Skin autografting

INTRODUCTION — The routine use of skin grafting, skin substitutes, and tissue flaps with or without skin grafting has dramatically broadened the ability of the surgeon to perform reconstructive surgery and improve outcomes and quality of life for trauma patients, burn patients, and cancer patients.

A split-thickness graft is composed of epidermis and a variable amount of dermis. A full-thickness graft includes all the layers of the skin. The survivability of a skin graft depends entirely on the blood supply of the recipient wound bed. A number of patient-related factors may influence graft take (eg, comorbidities, nutritional status).

This topic provides an overview of the use of skin grafts in reconstructive surgery. The use of tissue flaps is reviewed separately. (See "Overview of flaps for soft tissue reconstruction".)

SKIN ANATOMY — The skin, which is the largest organ of the body, is responsible for physical protection, homeostasis, temperature control, and immunologic surveillance. It provides an envelope for the subcutaneous tissue, connective tissue, and deep structures and serves as an attachment site (eg, fascia). It is also the ultimate representation of cosmetic appearance, beauty, and aging. The skin is composed of an outer expendable layer of epidermis (figure 1), which is in continuous regeneration, and an inner layer of dermis responsible for elasticity, pliability, and neurovascular supply of the skin.

●The epidermis is subdivided into five sublayers or strata: basale, spinosum, granulosum, lucidum, and corneum. The cellular content is substituted by keratin nearly completely in the uppermost stratum of corneum. The basal layer separates epidermis and dermis. The dermoepidermal junction is the area of the skin where pigmentation cellular components are located.

●The dermis is subdivided into an outer layer called the papillary dermis (separated from the epidermis by the dermoepidermal junction) and an inner layer called the reticular dermis that neighbors the subcutaneous tissue. The dermis is composed of cells, fibers, and a ground substance. The epidermal appendages are subdermal epithelial structures that include sebaceous glands, sweat glands, and hair follicles. The skin is supplied by vascular plexuses from deep-source perforating vessels.

AUTOGRAFTS — An autograft is the transfer of skin from a donor site to a recipient site in the same individual. These are the most used grafts for skin reconstruction for a variety of indications. Autografts can be harvested as split thickness or full thickness.

●Split-thickness skin grafts (STSGs), also called partial-thickness grafts, transfer a portion of the donor site skin, including the epidermis and some of the underlying dermis. This allows the donor site to heal from the epidermal elements left behind, provided that appropriate dermal structures remain viable.

●Full-thickness skin grafts (FTSGs) harvest the entire layer of skin as the graft. Thus, no dermal or epidermal elements remain at the donor site, which must be closed by local advancement of the adjoining skin, by a secondary local flap, or by using an STSG.

The transplanted skin does not have a blood supply and initially survives by absorbing transudate from the recipient site, a process called plasmatic imbibition [1]. Neovascularization from the graft bed capillaries then provides a blood supply to the graft over the next 48 to 72 hours. Traditional teaching is that STSGs are mainly vascularized from the wound bed while FTSGs are vascularized from the wound edge. The process of revascularization takes longer for an FTSG than for an STSG because of the increased thickness of the tissue. Full circulation is restored within four to seven days.

The advantages and disadvantages of STSGs and FTSGs are summarized here and described in more detail below. (See 'Split-thickness skin grafting' below and 'Full-thickness skin grafting' below.)

●Split thickness: Good for large areas of coverage, donor sites can be reharvested, fragile, prone to contracture.

●Full thickness: Smooth texture and pliability, thicker coverage, reduced take, poor drainage of accumulating fluid. Limited choice of harvesting sites due to need primarily of the donor site.

GENERAL PRINCIPLES

Indications — Indications for skin autografting include the following:

●Skin grafts are indicated for the coverage of a skin defect due to burns, trauma, infection, or following excision of a tumor if primary closure cannot be accomplished. (See "Skin laceration repair with sutures".)

●Skin grafts can also be used to cover and promote healing of chronic wounds provided the bed of the wound is well prepared and vascularized. (See "Overview of treatment of chronic wounds", section on 'Wound coverage/closure'.)

●Skin grafts may also be used as an adjunct to tissue flap reconstructive techniques. (See "Overview of flaps for soft tissue reconstruction", section on 'Skin'.)

Choice of coverage — Whether to use a skin graft versus a tissue flap depends upon the condition and requirement of the recipient bed. A skin graft depends on the vascularity of the recipient site. A well-vascularized bed can accept a graft while a devascularized bed (eg, cartilage or bone) requires flap coverage. In addition, size, location, and aesthetics often dictate the choice. Initially, a skin graft is erythematous and irregular, but over time as the graft matures (three to six months), the graft will smooth out but will retain the color and consistency of the donor site, which is a major shortcoming of a skin graft. A local flap will provide a better aesthetic result than a graft because it allows replacement of "like with like." Moreover, when large defects need to be filled or structures recreated, a flap will be required. (See "Overview of flaps for soft tissue reconstruction".)

Whether to choose a split-thickness skin graft (STSG) or full-thickness skin graft (FTSG) depends upon several factors. These include:

●The size of the defect to cover

●The anatomic area to reconstruct

●The availability of donor sites

It is important to take into account the anticipated scar contraction [2]. In general, the degree of contraction is less the thicker the skin graft. Minimal wound contraction occurs with FTSGs. However, with a thicker graft, better vascularity is required [3]. FTSGs are generally reserved for reconstruction of areas of special anatomic and functional importance that require a more pliable reconstruction than can be offered by STSGs. Such areas include cosmetically sensitive areas like the head, eyelids, perioral areas, and neck, and functional areas like the hands.

Examples for choosing between split thickness and full thickness grafts include:

●For a chronic ulcer, a thinner graft will have decreased metabolic needs, and an STSG is often chosen.

●For patients requiring grafts on the face, a FTSG is preferred because of the aesthetic benefits of minimal contraction, as well as better color match and contour.

●For patients with large skin defects of the trunk or extremities away from joints, STSGs are preferable because scar contraction will result in a smaller area of scarring.

●For patients requiring grafts over areas of mobility (joints) or functionally crucial areas (fingertips), FTSGs are preferable because of the functional benefits of minimal contraction.

Donor site selection — The donor site is selected to minimize discomfort and cosmetic issues while maximizing the outcome at the recipient site, which depends on the desired color, texture, and thickness of the skin at the recipient site. Donor site selection also depends on the availability of tissue. When large areas of skin coverage are needed, any area of the body may be used as a donor site. The donor site of an STSG will remain hyperpigmented for a number of months before returning to normal. An STSG that is harvested too thick will transform the donor site into a wound that may heal in a delayed fashion and with pathological pigmentation and scarring.

The quality of the donor site skin should also be evaluated for evidence of prior sun damage (eg, keratoses) and prior scarring.

●On the face, it is desirable to replace "like with like" and use skin as close to the recipient site as possible. As an example, nasal tip grafts are often best taken from the preauricular skin rather than the supracervical skin as the color and thickness match are better.

●An open wound of the trunk can be grafted from almost any donor site as the skin color and texture are not as important. The upper lateral thigh is a good choice for skin grafting an area on the trunk.

●STSGs from the scalp can be used for resurfacing the face and to improve the color match of the skin paddle for patients previously treated with a free flap [4].

Donor sites for FTSGs are from areas of redundant and pliable skin that can be harvested and closed without tension like the groin, medial arm, supraclavicular area, pre- and post-auricular area, and abdomen [5,6].

Recipient site preparation — Proper recipient site preparation is important for both STSGs and FTSGs. The wound bed must be well vascularized and free of all necrotic or ischemic tissue, and without inflammation or infection.

Surgically created wounds are designed to leave a well-vascularized bed, so no special preparation is required. Similarly, once injured and devascularized tissue is removed, acute traumatic wounds often have a healthy bed.

Chronic wounds may take a period of dressing changes to promote neovascularization in the bed. (See "Overview of treatment of chronic wounds", section on 'Wound bed preparation'.)

Granulation tissue can be heavily colonized, and, at the time of skin grafting, it should be gently debrided back to the wound base. Skin margins should be trimmed to expose healthy, unscarred dermis. Hemostasis must be meticulous to prevent blood or fluid collections from accumulating beneath the graft because these are a common cause of graft failure [7]. If the base is bony or tendinous, a graft may not take. The recipient site should also be thoroughly irrigated prior to graft placement.

Minimizing blood loss

Tumescent infiltration — Tumescent infiltration with large diluted volumes of local anesthesia (eg, bupivacaine 2 to 3 mg/kg maximum dose with epinephrine) or vasoconstricting agents (1 mL of 1:1000 adrenaline per 1000 mL) in normal saline reduces intraoperative blood loss and postoperative pain [8-11]. Various techniques are used, and the devices used for injecting tumescent infiltration into the skin vary from simple syringes and needles for small areas to powerful mechanically assisted devices that deliver large volumes of infiltration through large, wide needles. Our standard infiltration of both burned tissue and donor sites is one liter of normal saline with an ampule of 1:1000 epinephrine. For local anesthesia, we use a mixture of 1% lidocaine and bupivacaine 0.25%. The bupivacaine provides longer duration analgesia for donor site pain as these areas are the most problematic for postoperative pain control.

Tumescent infiltration to facilitate graft harvesting can reduce intraoperative blood loss and postoperative pain, particularly in the setting of burn surgery [8-10,12]. In a nonrandomized study, tumescent infiltration of the donor and burn sites with subdermal injections of diluted epinephrine resulted in a significant reduction of intraoperative blood loss compared with a similar group of burn patients not treated with these techniques [12].

Other methods — Other methods for reducing blood loss during split-thickness skin grafting include direct pressure, the use of topical hemostatic agents (table 1), electrosurgical devices for wound bed hemostasis, and tranexamic acid. Topical hemostatic agents and electrocautery devices are reviewed separately. (See "Overview of topical hemostatic agents and tissue adhesives" and "Fibrin sealants" and "Overview of electrosurgery".)

Systemic tranexamic acid (TXA) has been used to minimize blood loss in other types of surgery (eg, hip arthroplasty, scoliosis surgery) and may also to be effective for burn excision [13]. A handful of observational studies have reported reductions in blood loss transfusion and fluid requirement for burn patients receiving TXA [13-15]. In a small randomized trial, 30 patients with burns (<30 percent TBSA) were randomly assigned to a single dose of intravenous tranexamic acid (15 mg/kg) or placebo (10 mL saline) [16]. The average blood loss per cm² burn area excised was significantly lower for those who received TXA compared with the placebo group (0.45 versus 0.73 mL/cm²; mean difference 0.28 ± 0.025 mL/cm², 95% CI 0.23-0.33). The total volume of blood loss was also lower in TXA group but was not statistically significant (258.7 versus 388.1 mL). Graft take was similar for both groups (near 100 percent). None of the patients required transfusion, and fluid requirements were similar between the groups.

Grafting — Techniques by which to accomplish partial-thickness and full-thickness skin autografting are well established and follow an orderly sequence. Allografts and xenografts are placed in a similar manner but without the need to harvest tissue. The steps involved are discussed fully below. (See 'Split-thickness skin grafting' below and 'Full-thickness skin grafting' below.)

The application of skin substitutes is similar, also without the need to harvest tissue. (See "Skin substitutes".)

Graft take — The rate of graft take, or skin graft survival, for STSG (sheet or meshed) is approximately 95 percent. Optimal rates require that the wound is free of infection and that the patient has optimal infection control and nutritional status. The graft take for FTSGs is similar, provided the wound is appropriately and freshly debrided, the patient's physiology and ability to heal is unaffected, and there are no microbiology concerns. When there is less-than-optimal debridement, infection, or deranged physiology, graft take will be compromised.

The local and systemic factors that decrease the survival of skin grafts are similar for STSGs and FTSGs. The main factor that reduces graft take and survival for skin grafts is a lack of initial adhesion to the recipient site due to the presence of a hematoma or seroma that inhibits revascularization. For FTSGs, small perforations may not be sufficient to drain any accumulating fluid. Other local factors that are associated with decreased skin graft survival include inadequate vascularity, such as the presence of unvascularized bone or tendon or local tissue hypoxia from underlying vascular disease, prior irradiation or smoking, excess mobility, and placement in an area of high contact or friction (eg, back, anorectal area).

Systemic factors that may decrease the survival of STSGs include older age, malnutrition, medical comorbidities, and pharmacologic therapies known to affect wound healing (eg, glucocorticoids), among others. (See "Risk factors for impaired wound healing and wound complications".)

SPLIT-THICKNESS SKIN GRAFTING — The split-thickness skin graft (STSG) is the most frequently used donor for tissue coverage. An STSG includes the epidermis and varying amounts of dermis, ranging between 8/1000 of an inch (0.196 millimeters) and 12/1000 of an inch (0.294 millimeters).

Advantages — The main advantages of split-thickness skin grafting include the ability to cover large surface areas with less donor skin, and that donor sites may be reharvested once healing is complete (generally in 10 to 15 days). Reharvesting, together with expansion of the graft by meshing techniques, and combination with allograft techniques (sandwich technique: 1:2 autograft covered with 1:4 allograft) allow for coverage of larger defects. A degree of caution needs to be observed in older adults in whom the dermis is thinner; injudicious thick harvesting may lead to difficult-to-heal wounds.

Prior to reharvesting, the patient's nutritional status must be optimized, and the donor site wound must show evidence of reepithelialization with no evidence of local infection.

Disadvantages — The disadvantages of STSGs include fragility, abnormal pigmentation, lack of smooth texture, and lack of hair. The lack of a dermal element and, thus, limited pliability and elasticity increase the likelihood of contracture. When used to reconstruct large burns of the face, STSGs may yield an undesirable, mask-like appearance. In addition, the donor site is an additional cause of significant pain.

STSG technique — The steps involved during split-thickness skin grafting are described in the sections below. Harvesting can be performed using local anesthesia if the size of the graft harvesting is small. Otherwise, the procedure is performed with additional sedation or under general anesthesia.

The harvesting area is chosen according to availability. Characteristically, a convex area is chosen for ease of harvesting, such as the lateral and anterior thigh. (See 'Donor site selection' above.)

The area is shaved and marked, and tumescent infiltration with a local anesthetic and/or epinephrine mixed with saline is performed at the donor and burn wound sites. (See 'Tumescent infiltration' above.)

Skin harvest — The methods of STSG harvesting have evolved from free-hand with a knife to the use of a handheld dermatome. Either an electrical or compressed air-powered dermatome (authors' choice) can be used [17].

The dermatome has a large scalpel-like blade with adjustable depth gauge. Dermatomes are graded in multiples of 1/1000 of an inch and 5/100 of a millimeter, with most grafts harvested between 8/1000 and 12/1000 of an inch. Harvesting thicker grafts requires a longer time for donor sites to heal and may preclude that site from repeat harvesting, which is particularly important in burn patients.

The harvesting area is layered with liquid paraffin, mineral oil, or surgical water-based lubricating gel to reduce friction and facilitate harvesting. The donor site is put on tension by the assistant and the dermatome engaged on the skin surface at an angle of approximately 45 degrees and gently pushed forward while exerting a modest amount of downward pressure on the dermatome. The partial-thickness skin will come off the blade as the dermatome is moved forward. At the completion of the harvest, the dermatome is lifted, which usually severs the graft. If the graft does not come completely off the donor site, a scalpel can be used to complete the final cut. The graft is then transferred to the recipient site, or meshed prior to transfer. (See 'Graft meshing' below.)

Intraoperatively, while the graft is being meshed and inset into the recipient site, hemostasis at the donor site can be achieved using gauze soaked in a solution of one liter normal saline and one ampule of 1:1000 epinephrine. Local anesthesia (generally bupivacaine 0.5% with epinephrine) can be infiltrated at the donor site to provide pain relief in the perioperative period. STSG donor sites are subsequently covered with a nonadherent dressing. (See 'Donor site dressings and care' below.)

Graft meshing — The harvested STSG can be expanded through a meshing device (1:1.5 to 1:9 expansion) to increase its surface area when additional coverage is needed (picture 1 and picture 2 and picture 3). Meshed skin grafts also allow fluid to drain freely from the interstices (ie, openings) of the meshed graft, which improves graft take. The most common ratios for meshing skin grafts include 1:1 mesh (mini mesh), 2:1 mesh, and 4:1 mesh (with overlying 2:1 meshed allograft), depending on the availability of donor sites.

Larger mesh ratios are reserved for patients with limited donor sites such as patients with severe burns. However, meshed grafts heal with more scarring due to the secondary healing of the interstices and are therefore less aesthetically appealing (picture 4) compared with sheet (unmeshed) skin grafts. Accordingly, graft meshing is reserved for areas where the aesthetic outcome is of less importance. Unmeshed sheet grafts are used in cosmetically sensitive areas, such as the face and hands [18,19].

The Meek technique, first described in 1958, is an alternative technique for expanding autografts. It uses a special dermatome and prefolded gauzes to obtain a regular expansion of autograft squares from small pieces of split skin grafts of up to a 1:9 expansion. The Meek techniques can be used on its own or combined with other techniques such as allograft, dermal templates, or cultured keratinocytes both in the adult and pediatric populations [20-23]. In our experience, the ultimate cosmetic appearance of a Meek-covered area is superior to that of other widely meshed techniques.

Graft placement and fixation — Prior to placement of the skin graft, the wound bed is debrided and must be free of a hematoma, exudate, or infection. (See 'Recipient site preparation' above.)

STSGs are transferred dermis-side-down to the recipient site and fixed into place. The grafts can be secured using staples, sutures, or tissue glue.

Staples are the fastest method of securing the graft to the wound. The technique is straightforward, and the staples are relatively inexpensive. If the wound has an unusual surface contour, multiple tacking sutures can also be used. Placement of a large number of staples will generally require removal in the operating room and may require general anesthesia. There is also the potential of leaving embedded staples in the wound, which may result in nonhealing wounds, infection, and pain.

For small skin grafts in sensitive anatomic areas in our practice, we use 4-0 or 5-0 rapidly absorbable suture (eg, 4-0 Vicryl Rapide, 5-0/6-0 Vicryl Rapide for the head and neck). For other small STSGs, tissue adhesives can be used to secure a graft instead of suture [24-26]. Fibrin sealants are used for their hemostatic and adhesive properties [27]. In addition, with less movement of the graft, fewer sutures or staples are needed to secure the graft to the wound bed. Two prospective multicenter trials found a significant decrease in hematomas and seromas and improved viability with the use of fibrin sealants compared with staples in burn wounds [28-30]. For non-burn skin grafting, in one series of 15 patients with 17 lower extremity ulcers, most of the skin grafts (13/17) healed successfully using fibrin glue instead of suture to secure STSGs [26]. There are no trials comparing other types of glue (eg, cyanoacrylates) with suture for fixation of STSGs. The typical concentration used is 4 to 5 units/mL. This reduced concentration does increases the time for the sealant to set, allowing more time to manipulate the graft on the wound [31]. (See "Overview of topical hemostatic agents and tissue adhesives", section on 'Tissue adhesives and sealants' and "Fibrin sealants", section on 'Graft or flap adhesion'.)

Once the STSG is fixed in place, appropriate coverage is necessary to stabilize the skin graft. Recipient site dressings and care are discussed below. (See 'Recipient site dressings and care' below.)

Donor site dressings and care — The donor site dressing should promote reepithelialization with a minimum amount of pain and discomfort [32]. Since regenerated skin from the donor site may need to be reharvested, meticulous care is warranted for maintaining tissue availability and integrity and to minimize the risk of infection. The donor site is evaluated every 72 hours until healed.

Dressings — Several types of dressings are available to manage the donor site wound [33-35]. (See "Topical agents and dressings for local burn wound care".)

The optimal dressing for donor sites continues to be debated, and no one dressing has been proven superior to another. The type used typically depends upon surgeon preference and availability [32,36-38]. A review that included 35 randomized trials and 22 observational studies noted difficulties in making accurate comparisons between moist and nonmoist dressings because of methodological heterogeneity [36]. Although nonmoist adherent dressings may be the most commonly applied dressings to the donor site (eg, bismuth-impregnated petrolatum gauze), there is some weak evidence to support the use of moist dressings, which appear to be associated with less pain and may have lower rates of infection and improved quality of healing.

In our unit, we place a nonadherent dressing pad (eg, Telfa Clear [polyethylene terephthalate], Mepitel [silicone], or Jelonet [paraffin gauze]) as the contact layer on the donor site, covered with a layer of thick gauze to absorb any fluid and secured with a crêpe wrap bandage, Elastoplast elastic bandage, or Tegaderm adhesive dressing [39,40]. In a pilot study assessing pain and ease of removal of the donor site dressings, Telfa Clear was easier to remove and less painful compared with Jelonet; however, donor sites covered with Jelonet appeared to heal faster [39]. Another small trial compared a film dressing (Mepitel) with traditional gauze dressings at skin graft donor sites [40]. The film dressings had lower pain scores and complication rates compared with gauze dressings. However, there is a tendency for moist dressings to be labor intensive for both the patient and the caregiver. In a randomized trial that included 22 patients, management of the donor site with an absorbent synthetic dressing with properties of natural epithelium (ie, Suprathel) had similar healing times and reepithelialization rates compared with Jelonet [35]. However, there was less pain, less frequent dressing changes, and better attachment to donor site surfaces with Suprathel.

For donor sites on the back, we use Biobrane as the primary contact dressing, covered with a layer of Jelonet, povidone iodine-soaked gauze, dry gauze, and a securing dressing. Some have noted that attempts at using moist dressings such as Tegaderm and Biobrane improved pain control, but with a higher rate of drainage from the site and need for caregiver intervention prior to healing.

Hydrocolloid dressings may be associated with the fastest healing rates of the donor site wound following split-thickness harvesting [32,41]. In a randomized trial that included 289 patients with a donor site wound, 49 patients managed with hydrocolloid dressings reepithelialized seven days faster compared with patients managed with other dressings (ie, alginate, film, gauze, hydrofiber, silicone; median 16 versus 23 days) [32]. The risk of infection was higher for patients managed with gauze compared with all other dressings (18.0 versus 7.6 percent, relative risk [RR] 2.38, 95% CI 1.14-4.99). Overall pain scores were low, with the lowest pain score associated with film.

Adjuncts for healing — Less common approaches to enhance healing of the donor site wound include overgrafting donor sites [42] extracorporeal shock wave therapy [43] and keratinocyte cell spray [44,45].

●Overgrafting donor sites with widely meshed spare skin is particularly useful in older adults where delayed donor site healing can be a problem. While initially described over 30 years ago [42], interest in the technique has increased [46,47].

●Extracorporeal shock wave therapy enhances revascularization and repair of healing soft tissue [43]. In a trial of 28 patients with burns or acute traumatic wounds, the delivery of a single treatment to the donor site immediately after harvesting reduced the time to reepithelialization compared with standard topical therapy (13.9 versus 16.7 days). Time to reepithelialization was defined as the time from skin graft harvest to first documentation of greater than 95 percent reepithelialization.

●Cell-based therapies (eg, keratinocyte spray) have been used to augment healing in grafted burn wounds and donor sites and have been shown to reduce donor site requirements and improve patient comfort [48,49]. ReCell is a rapid, autologous cell harvesting procedure that enables the cells from an STSG biopsy to be processed into an immediate cell population and is applied as a spray to cover the wound to be treated as well as the biopsy donor site [44]. In a randomized trial of 82 patients with deep partial-thickness burns, patients treated with ReCell had similar aesthetic and functional outcomes compared with patients treated with the conventional STSG [45]. Patients treated with ReCell had significantly less postoperative pain by the visual analogue scale (3.3 versus 6.8) and smaller STSG donor sites (2.2 versus 110 cm²).

FULL-THICKNESS SKIN GRAFTING — Full-thickness skin grafts (FTSGs) harvest the entire layer of skin as the graft, including the dermal and epidermal elements. Because of the increased thickness of the tissue, revascularization of the donor skin takes longer for an FTSG than for a split-thickness skin graft (STSG).

Advantages — FTSGs provide improved texture, pliability, elasticity, aesthetics, and color match and are more resistant to secondary contracture compared with STSGs [50]. FTSGs have an aesthetic advantage when used to cover wounds affecting the face and hands. There is also greater patient satisfaction for both the recipient site and donor site [50].

Disadvantages — The major limitations and disadvantages of using FTSGs include the following:

●Limited availability of high-quality donor skin since donor sites lack the ability to self-regenerate. Reharvesting in the same area is limited by the elasticity of surrounding skin.

●Not all areas of the body are suitable as donor sites, because an FTSG should ideally match the recipient site for color, skin thickness, and texture. A drawback of applying an FTSG to the face is the potential color mismatch, with results varying from hypopigmentation to hyperpigmentation [51].

●Lack of interstices in FTSGs increases the risk for hematoma and seroma formation and may reduce graft take [52]. (See 'Graft take' above.)

FTSG technique — The steps involved during full-thickness skin grafting are described in the sections below. Harvesting can be performed using local anesthesia if the size of the graft harvesting is small. Otherwise, the procedure is performed with additional sedation or under general anesthesia.

The harvesting area is chosen according to availability. There is sufficient laxity and pliability of the skin in the supraclavicular and groin regions and the inner upper arm areas to permit mobilization of the surrounding tissues to achieve a primary closure of the donor site. (See 'Donor site selection' above.)

The area is shaved and marked, and tumescent infiltration with a local anesthetic and/or epinephrine mixed with saline is performed at the donor and burn wound sites. (See 'Tumescent infiltration' above.)

The donor site is closed primarily by local advancement of the adjoining skin by using a secondary local flap or occasionally an STSG (if the donor site is very large). (See 'Skin harvest' above.)

Skin harvest — An FTSG is harvested free-hand using a scalpel, without the use of a dermatome.

Since an FTSG contracts very little as it heals, the donor skin should be tailored to fit the exact size and shape of the defect. A template of the defect should be made using a flexible material (eg, sterile paper or gauze) that can conform to the defect. This allows for a "tailor-made" fit for the harvested skin, without removing more skin than is required.

Donor site incision should be planned along natural skin creases (relaxed skin tension lines or Langer's lines), particularly in the face (figure 2 and figure 3). Violating these lines leads to more visible scars as a result of wound closure. Excess tension in a skin closure can lead to unsightly hypertrophic scarring.

The incision is made with a scalpel, and sharp dissection of the full thickness of skin is performed. The use of electrocautery during graft harvest should be minimized to minimize thermal injury to the graft. We depilate and remove the subcutaneous adipose tissue from the dermis of the FTSG (ie, defatting), as needed, prior to placing it in the recipient site. This can be accomplished using sharp, fine scissors (eg, McIndoe scissors), holding the graft between the thumb and the index of the nondominant hand on top of a wet gauze swab.

Graft placement and fixation — The wound is debrided and must be free of a hematoma, exudate, or infection. (See 'Recipient site preparation' above.)

The FTSG is inset into the recipient site and sutured into place using fine, rapidly absorbable sutures (eg, 4-0 Vicryl Rapide, 5-0/6-0 Vicryl Rapide for the head and neck). Quilting sutures can be used to fix the graft to the recipient site. Small incisions are made to perforate the full thickness to facilitate evacuation of blood exudate without compromising graft integrity.

Tissue adhesives have also been used for FTSGs [29,53]. (See "Fibrin sealants", section on 'Graft or flap adhesion'.)

Donor site closure — FTSG donor sites are managed by meticulous hemostasis and primary closure with absorbable or nonabsorbable sutures, ensuring there is no tension on the wound.

Steri-Strips are applied to the suture line, followed by dry gauze secured with a wrap bandage or adhesive dressing.

The use of skin substitutes (single layer, bilayer) has increased the number of reconstructive options for surgeons. (See "Skin substitutes".)

RECIPIENT SITE DRESSINGS AND CARE — The dressing in contact with the graft recipient site should be nonadherent. In our practice, we prefer to use clear, plastic-based wound dressings that allow inspection of the wound, are atraumatic, and can be covered by a layer of silver nitrate or iodine soaks. After removal of the bandages, the graft will be dry, and a gentle daily application of moisturizer is helpful.

When Integra is used, we cover it with a double layer of nonadhesive iodine-impregnated dressing as the primary dressing.

Graft immobilization — Immobilization of the graft to the recipient bed is imperative to prevent shearing of the graft and/or accumulation of fluid under the graft, which would prevent the process of neovascularization, thus causing skin graft failure. Although meshed STSGs can drain underlying wound fluid through the interstices, the graft still needs to be immobilized to facilitate healing. For FTSGs, immobilization is also crucial as there are no mesh interstices to allow fluid drainage. A bolster dressing (picture 5) or a negative pressure wound therapy device can be used to ensure immobilization of the healing graft. (See "Negative pressure wound therapy".)

Negative pressure wound therapy (figure 4) minimizes shearing and subgraft fluid accumulation [54-56]. For large areas, and specifically for those close to joints, we always use negative pressure wound therapy dressings in the immediate post-graft period. It is also our preference for most other areas, when available. The device is usually left in place for 5 to 10 days after graft placement.

If negative pressure wound therapy is not available, independent of the size of the graft, we use a bolster. Bolster dressings have long been used to cover the graft and hold it in place. Bolstering and tie-over of the grafts may help in protecting the skin grafts, though their usefulness in applying pressure in the interface between recipient and graft area to ensure better take has been questioned [57]. A gauze or cotton bolster is usually applied to absorb the exudate. The bolster dressing can be sewn in place by placing stitches (3-0/4-0 nylon or polypropylene, 5-0/6-0 in the head and neck) around the periphery of the graft and leaving them long enough to tie together over the bolster.

Limb immobilization and elevation — STSGs that are placed in areas subjected to shear because of motion (eg, axilla, antecubital fossa, or popliteal fossa) also require stabilization with a splint prior to leaving the operating room. Postoperatively, splinting provides for anatomical and functional preservation and minimizes early abnormal scar formation [58,59].

In addition, extremities that are grafted should be elevated for four to five days to decrease postoperative edema.

POSTOPERATIVE CARE AND FOLLOW-UP — Close surveillance of the grafted wound facilitates early detection of graft shearing, hematomas, seromas, or any other problems that may affect graft survival. Thus, we inspect all recipient sites on postoperative day 2 and donor sites at postoperative day 5. For skin substitutes (eg, Matriderm, Integra), we remove the bolster for inspection at three to five days.

In the early postoperative period, immobilization of the reconstructed grafted wound by limiting physical activity is important to avoid rebleeding, hematoma, or dehiscence until graft inspection. This period of rest allows successful graft adhesion and revascularization. Precautions are maintained until early maturation and donor site healing have occurred, typically at approximately one month post-procedure.

A fundamental component to postoperative management is mobilization of the patient with the initiation of occupational therapy and/or physical therapy. A careful balance must be achieved between graft protection and preservation of motion in joints. Early mobilization is necessary to preserve function, but excessive early joint mobilization before full graft take or adequate wound healing will shear and destroy grafts by interfering with graft adhesion and compromise the reconstruction. There have been a number of studies [60] showing that early mobilization and ambulation do not adversely affect the take of STSGs in the lower limb and are important in enhanced recovery programs.

COMPLICATIONS

Graft failure — Graft failure can result from insufficient vascularity of the recipient site, hematoma, seroma, infection, excessive tension, or mechanical shearing forces. Proper preparation of the wound bed, meticulous hemostasis, careful inset of the graft, and proper dressing along with immobilization during the healing period can help avoid most of these complications [1].

Comorbidities, including diabetes, smoking, and protein or vitamin deficiencies, can affect vascularity and wound healing. In addition, medications such as steroids, immunosuppressive medications, and anticoagulants can interfere with wound healing. These are discussed in detail elsewhere. (See "Risk factors for impaired wound healing and wound complications".)

Infection is most commonly due to methicillin-resistant coagulase-positive staphylococci (MRSA), beta-hemolytic streptococci, or pseudomonas [1]. Cultures should be obtained to direct antibiotic treatment. Partial graft loss can be treated with wet to moist saline-soaked gauze or other local dressings and usually will heal secondarily. Complete graft loss requires reassessment of the bed. When the wound bed is well vascularized, then regrafting can be attempted.

Hypertrophic scarring and keloid formation — All grafted areas will leave a scar at both the recipient and the donor site. Such a scar can turn into a hypertrophic or keloid scar that may require appropriate management. Preventive measures and treatment of established scars are discussed separately. (See "Keloids and hypertrophic scars" and "Hypertrophic scarring and keloids following burn injuries", section on 'Preventive strategies and their efficacy'.)

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

●Skin autografting – A skin autograft is defined as a transfer of skin from the donor site to the recipient site without the benefit of any blood supply. The routine use of skin autografts and flaps has dramatically broadened the ability of the surgeon to perform reconstructive surgery and improve outcomes and quality of life for trauma patients, burn patients, and cancer patients. (See 'Skin anatomy' above.)

•Split-thickness skin grafts – Split-thickness skin grafts (STSGs) transfer a portion of the donor site skin layer including the epidermis and some of the underlying dermis. The use of STSGs and techniques for placement are reviewed above. (See 'Split-thickness skin grafting' above.)

•Full-thickness skin grafts – Full-thickness skin grafts (FTSGs) harvest the entire layer of skin as the graft. The use of FTSGs and techniques for placement are reviewed above. (See 'Full-thickness skin grafting' above.)

●Wound bed preparation – Proper preparation of the recipient site is crucial for both STSGs and FTSGs. Prior to grafting any wound bed, the surgeon must make certain that the bed is ready to accept the graft and free from necrotic or ischemic tissue, inflammation, and infection. (See 'Recipient site preparation' above.)

●Complications – The main cause of skin graft failure is graft movement, which interferes with neovascularization and encourages fluid collection under the graft, which can lead to infection and poor revascularization. (See 'Graft failure' above.)