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.

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.

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.

The skin is immediately placed onto paraffin gauze, with the under, shiny side facing upwards

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.

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.

The donor area is dressed with hydrogel, plastic film, or calcium alginate to provide a moist environment.

Full thickness

The recipient area is carefully prepated with complete haemostasis.

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.

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.

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.