Ankylosing Spondylitis (AS)

Region affected

Spine / Sacroiliac joints

Common in

Adults under 40, male predominance

Onset

Gradual (inflammatory)

Related conditions

SIJ Dysfunction, Spinal Stenosis, Facet Joint Syndrome

Ankylosing spondylitis (AS) is a form of inflammatory arthritis that primarily affects the spine and sacroiliac joints. It belongs to a broader group of conditions known as axial spondyloarthritis, and causes inflammation within the spinal joints and ligaments that, over time, can lead to stiffness, reduced mobility and in some cases fusion of spinal segments.

AS typically begins in early adulthood, usually before the age of 40, and often goes undiagnosed for years because its early symptoms closely resemble common mechanical back pain. Unlike mechanical back pain, however, ankylosing spondylitis follows an inflammatory pattern: symptoms are typically worse after rest and improve with movement. Morning stiffness lasting more than 30 to 60 minutes is a characteristic feature. There is also a strong genetic association, the HLA-B27 gene is present in the majority of people with AS, though most HLA-B27 carriers do not develop the condition.

Physiotherapy is a cornerstone of AS management at all stages, alongside medical treatment coordinated by a rheumatologist.

What Causes Ankylosing Spondylitis?

Signs and Symptoms

The exact cause of ankylosing spondylitis is not fully understood, but key factors include:

AS symptoms typically develop gradually and may include:

  • Genetic predisposition – the HLA-B27 gene is present in approximately 90% of people with AS
  • Family history of ankylosing spondylitis or related spondyloarthritis
  • Onset of chronic inflammatory back pain before the age of 40
  • Environmental triggers that activate the inflammatory response in genetically susceptible individuals
  • Persistent low back and buttock pain and stiffness, often worse in the second half of the night
  • Morning stiffness lasting more than 30-60 minutes that improves with movement
  • Symptoms that ease with activity and worsen with prolonged rest
  • Reduced spinal mobility over time, particularly into extension and rotation
  • Fatigue as a significant associated feature
  • In some presentations, involvement of the hips, shoulders or peripheral joints

What Causes Ankylosing Spondylitis?

The exact cause of ankylosing spondylitis is not fully understood, but key factors include:

  • Genetic predisposition – the HLA-B27 gene is present in approximately 90% of people with AS
  • Family history of ankylosing spondylitis or related spondyloarthritis
  • Onset of chronic inflammatory back pain before the age of 40
  • Environmental triggers that activate the inflammatory response in genetically susceptible individuals

Signs and Symptoms

AS symptoms typically develop gradually and may include:

  • Persistent low back and buttock pain and stiffness, often worse in the second half of the night
  • Morning stiffness lasting more than 30-60 minutes that improves with movement
  • Symptoms that ease with activity and worsen with prolonged rest
  • Reduced spinal mobility over time, particularly into extension and rotation
  • Fatigue as a significant associated feature
  • In some presentations, involvement of the hips, shoulders or peripheral joints

How The MSK Studio Treats
Ankylosing Spondylitis

At The MSK Studio in Adelaide, physiotherapy management of ankylosing spondylitis focuses on maintaining spinal mobility, preserving posture, managing pain and stiffness, and building the physical capacity to support long-term spinal function. We work closely with treating rheumatologists and GPs to ensure our physiotherapy program aligns with the medical management of the condition.

See our low back pain physiotherapy service below: