POS0973 INFLUENCE OF ANATOMICAL VARIATION OF THE SACROILIAC JOINTS ON INFLAMMATORY LESIONS ON MAGNETIC RESONANCE IMAGING

Background Anatomical variation of the sacroiliac (SI) joints is more common among patients with LBP than healthy controls; increased biomechanical strain to joint may play a role in axial spondyloarthritis (axSpA). Objectives To assess association lesions shape on inflammatory SI magnetic resonance imaging (MRI) axSpA. Methods In this post-hoc analysis total 684 from four different prospective cohorts were evaluated (379 axSpA). Two readers independently scored all for form, erosion, sclerosis, fat metaplasia and bone marrow edema (BME). Logistic regression analyses used form; was performed separately axSpA controls. Results Typical observed 56.5% (200/354) 55.7% control (169/303); exhibited significantly higher proportion intra-articular variants (18.4% vs. 11.6%; p<0.001) crescent shapes (11.0% 5.3.%; AxSpA intraarticular form had odds erosions (OR 2.09; 95%CI 1.18-3.69) BME 1.79; 1.13-2.82); not seen Accessory sclerosis 2.54;95%CI 1.10-5.84) (2.05; 1.03-4.07) 17.91; 6.92-46.37) Conclusion Joint variations are associated MRI but indicates atypical forms sacroiliitis. References [1]Ziegeler, K., Kreutzinger, V., Proft, F., Poddubnyy, D., Hermann, K. G. A., & Diekhoff, T. (2021). anatomy spondyloarthritis: strong associations between symptomatic disease. Rheumatology (Oxford). doi:10.1093/rheumatology/keab318 Disclosure Interests Katharina Ziegeler Grant/research support from: Received research grant Assessment Spondyloarthritis international Society (ASAS)., Sevtap Tugce Ulas: None declared, Denis Poddubnyy Speakers bureau: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, Bristol-Myers Squibb, Roche, UCB, Biocad, GlaxoSmithKline Gilead, Fabian Proft AMGEN, BMS, Hexal, Janssen, Pfizer Lilly Valeria Rios Rodriguez AbbVie Falk e.V, Judith Rademacher: Kay-Geert Hermann Employee of: Co-owner BerlinFlame GmbH, Torsten Diekhoff Novartis