How diagnosis of ankylosing spondylitis?

Diagnosis of ankylosing spondylitis, it was important to make an inspection is the sacroiliac joint is situated X-ray. If the X-ray found unilateral or bilateral sacroiliitis arthritis, patients with the diagnosis of ankylosing spondylitis main conditions. In some basis, as long as the patients have low back pain (whether past or now), or lumbar (flexion, extension, lateral bending) completely restricted, or measurement of the expansion of activities of the thorax equal to or less than 2.5 cm, Some three more than an anomaly, can be diagnosed with ankylosing spondylitis.