Biomechanical Modeling of the Forces Applied to Closed Incisions During Single-Use Negative Pressure Wound Therapy

Objectives: The use of negative pressure wound therapy (NPWT) on closed surgical incisions is an emerging technology that may reduce the incidence of complications such as surgical site infections. One of the mechanisms through which incisional NPWT is thought to operate is the reduction of lateral tension across the wound. Methods: Finite element analysis computer modeling and biomechanical testing with Syndaver SynTissue™ synthetic skin were used to explore the biomechanical forces in the presence of the PICO(⋄) (Smith & Nephew Ltd, Hull, United Kingdom) negative pressure wound therapy system on a sutured incision. Results: Finite element analysis modeling showed that the force on an individual suture reduced to 43% of the force without negative pressure (from 1.31 to 0.56 N) at −40 mm Hg and to 31% (from 1.31 to 0.40 N) at −80 mm Hg. Biomechanical testing showed that at a pressure of −80 mm Hg, 55% more force is required for deformations in the tissue compared with the situation where no negative pressure wound therapy dressing is active. The force required for the same deformation at −120 mm Hg is only 10% greater than at −80 mm Hg, suggesting that most of the effect is achieved at −80 mm Hg. Conclusions: The results show that a canister-less single-use NPWT device is able to reduce the lateral tension across a closed incision, which may explain observed clinical reductions in surgical site complications with incisional NPWT.