Fig. 1

A lateral radiograph of the cervical spine obtained from a 39-year-old ankylosing spondylitis patient with a disease duration of 18 years. At C3–C4 level, cervical facet joint with complete ankylosis is seen (arrowhead, a score of 3 according to de Vlam et al. [14]). Partial ankylosis and joint space narrowing is seen at C2–C3, C4–C5, and C5–C6 (white arrows, a score of 2) and C6–C7 level (dashed arrow, a score of 1), respectively. On the anterior side of the spine, bridging syndesmophtyes are seen