Axial Spondyloarthritis Explained: Symptoms, Diagnosis and Treatment
Axial spondyloarthritis (often shortened to axSpA) is a form of inflammatory arthritis that mainly affects the spine and pelvis. It is an important cause of persistent back pain in younger adults, yet it is often under-recognised and diagnosed later than it should be.
Understanding how axial spondyloarthritis differs from more common mechanical back pain helps explain when specialist assessment is needed and why early diagnosis matters.
What Is Axial Spondyloarthritis?
Axial spondyloarthritis is an immune-mediated inflammatory disease affecting the axial skeleton — the spine and the sacroiliac joints (which connect the spine to the pelvis).
Inflammation may involve:
the sacroiliac joints
joints between the vertebrae
ligaments and tendons where they attach to bone (entheses)
Unlike mechanical back pain, axSpA is not caused by strain or “wear and tear”, but by ongoing immune-driven inflammation.
(Related reading: Inflammatory Back Pain – When to Seek Specialist Advice)
Axial Spondyloarthritis and Ankylosing Spondylitis
Axial spondyloarthritis describes a spectrum of disease, which includes:
Non-radiographic Axial Spondyloarthritis
Symptoms and inflammation are present
X-rays are normal
MRI may show active inflammation
Ankylosing Spondylitis
Longer-standing disease
Structural changes visible on X-ray
These changes reflect past inflammation
Both forms represent the same underlying condition. Many patients experience symptoms for years before X-ray changes develop, which is why MRI and clinical assessment are central to modern diagnosis.
Men and Women With Axial Spondyloarthritis
Axial spondyloarthritis affects both men and women, but patterns of disease can differ.
Women are more likely to have non-radiographic disease
Men are more likely to develop visible X-ray changes over time
Women often experience longer delays to diagnosis
Blood tests and imaging may appear normal for longer in women
Awareness of these differences is important to avoid missed or delayed diagnoses, particularly in women with persistent inflammatory back pain.
What Causes Axial Spondyloarthritis?
Axial spondyloarthritis develops due to dysregulation of the immune system in genetically susceptible individuals.
Genetic Factors and HLA-B27
HLA-B27 is strongly associated with axSpA
Many people with HLA-B27 never develop arthritis
Some people with axSpA are HLA-B27 negative
HLA-B27 is therefore supportive but not diagnostic.
Immune Pathways
Key inflammatory pathways include:
tumour necrosis factor (TNF)
interleukin-17 (IL-17)
These pathways drive inflammation, pain and stiffness and are the targets of modern biologic therapies.
(Related reading: Anti-TNF Treatments in Rheumatology)
Common Symptoms
Symptoms usually begin gradually, often in early adulthood. Typical features include:
persistent lower back or buttock pain
morning stiffness lasting more than 30–45 minutes
improvement with movement or exercise
worsening with rest
night pain, particularly in the second half of the night
fatigue
Associated Conditions and Overlap With Other Diseases
Some patients also experience:
peripheral joint inflammation
tendon or heel pain (enthesitis)
uveitis
psoriasis
inflammatory bowel disease
These overlaps reflect shared immune pathways.
(Related reading: Psoriatic Arthritis Explained)
Why Blood Tests May Be Normal
In axial spondyloarthritis:
CRP and ESR may be normal
autoimmune antibodies are usually negative
Inflammation may be localised to the spine or sacroiliac joints and not detectable in routine blood tests.
(Related reading: Blood Tests in Rheumatology – What Do CRP, ESR and Autoantibodies Really Mean?)
Delays in Diagnosis and Why Early Diagnosis Matters
Axial spondyloarthritis is associated with some of the longest diagnostic delays in rheumatology, often several years.
Delays occur because:
back pain is extremely common
early symptoms may be intermittent
blood tests are often normal
early X-rays may be reassuring
Early diagnosis matters because it allows:
better symptom control
preservation of spinal mobility
prevention of long-term structural damage
earlier access to effective modern treatments
Treatment Options
Treatment is individualised and depends on disease activity and severity.
Non-Drug Approaches
regular exercise and physiotherapy
posture and spinal mobility work
maintaining general fitness
Medications
non-steroidal anti-inflammatory drugs (NSAIDs)
biologic therapies targeting TNF or IL-17 for more active disease
Biologic treatments have transformed outcomes for many patients when used appropriately.
Living With Axial Spondyloarthritis
Axial spondyloarthritis is a long-term condition, but many people achieve:
good symptom control
low disease activity or remission
maintained independence and quality of life
Regular follow-up allows treatment to be adjusted and supports long-term outcomes.
In Summary
Axial spondyloarthritis is an inflammatory condition affecting the spine and pelvis
Symptoms often begin in early adulthood and improve with movement
Blood tests may be normal
MRI plays a key role in diagnosis
Early recognition and treatment improve outcomes
Persistent back pain with inflammatory features deserves careful assessment, even when initial tests appear reassuring.
Trusted Patient Information Resources
Arthritis UK
Clear patient information on axial spondyloarthritis, symptoms and treatment.
National Axial Spondyloarthritis Society
Specialist resources dedicated to axial spondyloarthritis.
NHS
Overview of ankylosing spondylitis and inflammatory back pain.
Please note, these posts are for general information only and do not constitute medical advice. Dr Singh would encourage you to speak to your healthcare professional to be assessed and managed for your specific symptoms.