Tissue changes and pain: explaining their relevance
Structure is not Destiny...but it still might be important.
We know that degenerative changes can exist on a spinal MRI and people can have no pain. Those changes aren't sufficient for pain
they aren't completely irrelevant.
A recent systematic review by Brinjkji et al 2015 suggests that those with low back pain have a greater prevalence of changes or "abnormalities" on their MRIs. This finding was echoed by the work of Hancock et al 2017 also showing that those with low back pain were more likely to report a greater number of changes on MRI
These were same systematic review researchers who show that degenerative changes are normal and are like "Wrinkles on the inside" (link here). Meaning changes on MRI or abnormalities can absolutely occur without any pain. It would be weird after a certain age (20ish) not to have changes on an MRI. Its what we do. Again, the diagnosis is...HUMAN.
We also see this in other structures like tendons where tendinosis is a risk factor for future tendinopathy (tendinosis plus pain) Link here https://www.ncbi.nlm.nih.gov/pubmed/27633025
But here we are confronted with seemingly two conflicting themes. One suggesting that you can degenerative changes and no pain and the other suggesting that those that have pain have more degenerative or structural changes.
So how we do we reconcile this?
Perhaps we want to view these structural changes as similar to kindling for a fire.
Kindling is not a fire. Its a precursor and before it can become a fire you need some accelerant or spark. We can view degenerative changes the same way. They aren't sufficient for pain but perhaps you need some sort of sensitizing agent to create that "spark' and the "fire" of pain.
Sometimes the accelerant is too much physical loading. Perhaps the accelerant is too much psychological load. Or some change in any of life's stressors which we fail to adapt to. Pain is multidimensional and the accelerant come from anywhere...but so can the solution :). The kindling is now the precursor for a fire and the sensitizers are the sparks that lead to the flame. So now we are cooking.
Putting out the fire and getting out of pain
What is great is that we don't have to change the structure to get out of pain. Which is good because we rarely can. Roughly, we can do two things:
1. We have to change the sensitizing agent and this can be done a number of ways.
2. we build our tolerance to the sensitizing agent or the structural change.
This is similar to our cup analogy for pain. Pain occurs when all of the sensitizing agents in our life "fill" the cup and the cup overflows. Pain is that overflow.
We can either decrease the sensitizing agents or we can build a bigger cup. This is well illustrated with tendinopathy. You don't change the degeneration/tendinosis dramatically rather you build up the healthy tendon around the tendinosis and now normal loading is no longer sensitizing. The slow application of load to a person with tendinopathy is probably both building a bigger cup (the tendon adapts, the person might develop modulation of nociception etc) and it can decrease the sensitizing agents (one loads a tendon without dramatic increases in pain and this in turn might increase self efficacy, decrease fear, build resilience, increase hope or even decrease nociception).
Why are we using this explanation?
If I am very honest, I don't want to. In my practice, I've been saying for decades (and yes we have know it that long) that you can have big degenerative changes, disc herniations, muscle tears and tendinopathies without pain. That is a great message is still very true. But its not clinically honest to say that those changes are wholly irrelevant. We just don't want to say that they are destiny (see this old post on structural changes being poorly related to pain).
Using this analogy/metaphor helps validate our patient's beliefs about their pain and even about their scans. It also gives them hope when they have a scan that they believe automatically equals pain. They get to treat the sparks and get out of pain.
P.S. I use this same framework for assumed biomechanical movement "dysfunctions" or "impairments". You can have weakness, tightness, rigid movements, knee valgus, scapular dyskinesis and never have pain. You don't even have to change them when someone is in pain. But sometimes they might be relevant under some conditions and addressing them can help with pain if you so chosse or addressing other areas allows one to tolerate them. That is the beauty about the cup. There are a lot of different things we can address to change and manage pain. Rarely, is there ever one thing that needs fixing. And asking yourself that clinical question "Is there ever something that needs fixing in this case" is always a good clinical thought process. Have a look at this contentious post for more on this theme - Why I put strength on dysfunction.