Grafts and flaps - Plastic surgery

Question 1

Survival of grafts ?

Answer 1

1. Full thickness & split thickness skin grafts survive by the same mechanisms:
   a. Plasmatic imbibition: Initially, the skin grafts passively absorbs the nutrients in the wound bed by diffusion.
   b. Inosculation: By day 3, the cut ends of the vessels on the underside of the dermis begin to form connections with those of the wound bed.
   c. Angiogenesis: By day 5, new blood vessels grow into the graft and the graft becomes vascularized.
2. Skin grafts fail by four main mechanisms:
   a. Poor wound bed:
   » Because skin grafts rely on the underlying vascularity of the bed, wounds that are poorly vascularized with bare tendons or bone, or because of radiation, will not support a skin graft.
   b. Sheer:
   » Sheer forces separate the graft from the bed and prevent the contact necessary for revascularization and subsequent “take”.
   c. Hematoma/seroma:
   » Hematomas and seromas prevent contact of the graft to the bed and inhibit revascularization.
   » They must be drained by day 3 to ensure “take”.
   d. Infection:
   » Bacteria have proteolytic enzymes that lyse the protein bonds needed for revascularization.
   » Bacterial levels greater than 105 are clinically significant.