Inflammatory back pain is usually a dull ache, difficult to localize, and felt deep in the buttocks or lower back. The back pain is frequently associated with stiffness and spasm of the paraspinal muscles and inflammation of the sacroiliac (SI) joints. In some cases, ankylosing spondylitis symptoms can also start in the neck or peripheral joints such as the hips and shoulders.
Prolonged inactivity usually worsens the pain and stiffness, while exercise and physical activity tend to ease them. Pain may awaken the patient at night. Some patients find it necessary to exercise or move about for a few minutes before returning to bed and may have difficulty getting out of bed in the morning.
AS patients may have a fused spine and an 11 times higher risk of spinal fracture.