34-year-old male with AS. Inflammatory lesions of the anterior chest wall are shown (curved arrows). Inflammatory changes are seen in the lower thoracic spine and L1 (arrows).<unk>  is a member of the more broadly defined disease axial spondyloarthritis. Axial spondyloarthritis can be divided into (1) radiographic axial spondyloarthritis (which is a synonym for<unk>  and (2) non-radiographic axial spondyloarthritis (which include less severe forms and early stages of<unk> . While<unk>  can be diagnosed through the description of radiological changes in the sacroiliac joints and spine, there are currently no direct tests (blood or imaging) to unambiguously diagnose early forms of<unk>  (non-radiographic axial spondyloarthritis). Diagnosis of non-radiologic axial spondyloarthritis is therefore more difficult and is based on the presence of several typical disease features. These diagnostic criteria include: * Inflammatory back pain:Chronic, inflammatory back pain is defined when at least four out of five of the following parameters are present: (1) Age of onset below 40 years old, (2) insidious onset, (3) improvement with exercise, (4) no improvement with rest, and (5) pain at night (with improvement upon getting up) * Past history of inflammation in the joints, heels, or tendon-bone attachments * Family history for axial spondyloarthritis or other associated rheumatic/autoimmune conditions * Positive for the biomarker HLA-B27 * Good response to treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) * Signs of elevated inflammation (C-reactive protein and erythrocyte sedimentation rate) * Manifestation of psoriasis, inflammatory bowel disease, or inflammation of the eye (uveitis) If these criteria still do not give a compelling diagnosis magnetic resonance imaging (MRI) may be useful. MRI can show inflammation of the sacroiliac joint. Imaging X-rays The earliest changes demonstrable by plain X-ray shows erosions and sclerosis in sacroiliac joints. Progression of the erosions leads to widening of the joint space and bony sclerosis. X-ray spine can reveal squaring of vertebrae with bony spur formation called syndesmophyte. This causes the bamboo spine appearance. A drawback of X-ray diagnosis is the signs and symptoms of AS have usually been established as long as 7–10 years prior to X-ray-evident changes occurring on a plain film X-ray, which means a delay of as long as 10 years before adequate therapies can be introduced. Options for earlier diagnosis are tomography and MRI of the sacroiliac joints, but the reliability of these tests is still unclear. File:AnkSponTLateral2016.Lateral X-ray of the mid back in<unk>  File:AnkSponCLateral2016.Lateral X-ray of the neck in<unk>  File:Bamboo spine<unk> .X-ray showing bamboo spine in a person with<unk>  File:Ankylosing<unk> .CT scan showing bamboo spine in<unk>  File:M Bechterew2 Spond li ISG MR pcor T1 FatSAT mit GD.T1-weighted MRI with fat suppression after administration of gadolinium contrast showing sacroiliitis in a person with<unk>  Blood parameters During acute inflammatory periods, people with AS may show an increase in the blood concentration of CRP and an increase in the ESR, but there are many with AS whose CRP and ESR rates do not increase, so normal CRP and ESR results do not always correspond with the amount of inflammation that is actually present. In other words, some people with AS have normal levels of CRP and ESR, despite experiencing a significant amount of inflammation in their bodies. Genetic testing Variations of the HLA-B gene increase the risk of developing<unk> , although it is not a diagnostic test. Those with the HLA-B27 variant are at a higher risk than the general population of developing the disorder. HLA-B27, demonstrated in a blood test, can occasionally help with diagnosis, but in itself is not diagnostic of AS in a person with back pain. Over 85% of people that have been diagnosed with AS are HLA-B27 positive, although this ratio varies from population to population (about 50% of African Americans with AS possess HLA-B27 in contrast to the figure of 80% among those with AS who are of Mediterranean descent). BASDAI The Bath<unk>  Disease Activity Index (BASDAI), developed in Bath (UK), is an index designed to detect the inflammatory burden of active disease. The BASDAI can help to establish a diagnosis of AS in the presence of other factors such as HLA-B27 positivity, persistent buttock pain which resolves with exercise, and X-ray or MRI-evident involvement of the sacroiliac joints. It can be easily calculated and accurately assesses the need for additional therapy; a person with AS with a score of four out of a possible 10 points while on adequate NSAID therapy is usually considered a good candidate for biologic therapy. The Bath<unk>  Functional Index (BASFI) is a functional index which can accurately assess functional impairment due to the disease, as well as improvements following therapy. The BASFI is not usually used as a diagnostic tool, but rather as a tool to establish a current baseline and subsequent response to therapy. Children Juvenile<unk>  <unk>  is a rare form of the disease which differs from the more common adult form. Enthesophathy and arthritis of large joints of the lower extremities is more common than the characteristic early-morning back pain seen in adult AS.<unk>  tarsitis of the ankle is a common feature, as is the more classical findings of seronegative ANA and RF as well as presence of the HLA-B27 allele. Primary engagement of the appendicular joints may explain delayed diagnosis, however other common symptoms of AS such as uveitis, diarrhea, pulmonary disease and heart valve disease may lead suspicion away from other juvenile spondyloarthropathies. Schober's test The Schober's test is a useful clinical measure of flexion of the lumbar spine performed during the physical examination.
Ankylosing spondylitis
Plantar fasciitis
Axial spondyloarthritis
Oligoarthritis
Osteoarthritis
Spondyloarthropathy
Enteropathic arthropathy
Spondylolysis