Axial Spondyloarthritis: Symptoms, Causes & Treatment Guide

What Is Axial Spondyloarthritis?

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease primarily affecting the spine and sacroiliac joints in the pelvis. It belongs to a group of related conditions called spondyloarthritis and typically causes chronic back pain, stiffness, and fatigue that characteristically improve with movement but worsen with prolonged rest.

The term "axial spondyloarthritis" encompasses a spectrum of inflammatory spine disease. At one end is non-radiographic axial spondyloarthritis (nr-axSpA), where inflammation is present but not yet visible on standard X-rays. At the other end is ankylosing spondylitis (AS), also known as radiographic axial spondyloarthritis, where structural damage is visible on X-rays. Both conditions can cause significant symptoms and require treatment, and many patients with nr-axSpA eventually develop ankylosing spondylitis over time.

The disease typically begins in the sacroiliac joints, where the spine connects to the pelvis, and may progress upward along the spinal column. The inflammation affects various tissues including ligaments, tendons, and the joints between vertebrae. Over time, in some patients, the inflamed tissues can transform into bone, leading to fusion of the vertebrae and reduced spinal mobility. This process, known as ankylosis, is what gives ankylosing spondylitis its name.

Understanding the nature of axial spondyloarthritis is crucial because early recognition and treatment can significantly improve outcomes. Modern treatments, including biologic medications, can effectively control inflammation and may slow or prevent structural damage when started early. The disease affects approximately 0.5-1.4% of the population worldwide, making it one of the more common inflammatory rheumatic conditions.

The Spondyloarthritis Family

Axial spondyloarthritis belongs to a broader family of related conditions collectively called spondyloarthritis. These conditions share common features including inflammation of the spine and peripheral joints, a genetic association with HLA-B27, and the absence of rheumatoid factor (making them "seronegative"). Other members of this family include psoriatic arthritis, reactive arthritis, and arthritis associated with inflammatory bowel disease. Understanding this relationship is important because patients with axial spondyloarthritis may develop features of these related conditions, and treatment approaches often overlap.

What Are the Symptoms of Axial Spondyloarthritis?

The hallmark symptoms of axial spondyloarthritis include chronic lower back pain lasting more than three months, morning stiffness lasting more than 30 minutes, pain that improves with exercise but worsens with rest, and alternating buttock pain. Additional symptoms may include fatigue, eye inflammation, and pain in other joints or at tendon attachment points.

Axial spondyloarthritis typically begins gradually, often in young adulthood, with symptoms developing slowly over weeks to months. The onset is usually before age 40, and this age criterion is actually part of the diagnostic criteria. The insidious onset distinguishes inflammatory back pain from mechanical back pain, which often has a sudden onset related to injury or strain.

The back pain of axial spondyloarthritis has distinctive characteristics that differentiate it from common mechanical back pain. This "inflammatory back pain" typically begins insidiously in the lower back and buttocks, and it characteristically worsens with rest and inactivity, particularly at night and in the early morning hours. Many patients find they need to get up and move around during the night due to pain and stiffness. The pain and stiffness are usually worst first thing in the morning and improve significantly with exercise and physical activity.

The severity of symptoms can fluctuate considerably over time. Many patients experience periods of increased disease activity, known as flares, alternating with periods of relative remission. During flares, symptoms intensify and may be accompanied by increased fatigue and a general feeling of being unwell. These fluctuations can make the disease unpredictable and challenging to manage, though modern treatments have significantly improved the ability to control disease activity.

Spinal Symptoms

The primary symptoms involve the axial skeleton, particularly the lower back and sacroiliac joints. Patients often describe a deep, dull, aching pain in the lower back and buttocks that is difficult to localize precisely. The pain frequently alternates between the left and right buttocks, a characteristic feature known as "alternating buttock pain." As the disease progresses, the inflammation may spread up the spine, potentially affecting the thoracic spine and even the neck.

Morning stiffness is a hallmark feature, typically lasting more than 30 minutes and sometimes persisting for several hours. This stiffness affects the entire back and can make simple activities like getting out of bed challenging. The duration and severity of morning stiffness often correlate with disease activity and can be used to monitor treatment response.

Extra-Spinal Symptoms

Axial spondyloarthritis frequently affects areas beyond the spine. Uveitis, inflammation of the eye, occurs in approximately 25-40% of patients at some point during their disease course. It typically presents as a red, painful eye with light sensitivity and blurred vision. Uveitis is a medical urgency requiring prompt ophthalmological evaluation to prevent vision complications.

Enthesitis, inflammation where tendons and ligaments attach to bone, is another common manifestation. The Achilles tendon and plantar fascia at the heel are frequently affected, causing heel pain that can be severe and debilitating. Other common sites include the knees, hips, and chest wall.

Peripheral joint involvement occurs in many patients, with the hips and shoulders being most commonly affected. Hip involvement can be particularly problematic as it may lead to significant disability and sometimes requires joint replacement surgery. Some patients also experience inflammation of the fingers or toes, causing them to swell and appear sausage-like, a condition called dactylitis.

Systemic Symptoms

Fatigue is one of the most common and often underappreciated symptoms of axial spondyloarthritis. It can be profound and significantly impact quality of life and daily functioning. The fatigue results from a combination of the inflammatory process itself, disrupted sleep due to pain, and the chronic nature of the disease. Many patients report that fatigue is as disabling as the pain.

Other systemic symptoms may include loss of appetite, mild weight loss, and low-grade fever during periods of increased disease activity. These symptoms reflect the systemic inflammatory nature of the condition.

What Causes Axial Spondyloarthritis?

The exact cause of axial spondyloarthritis is not fully understood, but it involves a complex interaction between genetic factors (particularly HLA-B27), immune system dysfunction, and environmental triggers. The disease is highly heritable, with genetic factors accounting for over 90% of disease susceptibility.

Axial spondyloarthritis develops through a complex interplay of genetic predisposition and environmental factors that trigger an abnormal immune response. The immune system, which normally protects the body from infections, becomes misdirected and attacks the body's own tissues, particularly the entheses (where tendons and ligaments attach to bone) and the joints of the spine and pelvis. This leads to chronic inflammation that, if left untreated, can cause progressive structural damage.

The inflammation begins at the entheses, particularly around the sacroiliac joints and spine. The inflammatory process involves accumulation of immune cells, including T cells and macrophages, and production of inflammatory cytokines such as tumor necrosis factor (TNF) and interleukin-17 (IL-17). These cytokines drive the inflammatory process and cause the tissue damage seen in the disease. Understanding these mechanisms has led to the development of highly effective biologic treatments that target these specific pathways.

Genetic Factors

Genetics play a dominant role in axial spondyloarthritis, with heritability estimated at over 90%. The HLA-B27 gene is the strongest genetic risk factor, present in 80-95% of patients with the disease compared to only 5-8% of the general population. However, carrying HLA-B27 is neither necessary nor sufficient to develop the disease - most people with HLA-B27 never develop axial spondyloarthritis, and some patients are HLA-B27 negative.

Beyond HLA-B27, numerous other genes contribute to disease susceptibility. These include genes involved in immune regulation, inflammation, and bone formation. The polygenic nature of the disease helps explain why only a small percentage of HLA-B27 positive individuals develop the condition. First-degree relatives of patients have approximately a 10-20 times increased risk of developing the disease compared to the general population.

Environmental Triggers

While genetics provide the foundation for disease susceptibility, environmental factors appear to trigger disease onset in genetically predisposed individuals. The gut microbiome has emerged as a potentially important factor, with alterations in intestinal bacteria observed in patients with axial spondyloarthritis. Some researchers believe that bacterial products crossing from the gut may trigger or perpetuate the inflammatory response in susceptible individuals.

Smoking is the most clearly established environmental risk factor that worsens disease outcomes. Smokers with axial spondyloarthritis have more severe symptoms, greater structural damage, and poorer response to treatment compared to non-smokers. The mechanisms are not fully understood but may involve direct effects on bone metabolism and inflammation. Smoking cessation is strongly recommended for all patients.

Risk Factors

Several factors increase the risk of developing axial spondyloarthritis or experiencing more severe disease:

• HLA-B27 positive status: The strongest genetic risk factor
• Family history: Having a first-degree relative with the disease increases risk 10-20 fold
• Male sex: Men are more than twice as likely to develop the condition, though women may be underdiagnosed
• Age: Typically develops in young adulthood (teens to thirties)
• Smoking: Increases risk and worsens disease progression
• Having related conditions: Psoriasis, inflammatory bowel disease, or uveitis increase risk

How Is Axial Spondyloarthritis Diagnosed?

Diagnosis of axial spondyloarthritis involves a combination of clinical assessment, imaging studies (MRI and X-ray), and blood tests. The ASAS classification criteria are used, requiring either evidence of sacroiliitis on imaging plus one spondyloarthritis feature, or positive HLA-B27 plus two spondyloarthritis features. Early diagnosis is crucial for optimal outcomes.

Diagnosing axial spondyloarthritis can be challenging, particularly in the early stages, because symptoms often develop gradually and overlap with more common causes of back pain. The average delay between symptom onset and diagnosis has historically been 7-10 years, though this has improved with increased awareness and better diagnostic tools. Early diagnosis is crucial because treatment started early can prevent or significantly slow structural damage.

The diagnostic process typically begins with a thorough medical history and physical examination. The physician will ask detailed questions about the nature of the back pain, including when it started, what makes it better or worse, how long morning stiffness lasts, and whether it wakes you at night. Questions about family history, associated conditions (like psoriasis or inflammatory bowel disease), and other symptoms (like eye inflammation or heel pain) are also important.

Physical examination focuses on assessing spinal mobility and identifying areas of tenderness. Tests include measuring how far you can bend forward, backward, and sideways, as well as chest expansion. The sacroiliac joints are examined for tenderness, and peripheral joints are assessed for swelling or limited motion. While these findings support the diagnosis, imaging and laboratory tests are essential for confirmation.

Imaging Studies

MRI (Magnetic Resonance Imaging) has revolutionized the early diagnosis of axial spondyloarthritis. MRI can detect active inflammation (bone marrow edema) in the sacroiliac joints and spine years before any changes are visible on X-rays. This allows for earlier diagnosis and treatment, potentially preventing irreversible structural damage. MRI is particularly important in younger patients and those with a shorter duration of symptoms.

X-rays of the sacroiliac joints and spine can show structural changes in established disease, including erosions, sclerosis (increased bone density), and fusion. In ankylosing spondylitis, the classic "bamboo spine" appearance results from fusion of vertebrae. However, these changes take years to develop, making X-rays less useful for early diagnosis. X-rays remain important for distinguishing between non-radiographic and radiographic axial spondyloarthritis and for monitoring disease progression.

Laboratory Tests

HLA-B27 testing is an important diagnostic tool. While a positive result supports the diagnosis, it's important to remember that many people with HLA-B27 never develop the disease, and some patients are HLA-B27 negative. Therefore, the test is useful but not diagnostic on its own.

Inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are often elevated in axial spondyloarthritis, reflecting active inflammation. However, up to 30-50% of patients have normal inflammatory markers despite active disease, so normal results don't exclude the diagnosis. These markers are more useful for monitoring disease activity and treatment response over time.

Other blood tests may be performed to rule out other conditions, assess overall health, and ensure safe use of medications. These may include complete blood count, kidney and liver function tests, and tests for other autoimmune conditions.

When Should You See a Doctor?

You should see a doctor if you have chronic back pain lasting more than three months, especially if it started before age 40, improves with exercise, worsens with rest, or causes prolonged morning stiffness. Seek urgent care if you develop sudden eye pain with redness, significant new joint swelling, or any neurological symptoms like numbness or weakness.

Recognizing when to seek medical attention for back pain can be challenging because back pain is extremely common and usually due to benign causes. However, certain features should prompt evaluation for possible axial spondyloarthritis. The combination of chronic back pain (lasting more than three months), onset before age 40, and the characteristic "inflammatory" features of the pain (improving with exercise, worsening with rest, causing significant morning stiffness) should raise suspicion for the condition.

If you have back pain with these features, start by seeing your primary care physician. They can perform an initial evaluation and, if appropriate, refer you to a rheumatologist for specialized assessment. Rheumatologists are specialists in inflammatory joint diseases and have expertise in diagnosing and treating axial spondyloarthritis. Early referral to a rheumatologist is important because they can order specialized tests and initiate appropriate treatment promptly.

Symptoms Requiring Urgent Attention

Certain symptoms require prompt medical evaluation:

• Eye symptoms: Red, painful eye with light sensitivity and blurred vision may indicate uveitis, which requires urgent ophthalmological evaluation to prevent vision loss
• Significant new joint swelling: Especially if accompanied by fever, could indicate infection requiring immediate treatment
• Neurological symptoms: New numbness, weakness, or bladder/bowel dysfunction could indicate spinal cord compression
• Severe pain unresponsive to usual treatments: May indicate a flare requiring treatment adjustment or other cause
• Chest pain: While chest wall inflammation is common in axSpA, new chest pain should be evaluated to exclude cardiac causes

How Is Axial Spondyloarthritis Treated?

Treatment of axial spondyloarthritis combines non-pharmacological approaches (regular exercise, physical therapy) with medications. First-line drug treatment is NSAIDs. If NSAIDs are insufficient, biologic medications (TNF inhibitors or IL-17 inhibitors) are highly effective. The goal is to control inflammation, relieve symptoms, maintain function, and prevent structural damage.

The management of axial spondyloarthritis has been transformed over the past two decades with the development of effective biologic therapies and a better understanding of the disease. Treatment is individualized based on disease severity, symptoms, patient preferences, and response to therapy. The overall goals are to reduce inflammation and pain, maintain spinal mobility and function, prevent structural damage, and improve quality of life.

Treatment follows a step-wise approach, starting with non-pharmacological measures and first-line medications, then progressing to more targeted therapies if needed. Most patients can achieve good disease control with appropriate treatment, though finding the right combination may require some trial and adjustment. Regular monitoring by a rheumatologist helps ensure treatment remains effective and safe.

Non-Pharmacological Treatment

Exercise is the cornerstone of axial spondyloarthritis management and should be part of every patient's treatment plan, regardless of disease severity or other treatments. Regular physical activity helps maintain spinal mobility, reduce stiffness and pain, improve posture, strengthen muscles supporting the spine, and enhance overall well-being. Studies consistently show that patients who exercise regularly have better outcomes than those who don't.

Physical therapy with a physiotherapist experienced in treating axial spondyloarthritis is highly beneficial. They can design an individualized exercise program focusing on stretching, strengthening, and posture. Water-based exercises in a warm pool can be particularly helpful as the warmth and buoyancy make movement easier. Regular physiotherapy sessions help ensure exercises are performed correctly and the program evolves with your needs.

Additional non-pharmacological approaches that may help include:

• Heat therapy: Applying heat to stiff, painful areas can provide relief
• Massage: May help relax tense muscles and reduce pain
• Good posture: Maintaining proper posture helps prevent deformity
• Smoking cessation: Essential for improving outcomes
• Sleep positioning: Sleeping on a firm mattress and avoiding excessive pillows can help

First-Line Medications: NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) are the first-line pharmacological treatment for axial spondyloarthritis. They are remarkably effective in this condition, often providing more relief than in other types of inflammatory arthritis. NSAIDs work by reducing inflammation and pain, and some studies suggest they may also slow structural progression when taken continuously.

Common NSAIDs used include ibuprofen, naproxen, diclofenac, and etoricoxib. Long-acting formulations taken at bedtime can be particularly helpful for reducing morning stiffness and night pain. Your doctor will help you find the right NSAID and dose, balancing effectiveness with potential side effects. Regular monitoring is important to watch for gastrointestinal, cardiovascular, and kidney effects.

Biologic Medications

If NSAIDs are insufficient or cannot be tolerated, biologic medications offer highly effective alternatives. These targeted therapies work by blocking specific molecules involved in the inflammatory process.

TNF inhibitors were the first biologics used for axial spondyloarthritis and remain highly effective. Options include adalimumab, etanercept, infliximab, golimumab, and certolizumab. They work by blocking tumor necrosis factor, a key inflammatory molecule. TNF inhibitors can dramatically reduce symptoms, improve function, and may slow or prevent structural damage, especially when started early.

IL-17 inhibitors (secukinumab, ixekizumab) are newer biologics that target interleukin-17, another important inflammatory pathway in axial spondyloarthritis. They are similarly effective to TNF inhibitors and provide an alternative for patients who don't respond to or cannot tolerate TNF inhibitors. IL-17 inhibitors may be preferred in patients with significant skin psoriasis.

JAK inhibitors (tofacitinib, upadacitinib) are oral medications that target intracellular signaling pathways involved in inflammation. They are approved for ankylosing spondylitis and offer an oral alternative to injectable biologics.

Other Medications

Corticosteroid injections can be helpful for localized inflammation, such as a single inflamed sacroiliac joint or enthesitis at the heel. Systemic corticosteroids (like prednisone) are generally not recommended for axial symptoms but may be used briefly during severe flares.

Conventional DMARDs like sulfasalazine or methotrexate are sometimes used for peripheral joint involvement (arthritis in arms and legs) but are not effective for spinal disease. They may be considered in patients with significant peripheral arthritis in addition to spinal involvement.

What Can You Do Yourself?

Self-management is crucial in axial spondyloarthritis. Key strategies include daily stretching and exercise, maintaining good posture, applying heat for stiffness, getting adequate rest, not smoking, and taking medications as prescribed. Regular low-impact activities like swimming, walking, and yoga can significantly improve symptoms and function.

While medical treatment is important, what you do yourself every day has a profound impact on your disease course and quality of life. Self-management strategies complement medical treatment and can make a significant difference in symptoms, function, and overall well-being. The most important things you can do are to stay active, maintain good posture, and adhere to your treatment plan.

Exercise and Physical Activity

Regular exercise is perhaps the single most important thing you can do for your condition. Unlike many other types of pain where rest is beneficial, the pain and stiffness of axial spondyloarthritis improve with movement and worsen with inactivity. Aim for at least 150 minutes of moderate-intensity activity per week, spread throughout the week rather than concentrated in one or two sessions.

Recommended activities include:

• Stretching: Daily stretching exercises help maintain flexibility and reduce stiffness. Focus on the spine, hips, and shoulders.
• Swimming and water aerobics: The buoyancy of water reduces stress on joints while the warmth helps relax muscles.
• Walking: A simple, accessible activity that can be done anywhere.
• Cycling: Low-impact and good for cardiovascular fitness.
• Yoga and Pilates: Improve flexibility, posture, and core strength. Look for classes or instructors familiar with spinal conditions.

It's important to continue exercising even during flares, though you may need to reduce intensity. Complete rest typically makes symptoms worse. Working with a physiotherapist can help you develop a sustainable exercise routine that you can maintain long-term.

Posture and Ergonomics

Maintaining good posture helps prevent the development of fixed spinal deformity. Pay attention to your posture throughout the day, particularly when sitting, standing, and sleeping. Avoid prolonged positions that encourage forward bending of the spine. Ergonomic modifications at work, such as an adjustable desk, supportive chair, and proper monitor positioning, can help maintain good posture during working hours.

Lifestyle Modifications

• Stop smoking: If you smoke, quitting is one of the most important things you can do. Smoking worsens disease activity and outcomes.
• Manage stress: Stress can worsen symptoms. Techniques like mindfulness, meditation, or relaxation exercises may help.
• Get adequate sleep: Good sleep hygiene is important. A firm mattress and proper positioning can help.
• Maintain a healthy weight: Excess weight puts additional stress on the spine and joints.
• Apply heat: Warm showers, heating pads, or warm baths can help relieve stiffness and pain.

What Are the Possible Complications?

Potential complications of axial spondyloarthritis include spinal fusion leading to reduced mobility, osteoporosis and increased fracture risk, eye inflammation (uveitis), hip involvement requiring surgery, and rarely heart or lung complications. Early treatment significantly reduces the risk of these complications.

With modern treatment, many complications of axial spondyloarthritis can be prevented or minimized. However, it's important to be aware of potential complications so they can be detected and addressed early. The risk of complications is higher in patients with more severe disease, delayed diagnosis, or inadequate treatment.

Spinal Complications

Spinal fusion (ankylosis) occurs when new bone forms between vertebrae, causing them to fuse together. This reduces spinal flexibility and can lead to a fixed, stooped posture if it occurs in the neck and upper back. The "bamboo spine" appearance on X-rays describes severe, widespread fusion. Modern treatments, particularly biologics started early, appear to slow or prevent fusion in many patients.

Osteoporosis is common in axial spondyloarthritis due to inflammation and reduced physical activity. This increases the risk of fractures, which can be particularly dangerous in a fused spine. Bone density monitoring and preventive treatment may be recommended.

Extra-Spinal Complications

Uveitis (eye inflammation) affects 25-40% of patients and can lead to vision problems if not treated promptly. Regular eye examinations and immediate attention to new eye symptoms are important.

Hip involvement can be severe and may require hip replacement surgery in some patients. Early treatment and regular monitoring of hip function are important.

Cardiovascular disease risk is slightly increased in axial spondyloarthritis, thought to be related to chronic inflammation. Managing traditional cardiovascular risk factors (blood pressure, cholesterol, smoking) is important.

What Is the Long-Term Outlook?

The prognosis for axial spondyloarthritis has improved significantly with modern treatments. Most patients can maintain good function and quality of life with appropriate management. Early diagnosis and treatment, regular exercise, and adherence to medication all contribute to better outcomes. The disease is chronic but manageable.

Living with axial spondyloarthritis is a long-term journey, but the outlook has never been better. With early diagnosis, effective treatments, and active self-management, most patients can lead full, active lives. The disease varies considerably between individuals - some have mild symptoms that are easily controlled, while others have more severe disease requiring intensive treatment.

Factors associated with better outcomes include early diagnosis and treatment, good response to NSAIDs, absence of hip involvement, regular exercise, non-smoking status, and adherence to treatment. Factors associated with more severe disease include male sex, early onset, elevated inflammatory markers, presence of hip involvement, and smoking.

Many patients find that while they need to make some accommodations for their condition, they can work, exercise, travel, and participate fully in life. Support from healthcare providers, family, and patient organizations can help you navigate the challenges and maximize your quality of life.

Can You Have Children with Axial Spondyloarthritis?

Most people with axial spondyloarthritis can have children. Pregnancy planning is important because some medications need to be adjusted before conception or during pregnancy. Work closely with your rheumatologist and obstetrician to ensure safe management throughout pregnancy and breastfeeding.

Axial spondyloarthritis itself does not prevent pregnancy, and most women with the condition have healthy pregnancies and babies. However, pregnancy planning is important because some medications used to treat the disease may need to be stopped or adjusted before conception or during pregnancy. Men should also discuss their medications with their doctor when planning a family, as some treatments can affect sperm.

During pregnancy, the disease may remain stable, improve, or flare - individual experiences vary. Some women find their symptoms improve during pregnancy due to hormonal changes, while others may experience increased back pain, particularly in the third trimester. Close monitoring by both a rheumatologist and obstetrician is important to manage the disease while ensuring the safety of mother and baby.

After delivery, some women experience disease flares, particularly in the first few months postpartum. Breastfeeding considerations may affect medication choices. Planning ahead and working with your healthcare team ensures you can safely manage your condition while caring for your baby.