Damage Modeling and Vascular Imaging Correlation with Implant Induced Skin Necrosis - Abstract Skin necrosis over implants is a major complication in facial plastics reconstruction over implants (nasal and auricular reconstruction), craniofacial skeletal implants (e.g. chin implants) and spinal scoliosis hardware. These complications have severe clinical implications, including infection, the need for implant removal, requirement for multiple additional surgeries and skin grafting. In fact, skin dehiscence over auricular implants is a major reason that much more complex and difficult rib grafts are used for auricular reconstruction. Although it is widely postulated that high stress and compression ischemia are responsible for skin ischemia, no quantitative investigations of vascular compromise nor skin damage have been performed. Such quantitative measures are necessary to better design mitigation methods for skin dehiscence over auricular and other implants placed under the skin. It is hypothesized here that high skin stress initiates compression induced skin ischemia that leads to adverse skin remodeling and loss of mechanical properties, finally resulting in skin dehiscence and implant/scaffold exposure. It is further hypothesized that finite element damage modeling predictions will correlate with in vivo skin damage, and thus will be a useful tool to design methods for skin dehiscence. In this proposal, continuum damage finite element modeling, photoacoustic tomography, and ultrasound elastography will be used to make in vivo measurements to test this hypothesis. In Aim 1, 3D print porous implants of two different topologies will be printed with different finite element predicted damage predictions to determine if this leads to different in vivo ischemia and damage distributions, establishing quantitative measures/correlations between FE model predicted damage and in vivo skin damage. In Aim 2, these in vivo measurements will be applied to determine how will structural versus structural plus biologic dehiscence mitigation measures compare in a large Yucatan miniswine model. Additionally, the in vivo measurements will be related to continuum damage nonlinear FE model predictions. The results of this proposal will lead to modeling procedures to design better implants that reduce dehiscence complications and imaging methods that can be used to predict which patients may be most at risk for suffering dehiscence complications.
