Q: Is there a hereditary kind of back arthritis?
A: Axial spondyloarthritis (AS) is a condition strongly associated with inheriting the HLA-B27 gene (over 5% of people with this gene develop the condition), although not all patients diagnosed with this condition have this gene. There are two subtypes of AS; ankylosing spondylitis, which shows sacroiliac inflammatory changes on X-ray (or other imaging), and non-radiographic AS which is similar to ankylosing spondylitis but without the changes on imaging tests.
AS is thought to be due to inflammatory changes which cause abnormal bone erosion and then regrowth in the spine (and in some patients other locations) and which may have an autoimmune component (the body "attacks" itself). The bone regrowth can cause adjacent bones (for example adjacent vertebrae) to fuse together.
The diagnosis of AS relies heavily on the history and physical examination since X-rays, other imaging and even genetic testing cannot rule it out. Therefore, this condition should be in the differential diagnosis of any patient who develops symptoms consistent with it.
The symptoms of AS include back pain that initially is worse at rest (improving with activity and movement), and which may progress to disabling back pain and/or spinal deformity (including a "hunchback" deformity, osteopenia, fractures, neurological conditions if the spinal cord is compromised from the spinal changes, mobility limitations, other), although the hips, shoulders and other joints/tissues (such as tendons and ligaments, for example the Achilles’ heel) may be involved as well. The autoimmune aspect of this condition is thought to be the reason that other body organs may be involved, leading to complications such as uveitis, inflammatory bowel disease, psoriasis and/or other conditions.
AS affects between 1 in 200 and 1 in 10,000 people (more than 2 million Americans in total); this wide variation is because AS is much more common in certain ethnic groups (for example, the HLA-B27 gene is present in up to 8% of Caucasians, but in less than 1% of people of Japanese descent).
The goals of treatment include minimizing symptoms (including pain), bone changes/deformities and other complications (including the disabling back changes as well as the other complications noted above). Non-steroidal anti-inflammatory drugs (NSAIDs) are usually the first line treatment, but other treatments may include other anti-inflammatory medications (such as tumor necrosis factor and/or certain biologic agents) and even monoclonal antibody medications (that “tag” certain proteins, such as the IL-17 protein, to guide the patient’s own immune system to combat the inflammation).
The prognosis for patients with AS depends on the age of onset, the severity and speed of progression of symptoms and on what complications develop. Treatment must be personalized for each individual patient and changed as necessary if/when their symptoms/disease progresses or changes.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com