How do the radiographic features of sacroiliac and spine involvement in ReA compare with those in ankylosing spondylitis?
Note that 100% of patients with ankylosing spondylitis develop radiographic changes in the sacroiliac joints compared with only 20% to 25% of ReA patients. Patients with inflammatory bowel disease also develop radiographic changes of their spine similar in appearance to those of ankylosing spondylitis, whereas psoriatic arthritis produces changes similar to ReA.
Radiographic Features of Sacroiliac and Spine Involvement in Reactive Arthritis in comparison with those in Ankylosing Spondylitis
| Ankylosing Spondylitis | Reactive Arthritis | |
|---|---|---|
| Sacroiliitis | Bilateral, symmetric | Unilateral or asymmetric |
| Spondylitis | Bilateral, thin, marginal syndesmophytes | Asymmetric, nonmarginal, “jug-handle” syndesmophytes |
Note: Unilateral sacroiliitis without peripheral arthritis does not occur in ReA and should suggest another diagnosis (e.g., infection).
