A first degree or superficial burn heals naturally because your body is able to replace damaged skin cells. Deep second and full-thickness burns require skin graft surgery for quick healing and minimal scarring. In the case of large burn size, patients will need more than one operation during a hospital stay.
Skin grafting is done in a surgical procedure that consists of:
- The removal of injured tissue
- Selection of a donor site, an area from which healthy skin is removed and used as cover for the cleaned burned area
- Harvesting, where the graft is removed from the donor site
- Placing and securing the skin graft over the surgically-cleaned wound so it can heal
To help the graft heal and become secure, the area of the graft is not moved for five days following each surgery. During this immobilization period, blood vessels begin to grow from the tissue below into the donor skin, bonding the two layers together. Five days after grafting, exercise therapy programs, tub baths and other normal daily activities resume.
There are a variety of skin grafts, some that provide temporary cover and others that are for permanent wound coverage.
Temporary burn wound covering
Allograft, cadaver skin or homograft is human cadaver skin donated for medical use. Cadaver skin is used as a temporary covering for excised (cleaned) wound surfaces before autograft (permanent) placement. Cadaver skin is put over the excised wound and stapled in place. After surgery, the cadaver skin may be covered with a dressing. This temporary covering is removed before permanent autografting.
Xenograft or heterograft is skin taken from a variety of animals, usually a pig. Heterograft skin became popular because of the limited availability and high expense of human skin tissue. Wound coverage using heterograft is a temporary covering used until autograft.
Permanent burn wound covering
Autograft is skin taken from the person burned, which is used to cover wounds permanently. Because the skin is a major organ in the body, an autograft is essentially an organ transplant. Autograft is surgically removed using a dermatome (a tool with a sharp razor blade). Only the top layer of skin is used for donor skin. The site the skin is taken from will heal on its own. There are two types of autografts used for permanent wound coverage:
Sheet graft is piece of donor skin harvested from an unburned area of the body. The size of the donor skin is about the same size as the burn wounds. The donor sheet is laid over the cleaned wound and stapled in place. The donor skin used in sheet grafts does not stretch; it takes a slightly larger size of donor skin to cover the same burn area because there is slight shrinkage after harvesting. When the body surface area of the burn is large, sheet grafts are saved for the face, neck and hands, making the most visible parts of the body appear less scarred. When a burn is small and there is plenty of donor skin available, a sheet graft can be used to cover the entire burned area.
The disadvantages of sheet grafts are that small areas of graft might be lost from build-up of fluid (hemotoma) under the sheet right after surgery and also need a larger donor site than does meshed skin. A sheet graft is usually more durable and scars less.
Meshed skin grafts Very large areas of open wounds are difficult to cover because there might not be enough unburned donor skin available. It is necessary to enlarge donor skin to cover a larger body surface area. Meshing involves running the donor skin through a machine that makes small slits that allow expansion similar to fish netting. In a meshed skin graft, the skin from the donor site is stretched to allow it to cover an area larger than itself. Healing occurs as the spaces between the mesh fill in with new skin growth. The disadvantages of meshing are that it is less than a sheet graft and that the larger the mesh, the greater the permanent scarring.
Meshing allows blood and body fluids to drain from under the skin grafts, preventing graft loss, and it allows the donor skin to cover a greater burned area because it is expanded.
How skin grafts are held in place
Surgical staples are used to secure the edges of a graft to healthy skin. The staples are put in and taken out with a tool that looks like a pliers. Once the edges have healed together and the graft is stable, the doctor removes the staples.
Sometimes the doctor sutures (stitches) a graft in place with a needle and silk or nylon thread. When the graft is stable, the stitches are removed.