Chapter 159: Principles of Skin Grafting and Flaps

BACKGROUND

The grafting of skin originated among the tile-maker caste in India approximately 3000 years ago.¹ In 1804, an Italian surgeon, Baronio, successfully performed a full-thickness skin autograft of a lamb.² Since then, numerous pioneers and historical developments have evolved making this procedure common place among almost all surgical disciplines. With proper techniques and instrumentation, and the exercise of appropriate principles, skin grafting has become a reliable and successful operation for wound coverage. In situations in which the wound or defect is not amenable to a skin graft, or in which the defect is better served with more durable coverage, flap coverage would be performed instead. The use of flaps for reconstruction dates back to 600 bc  with the earliest recorded application of pedicle flaps for nasal reconstruction, which was attributed to the Sushruta Samhita.³ It was not until the 1960s to 1970s with the advancement in the understanding of anatomy and medical technology (microsurgical instrumentation) that the reconstruction field experienced an explosion in the development of new categories of flaps and ever-increasing named flaps based on blood supply and location of origin. In this chapter, the reader is introduced to the general principles of skin graft and flap surgery. Other chapters  demonstrate the applications of various flaps in reconstruction of oncological defects; therefore, clinical application of flaps is not thoroughly discussed in this chapter.

SKIN GRAFTS

For skin defects which cannot be closed by direct approximation or allowed to heal by secondary intention, either skin grafts or flaps can be employed. Grafts are harvested from a donor site and transferred to the recipient site without its own blood supply. The skin graft relies on regeneration of new blood vessels from the recipient bed. Skin grafts can be categorized as a split-thickness graft or a full-thickness graft. When a graft includes only a portion of the dermis, it is referred to as a split-thickness skin graft (STSG), whereas when the entire dermis is included it is called a full-thickness skin graft (FTSG). The thicker the dermis which is included in the harvest, the less likely the graft will take. A STSG has a higher chance to take, but it will encounter a greater amount of postoperative contracture. A better vascular bed is required for the survival of a FTSG, but it will undergo less contracture upon healing, resist trauma better, and generally look more natural than a STSG. A typical thickness for a split-thickness graft is 0.012 to 0.018 in. (0.30 to 0.45 mm). The donor site generally will heal spontaneously within 7 to 21 days, depending on the thickness of the graft, the donor site skin thickness, and patient factors. Re-epithelialization occurs from adnexal remnants, the hair follicles, and sweat glands. In contrast, with FTSG donor sites, re-epithelialization is generally not feasible. When planning for a FTSG, the surgeon intends to harvest sufficient skin needed but will be able to ...