Ankylosing spondylitis (AS)
Ankylosing spondylitis (AS) is a type of arthritis that mainly affects the back. It causes inflammation in the joints and spine, resulting in pain, stiffness and loss of function.
The main symptoms include low back or neck pain and stiffness in the morning which wears off during the day and improves with activity.
It can be associated with pain in the joints at the base of the spine, buttocks or backs of your thighs (sacroilitis) and be associated with fatigue. It may also be associated with pain, stiffness and swelling in other joints; tenderness around the heels (enthesitis); and swollen fingers or toes (dactylitis).
It can also cause inflammation of the chest wall can cause chest pain and inflammation of the eye.