, and, in severe cases, microsurgical reconstruction with toe transfer. Thumb reconstruction methods depend on the location of the amputation and damage to adjacent structures [53,54].

Pollicization with a transposable index ray provides the most rapid and effective means of restoring thumb function. In a review of 15 pollicization procedures in severely burned pediatric hands, 94 percent (14/15) demonstrated improved postoperative function for pinch, grasp, and opposition [55]. Multiple digital toe transfers have been described to replace loss of fingers following burn injuries [56].

Electrical burns — One of the more devastating burns to the upper extremity is the electrical burn. The electrical source is grasped by the hands (94 percent) and the current exits through the lower extremities (78 percent) [57]. High tension injuries often cause extensive tissue damage, and despite early and aggressive treatment and decompression of the neurovascular structures, there is a high likelihood of amputation or a nonfunctioning arm (picture 2) [58]. (See "Electrical injuries and lightning strikes: Evaluation and management".)

LOWER EXTREMITY RECONSTRUCTION — The key complications of lower extremity burns include contractures in the inguinal and popliteal areas; exposure of neurovascular structures, bone, and joints; and rehabilitation. Major joints that are scarred result in deformity and disability. The primary goal of secondary reconstruction is to restore function. Exposed deep structures that are not amenable to simple reconstruction with split-thickness skin grafts (STSGs) or full-thickness skin grafts (FTSGs) may require complex procedures with regional flaps or free flaps and microvascular anastomosis.

Inguinal region — Limited abduction of the hip is a common complication of burns to the inguinal region [22]. Secondary reconstruction following release of inguinal contractures is usually straightforward, and, provided that no deep neurovascular structures are exposed, the use of skin grafts with or without the addition of a dermal regeneration template is usually sufficient.

Successful permanent release of contractures is limited by tension and movement in the inguinal region. The application of topical negative pressure to the grafted wound [59]:

●Protects the skin graft from shearing

●Absorbs wound drainage (eg, hematoma, seroma)

●Avoids desiccation of the graft

●Reduces risk of infection

●Serves as a barrier to contamination from the genitalia or perineum

Dermal regeneration templates (eg, Integra, Biodegradable Temporizing Matrix [BTM]), used in acute burn wound care, also are used to manage hypertrophic and keloid burn scars [60]. (See "Skin substitutes".)

The scar is excised, Integra (or BTM; gaining in popularity) is placed over the wound, and several weeks later a very thin split-thickness skin graft (6/1000 inch) is placed over the stabilized matrix. In a retrospective, multicenter evaluation of Integra in hypertrophic scar reconstruction release procedures involving 127 contracture sites, physicians rated the outcome of function as good or excellent in 76 percent of cases, and 82 percent of the patients expressed overall satisfaction of the results [61]. Patient satisfaction was 86 percent for range of motion, 82 percent for cosmetic appearance, and 84 percent for alleviation of pain. Contractures recurred in 25 percent of patients. The patient population of the study included burns and other trauma in adults and children and various anatomic sites. There are no high-quality data from prospective trials that assess the long-term outcomes of using dermal regeneration templates in burn scar reconstruction of the inguinal region.

In the patient with extensive burns, there may be insufficient skin available to create full-thickness grafts to cover the inguinal soft tissue defect. The next option is to use local transposition flaps based on the Z-plasty principle. In our experience, straight forward transposition of triangular flaps based on the Z-plasty principle is usually sufficient to warrant adequate release of contracture bands. The seven-flap plasty is an interdigitation flap that serves to release the contracture without the need for prolonged immobilization, splinting, or physical therapy [22]. A retrospective review of nine patients with burn scar contractures in the axilla or inguinal region treated with the seven-flap plasty reported that shoulder and hip range of motion improved, and no recurrences were identified at 24 months of observation.

Vascular pedicled flaps are used to cover deep structures in the inguinal region and require undamaged or unburned tissue for a successful, pliable coverage [62]. Five patients treated with a pedicled anterolateral thigh flap for an inguinal contracture resulting from a burn had no recurrence of the contracture at 10 months after surgery. The flap has a reliable blood supply and can be used to cover large defects.

Popliteal fossa — Burn scar contractures in the popliteal fossa and knee limit the extension and flexion of the leg and therefore limit mobility and increase disability. Treatment options for burn scars in the popliteal fossa like those described for secondary reconstruction of the upper extremity and inguinal scars. There are no high-quality trials that have reported on the optimal reconstruction of burn scars in the popliteal fossa.

Simple contracture bands can be treated using Z-plasties, Y-V plasties, or other alphanumeric interdigitating flaps. A prospective trial found that two patients achieved 135 percent immediate postoperative percentage gain in length using the seven-flap interdigitating plasty in the popliteal fossa, which compared favorably to an average of 121 percent for all other anatomic regions evaluated (n = 47) [21]. If healthy tissue is available in the immediate vicinity of the contracture area, a transposition flap containing fascia and based on a patent and undamaged perforator vessel provides pliable and durable tissue.

If realignment of the scar is not an option, excision of the contracture area and resurfacing with skin grafts or dermal regeneration templates (eg, Integra or Matriderm) adds elasticity to the reconstruction and decreases the possibility of recurrence. Fixing the grafts with topical negative pressure and splinting the joint in extension maintains the normal anatomic integrity of the joint [59].

The use of tissue expanders in burned lower extremities provides donor skin that is an optimal match for color, texture, sensation, and hair-bearing qualities but has risks and complications [63,64]. Technical challenges include difficulty in creating a pocket for the expander, potential suboptimal subcutaneous tissue to cover the expander, and an incision in the area to be expanded. Extrusion of the implant occurs for these reasons as well as the mechanical compressive and disruptive forces from the muscles.

A retrospective review of 20 expanders placed in burned limb sites (upper and lower) found no significant difference in rate of complications (30 versus 10 percent) or failure (15 versus 2.5 percent) compared with 40 expanders placed in burned nonlimb sites [64]. There were seven expanders inserted into the lower extremity, four were infected including one partially extruded, and two were subsequently removed. There is insufficient evidence to support the use of tissue expanders in burned lower extremities. If the surgeon elects to insert expanders in burned lower extremities, particularly in situations when there may be no other options, close observation of the patient is necessary to prevent complications proceeding to failures. Nonetheless, meticulous technique, attention to detail, and close observation will increase the success of this technique in the lower limb (picture 5).

Exposed bone and joint — Exposed bone and joints, such as the tibia and knee, that occur from the burn are classified as deep burn injury (figure 2). Exposure can also be the result of overzealous fascial debridement. These complicated burns require multistage reconstructive procedures, but limb salvage is possible in the majority of cases [65]. In a 10-year retrospective review of 21 patients with fourth-degree burns involving 40 lower extremities, a mean of eight operations was required for limb salvage, 18 percent of limbs were amputated, and 77 percent of patients were ambulatory at one year following hospital discharge. There are no high-quality data from prospective trials regarding the optimal reconstruction of exposed bone in the tibia or knee following a burn injury.

Osteomyelitis and septic arthritis are serious complications of an exposed bone or joint. There are little data regarding the incidence of bone and joint infections following severe burns. A retrospective study of 80 burn patients with a range of follow-up from six months to over five years found the clinical rate of osteomyelitis was 1.25 percent and radiographic evidence was present in 2.5 percent [66]. A retrospective study of 41 severely burned children undergoing a total of 357 skeletal fixation procedures found the rate of osteomyelitis to be 4.8 percent [67]. Loose pins, pin site cellulitis, burn wound infection, and sepsis were not associated with osteomyelitis.

Knee joint — Deep burns to the knee and joint capsule, which includes the tendons, ligaments, and the femoral and tibial condyles, can be reconstructed with an autologous dermis graft [68]. A small retrospective series of cases of burns to the knee has shown that this procedure can provide good and rapid articular stability, and early mobilization, with maintenance of flexibility at one year of observation.

Negative pressure wound therapy of a knee burn may encourage the growth of granulation tissue. However, this technique cannot be used when tendons and ligaments are exposed. Soft tissue coverage of the knee in these situations is achieved by using gastrocnemius muscle flaps or fasciocutaneous flaps [69]. Functional outcome is reported to be good. These approaches are adapted from principles for coverage of the knee in other clinical situations (eg, trauma, infection) [70-72].

Tibia — Exposed bone and limited local tissue with a poor vascular supply and little laxity of the tissues are major challenges in reconstructing burns wounds involving the tibia. Options that can be used to facilitate secondary reconstruction and subsequent placement of the exposed tibia include burring the bone and topical negative pressure. These procedures serve as the basis for skin graft; pedicle or free flaps can also be used.

●Burring of the bone to expose vascularized tissue, including the tibia, can stimulate the growth of granulation tissue [65,73]. In a review of five burn patients treated with the burring technique of the tibia, all had developed significant granulation tissue for skin grafting.

●Applying topical negative pressure to exposed bone can prepare the site for later grafting or flap procedures [69,74]. Topical negative pressure has been shown to reduce tissue edema and promote granulation tissue growth in 75 patients with lower extremity wounds [75].

●In a review of 17 exposed bone wounds from burns or other trauma, coverage of the defect with artificial dermis and split-thickness skin grafts revealed complete healing in 88 percent of wounds [76].

Options that can be used for secondary reconstruction of exposed tibia include pedicled flaps and free microvascular flaps.

●Pedicled transfer flaps – Providing that the lateral and medial perforator arteries along the deep fascia surrounding the tibia are intact and can be mapped with a handheld Doppler, fasciocutaneous tissue flaps can be based on the perforator arteries to cover tibial defects. These flaps can be used as a "propeller" flap that turns itself up to 180 degrees to provide soft tissue cover.

•The proximal tibia can be reconstructed using gastrocnemius flaps [69].

•The middle and distal third of the tibia can be covered by soleus flaps or fasciocutaneous perforator flaps [77,78]. If the adjacent muscle is viable, a longitudinally split tibialis anterior turnover flap can be used for reconstructive coverage [79]. This flap is simple in design and reliable, with minimal donor site dysfunction.

•The distally based superficial sural flap [80] and the medial sural flap [81] can be used to cover the exposed distal tibia and ankle.

●Free microvascular transfer flaps – Free flaps are the most complex types of reconstruction and are the preferred wound coverage to salvage extremities and correct contracted burn scars when local and regional options are not available [82]. Muscle and fascia flaps along with the vascular pedicle (eg, latissimus dorsi, radial forearm, anterolateral thigh) are effective options for reconstruction.

•In a retrospective review of 11 patients with deep burns to the lower extremities with 9 exposed bones and 2 contracted scars, all lower extremity free flaps survived compared to 94 percent flap survival in the entire cohort of 53 free flaps used at various anatomic sites [82].

•The medial sural flap can also be transferred as a free flap to cover the exposed distal tibia, ankle, and foot [83].

•In a retrospective review of 215 cases of distal third leg defects, there was no significant difference in complication rates for patients treated with a pedicled flap compared to those treated with a microvascular free flap (18 versus 27 percent, respectively) [84]. Pedicled flaps used in this study included lateral supramalleolar, medial plantar, and soleus flaps. The latissimus myocutaneous flap was used as the free flap in this study for the distal leg, and a medial plantar flap or the lateral malleolus flaps were used to reconstruct the heel.

Ankle — The thinness of the skin and the limited available local tissue near the malleolar areas of the ankle are a challenge for burn reconstruction. Hypertrophic scar formation that results in contractures of the ankle or foot impairs ambulation. Reconstruction procedures are performed to improve function and ambulation. There are no high-quality data from prospective trials that have identified optimal reconstruction of the ankle or foot following a burn injury.

A simple scar contracture without exposure of the underlying structures is managed by realignment, incision, excision, skin grafting, or local flap coverage plus splinting. Perforator flaps and free flaps are options for complex burn scars as skin grafts cannot be used to cover exposed tendons, bones, or joints. Joint realignment procedures may be needed in cases of fourth-degree burns. (See 'Exposed bone and joint' above and 'Tibia' above.)

Dorsiflexion contractures — Dorsiflexion contractures limit ambulation and are not amenable to skin graft repairs. A Z-plasty technique can be used to release a scar traversing the ankle joint; however, triangular flaps are at risk for necrosis due to possible vascular impairment [85,86]. A three-quarter paratenon-cutaneous Z-plasty is used in cases of extensive scarring and lack of unburned adjacent skin.

Anterior contracture deformities — The anterior contracture deformities generally occur following improper splinting and scar formation. This deformity may be corrected by proper splinting and physical therapy; however, surgical intervention for scar contracture release and reconstruction of periarticular structures may become necessary in refractory cases. Capsulotomy and tendon transfers may also be performed to correct this deformity [86].

Pedicled tissue transfer and microvascular free flaps have been used in complex cases of burn scars and trauma. A distally based lateral supramalleolar adipofascial flap has been used in seven trauma patients for reconstruction of the dorsum of the foot and ankle [87]. The flap is versatile, thin, and can be used for both the foot and ankle.

Achilles tendon — The Achilles tendon is in a superficial location and vulnerable to injury by a deep burn. The paratenon is immediately beneath the subcutaneous tissue and frequently damaged in a severe burn; hence, skin grafts are not an option for coverage of an exposed tendon. Scar contractures can lead to a pes equinus deformity (toes extremely flexed) and ambulatory disabilities. An exposed Achilles tendon may be reconstructed with a reverse sural artery pedicle flap as a regional option or with a free flap (eg, anteromedial thigh fasciocutaneous flap with a vascularized iliotibial band) [88], negative pressure wound therapy [89], or an island adipofascial flap covered by a split-thickness skin graft [90].

Long-term follow-up at three years revealed almost complete normal range of motion for the patient treated with the anteromedial thigh fasciocutaneous flap [88]. In a review of 10 patients with an exposed Achilles tendon after trauma or burn, the island adipofascial flap was viable in all patients, there was no functional deficit of the Achilles tendon, and a good cosmetic appearance was reported for all patients [90].

Foot and toes — Dorsal and plantar contractures require splinting to maintain position and may require bone corrective surgery if joints have been permanently damaged. Incision and excision techniques with grafting are usually enough to provide adequate coverage for reconstruction. Because of the unique anatomy and function of the plantar surface of the foot, any full-thickness reconstruction will not be able to preserve the inherent resilience of the foot to trauma [91]. The key element to reconstruction is the preservation of foot function (eg, ambulation and weight bearing) by providing restoration of anatomy with avoidance of secondary deformities due to tendon or joint contracture. Adequate splintage preserves reconstruction integrity until adequate healing is achieved.

As described in the section on ankle and tibia burns, simple scars can be treated with realignment, incision, excision, and skin grafting. Flaps, including pedicled, perforator, and free flaps, are reserved for complex situations. (See 'Tibia' above and 'Ankle' above.)

When deep burns occur on the plantar surface of the feet and toes, plantar flexion and claw toes deformities are the most common complications [86]. There is a paucity of high-quality data from clinical trials regarding the optimal reconstruction of burns to the ankles, feet, and toes.

Plantar foot surface — The skin of the plantar surface of the foot is thick, glabrous, and carries the main weight stress of the body. The non-weight-bearing surface of the instep can be reconstructed with a full- or split-thickness skin graft and a dermal regeneration template. The weight-bearing surfaces are reconstructed using sensate and mechanically durable tissue. Flaps that lack sensation are more likely to be damaged because of lack of deep pressure sensation and unfavorable weight distribution [92].

Flaps based on the dorsalis pedis arterial system, such as the reversed dorsalis pedis flap, can be used to resurface the distal foot and great toe [91]. When regional options are not available, reconstruction is performed with free flaps. Key points that must be addressed and clear for patients with extensive loss of the plantar surface from burns include [93]:

●Amputation may be required in cases of extensive loss of tissue where functional outcome is uncertain

●Amputation may be required because of patient circumstances (eg, advanced age, comorbid illnesses) or lack of rehabilitation services

●Reconstruction is successful only if function is returned

●Deep burns treated with skin grafts will lead to unstable scars and exposure of deep structures

●Free muscle flap with skin grafts or a perforator-based skin flap are effective reconstruction options in the absence of local or regional options

Dorsal foot surface — The skin overlying the dorsal surface of the foot is thin and relatively taut. Burns to this area have been reconstructed with skin grafts if tendons are not exposed or with a distally based lateral supramalleolar adipofascial flap [87]. Other flaps for use on this surface include reverse flow fasciocutaneous island flaps based on the peroneal, anterior tibial, and posterior tibial arteries and a distally based medial plantar flap [94-97].

Plantar flexion deformities of the foot — A plantar flexion deformity can result from a deep burn to the heel and inadequate splinting of the ankle and foot [86]. Lengthening of the Achilles tendon, coverage of the burn, arthrodesis, and proper splinting can restore ankle mobility [98]. Burn wounds with exposed tendons can be covered with a fasciocutaneous Z-plasty or a three-quarter fasciocutaneous Z-plasty technique. (See 'Exposed bone and joint' above.)

Dorsally contracted or extended toes — Deformities to the toes can be caused by burn scars and scar contractures. The contracted toes are released by incising the scar at the level of the metatarsal phalangeal joint and the proximal interphalangeal joint [86]. For children with extension contractures, Kirschner wire insertion through the proximal phalanx will correct the deformity. Once the wires are removed, skin grafts can be applied as needed. A volar capsulotomy is used in adults to realign the joint. A three-quarter paratenon-cutaneous Z-plasty technique can be used to cover the joints [86].

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".)

SUMMARY AND RECOMMENDATIONS

●Extremity burn reconstruction – The primary goal of reconstruction of the upper and lower extremity is to restore function and achieve a cosmetically acceptable result. Traditional approaches to managing burn-related scarring include physiotherapy and scar management techniques (eg, stretching, mobilization, exercise, splinting, silicone sheeting, massaging, moisturizing, pressure garments) and reconstructive procedures, if needed. The use of laser techniques for the management of early scar hypervascularity and hypertrophy may help reduce the need for reconstruction. (See 'New approaches to scar management: the role of laser techniques' above and "Overview of surgical procedures used in the management of burn injuries", section on 'Burn scar revision and timing'.)

●Upper extremity (See 'Upper extremity burn reconstruction' above.)

•In the upper extremity (eg, axilla, antecubital fossa, wrist, and hand), low-grade contractures can usually be managed with conservative measures including range of motion exercises, splint fixation, massage, and pressure treatment with silicone gel sheets. Full-thickness or split-thickness skin grafts are reserved for the repair of minor-to-moderate contractions.

•For severe contractures of the upper extremity, the reconstruction procedure selected should be based on the type of contracture to be released and the size, depth, location, and shape of the area as well as the availability of unburned regional skin. Reconstruction options include split-thickness grafts together with dermal regeneration templates to increase pliability, full-thickness skin grafts, Z-plasty-type realignments, advancement flaps, free microvascular flaps, and rotation or transposition flaps.

●Lower extremity – The key complications of lower extremity burns include contractures in the inguinal and popliteal areas, destruction of the surface of the foot, and exposure of neurovascular structures, bone, and joints. Exposed deep structures that are not amenable to simple reconstruction with skin grafts, Z-plasty realignment procedures, or local flaps may require complex procedures with regional flaps or free flaps and microvascular anastomosis. The reconstruction procedure selected should be based on the type of contracture to be released and the size, depth, location, and shape of the area as well as the availability of unburned regional skin. (See 'Lower extremity reconstruction' above.)