The pattern of spinal and extraspinal hyperostosis in patients with ossification of the posterior longitudinal ligament and the ligamentum flavum causing myelopathy.

Thirty one patients suffering from myelopathy associated with ossification of the posterior longitudinal ligament and ligamentum flavum of the spine have been investigated. The pattern of spinal and peripheral hyperostosis was recorded in each case. Flowing anterior vertebral hyperostosis and ligamentous ossification at the enthesis around the pelvis and hips were the most frequent associations, occurring in approximately 86% of patients. The distribution and incidence of the spinal and extraspinal hyperostosis in this series corresponds closely to the findings in diffuse idiopathic skeletal hyperostosis (DISH). The present findings indicate that patients suffering from cervical myelopathy and ossification of the posterior longitudinal ligament should be regarded as manifesting focal features of a more generalised disorder producing skeletal hyperostosis.