Time course of radiologic lesions in spinal hyperostosis: an osteoradiometric study

The purpose of this study was to evaluate changes over time in the flowing spinal ossification characteristic of spinal hyperostosis. Thirty-two patients were studied. A QR-ORM osteoradiometry apparatus was used to measure variations in the surface area of the ossification on radiographs obtained after three, ten, and 20 years. The size of the ossification increased gradually in every case. Patients with a small ossification on the initial radiograph and younger patients were more likely to have larger ossification size increases over time; male gender and diabetes mellitus had a similar effect, although the differences were not significant, perhaps because of the small number of subjects. The magnitude of the ossification increase was not the same on the anteroposterior and lateral films at the various time points. The rate of ossification increase was slower in patients with long-standing disease or osteoporosis, although differences were not statistically significant. Over time, the density of the ossification increased, particularly near the vertebral bodies, perhaps as a result of transformation of fibrocartilage tissue into compact bone tissue.