Clinical Review of Operative Result for Myelopathy due to Ossification of Intraspinal Canal Ligaments in the Thoracic Spine

A series of 33 patients with thoracic myelopathy due to ossification of intraspinal canal ligaments, treated by laminectomy, were examined with an average follow-up of six years (range, 2-16 years) after operation.In a retrospective analysis of the patients, the postoperative outcome was compared in patients with ossification of the yellow ligament (OYL) alone, and patients with the coexistence of OYL and ossification of the posterior longitudinal ligament (OPLL).Excellent and good results were obtained in 56% of patients with OYL alone, but in only 23% of patients with coexistence of OYL and OPLL.Several factors were associated with the unsatisfactory results for the patients with the coexistence of OYL and OPLL: failure to decide the correct site of lesion; inadequate decompression by laminectomy for the lesion on thoracic spine with an physiological kyphosis; and the coexistence of the dural ossification.No serious postoperative kyphotic deformities were encountered.