Pos0513 Definition of Manubriosternal Joint Changes in Thorax Computed Tomography of Ankylosing Spondylitis Patients and Their Relationship With Clinical Features

Background: It is known that anterior chest wall involvement is common finding in Ankylosing Spondylitis (AS). Radiological changes of manubriosternal joint (MSJ) have not been well defined in literature and clinical importance of MSJ involvement is still unclear. The number of studies to assess MSJ involvement based on computed tomography (CT) is limited. Objectives: To define MSJ radiological changes of AS patients on Thorax CT and investigate relationship between MSJ involvement and other clinical features. Methods: Patients with AS diagnosis according to Modified New York criteria who underwent thorax CT imaging between 2013 and 2023 were included. Patients with a history of sternal surgical procedures were excluded. Demographic, clinical and radiographic data of the patients were recorded retrospectively based on Dokuz Eylul rheumatology database. Sagittal and coronal reformat images (in the bone window) on thorax CT were evaluated via the radiologist. Radiological changes were defined and classified into three group (Figure 1). Grade 0:Joint distance is normal, there is no sclerosis and erosion Grade 1:Joint distance is narrowed, there is subcortical sclerosis, cortical irregularity and erosion Grade 2:Partial or complete fusion of MSJ. Results: 236 AS patients (Male:165, 69.9%) were included. Mean age was 54.4±12 and mean age at diagnosis was 38.8 ±13. Median disease duration was 14 (1-50) years. Arthritis was occurred in 81 (34.3%) patients. 49 (20.8%) patients had history of heel enthesitis. Dactylitis was detected in only 2 patients. Uveitis was developed in 57 (24.2%) patients. Frequency of HLA-B27 positivity is 72% (n:108). Baseline C- reactive protein was high in 178 (75.4%) patients. 148 (62.7%) patients used methothrexate or sulfasalazin as monotherapy or combination therapy. Majority of patients (n:197, 83.4%) used biological therapy. In radiologic interpretation, 107 (45.3%) patients had bilateral grade 4 sacroiliitis, 30 (18%) patients had hip involvement. The prevelance of bamboo spine was % 20.7 (Table 1). 46 (19.5%) patients had normal MSJ on CT thorax. Most of patients had structural changes on MSJ. Grade 1 change was observed in 83 (35.2%) patients and grade 2 change was seen in 107 (45.3%) patients. MSJ involvement was not associated with demograhic and clinical parametres. While there was no relationship between hip involvement and MSJ changes, MSJ fusion was found more frequently in patients with syndesmophytes and bamboo spine (p<0.01). Conclusion: 1-Frequency of MSJ involvement was approximately 80% and fusion of MSJ was nearly 50%. 2-No relationship was observed between MSJ involvement and demographic and clinical parametres. 3-Radiological changes in MSJ were related with spinal involvement. Since the study group consisted of advanced stage patients with biologic therapy, the relationship between clinical features and MSJ may not have been revealed. A prospective study including early stage patients is needed to investigate the factors affecting MSJ involvement. REFERENCES: [1] Wendling D, Prati C, Demattei C, et al. Anterior chest wall pain in recent inflammatory back pain suggestive of spondyloarthritis. data from the DESIR cohort. J Rheumatol 2013;40(7): 1148–52 Acknowledgements: NIL. Disclosure of Interests: None declared.