Table 1.

Grading of radiographic sacroiliitis

Grade	Stage	Explanation
0	Normal	Unchanged morphology of the joint
I	Suspicious	Blurring of the joint margins
II	Minimal abnormality	Small localised areas of erosions or sclerosis, without alteration of the joint width
III	Unequivocal abnormality	Moderate/advanced sacroiliitis: ≥ 1 out of: erosions, sclerosis, widening/narrowing of the joint space, partial ankylosis
IV	Severe abnormality	Total ankylosis