34.9.2 STSG

The dressing should be changed weekly. At postoperative day 7, the petroleum jelly–impregnated gauze is removed from the STSG site by moistening with saline. The graft is held in place with saline-soaked, cottontipped applicators while the gauze is gently lifted. The STSG usually turns pink after 2 days. In the case of hematoma formation, the blood should be drained in order to reestablish proper graft to wound bed apposition, or the graft may fail. A large-bore needle or angiocatheter can be used for this purpose, and then the area can be flushed with saline. Grafts that are at a higher risk of failure should be examined sooner than 7 days. After 7 days, the sutures or staples holding the graft to the bed are removed. Protective and compression dressings should be continued for at least 2–3 weeks after complete healing.

The STSG donor site dressing is changed every 3 days or when the dressing leaks or falls off. The donor site may take several weeks to reepithelialize. Wound care should continue until the site is completely healed.

If a patient is not satisfied with the cosmetic outcome of the graft, dermabrasion may be considered after 6–12 weeks. This can allow for smoother graft edges and allow for blending of the graft with the surrounding skin.

Summary: Cultured Skin Substitutes

•Epidermal, dermal, and bilayered cultured skin substitutes can be useful for second intention healing and delayed grafts.

34.10 Cultured Skin Substitutes

Skin substitutes are grafts that have been processed or cultured prior to application. These may be: autologous, allogeneic, or xenogeneic; epidermal, dermal, or with elements of both; temporary or permanent; and biologic or synthetic [17].

34.10.1 Epidermal

Cultured epidermal autografts are obtained by first harvesting skin from the recipient. The culturing of the keratinocytes is then performed in the laboratory to

create large sheets of graftable epidermis. The process takes about 3 weeks after which large sheets of keratinocytes are available for permanent coverage with acceptable cosmesis. The grafts are fragile and can blister easily secondary to the lack of a dermal component.

Cultured epidermal allografts are useful for immediate use. As they are allogeneic in origin, prolonged persistence does not occur; however, neither does graft rejection. Donor cells are slowly replaced by the patient’s own cells. Therefore, these allografts serve as a temporary covering and stimulus for healing in acute and chronic wounds. It should be noted that these grafts are thin and are limited by their inherent fragility.

34.10.2 Dermal

Alloderm is a dermal, permanent skin substitute. Alloderm (LifeCell Corp., The Woodlands, TX) is derived from human allograft cadaver skin. Once the epidermis is removed, the dermal cells are removed prior to chemical processing to produce a nonantigenic acellular dermis. A complete intact basement membrane complex is present even though the epidermis is not. A meshed STSG can be layered over the Alloderm. Alternatively, cryopreserved Alloderm is hydrated prior to application and treated similar to a STSG, often being meshed prior to application [18].

Oasis (Cook Inc, Bloomington, IN) is porcine small intestine submucosa and is categorized as a bioactive dermal-like matrix. The freeze-dried cellular matrix retains its natural collagen and matrix structure and contains most of the bioactive matrix protein present in the human dermis. Advantages of Oasis are that it has a long shelf life and can be stored at room temperature. Wound bed incorporation occurs over about 7 days; therefore, it needs to be reapplied if the wound has not yet healed [19, 20].

34.10.3 Bilayered

Apligraf (Organogenesis, Canton, MA) is a bilayered, permanent human skin equivalent approved for venous leg ulcers and diabetic foot ulcers [21]. It is derived from bovine collagen and living allogeneic human skin keratinocytes and fibroblasts from neonatal foreskin. When examined histologically, Apligraf resembles human skin but lacks adnexal structures, Langerhans cells, or