Tension decrease during skin stretching in undermined versus not undermined skin: An experimental study in piglets

In a controlled study using 15 piglets, the efficacy of skin stretching usi ng a skin stretching device was tested by quantifying the tension decrease during skin stretching in undermined and not undermined wounds. The viabili ty of the skin margins was examined in both situations. Thirty standardized wounds was created: around 15 wounds on one flank, the surrounding skin wa s undermined; whereas around the 15 wounds on the opposite flank, the surro unding skin was not undermined. The force required to close tile 9 X 9 cm d efect was rneasllred at the beginning, after undermining, and after 30 minu tes of skin stretching. Also examined was tile wound healing after 1 day an d 1 week. A tension decrease of 3.02 N (13.6 percent reduction of the total force that is required to close the wound at the beginning) was seen due t o undermining the surrounding skin. Skin stretching for 30 minutes without undermining the skin showed a tension decrease of 6.10 N (26.5 percent). Th erefore, the tension decrease due to skin stretching was twice as high in c omparison with undermining the skin margins alone. This has been statistica lly proven to be significant (-d (difference) = 3.08,95 percent confidence interval = 2.16; -2.00, p < 0.001). When the undermined skin of tile wound was stretched for 30 minutes, we measured a total tension decrease of 7.60 N (34.1 percent). There was a statistically significant but small differenc e in total tension decrease as a result of undermining combined with skin s tretching in comparison with skin stretching without undermining (-d = 1.51 , 95 percent confidence interval = 0.77; 2.23, p < 0.001). Undermining the surrounding skin involved cutting musculocutaneous perforating vessels. Loo king at the viability of the skin, seven wounds, all found in the undermine d group, showed skin necrosis after 1 week. Excessive seroma formation was seen in all wounds around which the skin was undermined. In the not undermi ned wounds, there were ilo problems in wound healing. In conclusion, skin s tretching for only 30 minutes using a skin stretching device significantly reduces wound closing tension. The additional advantage of skin stretching over that of undermining alone is clearly shown. Undermining the wound marg ins before skin stretching gives a small additional tension decrease but ha s well-known complications, such as skin-edge necrosis and seroma formation .