Background Ankylosing Spondylitis (AS) is a chronic inflammatory disease characterized by inflammation at the enthesis in the spine and peripheral skeleton, which may lead to a local bony erosion or juxta insertionally osteoporosis in the early stages.

Osteoporosis has long been recognized as a common finding in patients with AS. In different reports, the osteopenia or osteoporosis frequency ranged from 50 to 92 percent. Osteoporosis arising from AS is caused by: genetic disposition, Calcium and Vitamin D absorption disorder, which relates to chronic inflammatory bowel damages and some taken medications in this group of diseased such as Glucocorticoids which effects are depending on the taken dose and treatment period.

Objectives To determine the frequency of osteoporosis in AS and to compare changes of bone densitometry (BMD) after one year treatment with or without Bisphosphonate.

Methods We checked two BMD with one year interval, early in our management and after one year treatment of disease with or without the use of Bisphosphonate. Total patients over whom we did our survey were 57, eight of which were women and 49 were men. 28 of patients, received standard treatment of AS and 29 other ones not only treated normally but also received Alendronate as well.

Results Before treatment, T-score average of lumbar vertebrae in the group which used Alendronate was -2.26 (± 1.69) and this amount in the other group was -1.14 (± 1.12) (p-value 0.00). After passing one year of treatment this amount changed to -1.67 (± 1.74) in the group which have taken Alendronate and -0.96 (± 1.48) (p-value 0.04) in the other group. In addition the average of T-score deference of lumbar vertebrae, before and after passing one year of treatment in that group received Alendronate was -0.59 (± 0.38) and 0.18 (± 1.17) in the other group (p-value 0.04). Before treatment, T-score average of the femoral neck in the group which used Alendronate was -1.6 (± 1.23) and this amount in the other group was 0.69 (± 0.9) (p-value 0.00). After passing one year of treatment this amount changed to -0.97 (± 1.29) in the group which have taken Alendronate and -0.77 (± 0.95) (p-value 0.02) in the other group. In addition the average of T-score deference of the femoral neck, before and after passing one year of treatment in the group that received Alendronate was -0.62 (± 0.68) and 0.08 (± 0.69) in the other group (p-value 0.00).

Conclusions Altogether, densitometry survey done over these two groups showed that T-score of diseased in both groups has been improved after treatment in comparison with the period they passed before treating, of course this amount of enhancement was more notable it the first group which received Alendronate.

Disclosure of Interest None Declared