Some thoughts on pain

This wasn’t supposed to be my next blog post but I got really excited to share this “aha” moment of mine!

I just read Bret Contreras’ transcribed interview with Stu McGill yesterday and I thought there were a lot of interesting discussions that made me stop and think. In particular, I really enjoyed their discussion on the biomechanical and biopsychosocial models. For those of you who don’t want to go through the whole thing, this is what was discussed:

Bret: Amen. Okay I know I said this but a couple more things and then we’ll be done. In the world of pain research, there – at one point I was purely all biomechanics and pain. You know, someone’s hurting, there’s a biomechanical reason for that. I need to fix it. Then I got exposed to these very bright individuals who studied pain and got exposed to the biopsychosocial model. I learned about things like the neuromatrix. The neuromatrix was fascinating to me. Talking about phantom limbs and how these people are still experiencing pain even though their limb has been amputated. Your brain has a mental map, a neuromatrix if you will. Your brain’s depiction of the body is not the actual body. These things are all important to know about pain.

However, when I help people – when I’ve tried to fix people. Again, I’m not a physical therapist but hell, everyone – you take the average client and they have some aches and pains and things that don’t feel so good. They also can – when you start getting them stronger – things arise. I always take a biomechanical approach to that. I don’t say to them, “Okay. You’re depressed. I’m gonna try to cheer you up.” I always use a biomechanical approach and I know that’s been the crux of your career. I guess my question is, do you keep this stuff in the back of your mind when you work with people and kind of realize that if you look at the research there is not a lot of research showing that anterior pelvic tilt increases the incidence of back pain? Or that people’s biomechanics really on average it does not lead to pain. But when you work with people, and you – like what you said – you provoke their pain. Usually you can find things that hurt it. Then you get them to avoid that and you get them to move in a way that’s not painful and then you gradually increase their fitness and build on those patterns. The biomechanics would say you are improving; you are decreasing their mechanical insults. You are improving their function, biomechanics, and decreasing pain.

Whereas, the pain scientist or biopsychosocial model might explain it differently. They might say that you have these neurotags and you’re having these threat responses. Through doing the new movement you are decreasing that threat response. You’re teaching the body to move in a different way and accept it. They’re working with a high level coach or trainer in your case, the world’s leading spinal biomechanics. They are comfortable. They are confident. So that’s gonna really affect the results of their recovery because they’re so confident with you. They’re expecting results. So it’s kinda like the placebo effect in a way. Is it important to know both sides or are you a pure biomechanics guy? Talk about that a little bit.

Stu McGill: I don’t think I’m a pure anything. It’s important to be as knowledgeable as you possibly can to explore alternate possibilities. Alternate explanations for what you’re observing. I could give you case after case where traditional pure biomechanical thought couldn’t give an explanation for what you’re seeing in front of you in a patient or athlete. Having said that, let me just take the other side and then I’ll come back to this. There are those who say, “Oh for pain, we’re going to teach them to live with their pain, to handle their pain. We’re gonna tell them that the pain is mostly in their head. It’s a perception and we’re gonna modulate their brain to handle their pain.” This is where I really start to disagree. If you can do provocative testing and cause their pain to get worse by putting them in an awkward posture or stressing the pain somehow. If they say, “Oh yeah. That hurts more.” You’ve just proven that it’s a mechanical variable that makes their pain worse and probably if you can take that mechanical insult away, the pain will be less and hopefully even disappear.

This is a rather harsh opinion, but those who are real proponents of all this psychosocial, they are very poor with their mechanical of understanding. Their mechanical understanding of the phenomenon. So it becomes a default diagnosis. By default, we can’t find the pain in you. Our interventions don’t work on you. It’s not that we’re bad doctors, it’s that you’re a bad patient. The pain is in your head. So it’s a default diagnosis and therefore, the patient should have physiological counseling. That’s what I really get annoyed with because we’ve had patients who have had these diagnosis and we find that sometimes it’s very simple and obvious. It’s just that they’ve never been tested for the mechanical cause of their pain. I had a patient yesterday, I phoned her, and asked how she was doing. I couldn’t figure out her pain. It didn’t make mechanical sense. Yet, she said she had surgery. They found that two nerve roots from two adjacent levels were coming through the same foramen. I had an anatomic anomaly. I’m going to be in the medical literature because I had a freak. I’m a freak with the anatomy and then I said, “Ah ha. Well that so explains how you are having both femoral and sciatic nerve symptoms.”

You know, again, it’s just when you keep the detective work going, you can usually find it. There are cases of fibromyalgia that I’ll see occasionally, where the person has as you said, a changed neuromatrix. What is movement to some person, their brain has now perceived this pain. To change their neuromatrix, the way we would attempt it (and admittedly we’re not very successful with it) but occasionally we are on the very tough cases who failed all other approaches including the psychosocial approaches. You teach the body to move pain free. Do what it can do pain free. And then slowly increase the repertoire of pain free movement as the brain learns how to perceive those movements. Anyway, there are a few discussions skirting around that issue of the whole psychosocial but you know, there’s no question. Mechanical things, injury, tissue stress causes pain,. How the person reacts to that it depends. If you’ve got a spouse who is yelling at you and stressing you out, chances are you will become more sensitized to that pain. If you hate your job and you really don’t wanna go back to work, that’s a social issue and you will probably magnify that pain.

Bret: I think they would say that it causes deformation and tissue damage, but the brain is what decides whether to elicit that pain response. But what I always wonder with some types – now I interviewed a guy named Jason Silvernail. I can’t tell you how much respect I have for him. He’s a CSCS. He cares about both sides of both worlds. But when I get someone who just tells me that there’s no association with biomechanics and pain, I want to say to them, “Let me have you do three sets of round-back deadlifts to failure. See how you feel the next day. “I bet if I did that to 100 people, all 100 would hurt. I’m talking full lumbar flexion, under heavy load. I could probably herniate some discs or snap some ligaments right there if I really loaded them up as heavy as possible. So I just wonder – trust me, I try to be cautious in my conclusions but sometimes I wonder if they’re not trying to meet in the middle and learn our side of the equation. Stu, you’ve worked with people with some of the most jacked up spines. I’ve seen the literature, like 50% of people have herniated discs and a lot of them are pain free. The point is when you work with a person, usually you can get them out of their pain by incorporating biomechanics and whether that’s working through the brain. You’re working through the psychological, biological model, but it’s all related. That’s what those guys would admit. Hey, the bio portion is biomechanical. Of course! I just think we kind of, since we deal with athletes, we tend to possibly look more at the mathematics, physics. But it’s very critical because I have heard of stories where people were kind of given a nocebo effect by being told that this movement causes pain, squats are bad for your back. Deadlifts are bad for your back. Or this is bad for your back. This posture is bad for your back. You have anterior pelvic tilt, you’re gonna have back pain. It’s very important to understand the limitations of the biomechanical model and to understand the biopsychosocial model but to keep them all in their place. That’s just my two cents at least.

I’m super happy that Bret asked that question because I had been wondering the same thing! I watched a few presentations last week (also very interesting and thought-provoking), as part of the Healthy, Wealthy, & Smart 2013 Virtual Conference for Physical Therapists, that were focused on applying pain neuroscience to patient rehabilitation. From the presentations that I did see, I got the impression that the biomechanical model was outdated and shouldn’t be used anymore (just my interpretation – it could very well be that I mis-interpreted what they said).

After reading Bret’s interview yesterday, I came to an understanding that both models have its place and that the biomechanical model doesn’t need to be thrown away completely. It seems to me that having poor biomechanics is certainly a risk factor for developing pain, but so is catastrophizing, being fearful of moving, emotional stress, etc. So, helping someone improve their biomechanics would take away one of these risk factors and thus reduce their risk of developing pain. On that note, this is another quote from McGill that I think is relevant to this post:

When I hear people criticize a study because it didn’t find statistical significance. On average there was no difference. Yet, they’ll leave the paper and walk away. You and I don’t do that. We will then go into the data and then we find low and behold, forty percent of the people had a positive effect of the intervention. 40% had a negative effect. The remaining 20% it made no damn bit difference. But 40% of those people were affected positively. What were the features of those people that it affected? Now we’re really getting into the nity gritty. That’s another key point. I love studies that on average, are statistically insignificant. I wanna know about the outliers.

So maybe, if there was a study looking at the effects of improving biomechanics on pain (I know, very general question here), and it had the results described above, overall it would seem like changing someone’s biomechanics has no statistically significant effects on their pain. But, perhaps it did help 40% of those subjects because for those subjects, poor biomechanics was the biggest risk factor for them. Whereas for the others, they had other larger risk factors that were not addressed so improving their biomechanics did not help their pain. I have no evidence supporting this at the moment but it’s just a thought!

To conclude, the human body is super complicated and there is a never a black/white answer. It’s important not to forget that the “biomechanical/biological” model is the “bio” part of the biopsychosocial model. And to end this post, I’ll leave you with my favourite quote from the interview:

This is all about friendship and we’re all trying to seek the truth.

Edit:  Nov 19, 2013
I was thinking about this more and it occurred to me that pain neuroscience is part of the “bio” part of the biopsychosocial model. I think I had been getting the impression that the biomechanical portion of the “bio” part was being pushed out by pain neuroscience when really, we should be considering both (and probably other models I don’t know about) in addition to the psychosocial aspects.

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