A new composite hemiface/mandible/tongue transplantation model in rats

Extensive head and neck deformities, including bone and soft tissue defects, are always challenging for reconstructive surgeons. The purpose of this study was to extend the application of the face/scalp transplantation model in rats by the incorporation of vascularized mandible, masseter and tongue (based on the same vascular pedicle), and to use this as a model to test new reconstructive options for extensive head and neck deformities with involving large soft and bone tissue defects.A total of 10 composite hemiface/mandible/tongue transplantations were performed in Lewis rats (RT1). Hemimandibular bone, masseter muscle, tongue and hemifacial skin flaps were dissected based on the same vascular pedicle of common carotid artery and external jugular vein. The flaps were then transplanted to the recipient inguinal region. Evaluation methods included flap angiography, plain x-ray, computed tomographic scan, and histology.All transplants survived indefinitely and no graft loss was noted. Flap angiography demonstrated intact vascular supply to the bone. Computed tomography scan and bone histology confirmed the viability of the bone components for the composite grafts. Hematoxylin and eosin staining determined the presence of viable bone marrow cells within the transplanted mandible. Viability of the tongue was confirmed by the presence of pink color and bleeding after puncture, as well as by histology.We have introduced a new composite hemiface/mandible/tongue transplant model. The main advantage of this model is the presence of vascularized bone marrow within the mandibular component, which may facilitate future studies on chimerism and tolerance induction. Although this mandible composite allograft is placed heterotopically to the recipient inguinal region, we believe that it may serve as a new reconstructive option for the coverage of combined bone and soft tissue defects within the head and neck region.