Background Ankylosing spondylitis (AS) is a chronic inflammatory disease, which destructs spine. After ivnolvement of sacroiliac joint, inflammation usually spreads from lower L spine to C spine. But it is hard to evaluate radiographic changes in T spine due to air in lung by X-ray.

Objectives We performed this study to find out how many patients have radiographic changes in T spine at first visit and if bone spurs of vertebral bodies are associated with radiographic changes in facet joints in spine.

Methods We enrolled the patients who were diagnosed as AS by modified NY criteria in Kyung Hee university hospital at Gangdong in Seoul, South Korea from Mar 2008 to Dec 2015. After diagnosis, we performed a whole spine CT in each patient according to the routine protocol of our clinic to evaluate the radiographic involvement of spine. Total 1,170 patients were enrolled and analyzed. We examined the presence of bone spurs in vertebral bodies (VB) and radiographic changes of facet joints in L and T spine and costovertebral joints (CVJ).

Results Of the 1,170 enrolled patients. 920 were men (79%) and 85% were HLA B27 positive. Incidences of past history of peripheral arthritis and uveitis were 29.0% and 30.6%, respectively. Mean age was 33.0 ± 10.0 years and mean disease duration was 10.5 ± 9.5 years. 34.1% of patients had at least one bone spur and 26.3% had at least one lesion in facet joints in L spine. In T spine, 47. 2% of patients had already at least one bone spur, 28.2% had at least one lesion in facet joints. 32.8% had already at least one lesion in CVJs. Each radiographic change is associated with one another (p=0.00). These all radiographic changes were significantly more frequently observed in the patients with old age and long disease duration at the point of diagnosis (p=0.00). The lesion of CVJs and facet joints in T spine were observed more frequently in male than female significantly (respectively p=0.02, 0.00). 19.2% of the patients had radiographic changes in T spine without in L spine.

Conclusions At the point of diagnosis, many patients already had radiographic changes in T spine. We suggest if radiographic change of T spine is included in radiographic progression score system such as mSASSS, we can more sensitively detect radiographic progression even in a short interval.

Disclosure of Interest None declared