Chronic inflammation affecting the axial skeleton of the body is known as axial spondyloarthritis. Non-radiographic axial spondyloarthritis is a subtype of this condition, defined by the absence of visible changes to the sacroiliac joint on plain X-rays.
Arthritis is a general term that refers to conditions of inflammation, pain, and impaired function affecting the joints, bones, and connective tissues of the body.
When arthritis primarily impacts your spine and the joints connecting it to your pelvis, the sacroiliac (SI) joints, it’s referred to as axial spondyloarthritis (axSpA).
Similar to many other arthritic conditions, axSpA is assessed with the aid of diagnostic imaging. If symptoms are present but clear changes to the SI joints are not visible on plain radiographs (X-rays), axSpA is diagnosed as non-radiographic axSpA or nr-axSpA.
Non-radiographic axial spondyloarthritis (nr-axSpA) is a chronic inflammatory condition primarily affecting the spine and pelvis. While it’s considered an
Nr-axSpA is a subtype of axSpA, representing one end of axSpA’s possible disease spectrum.
Nr-axSpA describes axSpA with little to no SI joint damage visible on X-ray. Your SI joints connect the sacrum at the base of the spine to the ilium bones of the pelvis. They’re responsible for supporting the weight of your upright body while providing shock absorption and stability.
SI joint damage is what differentiates nr-axSpA from ankylosing spondylitis (AS), the opposite end of the axSpA spectrum.
Sometimes referred to as
The exact causes of axSpA and its subtypes, including nr-axSpA, aren’t fully understood. Genetics, environmental factors, and overactive immune responses are all thought to be involved.
Some people who develop axSpA have a genetic predisposition to the condition. The most common gene implicated is HLA-B27, but having the HLA-B27 gene doesn’t guarantee you’ll develop axSpA.
Other people living with axSpA develop it after exposure to a bacterial or viral infection. Some develop axSpA after physical trauma from injury, repetitive stress, or poor body mechanics.
According to
Innate immunity is your body’s general response to potential invading threats, such as viruses and bacteria. Adaptive immunity is a targeted immune response. It involves specialized antibodies created to handle a specific pathogen.
Overactive adaptive immunity drives traditional autoimmune conditions where the body attacks its own cells directly.
The involvement of innate immunity in axSpA, however, suggests that other immune processes may also indirectly cause inflammation. For this reason, axSpA can be considered an immune-mediated condition with possible autoimmune features.
Non-radiographic axial spondyloarthritis typically emerges gradually over weeks to months, presenting as pain and stiffness in the lower back and buttocks. It can also cause discomfort in other areas of the body, including the following:
- jaw
- neck
- shoulders
- fingers
- wrists
- hips
- ribs
- knees
- heels
- toes
- eyes
Pain from nr-axSpA is usually caused by inflammatory back pain (IBP), which is different from mechanical back pain. IBP stems from persistent conditions of inflammation, while mechanical back pain develops from structural issues in the bones and connective tissues.
IBP features seen in nr-axSpA include:
- symptom onset before the age of 40 years
- pain that’s worse in the morning or evening
- symptom improvement with exercise but not with rest
- reduction of symptoms with nonsteroidal anti-inflammatory drugs (NSAIDs)
- often no history of trauma to the area
- alternating buttock pain
Some people living with nr-axSpA develop pain in other areas of the body before experiencing lower back pain. Females are more likely than males to report pain in peripheral joints or the neck first.
Nr-axSpA is also seen with common co-occurring conditions, such as:
- inflammatory bowel disease
- psoriasis
- acute anterior uveitis
There are no definitive tests to identify nr-axSpA.
A rheumatologist will determine your diagnosis based on the symptoms you’re experiencing and the results of diagnostic imaging.
X-rays are an essential part of diagnosis. They allow your rheumatologist to assess your SI joints for damage.
To receive a diagnosis of nr-axSpA, criteria known as the “modified New York criteria” must be met. The modified New York criteria are a revised set of axSpA diagnostic guidelines originating from a consensus meeting of experts held in New York.
They state that nr-axSpA is present when at least one of the following has been met:
- inflammatory lower back pain presented for more than 3 months
- lumbar motion in the sagittal (forward and backward) and frontal (side-to-side) planes is limited
- limitation of chest expansion
Plus:
- sacroiliitis (SI inflammation) meets grade 2 in both joints or grade 3 or 4 in at least one joint.
Classification of grade 2 or higher indicates clear changes can be seen in the SI joint.
In some cases, nr-axSpA may be diagnosed using other diagnostic imaging tools, such as magnetic resonance imaging (MRI). Like with X-rays, specific evidence of SI joint involvement must be seen.
In addition to diagnostic imaging, genetic screening and blood work can support a diagnosis of nr-axSpA by verifying the presence of genes like HLA-B27 as well as specific inflammatory markers.
While there’s no cure for nr-axSpA, treatment can improve your comfort and functionality.
Lifestyle changes, such as eating a balanced diet and exercising, are recommended. Currently, there’s no singular diet used to support nr-axSpA treatment, but avoiding inflammatory foods, including anti-inflammatory options, may help.
As a condition primarily caused by IBP, exercise often helps improve the pain associated with nr-axSpA. Range of motion work, balance, strengthening, and cardiovascular exercise can help you retain — and improve — mobility and flexibility.
IBP conditions also respond well to NSAID therapy. These medications are used to treat moderate to severe nr-axSpA. When symptoms are significantly impairing your daily life, your rheumatologist may prescribe more targeted drugs, such as biologics or JAK inhibitors, that work to stop specific inflammatory processes in the body.
Nr-axSpA is a chronic condition that can be successfully managed but not cured. Treatment can improve your physical function and overall quality of life.
Flare-ups, or periods of time where symptoms worsen, are possible.
AxSpA conditions can cause progressive damage, especially if left untreated, but the course of the disease varies significantly between people. Nr-axSpA doesn’t always progress to AS. In fact, it’s estimated that only 5–30% of people with nr-axSpA will go on to develop SI joint involvement.
Nr-axSpA can advance in other ways, however. You may never experience SI involvement, for example, but you may go on to develop conditions associated with nr-axSpA, such as psoriasis.
Non-radiographic axial spondyloarthritis is a subtype of axSpA, a chronic inflammatory condition primarily affecting the spine and pelvis. Nr-axSpA is diagnosed when axSpA is present, but there’s little to no visible damage to your SI joints.
While there’s no cure for nr-axSpA, treatment can improve your quality of life and help you regain and maintain your physical function.
To learn more about nr-axSpA and connect with local support networks, visit:
- Spondylitis Association of America
- Arthritis Foundation