Many key scientific studies over the years have undermined major structuralist assumptions. Some of the evidence is direct. Some is indirect, or “circumstantial,” as a criminal lawyer would put it. There is a strong pattern of all kinds of evidence converging on the same conclusion: structuralism does not produce effective therapies. It does not “deliver the goods.”29
My favourite direct evidence — not the best, but my favourite — has always been the simple leg length study published way back in 1984, in the venerable British medical journal Lancet. It showed that leg length differences were unrelated to back pain — no correlation even, let alone a causal relationship.30
The fear of an excessive curve in the low back, AKA the pelvic tilt myth, has spawned countless back pain “cures” based on stretching and strengthening to try to flatten it out a little, with the (coincidental I’m sure) bonus of flattening bellies at the same time. This is a well-studied question, and a 2008 systematic review of more than 50 studies found no association between measurements of spinal curves and pain.31 If there is any connection, it’s a weak one.
An excellent example is a failure of the Functional Movement Screen to detect actual recent injuries, let alone a subtle or specific biomechanical risk factor for injury. As mentioned in the introduction, FMS is a set of physical tests intended to “identify asymmetries and limitations,” based on the assumption that they are a problem — classic structuralism. However, a 2011 study in the International Journal of Sports Physical Therapy found that FMS test results didn’t change in people who had actually been injured within the last six months.32 If a test can’t detect the effect of recent injury on the body, or the risk of factors that led to it, it probably can’t detect future injuries either, and the structural assumption at the heart of FMS is therefore rather dubious.
The neck is a popular place for biomechanical bogeyman, but in 2007 Grob et al published findings in the European Spine Journal that abnormal neck curvatures do not have any connection with neck pain.33
Or the shoulder? “Shoulder dyskinesis” — fancy talk for bad shoulder movement — is a popular biomechanical bogeyman in this area, but there’s definitely no smoking gun evidence that funky shoulder movement leads inexorably to pain, and a nice fresh 2013 review in the British Journal of Sports Medicine concluded “no physical examination test of the scapula was found to be useful in differentially diagnosing pathologies of the shoulder.”34 (Funny story about that citation, too.35) 150 people who received a sham surgery recovered just as well as people who actually got their cartilage polished.
Perhaps the knee? A bizarre and amazing study published in the New England Journal of Medicine in 2002 showed that a placebo for knee osteoarthritis is just as good as real surgery.36 A more “mechanical” problem than rough knee cartilage can hardly be imagined, yet 150 people who received a sham surgery recovered just as well as people who actually got their cartilage polished. It’s hard to imagine a more crushing blow to structuralism! Except maybe this? A 2010 review of risk factors for the development of knee arthritis (after the loss of meniscal tissues) mostly eliminated “poor knee alignment” as a factor.37 Surely poor alignment would definitely spell trouble? That’s a common assumption! But not a safe one.
Numerous MRI studies of the back over the years have shown just terrible correlation between structural problems and back pain.38 Time after time, you find that people with low back pain have no mechanical problems, and people with mechanical problems have no low back pain.
Fang in your throat? The styloid bone at the back of the throat looks like the fang of a sabre-toothed squirrel. It can get too long and start to bother the sensitive anatomy around the tip (Eagle Syndrome). Except, surprisingly, most people with elongated styloids are just fine. Clearly, styloid length is not a hazard in itself — something else has to be wrong.39
Surely narrowing of the spinal canal is always painful? Perhaps not. Cranking up the counter-intuitiveness another notch, scientists found in 2006 that a structural problem that everyone previously assumed to always be painful — even I thought so! — turns out not to be. Spinal stenosis has always been regarded as an inevitable cause of back pain, but the Archives of Physical Medicine & Rehabilitation has showed clearly that it often does not cause pain after all.40
Poor correlation in animals, too! Here’s an interesting perspective from veterinarian Johnny Bat-Yonatan on canine hip dysplasia, an arthritic condition common in big breeds like Labrador retrievers, German shepherds, and rottweilers:
It’s a horrendous thing that often leads to the animal having to be euthanised, but the highly specialised grading of hip dysplasia doesn’t correlate directly with mobility and life quality. You have great x-rays of animals that can barely walk, and horrendous hips in dogs that don’t display any pain. X-rays sometimes tell a story, other times they’re a footnote. We learn early that we need to treat the animal, not the radiograph.
“Treat the animal, not the radiograph.” Nicely put, and equally apt for pets and their humans. We’re all animals! For more information, see Canine Hip Dysplasia, by Wendy Brooks, DVM, DipABVP.
If spinal instability were painful, surely stabilizing it would help? But a 2009 study showed that “stabilizing” fractured vertebrae by injecting bone cement doesn’t actually aid the recovery — at all!41 If such a straightforward method of stabilization doesn’t work, it’s pretty hard to make the case that instability could have been much of an issue in the first place.
A blow to the importance of muscle “balance” — symmetrical muscle mass and strength — was delivered by the British Journal of Sports Medicine in 2010.42 First the authors proved that major muscle imbalances do exist in elite Aussie-rules football players — bigger kicking muscles on one side! — and then proved that they were “not related to the number of injuries” in those athletes. I repeat: Not. Related. This is exactly the opposite of what any good structuralist would predict.43
Pronation is one of the greatest hits of structuralism, so prevalent that it’s routine to hear runners call themselves “pronators,” and it’s easy to see why: surely the ankle collapsing inward is a recipe for repetitive strain disaster? Not so much, and a number of lines of evidence have suffocated the idea over the years. One scientific blow landed in 2010 when American Journal of Sports Medicine published a study showing that shoes to control pronation had no apparent effect on injury rates in US Marines.44 The study wasn’t perfect, but it was suggestive and consistent with other evidence. There is probably no justification for labelling anyone as a dirty rotten pronator.
Sports injuries aetiology investigations have assumed a reductionist view in which a phenomenon has been simplified into units and analysed as the sum of its basic parts and causality has been seen in a linear and unidirectional way. This reductionist approach relies on correlation and regression analyses and, despite the vast effort to predict sports injuries, it has been limited in its ability to successfully identify predictive factors.
Bittencourt et al, “Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition-narrative review and new concept,” British Journal of Sports Medicine, 2016
Several other running risk factors: Pronation is only the most famous of a whole posse of similar biomechanical quirks that supposedly plague runners, including some already mentioned above. Most attempts to confirm these have failed. In 2004, Devan et al published in the Journal of Athletic Training that they couldn’t find any connection between knee injuries like iliotibial band syndrome and patellofemoral syndrome and any of the mechanical “usual suspects” that are blamed for those conditions.45 Another paper that year reported “no evidence that static biomechanical alignment measurements of the lower limbs are related to lower limb injury except patellofemoral pain syndrome.”46 In 2009, Ferber et al concluded “there is no definitive link between atypical foot mechanics and running injury mechanisms.” A 2016 study in the Eur J Sport Sci “did not find significant associations.”47 This is not to say that there are no structural risk factors for running injuries — there is some evidence pointing that way. But whatever associations there may be are clearly not very clear.
Core strength is still assumed to be important by nearly every professional and patient,48 and yet it has been thoroughly debunked by one experiment after another for twenty years now. No kind of core training has any special power over back pain, cannot produce any benefit greater than minor or greater than any other kind of therapeutic exercise, and does not reduce injury rates. This is all covered in much greater detail in my low back pain book.
My favourite recent example of core strength research is a 2010 study of more than 1,100 soldiers which found that specialized, “precise” core strengthening did little to improve rates of low back pain (or any other injury) compared to good old-fashioned sit-ups.49 Meanwhile, many other studies show that no kind of core strengthening is important.50
A large 2011 study of massage therapy for low back pain51 tested the effectiveness of a “structural” style of massage consisting of a blend of popular techniques and treatment approaches based on common structuralist assumptions. Massage therapists are prone to believing that “the right moves” will have a more profound therapeutic effect.
Moderately-trained therapists with more than five years of experience provided about 130 patients with 10 hours of this kind of massage. They also gave ordinary relaxation (Swedish) massage to another 130 patients. The effects on back pain of these two approaches were carefully measured over an entire year. The results were revealing: there was “no clinically meaningful difference between relaxation and structural massage” whatsoever! That is quite an embarrassing outcome for techniques that are routinely touted as “advanced.” If structuralism were a good basis for massage technique, shouldn’t it have produced impressively superior results?
My personal experience in studying this subject for the last several years is that I can hardly look anything up anymore without finding more evidence that structuralism is just generally a poor way of explaining people’s pain.