Illustration depicting<unk>  The signs and symptoms of<unk>  often appear gradually, with peak onset being between 20 and 30 years of age. Initial symptoms are usually a chronic dull pain in the lower back or gluteal region combined with stiffness of the lower back. Individuals often experience pain and stiffness that awakens them in the early morning hours. As the disease progresses, loss of spinal mobility and chest expansion, with a limitation of anterior flexion, lateral flexion, and extension of the lumbar spine, are seen. Systemic features are common, with weight loss, fever, or fatigue often present. Pain is often severe at rest but may improve with physical activity, but inflammation and pain to varying degrees may recur regardless of rest and movement. AS can occur in any part of the spine or the entire spine, often with pain referred to one or the other buttock or the back of the thigh from the sacroiliac joint. Arthritis in the hips and shoulders may also occur. When the condition presents before the age of 18, it is more likely to cause pain and swelling of large lower limb joints, such as the knees. In prepubescent cases, pain and swelling may also manifest in the ankles and feet where heel pain and enthesopathy commonly develop. Less commonly ectasia of the sacral nerve root sheaths may occur. About 30% of people with AS will also experience anterior uveitis, causing eye pain, redness, and blurred vision. This is thought to be due to the association that both AS and uveitis have with the inheritance of the HLA-B27 antigen. Cardiovascular involvement may include inflammation of the aorta, aortic valve insufficiency or disturbances of the heart's electrical conduction system. Lung involvement is characterized by progressive fibrosis of the upper portion of the lung.
Ankylosing spondylitis
Plantar fasciitis
Axial spondyloarthritis
Oligoarthritis
Osteoarthritis
Spondyloarthropathy
Enteropathic arthropathy
Spondylolysis