Ossification of the posterior longitudinal ligament in Down's syndrome

Cervical myelopathy in patients with Down's syndrome is not uncommonly the result of atlanto-axial instability, a condition that is caused by ligamentous laxity and which may be associated with congenital osseous anomalies at the occipito-atlanto-axial axis. Ossification of the posterior longitudinal ligament (OPLL) is well described, particularly in the Japanese population, and may be associated with diffuse idiopathic skeletal hyperostosis. This is the first case, to our knowledge, of OPLL occurring in a person with Down's syndrome presenting with myelopathy.