X-ray of the pelvis and sacral spine of a person suffering from ankylosing spondylitis, showing fusion of both sacro-iliac joints. Ankylosing spondylitis is a chronic inflammatory arthritis of the spine and sacro-iliac joints, which connect the sacral spine to the pelvis. Inflammation typically begins in the sacro-iliac joints or lumbar spine, & may progress up the entire spine. Shoulders and hips may also be affected. Pain and stiffness are treated with anti-inflammatory drugs (ibuprofen, piroxicam) and through physiotherapy, which attempts to preserve spinal mobility.