LAUSR

Background: The severity of Spondyloarthritis (SA) lies mainly in the progressive ankylosis of the axial skeleton and the deformations generated. The means of assessing the spinal static disorders in SA are currently subjective and difficult to reproduce. Multidisciplinary collaboration has led to the development of a new biplane low dose radiology technology named EOS. It allows a simultaneous acquisition of the axial skeleton and the lower limbs in a standard standing position. Objectives: We aimed to assess pelvic and spinal parameters and spinal stature in patients with SA using the EOS system. Methods: This is a prospective cross-sectional study conducted over a 10-month period (January-October 2018) involving 50 patients with SA meeting the criteria of Assessment of SpondyloArthritis International Society. An entire body EOS examination of the vertebral column in a standardized standing position was performed in all patients. Pelvic parameters measured by the EOS system were pelvic incidence (PI: normal value: 48-55°), sacral slope (SS: normal value: 36-42°) and lateral pelvic tilt (LPT: normal value: 12-18°). Spinal stature parameters were thoracic kyphosis (normal value: 41-48°), lumbar lordosis (normal value: 43-61°), sagittal vertical axis (SVA: normal value: <30mm) and spinosacred angle (SSA: normal value: <132). Results: We enrolled 29 men (58%) and 21 women (42%) with an average age of 42.6 ± 11.09 years [20 -79]. The mean duration of SA was 12.4 ± 9.71 years [2-46]. SA was axial in 17 patients (34%), and axial and peripheral in 29 patients (58%). The median PI was 50.7 ± 11.81°. The median SS was 35.8 ± 11.64°. The median LPT was 14.9 ± 8.97°. The average value of thoracic kyphosis was 52.1± 12.1°. The average value of lumbar lordosis was 37.4 ± 16. The median SVA was 25.2 ± 55.88 mm and the median of SSA was 123.9 ± 16.64°. Thus, deformity of the thoracic spine was found in 40 patients (80%) with thoracic hypercyphosis type and thoracic rectitude in 12% and 68% of cases respectively. The deformity of the lumbar spine was found in 40 patients (80%) with lumbar hyperlordosis type and lumbar rectitude in 74% and 6% of cases respectively. From this construction and segmenting the SS values, we were able to classify the type of back according to Roussouly : the type 2 back was the most frequently found (40%), followed by type 3 back (34%), type 4 back (24%), and type 1 back (2%). Spinal deformities were more frequent in women (p=0.004) and associated with a longer duration of the disease (p<0.0001) and a longer duration before initiation of treatment (p<0.0001) (Table 1). Conclusion: Our study showed that the EOS system was a useful technique in assessing pelvic and spinal stature in patients with SA.Abstract THU0402 –Table 1 Association of the spinal deformities with clinical parameters Parameter Spinal deformities Female sex p=0.004 Age p=0.126 Duration of the disease p<0.0001 Active disease p=0.233 Axial spondyloarthritis p=0.146 Duration before treatment p<0.0001 Disclosure of Interests: None declared