Gluteal Tendinopathy, the PT Chronic Pain Denier Movement, and Circular Arguments
POSTED ON IN Research BY Christopher Centeno
Likely the silliest movement in physical therapy and rehabilitation today is what I call the PNE chronic pain denier movement. It's bizarre not because of the overall concepts on which it is based, but more the religious fervor of its disciples and the crazy pseudoscience they're able to get published that purports to validate their movement. Most of this research is based on a logical fallacy called a circular argument. I've blogged on this before, but every time I see one of these silly papers published, I feel I need to point out what bovine excrement looks like in scientific drag. Today's entry is on chronic gluteal tendinopathy.
What Is Gluteal Tendinopathy?
The butt muscles (what physicians call the gluteals) can get wear-and-tear damage and as a result can cause pain at the side or back of the hip/pelvis. See the diagram below. I've placed the "X" marks where most patients feel pain.
The PNE Crazies
PNE stands for pain neuroscience education. The idea is an old one recycled from the '80s that there is no such thing as chronic pain caused by prolonged tissue injury. All chronic pain is a trick of the mind. Now, back in the '80s, we had no ability to image pain signals, so this little deception launched hundreds of millions of dollars of worthless multidisciplinary chronic-pain programs. The idea was that you could talk these patients out of being disabled. These programs were notorious for discharging patients who were still in pain after having blown through tens of thousands of dollars.
Now, PNE has updated this failed idea and instead of the pain being in the head of patients, it's in their nerves. This is because we can now "see" pain signals on imaging. However, the basic concepts are still the same. You can convince patients to ignore their wonky nerves, and since the pain signals aren't originating from real tissue damage, they will be better for it. What research do we have that supports this concept? Suffice it to say that all of it I have reviewed is merely a circular argument designed to confirm a flawed idea. Let me explain.
If you have kids, you're familiar with the logical fallacy called a circular argument. Something like, I need a new car because it will help my grades. What's that based on? Jenna got a new car and her grades went up. How do you know that was caused by the car? Because everyone knows that a new car always increases a student's grades.
The New PNE Study
This study involves gluteal tendinopathy, which is bizarre because this problem is so easily treated with platelet rich plasma. We see hundreds of these patients each year, and they promptly resolve, like a strep throat treated with antibiotics. In fact, I had this issue lingering for about a year until I had it injected, However, I suspect that the Australian physiotherapists and scientists who authored the article don't know that this is an easy way to treat the problem. They likely live in a medical-care system where all that's available is harmful steroid shots, physical therapy, or surgery. There's even a high-level study showing that PRP is superior to steroid injections for treating this condition.
The new PNE study looked at more than two hundred patients who had gluteal tendinopathy that was diagnosed on their MRI. They filled out a questionnaire that's focused on measuring the disability caused by tendinopathy. This is a series of questionnaires that are specific for different types of tendinopathy like Achilles, trochanteric, or gluteal. The authors then identified mild, moderate, and severe subgroups based on the questionnaire. They also measured physical and psychological characteristics.
What did they find? This is where it gets bizarre, as they found what you would expect if this was a physical problem and not "in the nerves" of patients:
- There were higher pain catastrophizing and depression scores in patients who had more severe tendinopathy based on the questionnaire. Yep, if you have a more severe disease, you will be more upset about it.
- Lower pain "self-efficacy" scores were found in the severe group compared to the moderate and mild groups. This is a questionnaire that determines how much a patient is able to do despite pain. Again, patients with more severe disease are likely to do less.
- The severe group was heavier and had a poorer quality of life compared to the mild group.
- Hip abductor muscle strength wasn't different between the mild, moderate, and severe groups.
What did they conclude? This is where the study comes off the proverbial rails. The authors stated, "the consideration of psychological factors in more severe patients may be important to optimize patient outcomes and reduce healthcare utilization." Huh? They seem to justify this conclusion based on the fact that patients with the most disability were fatter, had more psychological distress, and had a poorer quality of life.
There is, of course, another explanation of the results that seems to have escaped our PNE fanatic authors. Patients with more severe disease are more physically impacted and, therefore, have more psychological distress and poorer quality of life. Meaning, if you have a more severe injury that isn't improving and it is impacting your life, you're going to be more concerned about it and report that your quality of life is poorer.
This Is Just Another Poorly Executed PNE Study with Circular Reasoning Without an Internal Control
All studies about whether psychological factors are causing chronic pain need an internal control. This means that they need an objective measure that ties to the severity of the physical condition so that we can know what the patient should report. This shouldn't be measuring the cause of the problem, but an outside objective study. This could be an imaging study, a tissue biopsy, or stress imaging that places the tissue under force to look at its integrity.
Let's look at an example that isn't from medicine—let's look at a study on attitudes of bicycle owners toward their bikes. We could give bicycle owners questionnaires about how much they love or hate their bicycles. We would, of course, find that people who report that their bicycles are less reliable would have lower "bicycle satisfaction scores" and reported lower quality of life with their bicycles. However, if we tied all of this to a physical inspection of the state or repair of the bicycles, we could find out which people's hate for their bicycle was justified and which was not. Without that internal control of knowing which bikes were really broken, we would be left believing that people's dislike of their bicycles was "all in their head."
This study tried to use an internal control. They measured hip abductor strength, which didn't vary between the severity groups. Meaning the most severely impacted patients on the tendinopathy questionnaire didn't have more strength deficits than those who were in the mild severity group. The authors seem to have used this to conclude that the more severe group wasn't any more disabled than the least severe group. However, this is a poor internal control as hip weakness may be the cause of the disease. Meaning people with poor hip abductor strength may be more likely to get tendinopathy; hence, we're just measuring a cause and not an objective metric that determines severity.
In fact, there is research showing that using hip strength as an internal control here was a dumb idea. For example, this study showed that patients with gluteal tendinopathy had very real changes in the way they walked (an objective finding) and that their hip abductor strength was less. This is another study that also linked hip weakness to gluteal tendinopathy and postulated that it could cause the condition. Hence, we would expect all of these patients to have hip weakness and that this wouldn't necessarily have much to do with severity as weakness was a prerequisite for the disease.
The upshot? This is yet another physical therapy-based PNE study without an internal control and that uses circular reasoning to conclude that patients with a physical condition have psychological issues of coping with their bad nerves and no tissue injury. It's also yet another PNE study that isn't worth the paper it's written on. Why write about these crazy papers in this blog? Because the PNE crowd uses them as "proof" that talking patients out of pain by claiming that they aren't injured and only have overactive nerves is justified. In this case, the PNE crowd has picked an easy-to-fix physical problem caused by tissue damage. Given that high-level evidence exists that a PRP injection will help heal this tissue damage and reduce the pain, this places the PNE physical therapists in a dangerous spot. Meaning that any physical therapist that tries to convince these patients that their hip pain is due to overactive nerves and they should ignore tissue damage is likely committing malpractice.
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