Coloured x-ray of the right hip of a patient with ankylosing spondylitis. This is a progressive inflammatory disease that affects the joints, usually in the spine, but hip involvement is common. Here the hip is inflamed and there is some erosion of the ischium, the bone which forms the lower part of the pelvis, near the hip socket. Management of ankylosing spondylitis includes analgesic drugs and regular exercise.