MRI based 3D finite element modelling to investigate deep tissue injury.

Pressure ulcers occur due to sustained mechanical loading. Deep tissue injury is a severe type of pressure ulcer, which is believed to originate in subcutaneous tissues adjacent to bony prominences. In previous experimental-numerical studies the relationship between internal tissue state and damage development was investigated using a 2D analysis. However, recent studies suggest that a local analysis is not sufficient. In the present study we developed a method to create animal-specific 3D finite element models of an indentation test on the tibialis anterior muscle of rats based on MRI data. A detailed description on how the animal specific models are created is given. Furthermore, two indenter geometries are compared and the influence of errors in determining the indenter orientation on the resulting internal strain distribution in a defined volume of tissue was investigated. We conclude that with a spherically-shaped indenter errors in estimating the indenter orientation do not unduly influence the results of the simulation.