Disclosure Skin, also known as the integument, covers the entire external surface of the human body. The integumentary system is the principle interface with the surrounding world, and as such serves a multitude of specialized functions. It serves as a protective barrier to protect internal tissues from trauma, radiation, temperature changes, and infection. Other functions include thermoregulation (through sweating and vasoconstriction or vasodilatation) and control of insensible fluid loss. Restoration of an intact barrier is of critical importance following wounding and may be achieved in numerous ways, including grafting. Skin grafting was performed in India 2000 years ago, but widespread interest did not develop until the 19th century. During the last 200 years, skin grafting has evolved into an essential component of the reconstructive surgeon's armamentarium. Grafting may be used to accelerate healing, reduce insensible fluid loss from burns and other wounds, reduce scar contracture, and enhance cosmesis. A thorough understanding of the pertinent anatomy is essential in performing a skin graft, as with any procedure. The skin consists of 2 layers, the epidermis (the more external layer) and dermis. The epidermis is the stratified squamous epithelium, consisting primarily of keratinocytes in progressive stages of differentiation from deeper to more superficial layers. Melanocytes are found in the basal layer of the epidermis. The epidermis has no blood vessels, so it must receive nutrients by diffusion from the underlying dermis through the basement membrane that separates the 2 layers. The dermis is a more complex structure and is composed of 2 layers, the more superficial papillary dermis and the deeper reticular dermis. The papillary dermis is thinner, consisting of loose connective tissue containing capillaries, elastic fibers, reticular fibers, and some collagen. The reticular dermis consists of a thicker layer of dense connective tissue containing larger blood vessels, closely interlaced elastic fibers, and coarse branching collagen fibers arranged in layers parallel to the surface. The reticular layer contains fibroblasts, mast cells, nerve endings, lymphatics, and epidermal appendages. Surrounding the components of the dermis is the gel-like ground substance, composed of mucopolysaccharides (primarily hyaluronic acid), chondroitin sulfates, and glycoproteins. Epidermal appendages serve an important role as a source of epithelial cells, which accomplish re-epithelialization when the overlying epithelium is removed or destroyed in cases such as partial thickness burns, abrasions, or split-thickness skin graft harvesting. These intradermal epithelial structures (eg, sebaceous glands, sweat glands, hair follicles) are lined with epithelial cells that have the potential for division and differentiation. They are often found deep within the dermis. In the face, they may lie in the subcutaneous fat beneath the dermis, which accounts for the remarkable ability of the face to re-epithelialize even the deepest cutaneous wounds. Sebaceous glands (ie, holocrine glands) secrete sebum that serves to lubricate the skin and make it more impervious to moisture. They are found over the entire surface of the body, except the palms and the soles and dorsum of the feet. They are largest and most concentrated in the face and scalp, where they are responsible for the development of acne. Sweat glands (ie, eccrine glands) are found over the entire surface of the body, except the lips, external ear canal, and labia minora. They are most highly concentrated in the palms and soles of the feet. The normal function of these glands is to produce sweat, which cools the body by evaporation. Apocrine glands are similar in structure but not identical to eccrine glands. They are concentrated in the axillae and anogenital regions. They probably serve a vestigial sexual function because they produce odor and do not function prior to puberty. The hair follicle is another important source of epithelial cells, and many of the other dermal appendages actually open into the hair follicle, rather than directly onto the skin. The skin varies in thickness based on its anatomic location and the sex and age of the individual. Skin is thickest on the palms and soles of the feet, while the thinnest skin is found on the eyelids and in the postauricular region. Male skin characteristically is thicker than female skin in all anatomic locations. Children have relatively thin skin that progressively thickens until the fourth or fifth decade of life, when it begins to atrophy. This thinning is primarily a dermal change, with loss of elastic fibers, epithelial appendages, and ground substance.
Skin transplanted from one location to another on the same individual is termed an autogenous graft or autograft. These grafts consist of the entire epidermis and a dermal component of variable thickness. If the entire thickness of the dermis is included, the appropriate term is full-thickness skin graft. If less than the entire thickness of the dermis is included, appropriate terms are partial or split-thickness skin graft. Split-thickness skin grafts are categorized further as thin (0.005-0.012 in), intermediate (0.012-0.018 in), or thick (0.018-0.030 in), based on the thickness of the harvested graft. More characteristics of the normal donor skin are maintained following grafting when thicker dermal grafts are harvested, because more collagen content, dermal vascular plexuses, and epithelial appendages are contained within thicker grafts. However, thicker grafts require more optimal conditions for survival because of the greater amount of tissue requiring revascularization. The choice between full-thickness and split-thickness skin grafting depends on wound condition, location, and size and also aesthetic concerns. Split-thickness skin grafts require less ideal conditions for survival and have a much broader range of application than full-thickness grafts. They are used to resurface large wounds, line cavities, resurface mucosal deficits, close flap donor sites, and resurface muscle flaps. They are also used to achieve closure of wounds created by the removal of lesions that require pathologic examination prior to definitive reconstruction. Donor sites heal spontaneously because of the remaining epidermal appendages and may be reharvested once healing is complete. However, split-thickness grafts do have significant disadvantages that must be considered. Split-thickness grafts are more fragile, especially when placed over areas with little underlying soft tissue support, and usually do not withstand subsequent radiation therapy. They contract more during healing and do not grow with the individual. They tend to be abnormally pigmented (either pale or white) or hyperpigmented, particularly in darker-skinned individuals. Their thinness, abnormal pigmentation, and frequent lack of smooth texture and hair growth make split-thickness grafts more functional than cosmetic. When used to resurface large burns of the face, split-thickness grafts may yield an undesirable masklike appearance. Use of split-thickness grafts creates a second wound at the donor site that must be cared for and often causes more postoperative discomfort to the patient than the original grafted wound.
Split-thickness skin grafts may be harvested from any surface of the body, but the sites chosen should be concealed easily in recreational clothing. Common sites include the upper anterior and lateral thighs. The buttocks may be used as a donor site, but patients may have significant postoperative pain and will require assistance in caring for the wound. The scalp may be used for resurfacing areas of the face that are too large for a full-thickness graft and in severe burns in which donor-site availability is limited. Because of its thickness, scalp skin may be harvested repeatedly with minor risk of alopecia or subsequent hair growth at the recipient site. For hand wounds, the upper inner arm is a cosmetically superior donor site to the more accessible forearm. |
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Preparation of the wound to its optimal physiologic condition to accept and nourish the skin graft is the most critical component of successful grafting. Improper wound preparation is the source of most skin graft failures. Skin grafts will not survive on tissue with a limited blood supply (eg, cartilage, tendon, nerve). Skin grafts will survive on periosteum, perichondrium, peritenon, perineurium, dermis, fascia, muscle, and granulation tissue. Wounds that develop secondary to radiation are also unlikely to support grafts. Treat underlying conditions of wounds resulting from venous stasis or arterial insufficiency prior to grafting to increase the likelihood of graft survival. The wound must be free of necrotic tissue and relatively uncontaminated by bacteria. Bacterial counts greater than 100,000 per square centimeter are associated with a high likelihood of graft failure. Debridement, dressing changes, and topical or systemic antibiotics may be indicated prior to grafting to achieve an adequate wound bed.
Careful operative technique is necessary to maximize graft survival. After initiation of appropriate anesthesia, the wound is first prepared for grafting. This includes wound cleansing with saline or dilute Betadine, judicious debridement, and meticulous hemostasis. Hemostasis may be achieved through ligation, gentle pressure, application of a topical vasoconstrictor (eg, epinephrine), or electrocautery. Minimal use of electrocautery is recommended as it creates devitalized tissue. Use of epinephrine at the donor or recipient site does not compromise graft survival. HarvestingSplit-thickness grafts may be harvested in a variety of ways. The most commonly used technique involves use of a dermatome, which provides rapid harvest of large uniform-thickness grafts. Dermatomes may be air-powered, electric, or manually operated. Commonly used dermatomes include Castroviejo, Reese, Padgett-Hood, Brown, Davol-Simon, and Zimmer. All of these dermatomes harvest by the same mechanism. A rapidly oscillating side-to-side blade is advanced over the skin with thickness and width settings adjusted to surgeon preference. Regardless of technique, adequate anesthesia must be established because harvesting of skin grafts is a painful procedure. Lidocaine with epinephrine injected at the donor site may reduce blood loss and provide greater tissue turgor that assists in harvesting. Drum dermatomes (Reese, Padgett-Hood) deserve special mention and now are used less frequently. The oscillating blade is manually powered as the drum is rolled over the skin surface. These dermatomes are useful when the donor site is irregular or has a convexity, concavity, or bony prominence (eg, neck, flank, buttock), because the skin to be harvested is first made adherent to the drum with a special glue or adhesive tape. These dermatomes also allow harvesting of precise irregular patterns by varying the pattern of adhesive applied to the skin and drum. Disadvantages include injury to operating personnel by the swinging blade, flammable defatting agents necessary to prepare the donor site skin (eg, acetone, ether), and greater technical expertise required to safely and effectively operate these devices. Another method for harvesting split-thickness grafts is freehand with a knife. Although this may be performed with a scalpel, other devices (eg, Humby knife, Weck blade, Blair knife) are also available. Disadvantages include grafts with irregular edges and varying thicknesses. As with drum dermatomes, greater technical expertise is necessary, and graft quality tends to be more operator-dependent when compared to air- or electric-powered dermatomes. Air- or electric-powered dermatomes are the most commonly used devices today and avoid the disadvantages of drum dermatomes or freehand cutting techniques. However, surgeons must be familiar with the installation of the blade and depth settings and must check these before operating the device. The blade has a correct and an incorrect orientation, and inexperienced operating room personnel may easily confuse the two. Insertion of a No 15 blade scalpel simulates a thickness of 0.015 inches and can be used to check that depth settings are uniform and correct. Harvesting may begin after the blade is oriented and width guard and depth setting are confirmed. Wash off Betadine or other solutions used to sterilize the donor site at the beginning of the procedure. Do not use DuraPrep to prepare a donor site because its removal is difficult. It is useful to lubricate the skin and dermatome with mineral oil or pHisoHex (hexachlorophene soap) to allow easy gliding of the dermatome over skin. These substances may be gently washed from the graft with saline following harvesting and do not compromise graft survival. The dermatome is held in the dominant hand of the operator at a 30- to 45-degree angle from the donor skin surface. Greater angulation of the dermatome leads to gouging or trenching of the donor site skin. With the nonoperating hand providing traction behind the dermatome and the assistant providing traction in front of the dermatome, the dermatome is activated and advanced in a smooth continuous motion over the skin with gentle downward pressure. After an appropriate length has been harvested, the dermatome is tilted away from the skin and lifted off of the skin to cut the distal edge of the graft and complete the harvesting. The graft may then be gently washed of lubricant and used for grafting with or without meshing. Typically, the donor site exhibits numerous small punctate bleeding spots with thin to intermediate-thickness grafts. Harvesting thicker grafts yields fewer bleeding points that bleed more copiously. Any exposure of fat indicates that excision of the graft was performed too deeply, probably because of technical error in assembly of the dermatome. PlacementOnce harvested, a split-thickness skin graft may be meshed by placing the graft on a carrier and passing it through a mechanical meshing instrument. This technique allows expansion of the graft surface area up to 9 times the donor site surface area. This technique is indicated when insufficient donor skin is available for large wounds, as in major burns or when the recipient site is irregularly contoured and adherence is a concern. Expansion slits allow wound fluid to escape through the graft rather than accumulating beneath the graft and preventing adherence. However, expansion slits will not prevent graft loss due to underlying hematoma. Expansion slits must heal by re-epithelialization and may contract significantly. Also, the healed wound characteristically has a crocodile skin or checkerboard appearance. Because of secondary contraction and poor cosmesis, avoid using this technique in the face, hands, over joints, and in other highly visible areas. In these regions, split-thickness grafts may be pie-crusted to allow egress of wound fluid from beneath the graft. This technique is performed by making multiple stab wounds through the graft with a No 15 scalpel blade and does not serve to expand the surface area of the graft. Prior to graft placement, reinspect the recipient site for hemostasis. Then, the graft may be placed over the wound bed. It is important to place the dermal side down. Although this sounds simple and obvious, dermis and epidermis can appear very similar in lighter-skinned individuals without close inspection. Take care to prevent wrinkling or excessive stretching of the graft. The graft must then be secured in place to provide stability during initial adherence and healing. This is most often accomplished by suturing or stapling the graft to the surrounding wound bed. Avoid using staples, as they are painful to remove and may disrupt graft adherence to the wound when removed at approximately 7 days postoperatively. Absorbable sutures are preferable because they do not require removal. Usually, 4 corner sutures are placed to hold the graft in the proper orientation. Then, a running suture is placed around the periphery. It is helpful to pass the needle first through the graft and then through the surrounding wound margin to prevent lifting of the graft from the wound bed. Perfect epidermal-to-epidermal approximation will ensure optimal cosmetic results, and the sutures should approximate, not strangulate, the skin edges. Occasionally, central sutures may be indicated to ensure adherence of the graft over a concave portion of the wound, but they are not required routinely. Dressings and wound careA dressing is then chosen to provide uniform pressure over the entire grafted area through a nonadherent, semiocclusive, absorbent dressing material. These dressings are meant to immobilize the graft, prevent shearing, and prevent seroma or hematoma formation beneath the graft. Tie-over bolster dressings are useful over joints or other areas where motion is difficult to avoid, in wounds with irregular contours, and in wound locations where securing a dressing is difficult (eg, oral and nasal cavities, nasal tip). These bolsters may be constructed from foam rubber, N-terface, Adaptic, or Xeroform folded over moistened cotton balls. When sewn into place, these provide a constant light pressure that is molded to the contour of the wound. These dressings are then secured by placing nonabsorbable sutures radially around the wound and tying them to each other over the bolster dressing. Alternatively, sutures used to hold the graft in place may be nonabsorbable and left long to tie subsequently over the bolster. Another dressing choice for irregularly contoured wounds or wounds with high levels of exudate is the vacuum-assisted closure (VAC) sponge. These dressings conform to the wound surface by suction and promote skin graft adherence while removing exudate and edema from surrounding tissues. A nonadherent surface (eg, Adaptic) must be placed as an interface between the skin graft and the sponge to prevent peeling off the graft when removing the sponge. Grafts placed on the extremities may be managed with elevation and compression dressing for the entire extremity distal to the graft to avoid edema that can prevent graft adherence. Use of a cast or splint may also be helpful in poorly compliant patients and in cases of grafting over a mobile surface to prevent motion and shearing forces that disrupt graft adherence. Burn netting may also be useful for securing dressings in difficult locations (eg, pelvic and shoulder regions). Finally, the graft may be treated open with no dressing except a layer of ointment to prevent desiccation. This technique is susceptible to hematoma or seroma formation beneath the graft because no pressure is applied; it is used only occasionally in facial grafting. Graft adherence is maximal during the first 8 hours postgrafting, but the initial dressing should be left in place for 3-7 days unless there is pain, odor, discharge, or other signs of complications. When removing dressings, moisten them with saline to reduce adherence to the graft. The dressing may then be carefully removed to prevent lifting the graft off of the underlying wound bed. Treat hematomas or seromas encountered at dressing change by making a small incision over the collection and expressing the underlying contents. Rolling the fluid out from under the edge of the graft is not recommended because it disrupts adherence of the entire graft, not just the area of hematoma or seroma formation. The donor site must also be dressed appropriately at the conclusion of the operation. A variety of dressing options exists for split-thickness skin graft donor sites. After hemostasis has been achieved, apply a dressing with application of moist gauze containing epinephrine solution. The ideal donor site dressing should be one that promotes rapid re-epithelialization, causes little pain, requires little care, is inexpensive, and has a low rate of infection. Options include occlusive dressings (eg, DuoDerm), semiocclusive dressings (eg, Op-Site, Tegaderm), semiopen dressings (eg, Vaseline gauze, Xeroform, scarlet red), and no dressing. Although semiopen techniques that use a heat lamp to dry the donor site covered with Tegaderm or scarlet red have historically been popular, these dressings violate the most current concepts of promoting moist wound healing. In multiple studies, the superior dressings have been shown to be of the semiocclusive variety. These products have been shown to have the fastest healing rates (average of 9 days to re-epithelialization), lowest subjective pain scores, lowest infection rates (~3%), and are among the lowest in cost. They have the advantage of being transparent, which allows ongoing inspection of the site while maintaining sterility. Fluid collects under these materials, which promotes moist wound healing and probably accounts for the more rapid healing rates and decreased subjective pain scores. Remove the dressing and use another technique if the fluid becomes cloudy or otherwise suggestive of infection. If the fluid accumulation is significant enough that the covering appears tight and likely to rupture, the fluid may be withdrawn with a sterile needle, and a patch of similar material may be used to close the needle-stick site. Donor sites from split-thickness grafts heal spontaneously from epithelial cells remaining in epithelial appendages within the dermis and at the wound edges. Healing begins within 24 hours of harvesting. The rate of healing is proportional to the number of epithelial appendages remaining and inversely proportional to the thickness of graft harvested. The epidermis is regenerated and may be reharvested, but each harvesting removes a portion of dermis that is not regenerated. The initial epithelium that is regenerated is very delicate and easy to disrupt with tape or dressing changes. This is another reason to use the semiocclusive technique that does not require removal until healing is complete. Finally, hyperpigmentation may persist for many months following donor site healing, and darker-skinned individuals may experience hypertrophic scarring at the site.
After graft placement, an initial adherence to the wound bed via a thin fibrin network temporarily anchors the graft until definitive circulation and connective-tissue connections are established. This adherence begins immediately and is probably maximized by 8 hours postgrafting. The period of time between grafting and revascularization of the graft is referred to as the phase of plasmatic imbibition. The graft imbibes wound exudate by capillary action through the spongelike structure of the graft dermis and through the dermal blood vessels. This prevents graft desiccation, maintains graft vessel patency, and provides nourishment for the graft. This process is entirely responsible for graft survival for 2-3 days until circulation is reestablished. During this time, the graft will typically become edematous and increase in weight by 30-50%. Revascularization of the graft begins at 2-3 days postgrafting by a mechanism that is not completely understood. Several theories exist, but the true mechanism may be a combination thereof. Inosculation is the establishment of direct anastomoses between graft and recipient blood vessels. Some investigators have demonstrated vascular ingrowth of recipient bed vessels into the graft along the channels of previous graft vessels, a similar, but not identical theory to inosculation. Still others propose that random new vascular ingrowth of recipient bed vessels into the graft occurs without regard for previous graft vessels. Regardless of the true mechanisms, full circulation to the graft is restored by 6 or 7 days postgrafting. Without initial adherence, plasmatic imbibition, and revascularization, the graft will not survive. Several important aspects of skin graft healing deserve further discussion. Wound contraction may present serious functional and cosmetic concerns, depending on the location and severity. Wound contraction on the face may produce ectropion, retraction of the nasal ala, or distortion of the vermilion border. Over joints, it may limit functional range of motion. Contraction probably begins shortly after initial wounding, progressing slowly over 6-18 months following grafting. Myofibroblasts are believed to cause contraction. In general, full-thickness grafts contract less than split-thickness grafts, and thick split-thickness grafts contract less than thin split-thickness grafts. Furthermore, thin split-thickness skin grafts contract less than open wounds. The ability of a skin graft to resist contraction is related to the thickness of the deep dermal component included in the graft, not just the absolute thickness of the graft. This deep dermal component is able to suppress myofibroblast function by an unknown mechanism. Contraction can be ameliorated by splinting or compression devices (eg, facial masks, Jobst garments). These devices should be worn as much as tolerated each day for at least the first 6 months postgrafting and often even longer. Epithelial appendages must be regenerated following grafting. Hair rarely grows from split-thickness grafts, unless the grafts are quite thick. Sweat glands and sebaceous glands initially degenerate following grafting. Because only a portion of the gland is transferred, the remaining portion may not regenerate. Sweat gland regeneration is dependent on reinnervation of the skin graft with recipient bed sympathetic nerve fibers. Once this ingrowth has occurred, the skin graft assumes the sweating characteristics of the recipient site, rather than retaining the characteristics of the donor site. Sebaceous gland regeneration is independent of graft reinnervation and retains the characteristics of the donor site. Prior to regeneration, the skin graft is lacking the normal lubrication of sebum produced by these glands. This makes the grafts more susceptible to injury. The grafts may appear dry and scaly during this period. Patients frequently complain of pruritus. Recommend bland creams (eg, lanolin, cocoa butter) to moisturize the graft and reduce itching. Unfortunately, this condition often persists in thin split-thickness grafts. These glands also may regenerate on the deep surface of skin grafts and present as milia. When encountered, they should be unroofed with a needle. Reinnervation of the graft occurs from the recipient bed and from the periphery along the empty neurolemma sheaths of the graft. Sensation returns to the periphery of the graft and proceeds centrally. Usually, this process begins during the first month but is not complete for several years following grafting. Split-thickness grafts reinnervate more quickly, but full-thickness grafts reinnervate more completely. Reinnervation is always incomplete, and some degree of permanent derangement persists. Generally, the patient develops protective sensation but not normal perception. Pain is usually the first perceived sensation, followed later by touch, heat, and cold. Split-thickness grafts may remain pale or white or may become hyperpigmented with exposure to sunlight. It is generally recommended that the graft be protected from direct sunlight for at least 6 months or even longer postgrafting. Hyperpigmentation has been treated with dermabrasion and laser resurfacing.
Skin grafting may be unsuccessful for numerous reasons. The most common reason for skin graft failure is hematoma beneath the graft. Similarly, seroma formation may prevent graft adherence to the underlying wound bed, preventing the graft from receiving the necessary nourishment. Movement of the graft or shear forces may also lead to graft failure through disruption of the fragile attachment of the graft to the wound bed. Another common source of failure is a poor recipient site. The wound may have poor vascularity, or the surface contamination may have been too great to allow graft survival. Bacteria and the response to bacteria through the cellular and humoral immune responses lead to the release of enzymes and other harmful substances at the wound interface that disrupt the fibrin adherence of the graft. Technical error may also yield graft failure. Applying the graft upside down results in complete graft loss. Applying excess pressure, stretching the graft too tightly, or handling the graft in other traumatic ways may lead to partial or complete graft failure.
No discussion of skin grafting would be complete without mention of currently available alternative substances. Biologic skin substitutes may be intended for permanent replacement or as a temporary biologic dressing until a permanent solution is available or normal skin regeneration and healing occur. These substitutes serve multiple functions. They decrease bacterial counts and promote sterile wounds. They also slow the loss of water, protein, and electrolytes. They reduce pain and fever, help restore function, and facilitate early motion. They provide coverage of vessels, tendons, and nerves to prevent desiccation. The ideal skin substitute is one with little or no antigenicity, tissue compatibility, lack of toxicity, and lack of disease transmission. Cadaveric grafts and pig skin grafts are the historical skin substitutes with which most surgeons are familiar. Cadaveric grafts are termed allografts, or homografts, because they are transplanted from one organism to another within the same species. Pig skin grafts are termed xenografts, or heterografts, because they are transplanted from one organism to another of a different species. These grafts may be prepared for use in several ways. They may be treated with glycerol and rapidly frozen with liquid nitrogen, or they may be lyophilized and freeze-dried. Although graft processing does not ensure cell viability, the structural details, proteins, and enzymes remain intact. Eventually rejected by the body, these grafts may be used as temporary biologic dressings, especially in extensive burns where skin graft donor sites are limited. These dressings must normally be changed every 3 days to prevent a rejection response, but patients with burns, who tend to be relatively immunosuppressed, may require removal only every 5 days. A theoretical risk of disease transmission exists with cadaveric grafts. Cultured epithelial cells have also been developed, both as autografts and allografts. Cultured epithelial autografts require biopsies of the patient, followed by growth of these cells in culture. For this reason, they are not available for several weeks until they have grown to confluent sheets. Currently, this culturing process is quite costly and yields an extremely fragile sheet of cells that are very sensitive to infection. Allograft sheets are available immediately but share the structural weaknesses of autografts and the theoretical risk of disease transmission. Allografts are eventually rejected as well but in the interim can serve as a biologic dressing. Allograft dermis has also been developed. This structure is not actually rejected by the body because it is rendered immunologically inert during processing. The body instead remodels and replaces it with a native dermal substitute. Cultured epithelial sheets or thin split-thickness grafts may be placed over this dermal substitute once it has become incorporated. Bilayer collagen matrices are the latest development in this explosive field. These consist of a porous, spongelike lattice of bovine collagen, chondroitin-6-sulfate, and glycosaminoglycans that serve as the dermal substitute. The dermal substitute layer serves as a scaffold that facilitates ingrowth of native fibroblasts and blood vessels with its eventual replacement. An overlying silastic membrane simulates the epidermis and serves to seal the surface to reduce insensible fluid loss. This membrane is transparent, allowing wound inspection, and progressively becomes less adherent to the dermal layer as it is incorporated into the body. At about 3 weeks the silastic layer may be peeled off and replaced with cultured epithelial cells or thin split-thickness skin grafts. Current research in molecular biology, wound healing, and immunology will likely yield even better skin substitutes with which to treat patients in the future. One day, a synthetic bilayer membrane of quality equal to that of skin may be available off of the shelf for application as simple as that of a dressing change.
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