Early signs and symptoms of ankylosing spondylitis may include pain and stiffness in your lower back and hips, especially in the morning and after periods of inactivity. Over time, symptoms may worsen, improve or stop completely at irregular intervals.
The areas most commonly affected are:
- The joint between the base of your spine and your pelvis
- The vertebrae in your lower back
- The places where your tendons and ligaments attach to bones, mainly in your spine, but sometimes along the back of your heel
- The cartilage between your breastbone and ribs
- Your hip and shoulder joints
When to see a doctor
Seek medical attention if you have low back or buttock pain that came on slowly, is worse in the morning or awakens you from your sleep in the second half of the night — particularly if this pain improves with exercise and worsens with rest. See an eye specialist (ophthalmologist) immediately if you develop a painful red eye, severe light sensitivity or blurred vision.
Ankylosing spondylitis has no known specific cause, though genetic factors seem to be involved. In particular, people who have a gene called HLA-B27 are at significantly increased risk of developing ankylosing spondylitis.
In severe cases of ankylosing spondylitis, new bone forms as part of the body's attempt to heal. This new bone gradually bridges the gap between vertebrae and eventually fuses sections of vertebrae together. Those parts of your spine become stiff and inflexible. Fusion can also stiffen your rib cage, restricting your lung capacity and function.
Other complications may include:
- Eye inflammation (uveitis). One of the most common complications of ankylosing spondylitis, uveitis can cause rapid-onset eye pain, sensitivity to light and blurred vision. See your doctor right away if you develop these symptoms.
- Compression fractures. Some people experience a thinning of their bones during the early stages of ankylosing spondylitis. Weakened vertebrae may crumble, increasing the severity of your stooped posture. Vertebral fractures sometimes can damage the spinal cord and the nerves that pass through the spine.
- Heart problems. Ankylosing spondylitis can cause problems with your aorta, the largest artery in your body. The inflamed aorta can enlarge to the point that it distorts the shape of the aortic valve in the heart, which impairs its function.