Radiographic Evaluation of Thoracic Ossification of the Posterior Longitudinal Ligament(OPLL).

We reviewed the radiographic evaluation of patients with OPLL, especially in the thoracic spine. Subjects included 398 patients with OPLL (278 male, 120 female who ranged in age from 29 to 90 years (mean 59 years). Sixty nine of 398 patients had thoracic OPLL (29 male, 40 female). Thoracic OPLL was observed radiographically in 33.3% of all female patients in contrast to 10.4% of all male patients. In the cervical spine, the male to female ratio was 3:1, but the ratio was reversed in the thoracic spine. We think this difference in ratio results from hereditary factors and in our latest study, we postulate that thoracic OPLL may be different from cervical OPLL.