Study of the force distribution within wound dressing microstructures, using Finite Element models informed and validated by micro-CT imaging and Digital Volume Correlation (Industry Project)

The ABM CDT is a partnership between The Universities of Manchester and Sheffield. ALL APPLICATIONS should however, be submitted via the Manchester application system only.

There is a strong clinical need to improve the microstructure and material properties of wound dressing to optimise wound healing.

The process is affected by biomechanical and biological stimuli. However, most of current research neglects the biomechanical component, namely how the dressing exchange forces with the soft tissues it is applied to and deforms. This is due to the experimental challenges in measuring how the construct “soft tissue + wound dressing” deforms under load.

In this project we will use a combination of advanced imaging, biomechanical experiments and computer models to optimise the biomechanical properties of the dressing (its microstructure and material).

First, we will measure the local deformation of the dressing alone or applied to the tissue with state of the art experiments performed inside a high resolution scanner (XRay microCT) combined with advanced image processing (digital volume correlation). 

Then we will create realistic computational models (finite element models) of the dressing alone and applied to the soft tissues from the microCT images.

We will validate the local deformation of the tissues predicted by the models with the outputs of the experiments. 

Finally, we will use the validated models to evaluate the biomechanical properties of the dressing alone and when applied to the soft tissues, identifying the best microstructural and material properties of the dressing.

Project Description

Wounds are disruptions in the continuity of the epithelial lining of the skin or mucosa resulting from physical or thermal damage.  Wound dressings with different materials and microstructures are available, but it is difficult to optimise their properties to achieve optimal healing [1]. 

In fact, the microstructure and biomechanical competence of the dressing alone and when applied to the tissue is poorly understood. This is due to experimental challenges in measuring the local load distribution and deformation between the dressing and the soft tissue it is applied to.

3D finite element (FE) models have been used at the organ level to study the biomechanical competence of the dressing in different conditions [2].  However, these models do not consider the microstructure of the dressing. The deformation of soft tissues treated with wound dressing has been studied at the tissue level with 2D FE models [3], which however ignores the effect of complex 3D loads. Moreover, these models need to be validated against experiments before using them for preclinical and clinical assessment. 

Recently Digital Volume Correlation (DVC) approaches based on micro-computed tomography (microCT) images have been used to study the deformation in different types of tissues [4]. The DVC inputs two 3D images of the object scanned in its unloaded and loaded configurations. The outputs produced are the full 3D displacement and deformation fields. The DVC approach has been widely used to validate FE models of different hard tissues [5] and biomaterials but its application on soft tissues has been limited.

Main questions to be answered

The aim of this study is to develop a combined experimental and computational approach to evaluate the biomechanical competence of wound dressings applied to soft tissues, in order to optimise their microstructural and material properties.

Objectives:

1. To analyse the data from in situ microCT imaging and DVC test of a dressing alone and applied to soft tissues (porcine tissue to start with, including skin, subcutaneous fat, and muscle), extracting the important information to inform and validate the FE models
2. To create a finite element models of the dressing, informed and validated from the experimental tests
3. To create a finite element models of the dressing plus soft tissues, informed and validated from the experimental tests
4. To use the validated FE model to evaluate the force distributions for two types of available wound healing dressings.