Back pain is a common complaint presenting in > 80% of adults. Low back pain can be classified into acute, subacute, and chronic dependent on the duration of symptoms. Your Physiotherapist will use your consultation to screen for serious pathology and categorise whether the pain is inflammatory in nature, structural, radicular, disocgenic or that of a chronic pain disorder. Inflammatory back pain is oftentimes misdiagnosed as chronic back pain or SIJ disorders. The aim of this article is to clarify the diagnosis of inflammatory back pain and outline the steps needed by both patient and primary care provider for management.
What is it?
Inflammatory back pain or Spondyloarthritis is where inflammation impacts the structures of the spine and associated joints. Spondyloarthritis is an umbrella term which includes but isn’t limited to: axial spondyloarthritis (axSpA), ankylosing spondylitis (AS), psoriatic arthritis.
AxSpA is the result of elevated levels of inflammation within the body affecting the spine, neck and pelvis. As an autoimmune disease, the the immune system misinterprets the body’s own tissue as a hazard and attacks resulting in systemic inflammation. Symptoms can present in peripheral joints including the shoulders and hips, whilst also impacting organs such as the bowel, heart, lungs and skin. Importantly, this occurs in both classifications of axSpA being:
- Non-radiographic axSpA: no presence of damage or fusing seen on X-ray
- Radiographic axSpA: damage and fusion seen on X-ray
Symptoms
Symptom prevalence and severity varies between individuals dependent on disease progression. As multiple organ systems can be implicated, symptoms may include:
- Pain in the buttocks, lower back, pelvis and hips
- Redness, swelling or heat reported in peripheral joints
- Pain worsening in the morning and evening
- Symptoms that are unchanged or worsen with rest
- Symptom improvement with movement
- Pain or tightness in the chest
- Diarrhoea or bloating
- Painful, red eyes
- Blurred vision
- Fatigue
- Appetite loss
Characteristics
There are cardinal differences between mechanical and inflammatory back pain. When presenting to your general practitioner or physiotherapist, an extensive interview and objective assessment will be conducted to guide diagnosis. Key differences can be seen below:
| Inflammatory back pain | Mechanical back pain |
| Age under 40 | Any age |
| Onset is without cause, lasting > 3 months | Variable |
| Pain worsens or doesn’t settle with rest | Improves with rest |
| Pain improves with exercises | Can worsen with movement |
| Night pain | Nil night pain |
| Morning stiffness | Any morning stiffness settles quickly |
Cause
As an autoimmune disease, the immune system attacks the body’s healthy tissue triggering an increase in inflammation. This can cause elevated levels of the CRP or ESR in pathology testing. Unfortunately, there is not a definitive cause of inflammatory back pain. In individuals with specific genes, introduction to a virus or bacteria can act as a trigger. The HLA-B27 gene is not always characteristic of inflammatory back pain however can be present in those with existing symptoms and increases the strength of diagnosis.
Diagnosis
Unfortunately the time frame to diagnose AS from symptom presentation is up to 7 years. This is largely due to clinical misdiagnosis as mechanical back pain or a gap in knowledge. Inflammatory markers in pathology testing aren’t consistently elevated and X-ray changes are often seen later on, making it very difficult to formally diagnose. If your treating physician or physiotherapist is suspecting inflammatory back pain, further testing will be required in addition to a Rheumatologist referral.
Management
Management of inflammatory back pain is centred on reducing symptom severity and improving quality of life. Your Rheumatologist may prescribe non-steroidal anti-inflammatory drugs or biologic agents in conjunction with non-pharmacological tools. Physiotherapists work closely to ensure that joint range of motion, muscle strength and muscle length is maintained through formal structured exercise classes or the prescription of a home exercise program.
References:
Dubreuil, M & Sieper, J. (2019). Inflammatory back pain and axial spondyloarthritis: lessons for clinical practice and epidemiological research. Arthritis Rheumatol. 2018 Jul; 70(7): 981–983.