Fig. 2From: Radiographic involvement of cervical facet joints in ankylosing spondylitis: a longitudinal analysis in correlation with vertebral body lesionsFlowchart of included ankylosing spondylitis patients with spinal radiographic data. Several spinal radiographs within the given follow-up period were included per patient. (aSpinal radiographs were collected during any time point within the corresponding follow-up period. bCervical facet joints that were not visible on lateral radiographs or could not be evaluated due to spinal surgery)Back to article page