Ankylosing spondylitis definition, etiology, pathogenesis, clinical features, diagnosis, treatment is an inflammatory condition mainly affecting the spine, which causes progressive stiffness and pain It is part of a group of seronegative spondyloarthropathies conditions that are related to the HLA B27 gene The key joints affected in AS are: - the sacroiliac joints and - the spinal joints The inflammation causes pain and stiffness in these joints Around 90% of patients with AS have the HLA B27 gene, however only around 2% of people with this gene will develop AS This percentage is higher (around 20%) if they have a first-degree relative who has had ankylosing spondylitis Typical exam presentation is a young adult male in his 20s - The NICE guidelines (2017) provide guidance on the diagnosis of spondyloarthritis They point out that the disease affects women and men equally Symptoms develop gradually over more than 3 months The main symptoms are low back pain and stiffness, as well as sacroiliac pain in the buttocks The pain and stiffness are worse at rest and relieved by movement The pain is worse at night and may even wake the patient in the morning It takes at least 30 minutes for stiffness to relieve in the morning, and the pain gradually decreases with activity throughout the day Symptoms can fluctuate, with "flares" of worsening symptoms and other periods when symptoms improve Vertebral fractures are a key complication of AS -Systemic symptoms such as weight loss and fatigue -Chest pain, which is associated with the costovertebral and costothoracic joints -Enthesitis is inflammation of the entheses (inflammation at the attachment sites of tendons, fascia, ligaments to bones - i.e. where tendons or ligaments enter bone) This can cause problems such as plantar fasciitis and Achilles tendonitis -Dactylitis is inflammation of a finger or toe -Anemia -Anterior uveitis -Aortitis is inflammation of the aorta Heart block can be caused by fibrosis of the heart's conduction system Restrictive lung disease can be caused by limitation of chest movement Pulmonary fibrosis in the upper lobes of the lungs occurs in about 1% of patients with AS Schober's test Medication: -NSAIDs can be used to relieve pain -If there is no adequate improvement after 2-4 weeks of the maximum dose, consider switching to a different NSAID -During a flare-up, steroids can be used to control symptoms These can be oral, sustained-release intramuscular injections, or joint injections -Anti-TNF (anti-TNF) drugs such as etanercept or monoclonal antibodies against TNF such as: -infliximab, -adalimumab, or -certolizumab pegol is known to be effective in treating disease activity in AS Secukinumab is a monoclonal antibody against interleukin-17. NICE recommends it if the response to NSAIDs and TNF inhibitors is inadequate Additional management: -Physiotherapy -Exercise and mobilisation -Avoid smoking -Bisphosphonates to treat osteoporosis -Treatment of complications Sometimes surgery is required for spinal or other joint deformities