Upward subluxation of the axis in ankylosing spondylitis. A clinical pathologic report.

Upward subluxation of the axis associated with cord compression and death was noted in a patient with a long history of idiopathic ankylosing spondylitis. Upward subluxation of the axis has been recognized in up to 8 per cent of patients with rheumatoid arthritis but it is an exceedingly rare complication of ankylosing spondylitis. In this patient psoriasis and then psoriatic dactylitis developed 26 years after the onset of his ankylosing spondylitis. It is tempting to speculate that the unusual destruction of the joints around the atlas might be due to an added effect of psoriasis on idiopathic ankylosing spondylitis.