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play a distinct role at the early stages of contraction, to human skin. Pigskin resembles human skin in both
[17]
since studies have shown that keratinocytes are capable structure and function, having similar sparse hair coating,
of inducing collagen gel contraction in vitro. [12‑15] The a relatively thick epidermis, similar turnover kinetics, lipid
actinfilament organization within keratinocytes at the composition, carbohydrate biochemistry, lipid biophysical
wound margin appears to be responsible for the epidermal properties, and – what is most relevant to the present
“purse‑string phenomenon”. In addition, cytokines and study – a similar arrangement of dermal collagen and
[14]
growth factors such as ransforming growth factor‑β1, elastic fibers. [9,18] All these similarities establish the pig to
insulin‑like growth factor and fibroblast growth factors be an essential model in cutaneous research. Since in vivo
have also been found to play a major role in secondary experiments on primary skin grafts would require grafts
contraction. Unlike secondary contracture, which is of different shapes, minimum dimensions of 2 or 3 cm,
[15]
the result of a prolonged biological process, primary skin symmetrical locations of the grafts and suitable controls,
graft contraction is mainly an immediate physical change human experimental material is not available.
in graft dimensions mediated by the tough fibrous layer In our study, the skin grafts were harvested from pigs,
of the dermis, which is primarily composed of collagens, resulting in standardized specimens in terms of size, shape
glycosaminoglycans and elastins.
and location of the donor site and at the same time, skin
Davis and Kitlowski were the first to study the primary behavior close to that of human skin. The substantial
[3]
contraction of skin grafts. The authors used skin grafts from differences between our results and the results reported
patients of various age and donor sites and recorded the by Davis and Kitlowski, however, point out the different
[3]
percentage of skin contracture in relation to the thickness primary contraction behavior of human and porcine skin.
of the graft. Their results showed that, regarding the Although similar in many ways, different thicknesses and
“whole thickness skin grafts” (FTSGs), the mean amount of possibly different elastic properties between human and
shrinkage was 43.6% with little variations according to the porcine skin may lead to different contraction behaviors
donor site. The “half thickness skin grafts” (mid thickness of skin grafts. Furthermore, the rate of primary skin
split thickness STSGs) were presented with a mean shrinkage contraction probably depends on donor site characteristics.
of 24.86% and the “thick Ollier‑Thiersch grafts” (small grafts Clinical experience shows that skin harvested from the
with thinner periphery and thicker‑centered STSGs) with backs of patients presents limited contraction when
a mean shrinkage of 11.26% and 11.95% for abdominal compared with skin grafts from other sites. Furthermore,
and thigh donor sites, respectively. The very thin “true there was one specimen from the STSG group of the first
Ollier‑Thiersch grafts” (thin thickness STSGs) demonstrated part of the study that surprisingly showed 0% shrinkage.
a greatly reduced primary contraction of 1.24%. According Since 0% primary skin contraction before is rather unusual,
[3]
to the authors, the shrinkage observed was in direct we believe that this behavior was related to a specific
relation to the amount of dermis included in the harvested donor site and will be further investigated in upcoming
skin grafts. Using specimens from humans, however, had studies. Another possible reason for such a discrepancy
the limitation that the grafts and their donor sites could in skin graft shrinkage could be technical difficulties:
not be standardized according to the site, size and shape harvesting very thin skin grafts with small amounts of
of the examined grafts. Homogeneity of the samples was dermismay have been responsible for graft contraction.
further compromised due to variables like gender and age The mean percentage of primary skin graft contraction
of the studied subjects.
has found to be different in the two parts of the study,
Other authors had previously referred to the etiology of with mean values for both FTSG and STSG contraction
skin graft contraction, coming to the conclusion that the showing inconsistencies between the study series. These
network of elastic fibers of the dermis is responsible for unexpected differences were probably due to the small
its ability to stretch under the movement of the underlying number of specimens in the second part, which did not
[16]
tissues, as well as for the shrinkage of the skin graft. In yield statistically significant results. Furthermore, the use
Ragnell’s study on the secondary contracting tendency of of only one animal in the second part of the study may
free skin grafts, the elasticity of circular pieces of rabbit have magnified the role of biological variation, a matter
skin was estimated using a manometer device. The author that will be further investigated in future larger studies.
concluded that rabbit skin presented uniform elasticity, To the best of our knowledge, primary skin contraction
but no further studies on primary skin graft contraction in relation to the shape of the skin graft has never been
were performed. [16]
investigated before. In our study the mean graft shrinkage
Skin is a very complex, integrated, dynamic organ was 5.8% and 4.2% in circle‑shaped and square‑shaped
that has many functions. In mammals, the primary FTSGs, respectively [Table 2]. The difference was
functions of the skin include insulation and temperature more notable in the STSGs, where the circle‑shaped
regulation, although the role of the skin as an endocrine specimens showed graft shrinkage of 1.1%, whereas
organ and a critical component of the immune system the square‑shaped present a mere 0.31% [Table 2].
cannot be ignored. Species differences in all of these The difference recorded could be due to the relation of
[17]
functions may dramatically alter skin behavior regarding the line of contraction with the skin tension lines. Square
its mechanical characteristics or drug absorption. When specimens have one contraction vector that runs parallel
barrier, pelage, vascular, endocrine and immunological to the direction of the skin tension lines, whereas the
properties are considered en masse, pigskin is very similar round‑shaped specimens have multiple contraction

Plast Aesthet Res || Vol 2 || Issue 1 || Jan 15, 2015 25