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.
