Unusual radiographic features in a female patient with ankylosing spondylitis

A 71 year old woman suffering from ankylosing spondylitis with aggressive peripheral joint disease for 46 years developed unusual radiographic features in the hips and knees. The pathogenic processes responsible are uncertain, and no histology is yet available. Although she had been treated with radiotherapy to the knees, there was no similar history to explain the hitherto unreported appearance of the hips.