ABSTRACT
PURPOSE: The goal of this prospective study was to determine the prevalence of shoulder abnormalities on magnetic resonance imaging (MRI) in patients with ankylosing spondylitis (AS) who have normal shoulder X-ray examinations and no clinical shoulder abnormalities using a case-control study. MATERIALS AND METHODS: Fifty-three patients with AS according to the SpondyloArthritis international Society (ASAS) criteria were enrolled in the study. Fifty-three patients with no AS served as control subjects. Shoulder MRI examinations of patients in the two groups were analyzed and results were compared. RESULTS: In the patient group, 26/53 patients (49.1%) demonstrated one or two of the defined pathological shoulder MRI findings, whereas 5/53 patients (9.4%) had similar findings in the control group. In the patient group, 11/53 patients (20.8%) had enthesal bone marrow edema, 19/53 patients (35.8%) had increased synovial fluid, 8/53 patients (15.1%) had tendinitis, and 2/53 patients (3.8%) had bursitis. There was statistically significant difference between the patient and control groups in terms of prevalence of enthesal bone marrow edema, increase in synovial fluid, and tendinitis. CONCLUSION: Shoulder involvement is often overlooked in AS. Knowledge of the early-stage findings of the shoulder involvement due to AS is important to establish an early diagnosis and select treatment options.
