Ankylosing spinal hyperostosis (ASH) and ossification of the posterior longitudinal ligament (OPLL).

The clinical and radiological features of 70 patients with ankylosing spinal hyperostosis are presented. Pain in some region of the back was found in 49 patients. No significant deviations were found in HLA typing. Radiologically, the most characteristic features were bony spurs or bridges in the dorsal spine, where they predominated on the right and anterior aspects of the spine, especially in the lower dorsal region. Ossification of the posterior longitudinal ligament was found in 21 patients.