57.2 Split skin grafting

You can cut split skin grafts thinner or thicker by varying the setting of the knife. A thinner split skin graft: (1) resists infection better, (2) takes more easily, (3) allows the donor area to recover quickly, which is useful if you want to cut a second crop of skin from the same place, and (4) is less likely to cause keloid formation in the donor area. But a thinner split skin graft also: (1) gives a worse colour match, (2) contracts more, (3) wears worse, and (4) is more difficult to sew in place. In practice, being able to vary the thickness of a graft is not important, and a graft of average or even varying thickness is enough for most purposes, except in large burns.

You can cut split skin grafts with many kinds of knife. Here we list the Humby knife as modified by Blair and Watson. This has disposable blades, but if you handle them carefully, you can use them several times. You can also cut skin grafts with an ordinary safety razor blade, a ’cut throat razor’, or even with a carving knife (57-10), but they must all be sharp. You cannot cut a graft with a blunt blade.

Figure 57.2: ADJUSTING A HUMBY KNIFE. A, and B, the pattern of bleeding points in the donor area. A, from a thinner graft. B, from a thicker one. C, and D, looking at the gap between the roller and the blade to adjust the thickness of the cut. Kindly contributed by Ian McGregor and Peter Bewes.

You can apply split skin as: (1) Sheets which cover the wound completely. (2) Sheets which have been cut and expanded to make a mesh graft, as in Fig. 57-6. (3) Patches (stamp grafts). (4) Strips. The wound will only be completely covered if you use sheets of skin. In all other kinds of split skin graft, including mesh grafts, the epidermis has to grow across gaps. This it can easily do, but the cosmetic result will not be so good. So, use sheets if possible, because they give a better cosmetic result, and you can, if necessary, sew them in place.

Patch grafts are: (1) More resistant to infection because the exudate easily drains from under them. (2) Small enough to fit into the concavities of an irregular wound. (3) Easier to take.

But: (1) You cannot expand patch grafts into a mesh. (2) They do not require any less skin. (3) The wound takes longer to heal. (4) They are uglier than single sheet sheet grafts, so they are particularly contraindicated on the face. They are useful if, a wound is very irregular, or there is serious oozing, or infection is not completely controlled. They are very much better than nothing, but avoid them if you can, and try to improve your technique, so that you can take sheet grafts. Once you can, you will seldom use patches again.

Strip grafts are intermediate in their properties between sheets and patches. One use of strip grafts is to be able to alternate strips of a severely burnt child’s own skin, and his mother’s skin. Another is in babies where a strip may be the only skin you can get.