CRANIAL VAULT EXPANSION USING TRANSCUTANEOUSLY ACTIVATED MAGNETIC IMPLANTS

The technique of distraction osteogenesis has not been widely used in the treatment of problems of the head and face because of the need for external fixators. By using magnetic, rather than mechanical, forces to drive bone movement we hope to expand the applications of the techn ique to include the treatment of cranial vault deformities. Thirty imm ature rabbits were studied. Twenty-six of the rabbits underwent operat ions. Each of the 26 had 2 magnets fixed to its skull: one on the left parietal bone and one on the right parietal bone. Incomplete circumfe rential osteotomies were then performed around each magnet on 13 of-th e rabbits. A head frame was attached to each animal. Head frames witho ut magnets were placed on 6 of the rabbits (3 with osteotomy, 3 withou t osteotomy) while 20 of the animals (10 with osteotomy, 10 without os teotomy) had 2 magnets mounted on the frames which were of opposite po larity to those implanted. The remaining 4 rabbits served as nonoperat ive controls. Six weeks later all of the animals were sacrificed. Ther e were significant differences in the cranial volumes and contours bet ween the groups of animals. Many of the differences were increased by coincident osteotomy. Associated histologic findings are described.