Skin Grafting

Skin grafts are used to cover skin defects. The thicker the graft, the better the cosmesis. The recipient site must have a good blood supply or else the graft has to come with its own blood supply as in a flap graft. Free skin grafts are descrived here and may be:

  • Split skin suitable for large areas and takes well especially on healthy granulation tissue.
  • Full thickness (Wolfe) gives better cosmesis and wear, but cannot be used for large areas or on granulation tissue. They are ideal for facial defects or finger tip injuries.
  • Grafts will not take on necrotic or infected tissue. Any vascularised bed can be grafted but exposed bone, tendon and fat needs to granulate before receiving a split-skin graft.

Anaesthesia

General, local or regional, depending on the site and size of the donor and recipient areas.

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Split-Skin

  • The donor and recipient areas are prepared and draped.
  • The harvested skin donor skin must be adequate to cover the recipient defect. The inside of the thigh is commonly used. Re-harvesting from a site can be performed after 20 days of re-epithelialisation but should be restricted to two thin re-harvests.
  • Dermatomes are used to take split skin grafts. They have sharp blades and the most common include variations of the , (a) Humbly knife, (b) the Silver, or (c) mechanical dermatomes powered by electricity or compressed air.
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  • The blade on a skin grafting knife is adjusted to the appropriate gap to allow excision of split skin to the thickness required, varying from thin, 8-15jm (Thiersch) to thick, 20-30jm.
  • The donor skin is stretched by an assistant and the graft taken with smooth slicing strokes as shown using a Humby knife on the inside of the thigh.
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  • The skin is immediately placed onto paraffin gauze, with the under, shiny side facing upwards
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  • A series of perforations or stabs aids graft adhesion by preventing fluid accumulating and separating the graft from the underlying tissues.
  • The graft is placed on the recipient area, which has been prepared by debridement or abrasion of any granulation tissue, and trimmed into shape with scissors.
  • Meshing of the graft increases the area which can be covered from a given donor site, as well as increasing the take rate and confirmability of a graft.
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  • The graft is secured with sutures, clips or glue.
  • It is then firmly dressed under even pressure to ensure stable contact with the underlying tissues. Tie over dressings using flavine soaked wool are useful for concave wounds.
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  • The donor area is dressed with hydrogel, plastic film, or calcium alginate to provide a moist environment.
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Full thickness

  • The recipient area is carefully prepated with complete haemostasis.
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An exact pattern of the defect is made with paper or foil.

  • A non-hairy donor is chosen; common sites include the skin behind the ear, the supraclavicular area, or the front of the forearm.
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  • The pattern is laid on the donor site, and an exact area of skin is excused and prepared for grafting by removal of all subcutaneous fat with a sharp scissors.
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  • The graft is then placed on the defect and sutured to the margins without tensions.

It may then be secured and dressed with a tie-over dressing.

Finally, the donor site is closed primarily with sutures.</p.

Main Postoperative Complications

These are failure of the graft to vascularise with resultant necrosis and infection.

Related Technique

Other techniques used to obtain skin cover include:

  • Various local flaps - advancement, transposition and Z-plasties.
  • Random pattern flaps such as the cross-finger flap.
  • Fascio-cutaneous flaps that come with their specific arteriovenous system and may include other tissues (compound), such as muscle, e.g. the latissimus dorsi flap used for reconstruction after mastectomy.
  • Free tissue transfer flaps are often compound and require microvascular anastomosis to suitable vessels at the recipient site.
  • Tissue expansion, with subcutaneous silicone expanders over several weeks, can be used to provide a local flap.