Model parameter Identification of keloid-skin composite undergoing large deformations

International audienceThe aim of this paper is to characterize the mechanical behavior of cutaneous tissues with the long-term goal to prevent keloid development in patients. Keloids are non cancerous tumors [1] that grow continuously on the skin for several reasons. These specific tumors affect 11 million patients of all ages and are particularly frequent in the Asian and African populations. The evolution of keloids is related to genetic, biological, biophysical and biomechanical factors. Here we focus on the biomechanical aspects, such as the state of stress inside and surrounding the keloid, which is believed to significantly affect the keloid's growth [2]. We present a patient-specific methodology for the identification of hyper-elastic model parameters of a keloid-skin composite model of a patient. A keloid is observed on a patient using an ultrasound and optical microscopy. The 3D imageof the surface is use to develop the geometrical model of the keloid. To effectively characterize the mechanical behavior of the skin-keloid composite we investigate several hyper-elastic material models. The model parameters for the healthy skin and the keloid are determined using an inverse analysis approach; specifically, the model parameters are determined by minimizing the mismatch between the numerical and the experimentally obtained displacement fields. The experimental results are obtained in-vivo using a custom-made extensometer [3] and a digital image correlation (DIC) technique