Atlantoaxial subluxation associated with ossification of posterior longitudinal ligament of the cervical spine

Study Design. Two case reports. Objective. To demonstrate two rare cases of atlantoaxial subluxation associ ated with ossification of the posterior longitudinal ligament of the cervic al spine in which spastic quadriplegia developed. Summary of Background Data. There are only two reports of an association of diffuse idiopathic skeletal hyperostosis with atlantoaxial subluxation. Th is condition often accompanies ossification of the posterior longitudinal l igament of the cervical spine, but there is nothing in the literature about the association of ossification of the posterior longitudinal ligament wit h atlantoaxial subluxation. Methods. Clinical and radiographic findings of these two cases were demonst rated. In both cases laminoplasty of the cervical spine was performed with occipitoaxial arthrodesis. Results. The spastic quadriplegia of these two patients caused by myelocomp ression improved after surgical intervention. Conclusion. Ossification of the posterior longitudinal ligament of the cerv ical spine may case atlantoaxial subluxation.