Abstract. The frequency of pathology of the musculoskeletal system against the background of inflammatory bowel diseases (IBD) reaches 40%. The aim of the study was to assess the frequency, clinical, biochemical, and radiological features of axial (ankylosing spondylitis) and peripheral arthropathy type I, biochemical markers of bone metabolism disorders, and bone mineral density (BMD) parameters in comparison with the phenotype, clinical features, and morphometric characteristics of CD3-immunopositive colonocytes in patients with Crohn’s disease (CD) and ulcerative colitis (UC).
Material and methods. The study included 157 patients with UC and 37 patients with CD. In patients with ankylosing spondylitis in IBD, a quantitative assessment of the general state of health was performed using the BASDAI questionnaire, the combined ASDAS index of CRP, and the functional activity of patients using the DFI index. Structural changes in the musculoskeletal system were verified by X-ray examination of the sacroiliac joint, spine, and large joints. To assess the biochemical markers of BMD, the levels of tartrate-resistant acid and alkaline phosphatase, and ionized calcium were determined in the blood serum. Instrumental methods included densitometry with the determination of the T-score. The results of morphometric and immunohistochemical studies were taken into account with the assessment of the quantitative density of CD3-positive colonocytes of the epithelium and the own plate of the colon mucosa.
Results and conclusion. Pathology of the musculoskeletal system in IBD was diagnosed in 48,6% of patients with CD and in 14% of patients with UC. Bowel disease debuted as arthropathy in 2,5% of patients with UC and in 13,5% of patients with CD. For peripheral arthropathies of type I on the background of IBD, non-erosive changes in the articular surfaces without joint deformity were characteristic. Osteopenic syndrome was detected in 8,2% of patients. In UC, the risk factors for osteopenia were a recurrent course of the disease with a history of 3–5 years; in CD, terminal ileitis with a history of up to 1 year, a recurrent course. In 3,1% of cases, osteopenia is associated with steroid-dependent forms of IBD. Osteopenic syndrome in IBD was also associated with an increase in the quantitative density of CD3-positive colonocytes in the epithelium and in the self-plate of the colon mucosa. In patients with ankylosing spondylitis on the background of CD, the maximum increase in these parameters was observed.

Keywords: inflammatory bowel diseases, ulcerative colitis, Crohn’s disease, CD3-positive colonocytes, osteopenic syndrome, ankylosing spondylitis, peripheral arthropathies I type