Background
Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease. Osteoporosis is a common feature of AS, with a prevalence of 19% to 62%. Previous studies have indicated the increase of osteoclast activity responsible for the development of osteoporosis in AS. However, to our best knowledge, the osteogenic activities of osteoblasts in AS has never been addressed before. Therefore, the objective of this study was to investigate the proliferation and differentiation of osteoblasts derived from the vertebral body and lamina in AS patients and to compare the differences of osteoblast activities between AS and age-matched controls.