Ankylosing spondylitis of the cervical spine

Lateral view of the cervical spine (A) in a patient with ankylosing spondylitis shows ossification of the outer annulus fibrosis (arrowheads), which bridges adjacent vertebral bodies. This has resulted in bony fusion of the cervical vertebral bodies. Diffuse osteopenia is present. Image B is a magnified view and shows ossification of the annulus fibrosis (arrowheads).