Composite hemiface/calvaria transplantation model in rats

Extensive craniomaxillofacial deformities including bone and soft-tissue defects are always challenging for reconstructive surgeons. The purpose of this study was to extend application of the face/scalp transplantation model in the rat by incorporation of the vascularized calvarial bone, based on the same vascular pedicle, as a new treatment option for extensive craniomaxillofacial deformities with large bone defects.

Seven composite hemiface/calvaria transplantations were performed across major histocompatibility complex barrier between Lewis-Brown Norway and Lewis rats. Seven donor and seven recipient rats were used in this study. Hemicalvarial bone and face grafts were dissected on the same pedicle of the common carotid artery and jugular vein and were transplanted to the deepithelialized donor faces. All rats received tapered and continuous doses of cyclosporine A monotherapy. Evaluation methods included flap angiography, daily inspection, computed tomographic scan, and bone histology.

Flap angiography demonstrated the vascular supply of the bone. The average survival time was 154 days. There were no signs of rejection and there was no flap loss noted at 220 days posttransplantation. Bone histology at days 7, 30, 63, and 100 after transplantation revealed viable bone at all time points, and computed tomographic scans taken at days 14, 30, and 100 revealed normal bones without resorption.

For extensive face deformities involving large bone and soft-tissue defects, this new osteomusculocutaneous hemiface/calvaria flap model may serve to create new reconstructive options for covering during one surgical procedure.