Posterior fusion of the occipital axis in children with upper cervical disorder using both C2 pedicle and laminar screws (C2 hybrid screws)

INTRODUCTION: An occipital-cervical surgery for children is challenging for surgeons because of the immature bone quality, extensive anatomical variability, and small osseous structures. Furthermore, occipital-C2 fusion in children results in great stress on the C2 screws. We report a technique that uses both C2 pedicle and bilateral lateral mass screws (C2 hybrid screws) in children with an upper cervical disorder to preserve motion segment and secure strength in those who require occipital-cervical fusion. CASE REPORT: Case 1 was that of a 5-year-old girl with Down syndrome who had atlantoaxial dislocation and os odontoideum. Owing to the C1 hypoplasia, the posterior arch was fractured by the C1 lateral mass screw. Therefore, O-C2 fusion was performed. C2 bilateral lamina screws were added along with the C2 bilateral pedicle screws for reinforcement. Case 2 was that of an 8-year-old boy who presented with torticollis and neck pain. The patient was diagnosed as having atlantoaxial rotatory fixation. The right vertebral artery was obstructed, and the left vertebral artery was dominant. The C1 posterior arch was bifid and assimilated with the occipital bone. C2 bilateral lamina screws were added with the right C2 pedicle screw for reinforcement. Both cases attained bone union after O-C2 fusion surgery using hybrid screws. CONCLUSIONS: The use of C2 hybrid screws with both C2 pedicle and bilateral lateral mass screws can preserve mobile segments in the fusion area in young children who require occipital-cervical fixation.