Objectives to investigate the prevalence of ultrasound (US) abnormalities in shoulders of patients with ankylosing spondylitis (AS), and to determine predictive factors of ultrasound shoulder enthesitis.

Methods 38 AS patients were included with 38 age and sex-matched healthy controls. All patients fulfilled the modified New York criteria for ankylosing spondylitis. Clinical and demographical data were recorded. US examination of bilateral shoulders was performed by a musculoskeletal sonographer according to a defined protocol that included imaging of the insertions of supraspinatus, subscapularis and infraspinatus tendons, rotator cuff tendons, subacromial-subdeltoid bursa, acromioclavicular joint, and glenohumeral joint.

Results the mean age of patients and controls was 36 years, each group of patients and controls comprised 22 men (57.9%) and 16 women (42.1%). Disease duration was 9.6±7.2 years. Among 38 AS patients, 21 had coxitis (55%) and 19 had previous or current shoulder pain (50%). AS shoulders presented significantly more ultrasound enthesitis than controls shoulders (43 shoulders (56.6%) versus 8 shoulders (10.5%) respectively). Involvement of rotator cuff tendons was significantly higher in AS patients compared with control subjects (16/38 (42.1%) versus 6 (15.2%) respectively). However, involvement of glenohumeral and acromioclavicular joints was infrequent in both groups. In AS patients, we found that the presence of coxitis was the only significant predictive factors of shoulder enthesitis (Odds Ratio (OR) =9.4; Confidence interval (CI)95% (1.10; 81.9), p=0.04)

Conclusions Ultrasound abnormalities of shoulders are common in patients with ankylosing spondylitis, and the most frequent abnormality was enthesitis, which was associated with the presence of coxitis.

Disclosure of Interest None Declared