Axial spondyloarthritis, with Ankylosing Spondylitis (AS) as its prototype, is a chronic, progressive, painful form of inflammatory arthritis, the hallmark of which is sacroiliitis. 

The symptoms of axSpA include:

• A slow or gradual onset of back or buttock pain over weeks or months.
• Early morning stiffness or pain that wears off during the day as you move 
• Chronic back pain (lasting for more than 3 months) 
• Feeling better after exercise and worse after rest, particularly at night
• Interrupted sleep, tiredness and Fatigue
• Loss of appetite, weight loss
• In the early stages – mild fever
• Pain that is dull and persistent on one or both sides of the body
• Pain that starts in or spreads to the joints on the hands or feet
• Iritis or Uveitis, inflammation of the eyes

Onset of axSpA

The onset of axSpA is usually before age 45, and typically people start experiencing symptoms in their late teens or twenties. Women can experience more pain in the neck, hips, and knees than men, making their diagnosis more difficult. There is also outdated and inaccurate information that women do not get r-axSpA/AS; for many years Ankylosing Spondylitis (AS)  was referred to as a “man’s disease”.

Other effects of axSpA

There are additional effects, or extra musculoskeletal manifestations, of axSpA for many patients. These include acute anterior uveitis (inflammation of the uvea of the eye). As many as 50% of patients with axSpA have experienced uveitis, usually in one eye only, over their lifetime. About 10% of patients will experience Inflammatory Bowel Disease (IBD – ulcerative colitis or Crohn’s Disease) while 5%-10% will have psoriasis.

Diagnosis of Axial Spondyloarthritis

One of the biggest challenges facing patients with axSpA is the length of time it takes for most patients between when they began experiencing symptoms to being properly diagnosed with the disease. There are many factors that contribute to this delay to diagnosis. These include a lack of awareness amongst the general public and in some cases the medical community of axSpA and the difference between mechanical back pain and inflammatory back pain. Another is that the disease can be difficult to diagnose even when a form of SpA is suspected. 

Back pain is one of the most common complaints that people take to their family physicians and other healthcare practitioners. Most people will experience some form of back pain in their lives. For some, it is relatively minor inconvenience, whereas others are unable to work and function as they want to because of severe back issues.

The vast majority of back pain is mechanical in nature. In the early stages, inflammatory and mechanical back pain can be difficult to tell apart, but if you are younger than 45 years old with back pain persisting for longer than 3 months, and experience morning back stiffness that eases with activity, you should ask your physician about axSpA.

Mechanical or acute back pain comes from some dysfunction in the structures that connect to your back, including the spine, muscles, and discs. Mechanical back pain can happen at any time in your life and generally comes on quickly and lasts for a short period, up to a few months. It can also often be eased with rest and care from your doctor or other healthcare practitioner, like a physiotherapist or chiropractor. If you’ve ever thrown your back out, or had a bout of sciatica, you’ve experienced mechanical pain.

Inflammatory back pain is caused by an autoimmune response, when your body attacks healthy tissues, causing inflammation and pain. The pain comes on slowly and persists for many months or years. The pain and stiffness are usually worse in the morning but improve with some movement and light exercise.

Inflammation can be localized to your back and hips, but usually the inflammation causing pain is systemic, which means you may also experience pain or swelling in other parts of your body. Common areas include the eyes, ankles, and neck.

Inflammatory back pain often interrupts sleep or can make sleep difficulties worse. Your immune system working so hard against your body is also exhausting. It’s normal for someone experiencing inflammatory back pain to feel exhausted much of the time.

A rheumatologist is a specialist to whom you should be referred by your family physician. 

The rheumatologist will conduct a thorough physical exam, take a medical history including any family history of Spondyloarthritis diseases, look for the presence of any spondyloarthritis features, and finally order MRIs. They may also order blood tests for inflammatory markers and a test for the gene HLA-B27.

It is important to know that there is no single definitive test for axSpA or any of the spondyloarthritis diseases. There are also no commonly accepted diagnostic criteria for axSpA. Although classification criteria exist, such as the ASAS and Modified New York Criteria, diagnostic and classification criteria are not interchangeable and care should be taken to not use classification criteria for diagnosis. 

A diagnosis of axSpA is confirmed by the presence of sacroiliitis in MRIs or X-rays. One of the difficulties of diagnosis is in using X-rays since damage to the sacroiliac joints typically does not show up on X-ray until many years after disease onset. It is a contributing reason why there is such a long delay in diagnosis for many. The average delay to diagnosis is 7-9 years in Canada. For this reason, Magnetic Resonance Imaging (MRI) is the standard for diagnostic imaging because it can detect sacroiliitis much sooner after disease onset. It has been shown that Bone Marrow Edema (BME) in the SIJ, can appear in healthy young athletes and in postpartum women. This means that reading an MRI of the SIJ has to be done very carefully to ensure that the evidence of BME shows sacroiliitis and not something else.

Your rheumatologist may ask you to complete some questionnaires, such as the Bath Ankylosing Spondylitis Disease Activity Index, known as BASDAI, in order to help with the diagnosis and more importantly, to establish a baseline for disease progression. There are several Bath Indices, including the Bath AS Functional Index (BASFI), the Bath AS Radiology Index (BASRI), and the Bath AS Metrology Index (BASMI), which measures changes in spinal mobility. These indices are also applicable to people with nr-axSpA.

Download our AxSpA Guidebook here

Psoriatic Arthritis is defined as inflammatory arthritis associated with psoriasis, a chronic inflammatory skin condition that presents most commonly with itchy and painful red scaly patches on the skin of the elbows, knees, and scalp. Psoriasis can also affect the nails, which can be pitted, split, discoloured, and loose because of the condition. 

About 20%-30% of patients with psoriasis will develop Psoriatic Arthritis. PsA begins gradually and involves one or more peripheral joints to begin with, quickly spreading to other joints. Any and all joints can be involved, including the spine. The common features of PsA are enthesitis, inflammation of the site where tendons and ligaments attach to the bone; dactylitis, inflammation of the fingers or toes resulting in ‘sausage digits’, and spondylitis, inflammation of the spine including the sacroiliac joints and vertebrae.  

About 15% of people suffering from PsA develop arthritis before they have signs of psoriasis of the skin. 

Symptoms of psoriatic arthritis:

• Scaly skin patches
• Dactylitis – ‘Sausage’ fingers and toes caused by swelling of the joints
• Pain and swelling from enthesitis, particularly in the plantar fascia (soles of feet) and the Achilles tendon (back of the heel) but also in any joints.
• Pain and stiffness in the spine, especially at rest
• Discolouration of fingernails and toenails, together with pits, indentations, and crumbling
• Iritis or red, painful eyes

Download our Psoriatic Arthritis handbook  

The second subclassification of Spondyloarthritis is Peripheral SpA, which causes inflammation in joints and/or tendons outside the spine or sacroiliac joints. These can include the hands, wrists, elbows, shoulders, knees, ankles, and feet. Inflammation of the tendons can occur in the fingers or toes (dactylitis, colloquially known as sausage fingers) or where tendons and ligaments meet with bone (enthesitis). 

Peripheral SpA includes what have traditionally been, and are still referred to as, Psoriatic Arthritis (PsA), Enteropathic Arthritis (EnA), Reactive Arthritis (ReA), and Undifferentiated Spondyloarthritis (USpA). They are now grouped together as Peripheral Spondyloarthritis because they all share features of peripheral arthritis, enthesitis and/or dactylitis.

Diagnosis of Peripheral Spondyloarthritis can be challenging, particularly in the absence of SpA extra-musculoskeletal manifestations such as uveitis, psoriasis, or inflammatory bowel disease. 

Evaluation of disease activity by a rheumatologist should always include an assessment of objective signs of inflammation, particularly when  enthesitis is the only peripheral manifestation. The rheumatologist will conduct a thorough physical exam, take a medical history including any family history of Spondyloarthritis diseases, look for the presence of any spondyloarthritis features, and finally order MRIs. They may also order blood tests for inflammatory markers and a test for the gene HLA-B27.

The key features of peripheral Spondyloarthritis that will assist in the diagnosis of the patient are arthritis, enthesitis, or dactylitis.

Enteropathic arthritis (EnA) is also called Inflammatory Bowel Disease (IBD) related arthritis. Patients with EnA have both chronic swelling in their joints and inflammation in part of their digestive tract. Up to 10% of patients with spondyloarthritis will develop IBD, particularly Crohn’s Disease but also ulcerative colitis.

Symptoms of Enteropathic arthritis:

• Abdominal pain
• Bloody diarrhea
• Weight loss
• Pain and swelling in joints, particularly in the lower limbs
• Stiffness and pain in the spine

For more information on Enteropathic arthritis, we recommend these resources here

Children with onset of arthritis before the age of 16 years are classified as having juvenile idiopathic arthritis (JIA). Children with enthesitis and/or sacroiliitis are further classified as having JIA that is enthesitis-related, which is commonly called Juvenile Spondyloarthritis. 

Unlike adults with SpA, jSPA or JIA-ERA often starts as peripheral arthritis or enthesitis, with axial (back related) manifestations appearing much later. 

Symptoms of juvenile spondyloarthritis

• Enthesitis, especially in the lower body
• Pain in the pelvis, hips, knees, and ankles
• Swollen knees and ankles
• Pain and inflammation in the spine
• Psoriasis and other skin rashes
• Uveitis or iritis
• Crohn’s disease or colitis (inflammation of the intestines)
• Tiredness and fatigue

Diagnosis of juvenile onset spondyloarthritis

A pediatric rheumatologist is best placed to provide a diagnosis because JSpA symptoms can come and go. A thorough physical exam looking for enthesitis and a complete health history recording symptoms and a family history will help with the diagnosis. Although the presence of HLA-B27 may be useful in helping with the diagnosis, it does not provide a definitive diagnosis.

Reactive Arthritis (formerly known as Reiter’s Syndrome)

Reactive arthritis is a painful form of inflammatory arthritis that develops in reaction to infection elsewhere in the body, usually in the gastrointestinal or genitourinary (urinary and genital) systems. Reactive arthritis can cause inflammation and pain in joints, the skin, eyes, genitals, and bladder. It can cause persistent lower back pain. As usual, some, but not all, people who are diagnosed with reactive arthritis carry the HLA-B27 gene.

Reactive arthritis is uncommon. For most people, symptoms eventually disappear within 12 months. Flares may be experienced afterwards from time to time and some people may go on to develop arthritis that may be either mild or severe.

Symptoms of reactive arthritis

• Dactylitis – ‘Sausage’ fingers or toes
• Pain, swelling and stiffness in joints
• Skin rashes
• Fingernails and toenails that are thickened and abnormal looking
• Iritis, uveitis, conjunctivitis
• Enthesitis (inflammation where tendons attach to the bone)
• Cystitis (inflammation of the bladder or urinary tract)
• Genital blisters and sores
• Lower back or pelvic inflammation and pain

Undifferentiated Spondyloarthritis

The term USpA was introduced to classify patients who have the signs and symptoms of SpA but who could not be definitively diagnosed with AS, psoriatic arthritis, or the other SpA conditions.

These patients, over time, may progress to axSpA or develop psoriatic arthritis allowing them to be re-categorized into those entities. However, as the new classification system of axial and peripheral SpA encompasses most patients with SpA, there are very few patients who are classified as USpA now.

Symptoms of undifferentiated spondyloarthritis (USpA)

• Back pain
• Enthesitis
• Pain and swelling in the fingers or toes
• Buttock pain on one or both sides
• Heel pain
• Iritis
• Tiredness and fatigue