High sacral slope, lumbar lordosis, and sacral slope-to-pelvic incidence ratio are associated with new bone formation in ankylosing spondylitis

Abstrakt

Background/aim: Syndesmophyte formation appears to be site specific in Ankylosing spondylitis(AS),and new bone formation seems to occur in regions of micro-trauma that are prone to tensile forces.Pelvic and spinal parameters are unique for individuals. Pelvic tilt and sacral slope are important anatomical features that compensate in harmony in keeping the sagittal balance. After puberty, the sacral slope shapes the lumbar lordosis, whereas the pelvic incidence is set to an individual constant. This study aims to analyze the properties of pelvic parameters in AS patients with and without syndesmophyte formation in the spine after 15years of disease duration.Materials and methods:Whole spine radiographs of 104 AS patients and clinical data are analyzed according to radiographic damage in the spine.AS patients were grouped as with or without syndesmophytes. Patients with complete bridging in at least one vertebral unit were excluded. Sacral slope,pelvic tilt,pelvic incidence,and lumbar lordosis were measured. Results: The mean disease duration was 14.5 years, and 60% of AS patients were male. Groups were similar in terms of age, sex distribution,and disease duration. Although numerically higher in patients with syndesmophytes, the mean pelvic incidence of AS patients was not different between groups(55.2±13.6 vs. 57.2±15.4). The sacral slope was high in patients with lumbar syndesmophytes(p