Ankylosing spondylitis (AS) is a type of arthritis causing chronic multisystem inflammation mainly of the spine with variable involvement of peripheral joints and non-articular structures. It primarily affects the spine, sacroiliac joints in the pelvis and hip joints. AS is a form of inflammatory arthritis. Enthesitis is a major feature of this disorder which involves inflammation of the place where ligaments and muscles are attached to the bones and accounts for much of the pain and rigidity. This can finally lead to severe bony fusion of the joints resulting in decreased flexibility and mobility.
AS is a systemic rheumatic disorder that can affect and involve multiple organs such as the eye, heart, lungs, skin as well as the gastrointestinal…show more content… [2] The primary pathology is enthesitis, which is considered hallmark for ankylosing spondylitis. Tumour necrosis factor- alpha (TNFα) and IL-1 are also associated with AS. There is a supposed interaction between the HLA-B27 gene and the CD8+ T cell which triggers the immune system to attack the cartilage. [3]
Ankylosing spondylitis belongs to a group of seronegative spondyloarthropathies in which the rheumatoid factor tests [3] are negative and the typical histological finding is an inflammation of the enthesis which is the insertion of tendon, ligament, capsule or surrounding fascia into bone.
In Ankylosing spondylitis the enthesis is inflamed at the vertebrae, showing that the entheseal fibrocartilage is major target of the immune system. Early leisons usually occur in the SI joints which include subchondral granulation that erodes the joint and is slowly replaced by fibrocartilage and ultimately ossification. In the spine it occurs at the junction of the vertebrae and anulus fibrosus of the intervertebral discs. These discs ultimately undergo ossification which results in syndesmophytes .This leads to ‘bamboo spine’ appearance and fusion of the vertebrae.
In addition there may be mild inflammation of the synovium which is present as a cushion around the
