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            The name ankylosing spondylitis can be broken down as ankylosing means stiffening spondylo refers to the vertebra and itis refers to inflammation so ankylosing spondylitis is a chronic inflammatory disease that affects the vertebral joints and makes the spine really stiff but can also cause inflammation. In other parts of the body like the eyes and blood vessels ankylosing spondylitis also called bectoru disease is part of a group of diseases called seronegative spondyloarthropathies.

Spondyloarthropathies are all autoimmune diseases that affect the joints and they're seronegative which refers to the fact that rheumatoid factor which is an autoantibody is not found in the blood. Alright so in a healthy adult the vertebral column is made up of 33 bones from top to bottom the first seven bones are the cervical vertebrae the next 12 are the thoracic vertebrae and the last five are the lumbar vertebrae below that is a bone called the sacrum which is attached to the pelvic bone on either side called the ilium and where they meet is the sacroiliac joint below the sacrum is a tiny bone called the coccyx or tailbone.

Now there are two types of joints between the vertebrae between each of the vertebral bodies is an intervertebral disc which is made of type 1 and type 2 collagen and has two parts the annulus fibrosis an outer fibrous ring and the nucleus pulposus and inner jelly-like substance, this disc forms a joint between each vertebra and it allows slight movement and acts as a shock absorber. In addition to the inner vertebral discs, each vertebra has joints called facet joints with the vertebra above and the vertebra below one on each side these joints are synovial meaning they have a joint capsule and a small amount of synovial fluid in between. When you stretch your back the capsule in these joints stretches too and decreases the pressure in the joint space which makes any gas suddenly come out of the solution making a cracking sound these help guide and limit the range of motion in your spine.

In ankylosing spondylitis, there's a chronic inflammation of the inner vertebral joints and the facet joints of the spine the exact cause of inflammation is unclear but it's thought to be due to an autoimmune process which is when the immune system attacks its own tissue, in this case, the type 1 and type 2 collagen in the joints but unlike many other autoimmune conditions no autoantibodies been specifically linked to the disease normally. The cells of the immune system are ready to spot and destroy anything foreign that could cause the body harm help with this most cells in the body to have a set of proteins that combine together to form something called a major histocompatibility complex or MHC.

Class1 molecule that sits on the surface of their cell membrane most individuals with ankylosing spondylitis have the gene HLA b27 which is a gene that encodes for a specific type of MHC class1 molecule these specific proteins act kind of like a serving platter and presents molecules from within the cell for the immune system to continually sample a type of t lymphocyte called a Cd8positive t cell also known as a cytotoxic t cell uses its t cell receptors to bind to the antigen presented by the MHC class 1 molecule normally the molecule is just a sample from the cell and the immune system recognizes it as harmless and this is known as a self-antigen and there's no response but when these cells recognize a foreign molecule they use cytokines to signal other immune cells to migrate to the joint capsule in the joint space that's under attack cells like Neutrophils.

The Neutrophils release cytokines like tumor necrosis factor-alpha or TNF alpha and interleukin-1 or IL1 which worsen the inflammation over time the inflammation destroys the inner vertebral joints as well as the facet joints in the sacroiliac joints and fibroblasts replace the destroyed joint with fibrin layers and layers of fibrin form a tough fibrous band around the outside of the joints which limits their range of motion eventually osteoblasts get activated and a process called ossification start which is when the fibrous tissue turns to bone.

In the beginning, small bony outgrowths will form at the joint edges called syndesmophytes this makes the part of the spine that's affected immobile and sometimes that can be the entire spine other parts of the body can be affected too like the eye which can cause anterior uveitis the aortic valve can also sometimes get inflamed and damaged leading to aortic regurgitation there can also be inflammation of tendons like the Achilles tendon called enthesitis.

Ankylosing spondylitis is a systemic inflammatory disease that can cause symptoms like weight loss fevers and fatigue if ankylosing spondylitis affects the sacroiliac joints it typically causes buttock pain and if it affects the cervical or thoracic region it can cause neck or back pain and stiffness because the ribs and vertebrae are involved in breathing stiffness can cause shortness of breath. Ankylosing spondylitis can be diagnosed using MRI where there's typically erosion and narrowing of the joint spaces early on and joint fusion later on and X-RAY and CT often show a bamboo spine which is caused by the ossification of the annulus fibrosis on the outside of a straightened spine giving it a hollow appearance genetic testing for HLA b27 can be done to help confirm the diagnosis inflammation and pain from ankylosing spondylitis is usually treated with non-steroidal anti-inflammatory drugs like ibuprofen.

The pain can also be relieved by exercise or physical therapy in more severe cases disease-modifying anti-rheumatic drugs or DMARDS like sulfasalazine and methotrexate can be helpful, newer therapies called biologics can also be useful because they block the actions of cytokines like tumor necrosis factor-alpha and the interleukins surgery can repair damaged hip and knee joints but spinal surgery is typically considered risky and is rarely performed.

Alright as a quick recap enclosing spondylitis is an autoimmune process associated with the HLA b27 gene which attacks vertebral joints in this process collagen gets destroyed and replaced by fibrin and ultimately ossification sets in forming a bamboo spine on X-RAY or CT Scan, it can also affect the eyes, aorta, tendons, and lungs helping current and future clinicians focus learn retain and thrive.

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