The algebraic view-point in microskin grafting in burned patients.

Microskin grafting has proved to be an effective treatment for major burns when the area of available donor skin is inadequate. In fact, microskin grafting can be comparable to the patch graft of Gabarro. Further mincing procedures cut the skin patches into smaller pieces around 1 mm2. The healing process is completed by the epithelial migration between the micropatches. The possibly longest interpatch distance is related to the expansion ratio and the size of the microskin patch. From the equation L = x.(1.4 square root of Y-1.2) it is clear that the interpatch distance L is directly related to the patch side-length x. This means that when the patch side-length is doubled then the interpatch distance will be doubled. However the expansion ratio Y is related to its square root, so that the influence of the expansion ratio Y is much less important. For improving the healing process, the interpatch distance is better kept within 5 mm. With this understanding, we can calculate the required donor skin surface area for a given wound area according to the different side-length of micropatch, and also the possible maximum patch size for a given wound area for different available donor skin areas. As the area of available skin may be very limited, the maximum patch size may be smaller than the usual size (around 1 mm). Then we have to elongate the interpatch distance, though it would delay the healing. This is a purely theoretical reference. In normal clinical practice, the discussed conditions should be considered.