{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T17:26:25Z","timestamp":1779211585468,"version":"3.51.4"},"reference-count":39,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2025,2,8]],"date-time":"2025-02-08T00:00:00Z","timestamp":1738972800000},"content-version":"unspecified","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2025,1,28]]},"published-print":{"date-parts":[[2025,2]]},"abstract":"<jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>Anatomical variation of the sacroiliac (SI) joints is common and specific variants are associated with erosions and bone marrow oedema on imaging. Our investigation aims to evaluate whether anatomical variations influence the clinical presentation of axial spondyloarthritis (axSpA).<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>In this propensity score matched post hoc analysis documented clinical data from four prospective clinical cohorts was assessed. Classification of back pain as inflammatory (=IBP), human leucocyte antigen-B27 positivity, family history, disease activity according to Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), symptom duration, elevated acute phase reactants, peripheral and extramusculoskeletal manifestations were evaluated. Statistical analyses were done using (generalised) linear models, t-tests, \u03c7<jats:sup>2<\/jats:sup> tests and analysis of variances. Multiple testing was corrected according to Bonferroni.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>A total of 165 patients (86 women) were included. Atypical SI joints, defined by the presence of accessory joint facets, iliosacral complex or crescent-shaped ilii on MRI, were identified in 61 out of 165 patients with axSpA. Disease activity, assessed by BASDAI and symptom duration were similar in both groups (adjusted \u00df=\u22120.118 (95% CI -0.713, 0.476), p=0.696\u2009and 120.0 (107.4) vs 116.5 (98.3) months, p=0.838, respectively). There was no significant difference in IBP between the groups (adjusted OR=0.614 (95% CI 0.274, 1.377), p=0.236). Sex-stratified analysis revealed no statistically significant results.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusion<\/jats:title>\n                  <jats:p>Our analysis suggests that clinical phenotypes do not significantly differ between patients with axSpA with and without atypical joints.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/rmdopen-2024-004923","type":"journal-article","created":{"date-parts":[[2025,2,8]],"date-time":"2025-02-08T12:30:21Z","timestamp":1739017821000},"page":"e004923","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":3,"title":["Influence of sacroiliac joint variation on clinical features of axial spondyloarthritis: a comparative analysis"],"prefix":"10.1136","volume":"11","clinical-trial-number":[{"clinical-trial-number":"nct01277419","registry":"10.18810\/clinical-trials-gov"}],"author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-0485-0920","authenticated-orcid":false,"given":"Carolina Dominguez","family":"Aleixo","sequence":"first","affiliation":[{"name":"Department of Radiology, Charit\u00e9 University Hospital Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9763-2420","authenticated-orcid":false,"given":"Katharina","family":"Ziegeler","sequence":"additional","affiliation":[{"name":"Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3871-3746","authenticated-orcid":false,"given":"Sevtap Tugce","family":"Ulas","sequence":"additional","affiliation":[{"name":"Department of Radiology, Charit\u00e9 University Hospital Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3593-1449","authenticated-orcid":false,"given":"Torsten","family":"Diekhoff","sequence":"additional","affiliation":[{"name":"Department of Radiology, Charit\u00e9 University Hospital Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7945-0538","authenticated-orcid":false,"given":"Juliane","family":"Greese","sequence":"additional","affiliation":[{"name":"Department of Radiology, Charit\u00e9 University Hospital Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3690-1161","authenticated-orcid":false,"given":"Maximilian","family":"Lindholz","sequence":"additional","affiliation":[{"name":"Department of Radiology, Charit\u00e9 University Hospital Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7442-2570","authenticated-orcid":false,"given":"Judith","family":"Rademacher","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology, Charit\u00e9 - Universit\u00e4tsmedizin Berlin, Berlin, Berlin, Germany"},{"name":"Berlin Institute of Health at Charit\u00e9, Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5612-043X","authenticated-orcid":false,"given":"Valeria","family":"Rios Rodriguez","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology, Charit\u00e9 - Universit\u00e4tsmedizin Berlin, Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4537-6015","authenticated-orcid":false,"given":"Denis","family":"Poddubnyy","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology, Charit\u00e9 - Universit\u00e4tsmedizin Berlin, Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4306-033X","authenticated-orcid":false,"given":"Fabian","family":"Proft","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology, Charit\u00e9 - Universit\u00e4tsmedizin Berlin, Berlin, Berlin, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2025,2,8]]},"reference":[{"key":"2025090313004276000_11.1.e004923.1","unstructured":"Wong M , Sinkler MA , Kiel J . Anatomy, abdomen and pelvis, sacroiliac joint, disclosure: margaret sinkler declares no relevant financial relationships with ineligible companies. disclosure: john kiel declares no relevant financial relationships with ineligible companies. StatPearls. Treasure Island (FL) ineligible companies; 2023."},{"key":"2025090313004276000_11.1.e004923.2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(16)31591-4"},{"key":"2025090313004276000_11.1.e004923.3","doi-asserted-by":"publisher","DOI":"10.1136\/ard.2008.101501"},{"key":"2025090313004276000_11.1.e004923.4","doi-asserted-by":"publisher","DOI":"10.1002\/art.21619"},{"key":"2025090313004276000_11.1.e004923.5","doi-asserted-by":"publisher","DOI":"10.1136\/ard.2009.108233"},{"key":"2025090313004276000_11.1.e004923.6","doi-asserted-by":"crossref","DOI":"10.1186\/s13075-016-1093-z","article-title":"Prevalence of peripheral and extra-articular disease in ankylosing spondylitis versus non-radiographic axial spondyloarthritis: a meta-analysis","volume":"18","author":"de Winter","year":"2016","journal-title":"Arthritis Res 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