Answer:
The success of skin grafting, or “take,” depends on the ability of the graft to receive nutrients and, subsequently, vascular ingrowth from the recipient bed. Skin graft revascularization or “take” occurs in three phases. The first phase involves a process of serum imbibition and lasts for 24 to 48 hours. Initially, a fibrin layer forms when the graft is placed on the recipient bed binding the graft to the bed. Absorption of nutrients into the graft occurs by capillary action from the recipient bed. The second phase is an inosculatory phase in which recipient and donor end capillaries are aligned. In the third phase the graft is revascularized through these “kissing” capillaries. Because the full-thickness skin graft is thicker, survival of the graft is more precarious, demanding a well-vascularized bed.
Four theories have been proposed for graft revascularization: (1) There is neovascularization of the graft in which new vessels from the recipient bed invade the graft to form the definitive vascular structure of the graft, (2) Communication occurs between existing graft vessels and those in the recipient site, (3) There is a combination of ingrowth of new vessels and reestablishment of flow into existing vessels, (4) The vasculature of the skin graft is made up, primarily, from its original vessels before transfer.
To optimize take of a skin graft, the recipient site must be prepared. Skin grafts require a vascular bed and will seldom take in exposed bone, cartilage, or tendon devoid of its periosteum, perichondrium, or paratenon. There are exceptions, however, as skin grafts are frequently successful inside the orbit or on the temporal bone, despite removal of the periosteum. Close contact between the skin graft and its recipient bed is essential. Hematomas and seromas under the skin graft will compromise its survival and immobilization of the graft is essential. Shear is the number one cause of skin graft failure.