Occult radiological sacroiliac abnormalities in patients with inflammatory bowel disease who do not present signs or symptoms of axial spondylitis

Objective. To investigate radiological sacroiliac abnormalities in IBD patients without musculoskeletal symptoms and to determine the clinical and familiar differences between IBD patients with and without radiologic sacroiliac joint (SIJ) abnormalities. Subsequently, the patients with x-ray alterations were followed for 3 years in order to assess the onset of chronic inflammatory back pain (IBP). Methods. 81 patients (55 Crohn - CDand 26 ulcerative rettocolitis - UC) with remittent and low active IBD, from a tertiary referral centre of gastroenterology Unit, were studied using SIJ x-rays. Differences in IBD clinical variables (activity and duration of CD and UC, extra-intestinal involvement, treatment with surgery and not, ESR and CRP levels), familiarity (for psoriasis, IBD, spondyloarthritis, coeliac syndrome), between patients with SIJ x-ray findings and without were investigated. Patients with radiological sacroiliac joint abnormalities were followed up clinically for 3 years and the onset of symptoms of chronic (higher than 3 consecutive months) IBP was investigated. Results. 22/81 patients (27.1%) showed radiological SIJ abnormalities at baseline: isolated sclerosis in 17/22 (77.3%) and localised erosions in 12/22 (54.5%). Radiological SIJ involvement did not correlate with IBD clinical and familial variables. All patients were HLA B27 negative. At 3 years, 4/22 patients (18.1%) presented chronic IBP symptoms with bone oedema at MRI. Conclusions. In IBD, occult radiological SIJ alterations might precede the onset of axial symptoms but, in the absence of clinical signs, it is not possible to identify some IBD features or familiar predisposition that might be more frequent when SIJ abnormalities are involved. Clinical follow-up might be useful in these patients for a diagnosis of axial spondyloarthritis onset.