In my experience as a Physiotherapist, people commonly believe that their LBP is the result of acute injury/damage to specific structures in the Lumbar spine, such as a disc or muscle(s).
While this may be the case, LBP is frequently present in the absence of structural damage usually as a result of poor movement patterns and tissue strain. Either way, these are both examples of mechanical LBP. The National Ankylosing Spondylitis Society (NASS) defines mechanical LBP as pain arising from a structure within the spine including nerves, interverbal discs, facet joints, sacroiliac joints, spinal ligaments, spinal cord or paraspinal muscles (NASS, 2019).
While there appears to be a good awareness of mechanical LBP amongst patients, it is not the only cause of pain in this area. Inflammatory back pain is a collection of symptoms indicating inflammation of structures within the spine and entheses – the sites of tendon and ligament attachment into bone (NASS, 2019). It is important to differentiate between inflammatory and mechanical LBP, as the management can be quite different.
Inflammatory LBP can be difficult to diagnose, as the symptoms can be very similar to those of mechanical LBP. Symptoms can flare and settle over many years and flares are not always related to an incident. Due to this, there is often a delay in correctly diagnosing inflammatory LBP.
Research from the National Ankylosing Spondylitis Society, 2019 has indicated that there is an average 8.5‑year delay in diagnosis for a specific group of inflammatory LBP conditions. This group of inflammatory LBP conditions are called spondyloarthopathies. These can be classified into two types:
(National Health Service, 2020, National Institute for Health and Care Excellence, 2017, Rheumatoid Arthritis, 2018, Spondylitis Association of America, 2020)
There is a tendency to use the term axial Spondyloarthropathy (aSpA) to describe all these inflammatory presentations when they affect the spine now. The very early discrimination of the various sub-categories of disease can be challenging and delay in treatment due to semantic debate, and over diagnosis must be avoided.
Once we suspect that a patient has inflammatory LBP, there are several key questions we ask to differentiate it from mechanical LBP.
Inflammatory back pain usually, but not exclusively, begins in people <45 years old.
Mechanical LBP commonly has a sudden onset of symptoms. Inflammatory LBP is more insidious, and pain can have lasted for >3 months before presentation.
Generally, Inflammatory LBP improves with movement and exercise.
Generally, Inflammatory LBP doesn’t improve when at rest.
People with inflammatory LBP often experience waking during the second half of the night due to their symptoms.
In addition to the five key features above, other signs of inflammatory LBP we look out for include:
Early diagnosis is important. The initial management of inflammatory back pain is appropriate exercise-based rehabilitation – guidance for which can be obtained for patients through the NASS Back to Action app. However, the threshold for commencing patients with these conditions on medication known as ‘biologic agents’ is lowering. In the majority of cases this treatment is highly effective – especially when combined with exercise – and can transform the patient’s life.
National Ankylosing Spondylitis Society 2019, Back Pain Plus, National Ankylosing Spondylitis Society, viewed 28/09/2019, https://nass.co.uk/get-involved/campaign-with-us/back-pain-plus/
National Health Service 2020. Reactive Arthritis, National Health Service viewed on 03/02/2020, https://www.nhs.uk/conditions/reactive-arthritis/
NASS – Back to Action exercise App
National Institute for Health and Care Excellence 2017, Spondyloarthritis in over 16s: diagnosis and management, National Institute for Health and Care Excellence, viewed 28/09/2019, https://www.nice.org.uk/guidance/NG65/chapter/Recommendations
O’Sullivan, P, Caneiro, J.P, O’Keeffe, M, Smith, A, Dankaerts, W, Fersum, K, O’Sullivan, K. 2018 Cognitive Functional Therapy: An Integrated Behavioural Approach for the Targeted Management of Disabling Low Back Pain. Physical Therapy, 98, 5.
Rheumatoid Arthritis 2018, Seronegative RA: What are the Symptoms of Seronegative RA?, Rheumatoid Arthritis Support Network, viewed on 03/02/2020, https://www.rheumatoidarthritis.org/ra/types/seronegative/
Spondylitis Association of America 2020, Overview of Enteropathic Arthritis/Arthritis Associated With Inflammatory Bowel Disease, Spondylitis Association of America, viewed on 03/02/2020, https://www.spondylitis.org/Enteropathic-Arthritis.