gms | German Medical Science

Introduction: The disease course of non-radiographic axial spondyloarthritis (nr-axSpA), which is usually detected by magnetic resonance imaging (MRI), is often unclear at the time of diagnosis. We believe that early changes in the facet joints indicate a prognostically unfavorable course, which could impact therapeutic decisions.

Methods: Patients (n=56, age < 45 years, symptom duration 3–24 months) recently diagnosed with sacroiliitis through MRI, and met the Assessment of SpondyloArthritis International Society (ASAS) criteria for axial SpA were followed-up for 2 years. Clinical examination, laboratory values, and MRI of the sacroiliac joints (SIJs), lumbar spine, and facet joints were performed at diagnosis (t0), after 1 year (t1), and after 2 years (t2). The ASAS criteria and Berlin-score were used to score active inflammation and structural changes in the SIJs and spine [10–12]. A facet joint score was used based on the Weishaupt criteria describing the grade of osteoarthritis/chondropathy (0–3) modified and supplemented by the presence of synovitis (-/+) in each lumbar spine facet joint.

Results: Changes in the SIJs were assessed using the Berlin score. There was a significant increase in osteitis (bone marrow edema [BME] [p=0.001], ankylosis [p=0.001], sclerosis [left: p=0.012], and erosions [left: p=0.027; right: p=0.017] from t0 to t2. There was no significant change in fat lesions at the SIJ from t0 to t2. There were significant increases in synovitis (1.3 > 6.3) (- /+) and chondropathy (3.9 > 21.5, grades 0–3) at the facet joints between t0 and t2.

All changes to the vertebral bodies that is BME (p=0.001), fat lesions (p=0.001), and erosions (p=0.001), also significantly increased from t0-t2.

The presence of synovitis or chondropathy in the facet joints significantly influenced the changes in ankylosis at the SIJ, which varied between men and women (p=0.001). On the other hand, changes in osteitis at the SIJ were significantly associated with patient age (p=0.040) and the presence of synovitis at t0 (p=0.035).

Synovitis and chondropathy of the facet joints (≥2) significantly influenced the development of BME, fat lesions, osteitis, and erosion of the vertebral bodies.

Patient age in relation to the development of fat lesions and erosions on the vertebral bodies, sex in relation to BME on the vertebral bodies, and the absence of medication also influenced body changes. No influence was indicated for CRP, CRP-ASDAS, BASDAI, NSAIDs, or biologic medication.

Conclusion: Facet joint synovitis and chondropathy at the time of initial diagnosis of nr-axSpA could be a prognostic predictor of a less favorable disease course.

Disclosures: This study was funded from 2018 to 2021 by Novartis Pharma GmbH Germany.