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of the patient, anatomical area and grafting over mobile circle shape and meticulously defatted. The FTSGs were
tissues may prompt skin graft contraction. [1,5‑7] placed on a flat surface 15 min after skin graft harvesting
to facilitate complete primary contraction; their diameter
Skin grafting is a major element of reconstructive
surgery. It is, therefore, important that every aspect of its was measured in 3 axes (with an axis‑to‑axis angle of 120°)
practice is thoroughly investigated and evaluated. Primary and the average diameter was used to calculate the radius
contraction was first described and assessed by Davis of the circle [Figure 1]. The mean value of the diameter
and Kitlowski in 1931. The authors of that pioneering was computed, and the surface was again calculated using
[3]
2
study used human specimens, a practice that has some the formula: area = πr .
limitations regarding the number, size and shape of skin For the study of STSG contraction, a rectangle stripe of
grafts. Furthermore, although > 80 years have elapsed, 4 cm height and 40 cm width was drawn with a permanent
there have not been any studies that further looked marker on the pig. Additional lines were drawn vertically
further into the development and cause of primary to produce 10 squares of equal 4 cm sides [Figure 1]. The
contraction. In this preliminary in vivo porcine study, we area of each square was calculated using the formula:
assessed the degree of primary skin graft contraction and area = s , where s = side of the square and the initial
2
investigated whether the shape of skin grafts affects the area value of 16 cm were recorded. All STSGs were
2
degree of contraction. harvested with a dermatome adjusted to 0.014 inch
skin thickness, corresponding to moderate to thick skin
METHODS grafts. The stripe was cut into squares according to our
drawings, and the grafts were placed on a flat surface and
The study was conducted at an accredited animal research left there for 15 min before measuring [Figure 1]. Due
facility (CRO, Lahav Research Institute, Lahav, Israel) to the primary contraction, the initial squares changed
following national and institutional guidelines for the into rectangles. Each side of the contracted STSGs was,
[8]
care and use of laboratory animals. The animals were therefore, measured, and the surface was calculated
anesthetized female domestic pigs (Susscrofa), weighing using the formula: area = h × w, where h = height and
approximately 30 kg. The study was approved by the w = width.
Institutional Animal Care and Use Committee. In the second part, we examined whether the shape
The study consisted of two parts. In the first part, of the skin graft affected the degree of contraction.
we compared the contraction of FTSGs and STSGs. For that purpose, we took a total of 27 specimens,
Four animals participated in the study, and a total harvested from the back of a single pig [Figure 2]. Nine
of 67 specimens of skin grafts were harvested from of these specimens were circle‑shaped FTSGs, 6 were
the back of the pigs, 41 and 26 of FTSGs and STSGs, square‑shaped FTSGs, 8 circle‑shaped STSGs and 4
respectively. square‑shaped STSGs. The harvesting and calculation of
the area of FTSGs and that of square‑shaped STSGs were
For the study of the FTSG contraction, circles of 4 cm made in the same way as in the first stage of our study,
diameter were drawn with a permanent marker on the skin with the initial surface area being 12.56 cm and 16 cm
2
2
of each pig [Figure 1]. The area of the circles marked was for the circle‑ and square‑shaped specimens, respectively.
calculated using the formula: area = πr , where r = radius For harvesting circle‑shaped STSGs, we used a dermatome
2
of the circle and π =3.14, resulting in the area value of to create a “skin belt” graft, which was subsequently cut
12.56 cm . The skin was excised with a No. 15‑blade in a
2
into a circle‑shaped skin graft with scissors. All STSGs
were harvested with a dermatome adjusted to 0.014 inch
skin thickness [Figure 2].
Statistical analysis was performed using Microsoft Excel
2003 (Microsoft, Redmond, Washington, USA) and SPSS
®
®
version 14 (IBM‑SPSS Inc., New York, USA). Statistical tests
used Pearson’s Chi‑square test and Student’s t‑test.

a b

c a b
Figure 1: First part of study. (a) Skin grafts marked on the back of the Figure 2: Second part of study. (a) Investigation of possible relation
animal. Circles are drawn with a permanent marker for the full‑thickness of shape of skin graft with degree of primary contraction. Circle‑ and
skin grafts (FTSGs) and squares for the split‑thickness skin grafts square‑shaped skin grafts excised from the back of a single animal.
(STSGs). (b) Full‑thickness skin grafts after excision and defattening. (b) Circle‑ and square‑shaped full‑thickness skin grafts and split‑thickness
(c) STGSs after excision skin grafts after excision

Plast Aesthet Res || Vol 2 || Issue 1 || Jan 15, 2015 23