Figure 4

Theoretical basis of extended NPWT-assisted dermatotraction; The fasciotomy releases all the retention forces by fascia and skin, thus decrease the tissue pressures of the cylindrical compartment. (A). The cavitary NPWT increases the tissue pressure with shallow penetration to the deep tissue, and limits wound contraction because of the intervening sponge (B). The dermatotraction forces are concentrated on the anchoring point, which can disturb tissue perfusion and necrose the skin, especially in the stiff open fasciotomy wound of necrotizing fasciitis (red semicircle, C). Extended NPWT increases normal skin perfusion and sheers the wound margins to the central axis of the fasciotomy. This assists the dermatotraction by distributing the concentrated traction forces at the anchoring point and further approximating the wound margins. The near-circumferential adhesive surgical drape of the NPWT also limits tissue edema and delivers NPWT-generated increments of tissue pressure to the deep tissues like an elastic stocking (D).