What Is It?
Spondyloarthritis is a family of related inflammatory diseases that affect the joints and the entheses (the connective tissue between the bone and tendons or ligaments). This umbrella of diseases includes Ankylosing Spondylitis (AS) and closely related Psoriatic Arthritis (PsA), as well as Reactive Arthritis and Undifferentiated Arthritis.
(Pronounded "Anky low sing Spon dill eye tiss") The name of this type of arthritis comes from the Greek words angkylos (which means "bent", but in modern times "ankylosis" has come to mean "stiffening") and spondylos (which means "spinal vertebrae"). Any word ending in "itis" denotes inflammation. Therefore "spondylitis" means inflammation of the spinal vertebrae. If you put it all together you have "stiffening, bending and inflammation of the spinal vertebrae".
Other names for this disease include Bechterew Disease and Marie Struempell Disease.
AS is a chronic and systemic arthritis that is believed to be autoimmune in nature (with the exception of a few doctors who prefer to refer to it as autoinflammatory rather than autoimmune). It primarily affects the sacroiliac joints and the axial skeleton, although it also can involve the peripheral joints, shoulders, ribs, hips and jaw. Some of the classic clinical symptoms of the disease include back pain (sometimes severe) and increasing stiffness and immobility of the spine and ribs.
There may be other systemic manifestations as well, such as uveitis or iritis, inflammatory bowel disease and occasionally heart and/or lung involvement. In fact, about 40% of individuals with spondylitis will experience inflammation of the eye (uveitis or iritis). This is a serious condition that does require immediate attention from an Eye Doctor (Opthalmologist). See our page "Symptoms" for a complete list of all manifestations of the disease.
AS typically, but not always, manifests at a relatively young age compared to many other types of arthritis, on average between 20 and 30 years old, although it has been known to appear between the ages of 17-45. It also is more prevalent among males with a male-to-female ratio of about 3 to 1, although there is some geographical and ethnic variation.
Another key feature that distinguishes this arthritis from other types of wear-and-tear types of arthritis that develop with old age (such as osteoarthritis) is the systemic inflammation that comes along with it, meaning the inflammation affects your entire body in AS. This widespread inflammation, therefore, can have negative affects on multiple organs, blood vessels, and other joints and connective tissue besides the spine.
The systemic (all throughout the body) inflammation associated with AS not only causes severe and chronic pain and stiffness, but it also can lead to ankylosis (fusing of the bones) of the vertebrae, caused by new bone formation between the vertebrae, in the body's attempt to repair and reinforce the area after an inflammatory episode. If this happens, the spine in that section becomes frozen, fixed, and immobile, sometimes in a hunched over position (Kyphosis). Loss of flexibility and movement of the spine increases the risk for fractures. Pain and stiffness are still experienced regardless of whether fusion ever occurs and can be quite debilitating if left unchecked.
Thankfully, with modern intervention, including diet modification, conventional and complimentary medications, exercise, and attention to posture and sleeping positions, the fusing process is not as common as it once was.
How common is Ankylosing Spondylitis? AS is almost as common as Rheumatoid Arthritis. In fact, next to Rheumatoid Arthritis, it is the most common form of inflammatory arthritis (1). Overall, it is estimated to affect 1-2% of the UK and American population combined, or approximately 4-7 million people. This estimate is on the conservative side because it is believed that a sizable number of individuals go undiagnosed, or misdiagnosed, and may not even be aware that they have this disease.
1. ERAP1 Association With Ankylosing Spondylitis is Attributable to Common Genotypes Rather Than Rare Haplotype Combinations, Proc. Natl. Acad. Sci. USA 2017, Vol. 114 (3), Amity R Roberts, 558-561, doi: 10.1073/pnas.1618856114