Grade 0

Normal

Figure 1A. Grade 0 radiograph

Grade 1

Suspicious Changes

Figure 1B. Grade 1 radiograph

Grade 2

Minimum Abnormality

Figure 1C. Grade 2 radiograph

Small localized areas with erosion or sclerosis, without alteration in the joint width.

Grade 3

Unequivocal Abnorality

Figure 1D. Grade 3 radiograph

Moderate or advanced sacroiliitis with erosions, evidence of sclerosis, widening, narrowing, or partial ankylosis.

Grade 4

Severe Abnormality

Figure 1E. Grade 4 radiograph

Total ankylosis.