Biomedical Engineering Reference
In-Depth Information
Strains along DL axis:
-11% to - 67% (contrac
ons)
Strains along AP axis:
17% to 36% (extensions)
Fig. 8.7
Contraction of a full-thickness skin wound in the guinea pig dorsum. Tattoo marks were
placed 1 cm apart both along the anterior-posterior (AP) and dorsal-lateral (DL) directions outside
the 3·2 cm
2
full-thickness excisional defect. Marks close to wound edges were placed 2-3 mm
away from wound edges. Strains were determined as deformed length divided by the unstrained
length and were − 11 to − 67% (contractions) along the DL axis while being 17 -36 % (extensions,
possibly including translations) along the AP axis. Major deformation occurred by contraction
along the DL axis. (From Troxel 1994)
dermal edges, as well as translational perilesional movement of wound edges, also
participate in the closure process. However, the overall deformation pattern, as re-
ported by tattooing squares on the skin of the dorsal area of a guinea pig, has clearly
shown the presence of a reduction in skin wound area consistent with a principal
deformation axis along the dorsal-lateral (DL) axis for this defect. The deforma-
tions amounted to strains between − 11 and − 67 % (contractions) along the DL axis,
as well as lesser strains of 17 to 36 % (extensions, possibly including translations)
along the anterior-posterior axis (Fig.
8.7
, Troxel 1994). These observations were
nearly identical to the deformation pattern observed earlier in a guinea pig skin
wound using tattoo marks (Straile 1959).
8.3.2
Mechanics of Tissue Deformation During Spontaneous
Closure of Wounds
Mathematical models of the contractile force and the deformation during wound
closure in skin and peripheral nerve wounds are presented below. The models are
not designed to provide accurate representations of data. Instead, they provide a
