Computational modelling of wounded tissue subject to negative pressure wound therapy following trans-femoral amputation

Abstract

Proof-of-concept computational models were developed and applied as tools to gain insights into biomechanical interactions and variations of oxygen gradients of wounded tissue subject to negative pressure wound therapy (NPWT), following trans-femoral amputation. A macro-scale finite-element model of a lower limb was first developed based on computed tomography data, and distributions of maximum and minimum principal stress values we calculated for a region of interest (ROI). Then, the obtained results were applied iteratively as new sets of boundary conditions for a specific spatial position in a capillary sub-model. Data from coupled capillary stress and mass- diffusion sub-models were transferred to the macro-scale model to map the spatial changes of tissue oxygen gradients in the ROI. The −70 mmHg NPWT resulted in a dramatic change of a wound surface area and the greatest relative contraction was observed at −150 mmHg. Tissue lateral to the depth of the wound cavity revealed homogenous patterns of decrease in oxygenation area and the extent of such decrease was dependent on the distance from the wound surface. However, tissue lateral to the width of the wound demonstrated heterogeneous patterns of change, as evidenced by both gradual increase and decrease in the oxygenation area. The multiscale models developed in the current study showed a significant influence of NPWT on both macro-deformations and changes of tissue oxygenation. The patterns of changes depended on the depth of the tissue, the geometry of the wound, and also the location of tissue plane.Electronic supplementary materialThe online version of this article (doi:10.1007/s10237-017-0921-7) contains supplementary material, which is available to authorized users.

The potential of a canister‐based single‐use negative‐pressure wound therapy system delivering a greater and continuous absolute pressure level to facilitate better surgical wound care

“…18,19 In this clinical context, we hypothesise here that the continuous action of suNPWT may aid the healing of surgical wounds, by reducing the lateral tension along the incision line and, particularly, the levels of the mechanical stress concentrations around the suture sites (Figure 1). 20 Although computational finite element (FE) modelling has been used extensively to investigate the effects of various medical devices on tissue function, including, as in our own work, to study the roles of NPWT in wound closure, [20][21][22][23] very little research has been published on specifically modelling surgical incisions treated by NPWT. Wilkes and colleagues 24 who modelled a two-dimensional cross-sectional geometry of a closed incision managed through NPWT and Loveluck et al 25 who similarly simulated a thin-slice of a surgical incision treated by NPWT only considered the in-plane mechanical effects of NPWT in their respective FE models.…”

“…Although computational finite element (FE) modelling has been used extensively to investigate the effects of various medical devices on tissue function, including, as in our own work, to study the roles of NPWT in wound closure, 20‐23 very little research has been published on specifically modelling surgical incisions treated by NPWT. Wilkes and colleagues 24 who modelled a two‐dimensional cross‐sectional geometry of a closed incision managed through NPWT and Loveluck et al 25 who similarly simulated a thin‐slice of a surgical incision treated by NPWT only considered the in‐plane mechanical effects of NPWT in their respective FE models.…”

Wound contraction under negative pressure therapy measured with digital image correlation and finite-element analysis in tissue phantoms and wound models

“…In addition, practical challenges of experimental studies could be avoided in finite-element (FE) simulations, since they can assess the interactive force projection without a need to disturb the local structures [11]. The FE analysis was applied to predict the micro-deformations experienced by tissues during NPWT in both open [6,[12][13][14][15][16] and closed [17,18] wounds. Wilkes et al [17] modelled 2D crosssections of wounds through an incision with subcutaneous void and with sliding facial separation.…”

“…It was also demonstrated by the same authors [20] that the resulting mechanical forces within different tissue components varied substantially by the pressure applied with the NPWT device. A recent proof-of-concept study [16] developed a multi-scale computational model and applied it as tools to gain insights into biomechanical interactions and variations of oxygen gradients in wounded tissues subject to the NPWT.…”