Ossification of the posterior atlantoaxial membrane associated with an os odontoideum: a case report.

Abstract

We report a case of ossification of the posterior atlantoaxial membrane associated with an os odontoideum in a 46-year-old woman. She developed myelopathy following a minor motor vehicle accident. The patient underwent posterior atlantoaxial arthrodesis and resection of the ossified lesion and recovered uneventfully. Long-standing atlantoaxial instability might have played a role in ectopic ossification of the posterior atlantoaxial membrane.