Clinical and radiological evaluation of sacroiliac joints compared with ultrasound examination in early spondyloarthritis.

OBJECTIVE: To compare clinical and X-ray examinations with US findings of SI joints (SIJ) in early SpA patients. METHODS: Twenty-three early SpA patients, diagnosed according to Assessment of SpondyloArthritis international Society criteria, were investigated clinically [sacral sulcus tenderness, BASMI, BASFI, BASDAI, pain and fatigue visual analogue scale (VAS), morning stiffness and sleep disturbance], with SIJ X-rays (New York score) and with My Lab70 US 7-10 MHz US (Esaote, Genoa, Italy), evaluating the width of the SIJ capsule and posterior sacroiliac (PSL) and sacrotuberosus (STL) ligament thickness and comparing the results with 23 healthy controls. RESULTS: SIJ width [right 2.2 (0.6) and left 2.3 (0.7) in SpA vs 1.6 (0.1) and 1.7 (0.2) in healthy controls, respectively, expressed as mean (s.d.)] and STL thickness [right 3.9 (1.3) and left 3.4 (1.0) vs 1.8 (0.1) and 1.8 (0.1), respectively, expressed as mean (s.d.)] were higher in SpA patients than in controls (P < 0.001 and P < 0.05, respectively). PSL thickness was similar in patients and controls. Only STL thickness was higher when SIJ was tender at clinical examination (P < 0.01) and correlated with pain VAS (P < 0.001) and BASFI (P < 0.05). Furthermore, SIJ US results were unrelated to X-ray findings (similar when X-ray sacroiliitis was present and not). CONCLUSION: Our exploratory study suggested that in early SpA patients US might be a promising method, complementary to other imaging techniques, to study articular and soft tissue periarticular involvement of SIJ, independent of clinical and X-ray examination.