The influence of structure on back pain is a discussion I have had twice in the last 3 days.
I would not describe myself as an expert in this area but this area of discussion does leave me a little confused and I do take an interest in it, especially with the whole ‘forgetting the bio in the BPS’ thing.
These are just some thoughts and data, this is certainly not a comprehensive literature review, just information I have been exposed to and to be honest leave me more uncertain than certain.
Undoubtably the disc can be a source of nociception and relevant in back pain. The plausability is not in question here.
My key questions (not really answered yet) are:
1) How do we reliably identify discogenic back pain clinically?
2) How does this influence our management?
WARNING - the data below is likely to leave things much murkier than clear!!!
Prevalence of disc related factors in LBP
So firstly we see that disc degeneration is more prevalent in those with back pain.
We also see that more findings (3 or more) on an MRI report were more strongly associated with LBP than a single finding.
Here we see those with acute back pain are more likely to have disc herniations
But we also see lots of the same signs in those with no pain
Again a high prevalence of the same signs in asymptomatic populations.
People with previous back pain also had increased MRI findings but no current pain.
MRI findings also do not seem to be predictive of back pain.
Changes in MRI are also similar in symptomatic and asymptomatic populations
So maybe we need to think more about relevance than prevalence here? If both groups can have MRI findings then we cannot just assume.
Do symptoms of lower back pain correlate with structure?
These papers below would suggest it is not that simple to correlate the symptoms that people experience compared to imaging. Again this suggests that if there is nociception from the disc it is not the only factor at play.
It does appear to be difficult to diagnose discogenic pain with 90% being labelled as non specific. So we know it can be prevalent but it is difficult to find if it is relevant for your patient. Ultimately we need to be able to identify clinically to make the link in my opinion.
These are some recent clinical classification guidelines.
There is some support for centralisation in identifying discogenic pain.
This paper is pretty certain in being able to identify discogenic pain
This paper suggests that internal disc disruption is not a real thing!
How does this change management?
It was suggested to me that we would treat an annular sprain much the same as we would a sprained ankle. This would be through the concept of optimal or tolerable loading and could be done both via the magnitude of load and manipulating the load different movements might place on the disc through spinal kinematics.
I think this sounds fair however it brings us to the second point I raised of does this information make a big change in the management of LBP. We could treat a non specific LBP in a similar way so again I am left a little confused.
Over the longer term for conditions such as disc degeneration the famous Battie twin study would suggest loading has limited influence.
We can't draw to many conclusions from these two papers below, as they are observational, but perhaps they tell us that activity is not detrimental and MIGHT BE beneficial.