Skin grafts are sections of the epidermis or dermis that have been separated from one part of the body and reaffixed to a site where the skin has been removed or damaged. Unlike skin flaps which are still connected to the local blood supply, skin grafts do not have their own blood supply, and thus rely on the wound bed at the recipient site for nutrients. There are two different types of skin grafts: split-thickness and full-thickness.Figure 1: Healed skin graft
Split-Thickness Skin Grafts
Split-thickness skin grafts involve only the epidermis and a small portion of the dermis, leaving behind enough of the dermis for the donor site to heal by reepithelialization. Split-thickness grafts can survive in less ideal recipient sites (with less vascularity), but the thinner the graft, the more likely it is to contract as it heals. STSGs can then be meshed, allowing for smaller sections of tissue to be used to effectively cover larger areas. The combination of meshed appearance, varying pigmentation, and thinness makes STSGs more pragmatic than cosmetic. The thicker the graft, the more the characteristics of the donor skin will be evident as the wound heals.
Once the wound bed has been properly prepared to minimize the risk of infection or graft failure and the graft has been secured in place, an appropriate dressing should be applied to provide even pressure across the surface of the graft site. This even pressure will help prevent the graft from slipping, and will help prevent the formation of hematomas or seromas underneath the graft. For hard-to-dress areas or wounds with irregular contours, tie-over bolster dressings may be indicated to protect the graft and provide consistent pressure. Typically, the first dressing should be left in place for 3-7 days barring any complications. Prior to removal, moisten the dressing with sterile saline to minimize any lifting of the graft. The dressing should then be reapplied twice a week while monitoring the graft for infection, drainage, pain, and overall success of the procedure.
Full-Thickness Skin Grafts
Full-thickness skin grafts involve the epidermis and the entire dermis as well, allowing for most of the characteristics of the grafted skin to be preserved in the process. FTSGs are limited to smaller wounds and require well-vascularized wound beds in order to support the grafted skin. Since the entire dermal layer is removed and will not support regeneration, the resulting skin graft donor site will be left to heal by primary intention (sutured shut). However, the result of FTSGs is a graft that maintains more of the normal characteristics of the skin (notably texture, color and thickness), and is also less likely to contract as it heals. This makes FTSGs the more aesthetically pleasing choice for grafts on the face or other highly-visible areas of the body.
If the graft covers the entire wound bed and is well adhered, it may not require a dressing except to protect from mechanical damage.
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