Methods of Skin-Grafting.—Two methods are employed: one in which the epidermis is mainly or exclusively employed—epidermis or epithelial grafting; the other, in which the graft consists of the whole thickness of the true skin—cutis-grafting.
Epidermis or Epithelial Grafting.—The method introduced by the late Professor Thiersch of Leipsic is that almost universally practised. It consists in transplanting strips of epidermis shaved from the surface of the skin, the razor passing through the tips of the papillæ, which appear as tiny red points yielding a moderate ooze of blood.
The strips are obtained from the front and lateral aspects of the thigh or upper arm, the skin in those regions being pliable and comparatively free from hairs.
They are cut with a sharp hollow-ground razor or with Thiersch's grafting knife, the blade of which is rinsed in alcohol and kept moistened with warm saline solution. The cutting is made easier if the skin is well stretched and kept flat and perfectly steady, the operator's left hand exerting traction on the skin behind, the hands of the assistant on the skin in front, one above and the other below the seat of operation. To ensure uniform strips being cut, the razor is kept parallel with the surface and used with a short, rapid, sawing movement, so that, with a little practice, grafts six or eight inches long by one or two inches broad can readily be cut. The patient is given a general anæsthetic, or regional anæsthesia is obtained by injections of a solution of one per cent. novocain into the line of the lateral and middle cutaneous nerves; the disinfection of the skin is carried out on the usual lines, any chemical agent being finally got rid of, however, by means of alcohol followed by saline solution.
The strips of epidermis wrinkle up on the knife and are directly transferred to the surface, for which they should be made to form a complete carpet, slightly overlapping the edges of the area and of one another; some blunt instrument is used to straighten out the strips, which are then subjected to firm pressure with a pad of gauze to express blood and air-bells and to ensure accurate contact, for this must be as close as that between a postage stamp and the paper to which it is affixed.
As a dressing for the grafted area and of that also from which the grafts have been taken, gauze soaked in liquid paraffin—the patent variety known as ambrine is excellent—appears to be the best; the gauze should be moistened every other day or so with fresh paraffin, so that, at the end of a week, when the grafts should have united, the gauze can be removed without risk of detaching them. Dental wax is another useful type of dressing; as is also picric acid solution. Over the gauze, there is applied a thick layer of cotton wool, and the whole dressing is kept in place by a firmly applied bandage, and in the case of the limbs some form of splint should be added to prevent movement.
A dressing may be dispensed with altogether, the grafts being protected by a wire cage such as is used after vaccination, but they tend to dry up and come to resemble a scab.
When the grafts have healed, it is well to protect them from injury and to prevent them drying up and cracking by the liberal application of lanoline or vaseline.
The new skin is at first insensitive and is fixed to the underlying connective tissue or bone, but in course of time (from six weeks onwards) sensation returns and the formation of elastic tissue beneath renders the skin pliant and movable so that it can be pinched up between the finger and thumb.
Reverdin's method consists in planting out pieces of skin not bigger than a pin-head over a granulating surface. It is seldom employed.