SaveYourself.ca •Sensible advice for aches, pains & injuries
 
[Illustration of hands twisting a spinal column] by Gary Lyons

Spinal manipulation: underwhelming effects on back pain since 1895.

Does Spinal Manipulative Therapy (SMT) Work?

Adjustment, manipulation, and popping of the spinal joints and the subluxation theory of disease, back pain and neck pain

12,000 words, updated Jul 1st, 2014
by Paul Ingraham, Vancouver, Canada bio
I am a science writer, the Assistant Editor of ScienceBasedMedicine.org, and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I’ve written hundreds of articles and several books, and I’m known for sassy, skeptical, referenced analysis and a huge bibliography. I am a runner and ultimate player, and live in beautiful downtown Vancouver, Canada. • full bioabout SaveYourself.ca

SHOW SUMMARY

The idea of “adjusting” the spine refers to many different manual therapies that wiggle, pop and otherwise manipulate spinal joints. The correct umbrella term for these treatments is “spinal manipulative therapy” or SMT. Expert opinions on SMT range widely, with some prominent medical scientists expressing strong concern and skepticism. Its provenance in chiropractic subluxation theory is dubious, its benefits are minor at best, and yet there are serious risks, even including paralysis and death in the case of SMT for the joints of the neck.

Despite all the controversy, there has been little high quality scientific research to determine whether or not SMT is safe and really works. Major science reviews have either been thoroughly discouraging. Thus, SMT fails the “impress me” test — it can’t possibly be working any miracles.

And yet spinal joint popping in particular is something that people crave, and most clinicians believe that some forms of SMT can be helpful to some of their patients, some of the time. There seems to be almost no doubt that there is something of therapeutic interest going on in SMT, at least some of the time.

Can your spine be “out”? Can it be “adjusted”? Adjusting the spine (spinal manipulative therapy, or SMT) is complex and controversial, largely based on the chiropractic concept of a joint “subluxation.” SMT for the back probably has modest benefits and tolerable risks, while SMT for necks involves less benefit … and the rare but real risks of paralysis and death! Nearly all medical science experts and many chiropractors reject the century-old chiropractic belief that SMT can prevent or cure diseases. This article covers these topics thoroughly — it is one the most detailed online guides that I know of. I particularly discuss the pros and cons of SMT as it relates to the treatment of neck pain, back pain, and muscle pain.

Important science update, late 2012

In 2012, a large, credible Cochrane review of SMT science was published.1 Its conclusions were resoundingly negative and disappointing.

Historically, spinal manipulative therapy for acute low back pain has been regarded as the best example of evidence-based care routinely offered by the chiropractic profession. Even many fierce critics of chiropractic have supported this claim (or at least left it alone while focusing on other issues). Nevertheless, some critics have pointed out that even this “best” use of SMT has been damned with faint praise by the research.

This large meta-analysis supports the most critical view: the authors concluded that “SMT is no more effective in participants with acute low-back pain” than shams and placebos. Despite this, the rest of their conclusions seem crafted to prolong the controversy. They explain to clinicians why they should still refer patients for SMT (“preferences” and “costs”); they say that more research is needed to “examine specific subgroups.” (This is based on the rather faint hope that SMT might work so well for an unknown subcategory of patients that they can pull up the average.) And they say there’s a need for “an economic evaluation,” but if a treatment is not effective, it can’t be “cost effective.”

If it were possible to report good news on this topic, it would be here — and I would be happy about it. But it’s not, and the topic can probably be closed. It won’t be closed, of course — the controversy will go on for many years — but like a news network calling election results, there’s a point at which a certain conclusion is virtually inevitable. I believe we are now at that point with SMT.

Overview of a messy topic

The idea of “adjusting” the spine refers to many different manual therapies. The joints of the spine may be wiggled, popped, stretched, tapped and more. The correct umbrella term for these treatments is “spinal manipulative therapy” or SMT. Expert opinions on SMT range widely, with some prominent doctors and medical scientists expressing the strongest possible concern and skepticism. Its origins in chiropractic are dubious, its benefits are not major, and there are serious risks, including paralysis and even death.

…there is a “paucity of data related to beneficial effects of chiropractic manipulation of the cervical spine” and a “real potential for catastrophic adverse events.” That’s what the science says.

Dr. Harriet Hall on ScienceBasedMedicine.org, Aug 31, 2010

Controversial it may be, but the science is clear enough to have caused a major American health insurer to stop paying for cervical spine SMT in 2010.2 There has been little high quality scientific research to determine whether or not SMT really “works,” but what little does exist is discouraging indeed. Major reviews of that literature published in recent years came to “underwhelming” and half-baked conclusions. Thus, SMT fails the “impress me” test — it might work, but it can’t possibly work particularly well. An effective therapy should have no problem passing fair tests with flying colours.

And yet spinal joint popping/cracking is a sensation that people crave. I am one of them! And most clinicians — including myself, and including serious skeptics like Dr. Homola — believe that some forms of SMT can be helpful to some of their patients, some of the time. There seems to be almost no doubt that there is something of therapeutic interest going on in SMT. In rare cases involving joint adhesions, mechanical “locking” and loss of mobility, appropriate manipulation has clear value — which is primarily why physical therapists perform spinal manipulation.

It’s a complex picture, and it’s made even more complex by the messy idea of “subluxation.” This is a chiropractic concept of some kind of spinal joint dysfunction, with many shades of meaning — too many! Subluxation can mean many different things, depending on who is talking about it. Some chiropractors attribute great importance to subluxation, and “use spinal manipulation to treat visceral disease.”3 The chiropractic concept of subluxation has been both popular and controversial for many decades now, but it has never achieved medical respectability.45 It’s problematic that SMT is often based on such a slippery concept.

Perhaps it has too much baggage to be a useful term.

Even if you put aside all concerns about the quality of the theory, there is still not a shred of scientific evidence that any kind of spinal joint dysfunction — no matter how you define it — has any importance to your general health. In more than a century, nothing like that has ever been shown to be true.6 So do chiropractic subluxations even exist? And, even if they did, would they actually cause any problem, serious or otherwise? And how serious are chiropractors about all this anyway? I’ll address these questions over the next few sections.

My chiropractor says this is because the top of my neck attaches to my head. Is that a common problem?

from the “chiropractors say the darndest things” file, as reported by Dr. Grumpy (Only Outside Sleepy Hollow)

Reality check: is there such a thing as a chiropractic “subluxation”?

Joint mechanics and neurology are just insanely complex, and when that complex system fails in any way, we could (and should) call it a “joint dysfunction.” Such terminology is nice and safe. We can cram almost any kind of theory into that label — almost anything that might go wrong with spinal joints — without going too far out on a limb. There is little doubt that spinal pain often involves some kind of “joint dysfunction.”

But what kind? Chiropractors believe that they know: “subluxation.” A misalignment. A “spine out of line.”7 Many doctors and scientists disagree!

Chiropractors often propose “subluxation” as both the main cause of back and neck pain and of disease and poor health in general.8 The chiropractic idea of subluxation has been defined in many different ways over the years, but most definitions imply some kind of “misalignment” of the spinal joints that needs to be “adjusted” because it’s causing a disproportionate amount of trouble, both pain and poor health. This ominous definition of subluxation is both the most popular and the least defensible. Although there are other definitions — for instance, definitions that might be less controversial — they probably should not be used, because they are too easily confused with the main and original chiropractic definition.

In standard medical terminology, a subluxation simply refers to a partial traumatic dislocation of a joint. Ligaments around the joint may be painfully sprained, and cause severe pain closely coupled to movement, slowly fading over many weeks, like any other sprain. Slightly subluxed spinal joints often return to a more or less normal position immediately, like a dislocated shoulder popping back in.

Although that’s not the kind of “subluxation” that this article is about, such cases do provide important perspective, in that a true dislocation can be amazingly asymptomatic. There are many case reports of true spinal joint derangement and injury that cause little or no trouble, or certainly much less than most people expect. In the low back pain tutorial, I describe one of my own former patients with a very serious lumbar dislocation — and no low back pain (she came to see me for a foot problem). Another patient with extreme scoliosis, although often uncomfortable, was generally surprisingly fine and even fit. The patient pictured here, as reported in New England Journal of Medicine, had no “pain, weakness, or parasthesia”!9

ZOOM

Traumatic dislocation.

For perspective, here’s an example of a spine that is genuinely “out of line.” Although this is a serious dislocation, the patient was quite healthy. See Akhaddar.

ZOOM

Traumatic dislocation.

For perspective, here’s an example of a spine that is genuinely “out of line.” Although this is a serious dislocation, the patient was quite healthy. See Akhaddar.

Another case report in the journal Spine describes a man who was born with part of a neck vertebra entirely missing — he also had no serious symptoms until he fell one day, and his unstable spine was dislocated “.10 After that he certainly was symptomatic: he had severe pain, but only pain.

Another fun example of congential deformity or anatomical variation is The Amazing Owl Man! You don’t see this every day. Enjoy this campy, cringe-inducing bit news reel about a dude who can “owl” his neck — rotate 180˚ degrees! — if we can believe our eyes:

Man turns his head 180 degrees 2:05

What are we to make of this? Is this anything more than an eye-popping novelty? I have no idea how he can do that, but can I extract some clinical relevance from it anyway? Natürlich! (As my high school German language teacher used to say.) Many of these examples of dramatic joint injury and dysfunction actually cause less trouble than chiropractic subluxationsMany of these examples of dramatic joint injury and dysfunction actually cause less trouble than much less obvious chiropractic subluxations., never mind the more dire neurological problems that most people would assume to be the case, or the diseases and organ failures that much milder chiropractic subluxations can supposedly cause.

If a painful or stuck-feeling neck or low back involves a “subluxation” in any sense other than partial dislocation, then, it must be something more subtle — something nowhere near so obvious as a traumatic injury — which puts it firmly in the category of the classic chiropractic subluxation.

But is there even any such thing? There is a decades-old argument between doctors and chiropractors about the existence or nature of chiropractic-style subluxations. Many chiropractors still believe in them, in one form or another, and some do not.11 Sam Homola writes:

What I read in books written by orthopedic and physical medicine specialists made more sense to me than what I was being taught in chiropractic college. I rejected the vertebral subluxation theory as a basis for use of spinal manipulation.

Sam Homola, Doctor of Chiropractic, in “Can Chiropractors and Evidence-Based Manual Therapists Work Together?”

As far as most doctors and scientists are concerned, and even for many chiropractors, the argument is long over. They believe that either subluxations do not exist at all, or they only exist in some clinically insignificant form. They argue that chiropractors still can’t prove they can even find alleged subluxations reliably, let alone treat them. They doubt that a spinal joint can be literally “out” in a clinically significant way, and the belief that it can “keeps chiropractic marginalized and subject to ridicule by the scientific community”.12 Edzard Ernst writes, “The concepts of chiropractic are not based on solid science and its therapeutic value has not been demonstrated beyond reasonable doubt.”13

In all the years that they have been talking about them, chiropractors have never been able to furnish proof of these mysterious subluxations which they alone are able to see. They may convince their clients, but never have they provided proof of their pretensions to men of science.

College of Physicians and Surgeons of the Province of Quebec in 1966 in “The scientific brief against chiropractic”14

Reality check: are spinal nerves the wellspring of all health and vitality?

Even if subluxations exist, chiropractic subluxation theory depends heavily on one premise, a conceptual bottleneck through which the entire theory must pass: that spinal nerve roots are terribly important to your health, and interfering with them spells T-R-O-U-B-L-E.

In fact, interfering with the nerve roots can only do so much harm to a person. Most of our health and vitality is regulated by mechanisms other than nerve signals travelling through nerve roots — by other kinds of nerves, and by hormones (see sidebar for details). Common trouble with nerve roots is limited to the garden-variety symptoms like pain, tingling, numbness, weakness, and so on — not organ failure and disease.16 That interference with nerves does not cause a wide variety of health problems is plainly evident in people with spinal injuries: they are paralyzed, not diseased.17 And that is only when the nerve roots are severely damaged or even severed. Slightly pinched nerve roots only spell P-A-I-N and A-N-N-O-Y-A-N-C-E, at worst — no fun, no indeed, but hardly disease.

In any event, it’s also anatomically impossible for spinal joints to physically “pinch” nerve roots with anything less than extreme deformities of the spine.18

Some chiropractors go further with subluxation theory than others, and the further they go, the further out on a scientific limb they go. Most will argue that subluxations are at least responsible for chronic low back pain.

It’s extremely important to appreciate that minor variations in spinal anatomy are normal.19 Vertebrae are not Lego bricks, each one exactly like the other — they are biological and imperfect. Just because there is a slight variation in the lumps and bumps of your spine — something many of my patients worry about — does not mean that something is “subluxed.” And any such variation that is too subtle to be easily agreed upon is also unlikely to be clinically significant — and chiropractors, when tested, routinely cannot agree which joints in a given patient are actually “out.”20 One chiropractor will say it is the L3/4 joint that needs correcting, and the next will name another. This does not inspire confidence in the idea of subluxation.

There may be some truth somewhere in the chiropractic idea of subluxation, but it is clearly loaded and controversial and variable in meaning — too much so to be clinically useful. Instead, I encourage you to think in terms of the broader concept of “joint dysfunction” — that spinal joints can “misbehave,” perhaps in a variety of ways. If this sounds vague, you’re right — but that’s appropriate, because strong confidence in anything more specific than that is not really justified by the science. For instance, an intervertebral joint might move unevenly, as opposed to being out of place, and this could be clinically significant — but no one really knows.

So joint dysfunction almost certainly does not involve partial dislocation, misalignment, and serious interference with nerve root function, as implied by the traditional definition of “subluxation.” But many chiropractors have argued that this is all they really mean by “subluxation” these days anyway …

Is chiropractic subluxation theory really so different? How many chiropractors even believe it?

… we [chiropractors] have successfully distanced the concept of a chiropractic subluxation from that of an orthopedic subluxation.

Rosner, The Role of Subluxation in Chiropractic, 1997

I’ve heard many chiropractors scoff dismissively that “most chiropractors don’t believe subluxation theory anymore anyway.” Even if they are right, it admits that the profession is still burdened with a faction that does believe. But it’s not that small a faction. In fact, it’s probably a large one, between those who vocally defend the original, untainted theory and those who avoid the term because of its baggage but still believe it quietly, or who reject the most extreme versions but are still deeply influenced by the theory. Sam Homola:

Although many chiropractors are now backing away from the chiropractic vertebral subluxation theory, many continue to use the theory to justify treating a broad scope of health problems by “adjusting” the spine. … Some who do not use the word “subluxation” simply substitute another word or words, such as “joint dysfunction,” in support of their belief that some kind of segmental spinal “lesion” can affect overall health.

Openly defending the original chiropractic subluxation theory are many chiropractors who often call themselves “straight” chiropractors, meaning “pure.” Straights subscribe to the full, traditional “subluxation theory” more or less exactly as formulated more than a hundred years ago, they practice “subluxation-based chiropractic,” and they definitely think of a chiropractic subluxation as being fundamentally different than how a doctor would define subluxation. They believe that subluxations cause not only back and neck pain, but practically any health problem, simply by impinging or irritating spinal nerve roots.

An orthopedic subluxation, a true vertebral misalignment, or a mechanical joint dysfunction that affects mobility in the spine is not the same as a mysterious asymptomatic “chiropractic subluxation” that is alleged to cause disease by interfering with nerve supply to organs.

Chiropractic Vertebral Subluxations: Science vs. Pseudoscience, Homola (ScienceBasedMedicine.org)

Spinal manipulative therapy (SMT): Adjustment, manipulation and cracking of the spinal joints

The idea of “adjusting” the spine refers to many different manual therapies, usually performed by chiropractors, but also sometimes performed by other professionals.21 The knuckle-like facet joints of the low back may be mobilized (stragetically wiggled, basically22), cracked (like knuckles), tapped with a chiropractic “activator,” gently stretched or pushed on, and so on and on. Different styles may be intense or gentle — so gentle in some cases that you can hardly tell that anything is being done to you. It’s difficult to address them all at once, because there are so many different ways of going about it.

Spinal manipulative therapy is an extremely controversial topic, partly because of its connection to subluxation theory, and partly in its own right — is it safe and does it work? However, SMT for the low back joints is notably much safer and therefore less controversial than SMT for the neck. In the case of the neck, the risks are almost certainly much higher — it’s potentially lethal, in fact.23 I’ll discuss this more below. Here are the main concerns about SMT:

  1. Dubious provenance. SMT provided by chiropractors is largely based on the chiropractic idea of “subluxation,” which is itself a highly controversial theory that comes with a lot of baggage. To the extent that SMT is used to treat subluxations, it may be ill-conceived, over-prescribed, and inconsistent.
  2. Unimpressive benefits. SMT probably has some therapeutic effects on low back and neck pain, but they seem quite limited, and some methods of SMT probably don’t work at all. If SMT works at all, it certainly doesn’t work well enough to be an impressive and reliable therapy.
  3. Serious risks. SMT for low back pain has the potential to frighten patients and worsen their symptoms. SMT for the neck joints has the same risks, but with the chilling additional possibility that it can cause paralysis or death.

Indeed, not as many people want their spines “adjusted” as you might think. Despite the importance of the topic, only about 5% of the US population uses any kind of alternative therapy for their back pain, and only about 75% of those go to chiropractors.24 (SMT provided by physical therapists may be more common — I don’t have a statistic for that.) Still, even a small slice of the entire population is an awful lot of people.

Can SMT effectively treat neck and back pain? What does the science say?

Sam Homola points out that “there are at least 97 named antithetical adjustive techniques, all based on a nonsensical, nonfalsifiable chiropractic vertebral subluxation theory”25 — almost a hundred variations of SMT that cannot peacefully co-exist, the truth of one invalidating the others, like religions. So it’s hardly surprising that it’s difficult to determine, scientifically, what works and what doesn’t. Proponents of a flavour of SMT have a handy, comfortable defense: “my method is better than the method that was tested.”

Every published review of the literature comments on the lack of good quality evidence, making it impossible to be confident of anything.26 Even the most promising sources of research have had serious quality control problems.27 And yet plenty of that research evidence — weak though it may be — does give some hope that certain kinds of SMT might have some benefits.2829303132

However, most of those conclusions are also qualified by various gotchas and uncertainties. Sometimes even major journals publish results that sound fabulous, but critics find flaws so major that it one wonders if it was even worth doing. There was a particularly noteworthy example early in 2011.33 Neil O’Connell:

The email from the industry was effusive. In a cock-a-hoop, caps lock-happy frenzy it bellowed “ALL MANUAL MEDICINE PROVIDERS SHOULD BE AWARE OF THIS STUDY.”

Or not? Mr. O’Connell readily identified numerous serious problems with this research in an article for Body In Mind:

It is of course possible that the results of this study are accurate and maintenance manipulations are effective, but these problems make it difficult to judge. The message from this one back pain trial might seem appealing and I can see why the email was so enthusiastic. But by focusing on one particular cherry that seems so ripe and juicy we might miss the bigger picture from the rest of the tree. And there is always the chance that the tastiest cherries contain a few artificial sweeteners. Personally I would lay off the caps lock for now.

So much for that hype.

And some studies, of course, are better quality and have had negative results. For example, in 1998, Daniel Cherkin (with medical back pain expert Richard Deyo) published a paper in the New England Journal of Medicine showing that, over the long-term, “patients receiving [chiropractic manipulation] treatments had only marginally better outcomes than those receiving the minimal intervention of an educational booklet.”34 Dr. Nikolai Bogduk weighs in with a paper stating his conclusion right in the title, “Spinal manipulation for neck pain does not work.”35 Similarly, Bronfort ostensibly found a positive result treating neck pain, but concedes that just “a few instructional sessions of home exercise with advice resulted in similar outcomes at most time points.”36

Another of the more recent experiments is a good one to zoom in on, because it damns SMT with faint praise: it is one of the official “positive” studies, but so mildly positive that one can’t help feeling disappointed by it. Is this the best SMT can do?

SMT competes with standard care … barely

In the fall of 2009, the Annals of the Rheumatic Diseases published a reasonably good test of SMT.37

The researchers took a hundred patients with nasty, fresh cases of acute low back pain, and delivered half of them into the care of chiropractors, and the other half into “standard care” — advice and ordinary pain medications, namely. Note that it has often been argued that SMT is best for acute low back pain, not chronic, so this is right in chiropractic’s strike zone: if there is anything special, anything even remotely impressive about SMT, it should have done rather well in this contest. It should actually pretty much pull out a can of whupass on “advice and meds.” One would hope.

It didn’t.

There was basically no difference between the groups. They did equally well — or equally poorly, if you prefer. All the patients had the same experience that pretty much everyone with chronic back pain has: they got better slowly but surely over the course of a few weeks, roughly exactly as they would have without any therapy at all. The researchers found that “SMT is unlikely to result in relevant early pain reduction in patients with acute low back pain.”

Both groups did equally well — or equally poorly, if you prefer.

Now you might say, “Well, good: chiropractic was as good as drugs, so it could replace drugs. And that’s good!” But those drugs, taken in the quantities the subjects took them, are cheap and safe as houses. And their low cost was roughly appropriate for their took-the-edge-off effectiveness. Chiropractic therapy, by contrast, would have cost an order of magnitude more and required spending time on appointments with chiropractors.

So, yes, SMT “worked” — but how well? How impressed are you by SMT’s performance in this test? On a scale of ten?

Formal reviews of and expert opinions on this mess

So it’s a mess. What do reviewers make of it? Better them than me! I’ll take you on a whirlwind tour of some of their older reviews, and then look more closely at the most recent and best.

Going back to 1996, Hurwitz et al wrote that “cervical spine manipulation and mobilization probably provide at least short-term benefits for some patients with neck pain and headaches.”38 Not exactly a glowing endorsement, but others have been even less enthusiastic. Jumping to 2004, Bronfort et al wrote that “There are few studies, and the evidence is currently inconclusive,” and that for chronic neck pain, mobilization/manipulation “offers at most similar pain relief to … rehabilitative exercise in the short and long term,”39 But that review also presented an incredible rats’ nest of conclusions, some of which were positive, some negative, all of which amounted to, “Um, it’s kinda complicated, and we’re not really sure.”40

Going from bad to worse, in 2006 the prestigious journal Spine concluded that neck adjustments are “not beneficial” when used alone.4142 The journal Spine: neck adjustments are “not beneficial”In 2006 Fernandez-de-las-Penas et al wrote, “No controlled trials analyzing exclusively the effects of spinal mobilization were found,” and that what does exist has “overall poor methodology.”43 Also in 2006, Lenssinck et al concluded that “there is insufficient evidence to either support or refute the effectiveness of physiotherapy and (spinal) manipulation in patients with tension-type headache.”44

Although the scientific bottom line is (obviously) ambiguous and debatable due to the messiness of the data, things have been getting better. There is usually an exasperating absence of evidence about most manual therapies, but just a few years later the collective data for SMT is finally getting more substantive. And it’s still discouraging.

The best review so far

In 2012, an (updated) Cochrane (good!) review of SMT research was published.45 Cochrane reviews are pretty much the best available summaries of the available evidence,46 and unfortunately the authors just weren’t that impressed. In their first version of the review, they came to the underwhelming conclusion that “there is no evidence that spinal manipulative therapy is superior to other standard treatments for patients with acute or chronic low back pain.” It also performed no worse, though, and was more effective than a fake intervention. A few years later, considering a bunch of new evidence,47 they still found SMT to be “no better or worse” than other therapies … which damned it again with very faint praise, of course, because no therapy has ever been shown to be all that effective for low back pain.48

A fair criticism of this review is that it lumps together too many kinds of SMT for too many different kinds of patients. Could the benefits of some SMT have been “washed out”? What if SMT works really well when done one way, with one kind of patient, but quite poorly otherwise? Real benefits in specific situations might disappear or “wash out” when mixed in with too many other scenarios where a therapy is doomed to failure.

On the other hand, any truly worthwhile benefits to SMT (in any situation) should be obvious and noteworthy. They should pull up the average. I doubt that significant benefits would ever vanish into the statistics. So while I concede that modest real benefits of SMT might get obscured and overshadowed in a big review, I doubt that significant benefits would ever vanish into the statistics.49 Thus we are still left with SMT being damned with faint praise here. As Neil O’Connell of Body in Mind described these results: “a tiny effect size for manipulation that doesn’t really tickle the undercarriage of clinical significance.”

Indeed — and this is the clincher — there is no individual study that I know of that shows any significant benefit. Not one. If any specific flavour of SMT works especially well for any particular type of patient, that combination was not studied in any of the 26 experiments covered by this Cochrane review.

And, just to bang that coffin nail one more time, all this is echoed by another major review from just a couple years before.50

What the mess of science amounts to for patients is that SMT is pretty unimpressive on average, and a bit of a crapshoot … but there are enough flickers of hope here and there that it might be worth a shot for the particularly desperate patient. Chiropractor Sam Homola sums the situation up nicely:

There is no definitive evidence that spinal manipulative therapy is more effective than other forms of treatment for patients with acute or chronic low-back pain. However, manual therapists know from experience that spinal manipulation is often more effective for providing immediate short-term relief for some types of back pain.

“Can Chiropractors and Evidence-Based Manual Therapists Work Together?”

This echoes his opinion in his 1999 book, Inside Chiropractic: A Patient’s Guide, that “many patients have told me that manipulation was more effective [than physiotherapeutic management] in providing immediate relief.”51 My own clients have often reported the same thing. The benefits are almost certainly there, for some people, some of the time.

But, just as clearly, SMT is not working any miracles, and thus it fails the “impress me” test completely. Some evidence may support SMT, but it doesn’t support it strongly. No one — or almost no one — is getting “cured.” After decades of study, the effectiveness of a therapy should be quite clear and significant. If it’s still hopelessly mired in controversy, how good can it possibly be? That’s an awkward question for a lot of alternative therapies.

Is SMT safe?

In a word, no: SMT is definitely not a risk-free treatment. Few treatments are completely safe, of course. Other manual therapies are also unsafe. Half of all manual therapy treatments of any kind will result in some kind of unpleasant side effect.52 Unsurprisingly, neck manipulation can cause trouble — it’s a vulnerable structure. There is a risk of life-threatening injury to the brain stem or vertebral arteries. This is unlikely but extremely serious, and I’ll cover that separately in the next section. This section covers the lesser risks.

In 2010, Carlesso et al analysed the scientific literature looking for evidence of harm from SMT for the neck.53 They found a statistically insignificant trend towards the negative, an uncertain number that leaned in the direction of bad news: increased neck pain might be 25% more likely with SMT than if you did nothing, or if you just stuck to safe and neutral treatments. The same murky data could also suggest basically the opposite: the absence of a clear signal constitutes “strong evidence that neck manipulation or mobilization does not result in an increase in neck pain,” according to the authors. Debatable,54 but noted. What about non-pain syptoms?

Much more certainly and strikingly, the same data does show that SMT patients are 100% more likely to have “transient neurological symptoms” — anything from feeling a bit woozy all the way up to serious unpleasantness, such as severe dizziness, nausea and vomiting. A typical case is described in What Happened To My Barber?.

When performed intensely and/or carelessly — in the presence of undiagnosed vulnerabilities, say — SMT almost can cause direct injury. Even a completely healthy spinal joint could be mildly injured by a strong enough spinal manipulation. Most such injuries would be both rare and minor. Only extremely aggressive SMT could injure a healthy spine, and even if it did, it would probably just be a minor strain — hardly the result you want, but not that big deal and not that common.

…the chances of injury are multiplied when chiropractic neck manipulation is routinely used many times on every patient in a misguided attempt to improve health, as opposed to occasional use of neck manipulation by physical therapists and other manual therapists who are concerned only about restoring mobility in a stiff spine.

Chiropractic Vertebral Subluxations: Science vs. Pseudoscience, Homola (ScienceBasedMedicine.org)

The risks to an unhealthy spine are also quite rare, but somewhat more serious. Most practitioners are unlikely to use aggressive SMT on a spine exhibiting symptoms of any trauma, disease or other vulnerability. However, mistakes happen — it’s unlikely, but possible.

The main common risk of SMT, however, is psychological: SMT can badly frighten patients, which is a serious risk factor for chronic neck and back pain. This is certainly not a life-threatening risk, but it’s not trivial either. The nervous patient has much to lose with SMT. Patients may be nervous because:

Combining these factors — acute pain, minor potential therapeutic benefits, a high rate of harm, fear of your spine’s fragility, fear of the treatment — is all just a recipe for disaster. And so, although many clients have reported being “cured” by chiropractic treatment (sometimes even as they limp into my office still suffering from significant symptoms), many also have reported being “ruined” by a chiropractic treatment they found to be intense and terrifying and painful.

This unfortunate situation may then be more deeply aggravated by the therapist’s response: using the bad reaction as evidence of profound structural instability in the spine, and as a justification for (much) more treatment. People tend to emerge from such experiences hopelessly tangled up in the idea that they are fragile, broken and need regular SMT for the rest of their lives. It is quite tragic how one bad day can convince people that they have a really “bad back” that needs regular therapy almost forever.

Another surprising risk is that, even if all you have is back pain, chiropractors may recommend SMT for the neck even when your only symptoms are in your low back.56 And, as mentioned above, there may be substantial risks to neck adjustment. And most chiropractors don’t inform their patients about the risks.57 Let’s look at that topic now.

People tend to emerge from bad SMT experiences hopelessly tangled up in the idea that they are fragile.

SMT for the neck can probably maim and kill

SMT can probably cause stroke in one of two ways, either by tearing delicate blood vessels in the neck, or by causing brain stem injury in persons with unsuspected instability of the upper spine (atlantoaxial instability, AAI). The evidence for this will be discussed as we proceed. These hazards are certainly more likely for patients with severe and chronic symptoms. These are also therefore the patients most likely to desperately try a wide variety of treatment options, including more aggressive and frequent neck adjustments.

Disturbingly, AAI is such a complex condition that even substantial dislocation of the upper cervical spine can be clinically silent, and virtually impossible to diagnose without a specific type of X-ray (a type that chiropractors do not generally do).58 Thus, some people with AAI are walking around without so much as a headache as a warning sign … yet they are vulnerable to severe brain stem injury if they receive cervical SMT.

Less serious but extremely unpleasant consequences are also possible for patients with AAI. A light poke in the brain stem won’t kill you, but it can sure ruin your day! I knew a woman with a confirmed case of post-traumatic AAI who was treated too roughly by a student massage therapist, and she suffered about a day of severe disorientation, vertigo, and vomiting.

That’s what a poke in brain stem can do.

Incredibly, some therapists may dismiss such severe reactions with the absurdly unsafe theory that the body is just processing toxins released during the treatment. It’s difficult to imagine a more daft and irresponsible rationalization for a serious treatment mistake. For an emotionally compelling example of such dangerous incompetence, see the article What Happened To My Barber?

These dangers are, like everything else about SMT, controversial. Proof of the danger is hard to come by. Above we discussed a study by Carlesso et al showing clear evidence that minor to moderate neurological side effects are more than twice as likely with SMT than with other neck treatments. But they did not find “smoking gun” proof that neck adjustment can kill. In fact, they didn’t even try to calculate the relative risk — the data just wasn’t up to the task. That doesn’t mean that the phenomenon doesn’t exist.59

Considering the relatively minor benefits and the high stakes, is any risk acceptable? This has been a subject of fierce debate for many years, with the chiropractic profession consistently on the defensive,60 but even key sources like the infamous Cassidy paper are weak sauce.61 Credible experts continue to publish evidence that concern about this issue is justified. For instance, in recent years the journal Physical Therapy concluded that “the literature does not demonstrate that the benefits of manipulation of the cervical spine outweigh the risks,”62 and the journal Spine concluded that “adverse reactions to chiropractic care for neck pain are common.”63 The value of a treatment must be weighed against the potential harm. As a group of Canadian neurologists ask, “Is a headache worth dying for?” Their concerns are outlined in a detailed document, “Statement of Concern to the Canadian Public from Canadian Neurologists Regarding the Debilitating and Fatal Damage Manipulation of the Neck May Cause to the Nervous System.”64

Even the most dire risks to treatment are not necessarily unacceptable, however. The chances of dying in an accident on the way to the dry cleaner is probably much greater. For the chronic neck pain patient, the risks may be acceptable if there’s a reason to believe the treatment might actually work. Some cases of neck pain and crick are extremely severe — and such patients may literally feel they have little to lose.

Unfortunately, the rationale and scientific evidence to support the use of SMT for neck pain is poor, and some methods of SMT are almost certainly useless. In chiropractic offices with a traditional view (the majority), most of the point of SMT is to treat “subluxation” -- which, as we've discussed, is an idea so under siege that many chiropractors themselves have denounced it. If SMT is largely supposed to treat a problem that is poorly defined and highly controversial at best, and maybe doesn’t exist at all, how good can it possibly be?

Ineffective variants of SMT

Finally, there is the problem of SMT methods that are probably less effective. According to Dr. Homola, responsible chiropractic therapy for back pain should mostly be limited to mobilizing (wiggling) the lumbar intervertebral joints. However, there are numerous other methods.

A good example is the common use of an “activator” — a little tool that gently thumps the skin and muscle over the joint. The rationale for the use of the activator is extremely thin, in my opinion, and there is no credible evidence whatsoever that it actually does anything — it’s virtually unstudied, nor is there much reason to study it — it’s just not a strong idea.

Considering that even standard SMT isn’t working any miracles, you need to be skeptical of obscure variations on it, especially the “subtle” ones that hardly seem to be doing anything.

Scratching the itch you can’t reach: why joint popping feels good and possibly relieves pain

Joint popping and cracking can feel great. I know. I’m a crack addict, a junkie. Many of my joints pop easily and pleasantly, even if I don’t make the effort to do so. I find it hard to imagine life without joint popping!

I’m hardly alone. I have also observed many clients expressing relief and pleasure in response to incidental spinal “adjustments” — joint pops that occur in the course of doing massage therapy, little explosions as I glide up the spine. Many people seem to feel that a successful spinal adjustment feels like “scratching an itch you can’t reach.” The same feeling can result even without a pop. This feeling needs explaining!

Why does joint popping feel good? If SMT works, why does it work, and does it have anything to do with this relieving sensation?

The pretty obvious honest answer is that no one knows. If we knew how SMT worked, we would also know if it works! Obviously, if there were any clear science on this, SMT wouldn’t be controversial.

Whatever you have been told before, and despite the availability of many explanations on the internet, the nature of joint popping is not well understood.65 It is firmly in that category of trivial mysteries for which there is simply no research funding, and as such it will probably remain unexplained for some time to come. We simply do not know.

What is reasonably certain is that joint pops (and mobilizations) probably constitutes novel sensory input: a little blast of proprioceptive stimulation.66 Since all living systems seem to thrive on sensory input, and generally suffer without it, I speculate that a joint crack or mobilization feels something like getting “unstuck,” roughly the same feeling as finally getting to stretch your legs after getting off a long flight — and that analogy is not intended to trivialize it. The sensation of relief may be extremely strong! (In both the case of a joint pop and the stretching example.) The details of such a physiological effect are definitely not well understood, but the effect probably exists in some form.

The strength of this idea is that it has the potential to explain a lot, but without claiming too much. It’s reasonable and plausible. It can account for the satisfied feelings many people report, but it doesn’t promise the moon, either. Indeed, it might explain both why SMT works, and why it doesn’t work particularly well. For instance, it’s consistent with a widely reported problem with spinal adjustments: the benefits often don’t last long! Soon the “itch” needs to be “scratched” again.67

It also probably explains another common problem with SMT: why treatment results seem to be all over the map. What the nervous system does with novel sensory input certainly depends on a lot of factors. Some people, some of the time, seem to be able to enjoy and “exploit” such sensations and get a therapeutic effect. Other patients seem to largely ignore it — it just doesn’t make much of an impression on them. Still others are afraid of it! For that not-so-minor minority who find joint popping kind of alarming, SMT won’t seem refreshing and relieving, but more like a bitter medicine (at best) or just a bad idea. Such an unpleasant psychological context is probably all the more severe in the case of low back pain, where structural problems are so often feared by patients.

In the best case scenario, could such a simple sensory experience help to actually “cure” severe or chronic neck and back pain? Probably in a few cases, yes.

For instance, under the right conditions, the novel sensory input of SMT might have a significant therapeutic effect on muscle knots (trigger points). Bear in mind what gives trigger points their clinical importance: they often both cause and complicate other problems. Trigger points form in response to a joint that is dysfunctional for some other reason. Joint dysfunction and trigger points probably reinforce each other. Joint manipulation may help to break this vicious cycle, either relieving some of the reason the trigger points are persisting, or relieving the trigger points themselves.

Since trigger points are clinically significant in general, and the likely cause of most back pain, and can often be lessened or relieved by virtually any physical stimulation, it’s not surprising that there is a strong resemblance between the satisfaction of a good rub and the satisfaction of a good crack. A crack is effectively just a kind of “massage” of the joint and the tissues around it, and thus SMT may be about as relieving as anything else (i.e. heat, massage, stretching) that tends to reduce the discomfort of trigger points and stagnant, “grouchy” tissues.

Minimizing the risks of SMT

What you almost certainly want to avoid is the worst-of-both-worlds scenario in which you take the risks for the sake of a treating mild neck pain or — yeeks — only as a preventative treatment (as chiropractors often recommend).68 Don’t do that! There is simply no justification for SMT for the neck unless you have a problem that is worth the risk.

Here are some guidelines that may improve your chances of getting benefit from this approach, and minimizing risk. Evidence published by Manual Therapy shows that, if neck manipulation works at all, it may be more likely to work for people with these signs and symptoms.69 Perhaps to some extent this is also true of low back pain. Check all that apply to you:

And here are few more guidelines for safety of my own:

If you discover, or already know, that cervical spine adjustment is helpful for you, make an effort to find a chiropractor you trust, and establish a long term relationship, confident that most of the risks discussed here will be eliminated. “Good science-based chiropractors who do not subscribe to the vertebral subluxation theory and who use manipulation appropriately can offer a service of value,” Sam Homola writes. “Unfortunately, such chiropractors are not easy to find.”

About Paul Ingraham

I am a science writer, former massage therapist, and assistant editor of Science-Based Medicine. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook and Google, but mostly Twitter.

Further Reading

Here are some books I recommend:

And some more immediately accessible resources:

What’s New In this Article?

Thursday, December 1, 2011 — Added scientific cases studies, examples, pictures and video of true dislocation and abnormal anatomy to help drive home the point that even significant spinal joint dysfunction can be surprisingly harmless … never mind subtle joint problems.

Thursday, August 26, 2011 — Added footnote to “Minimizing the risks of SMT”, explaining how much SMT is too much.

Thursday, July 14, 2011 — Added reference to article in The Guardian about chiropractor disclosure of risk to patients.

Friday, October 8, 2010 — A good thorough editing and cleanup. There was a bit of a mess in the aftermath of the upgrades a few days ago.

Friday, October 1, 2010 — Major upgrades inspired by a new scientific paper about the dangers of spinal manipulative therapy, and by Dr. Sam Homola’s new article at ScienceBasedMedicine.org, Chiropractic Vertebral Subluxations. I revised and improved content and referencing throughout the article in this update.

July 24, 2009 — Original publication.

Notes

  1. Rubinstein et al. Spinal manipulative therapy for acute low-back pain. Cochrane Database of Systematic Reviews. 2012. PubMed #22972127. BACK TO TEXT
  2. In August 2010, Kaiser Permanente cut neck manipulation from their chiropractic coverage. Their revised policy states: “Given the paucity of data related to beneficial effects of chiropractic manipulation of the cervical spine and the real potential for catastrophic adverse events, it was decided to exclude chiropractic manipulation of the cervical spine from coverage.” Dr. Hall reported on the decision in detail. BACK TO TEXT
  3. Homola. Finding a Good Chiropractor. Archives of Family Medicine. 1998. BACK TO TEXT
  4. Mirtz et al. An epidemiological examination of the subluxation construct using Hill's criteria of causation. Chiropractic & Osteopathy. 2009. PubMed #19954544. A classic paper. Four chiropractors analyze subluxation theory and tear it out by the roots, finding that it fails to meet any of (Hill’s) criteria of causation: “No supportive evidence is found for the chiropractic subluxation being associated with any disease process or of creating suboptimal health conditions requiring intervention. Regardless of popular appeal this leaves the subluxation construct in the realm of unsupported speculation.” And yet it’s been there for more than a century, I’d like to add! Dr. Harriet Hall explained the significance of the paper in an article for ScienceBasedMedicine.org, The End of Chiropractic. BACK TO TEXT
  5. SY Ingraham. Spinal Nerve Roots Do Not Hook Up to Organs! One of the key “selling points” for chiropractic care is the anatomically impossible premise that your spinal nerve roots are important to your general health. SaveYourself.ca. 2495 words. One of the key “selling points” for chiropractic care is the anatomically impossible premise that your spinal nerve roots are important to your general health. BACK TO TEXT
  6. This conclusion was published in 1995 by a PhD and another chiropractor criticicizing his own profession: see Nansel and Szlazak. BACK TO TEXT
  7. This is a very well-used bit of chiropractic marketing language. The rhyme and the simplicity have been used to sell chiropractic services for a century. BACK TO TEXT
  8. In “Finding a Good Chiropractor”, Sam Homola writes, “With the development of osteopathy in 1874 and the appearance of chiropractic in 1895, spinal manipulation gave birth to a new theory. D. D. Palmer, the founder of chiropractic, a grocer, and a magnetic healer who healed by touch, announced his discovery that ‘…95 percent of diseases are caused by displaced vertebrae; the remainder by luxations of other joints.’” BACK TO TEXT
  9. Akhaddar et al. Dislocation of the Cervical Spine. New England Journal of Medicine. 2010.

    A case report (and disturbing X-ray) of a traumatic cervical spine dislocation, notable for being mostly asymptomatic: just torticollis and limited motion, but no pain, weakness or altered sensation. That such a serious injury can have so little impact on a person is quite interesting!

    A 22-year-old man presented with a 10-day history of torticollis. Two months before presentation, he had fallen from standing height but did not report subsequent cervical pain, weakness, or paresthesia. On examination, there was a reduced range of movement of the cervical spine without other neurologic deficits. Radiography of the cervical spine showed a marked reversal of the cervical lordosis, anterior displacement of 60% of C4 on C5, anterior callus formation, bilateral facet dislocation, and increased posterior interspinous distance (double arrow) (Panel A). Magnetic resonance imaging was performed. Sagittal T2-weighted imaging revealed a spinal cord angulation with mild compression but without intramedullary edema or hemorrhage (Panel B). The patient was admitted for surgery. With the use of an anterior approach, diskectomy, tricortical bone grafting, and insertion of a cervical plate were carried out, with a good outcome.

    BACK TO TEXT
  10. Moon et al. Traumatic subluxation associated with absent cervical pedicle: case report and review of the literature. Spine. 2008. PubMed #18708921.

    This paper describes the case of a man who developed severe neck and shoulder pain after a fall. It turned out that a part of one of his neck vertebrae was entirely missing, since birth (“a relatively uncommon developmental anomaly”). The fall subluxed the joint substantially. Although painful, the lack of neurological symptoms is surprising — and more evidence that nerve roots are not easily pinched.

    STUDY DESIGN: Case description.

    OBJECTIVES: To describe a case of traumatic subluxation in association with a congenitally absent cervical pedicle, and review the pertinent medical literature.

    SUMMARY OF BACKGROUND DATA: The congenital absence of a cervical pedicle is a relatively uncommon developmental anomaly that is frequently mistaken for a unilateral facet fracture-dislocation in the context of acute trauma. Because there is little evidence of recovery after surgery, and the symptoms are usually not disabling, surgery is not recommended for most cases.

    METHODS: A 62-year-old man presented with severe neck and right shoulder pain after falling. Plain radiographs and computed tomography of the cervical spine showed the typical features of a congenitally absent pedicle at C6 with anterolisthesis of C6 on C7. We performed anterior interbody fusion at C6-C7 because of persistent neck pain and progressive instability.

    RESULTS: Complete restoration of the C6-C7 subluxation was achieved with resolution of the presenting symptoms. At 18 months follow-up, flexion and extension dynamic radiographs demonstrated good alignment with solid fusion at C6-C7.

    CONCLUSION: Although conservative treatment is the primary treatment for this clinical entity, surgery is an alternative option for those patients who fail to achieve recovery after conservative treatment or exhibit instability.

    BACK TO TEXT
  11. Good examples of those who do not include chiropractor Dr. Sam Homola, author of Inside Chiropractic; Dr. Edzard Ernst, author of Trick or Treatment: The Undeniable Facts About Alternative Medicine (and who is not quite a chiropractor, but close enough); and Dr. Murphy , one of five research-oriented chiropractors who have bared their profession’s shortcomings in a 2008 article that calls for “dramatic changes” and states that chiropractic “finds itself in a situation in which it is rated dead last amongst healthcare professions with regard to ethics and honesty.” BACK TO TEXT
  12. Chiropractic Vertebral Subluxations: Science vs. Pseudoscience. Homola. ScienceBasedMedicine.org. 2010. BACK TO TEXT
  13. Ernst. Chiropractic: a critical evaluation. Journal of Pain & Symptom Management. 2008. PubMed #18280103. BACK TO TEXT
  14. Yes, this an old source! However, “men of science” (and women) remain unconvinced. The spirit of this statement is just as valid as it was more than forty years ago. BACK TO TEXT
  15. There is an exception, but it does not compromise the point: sympathetic nerves emerge from the spine and have an indirect and non-critical functional connection with organs. However, organs work just fine even when this connection is broken. BACK TO TEXT
  16. Nansel and Szlazak explain that pain and other symptoms referred from a spinal segment can “create overt signs and symptoms that can mimic, or simulate (rather than cause), internal organ disease.” This fact undermines vertebral subluxation theory in another interesting way — it explains a fairly straightforward mechanism by which chiropractors may have been fooled into believing subluxation theory in the first place. BACK TO TEXT
  17. Logically, if subtle interference with nerve root function could cause disease or even just mild malaise, then severe injury to the spine and/or nerve roots would cause much more noticeable disease states — but it does not! Quadriplegics with completely destroyed spinal nerve root function have many problems, but “disease” is the least of their worries. BACK TO TEXT
  18. Sam Homola describes in detail a scientific experiment in which a dissected spine is mangled by machinery in the attempt to discover just how far you have to bend a spinal joint before its nerve roots are impinged. The answer? Really damned far — you have to take the spine way beyond its normal anatomical limits. The fact is that the holes through which nerve roots exit the spine are quite generous, not at all a tight fit, and that only major injuries or disease processes can result in a pinched nerve root in this way. BACK TO TEXT
  19. Minor variation in any anatomy is normal! See You Might Just Be Weird: The clinical significance of normal — and not so normal — anatomical variation. BACK TO TEXT
  20. Undercover Investigations of Chiropractors. Barrett. QuackWatch.org. 2003.

    In a series of informal but devious and persuasive tests, physician Stephen Barrett contrived to challenge the diagnostic skills of a number of chiropractors. The results were inconsistent, and make for some fascinating and disturbing reading.

    BACK TO TEXT
  21. Doctors (especially osteopaths, physiatrists, and sports medicine specialists), physiotherapists, and massage therapists also practice forms of SMT, but typically do so for quite different reasons than many chiropractors. Despite the widespread use of SMT, it is primarily associated with chiropractic in the public imagination, and chiropractic is certainly defined by it: “The chiropractic profession, which began with a founding father in 1895, is identified primarily by its use of manipulation” (Homola). BACK TO TEXT
  22. “Joint mobilization” is the formal term for a type of passive movement of a skeletal joint. When applied to the spine, it is known as spinal mobilization. BACK TO TEXT
  23. This is a complex issue. I deal with it in the free article, What Happened To My Barber?, and in more detail in the neck pain tutorial. An excellent overview of medical concerns about SMT for the neck can be found in this statement of concern by a group of Canadian neurologists. BACK TO TEXT
  24. Kanodia et al. Perceived benefit of Complementary and Alternative Medicine (CAM) for back pain: a national survey. J Am Board Fam Med. 2010. PubMed #20453181. BACK TO TEXT
  25. Chiropractic Vertebral Subluxations: Science vs. Pseudoscience. Homola. ScienceBasedMedicine.org. 2010. BACK TO TEXT
  26. Fernandez-de-las-Penas writes “There are few published randomized controlled trials analyzing the effectiveness of spinal manipulation and/or mobilization … in the last decade.” Bronfort: “There have been few high-quality trials distinguishing between acute and chronic patients, and most are limited to shorter-term follow-up.” The 2006 Cochrane review of SMT found only 39 experiments to analyze, and most of those had small sample sizes. BACK TO TEXT
  27. Ernst et al. An independent review of NCCAM-funded studies of chiropractic. Clin Rheumatol. 2011. PubMed #21207089.

    Dr. Edzard Ernst is a highly qualified critic of sloppy researchers in alternative medicine. In this review of The National Center for Complementary and Alternative Medicine (NCCAM) studies of chiropractic therapy, he finds that “their quality was frequently questionable. Several randomized controlled trials failed to report adverse effects and the majority was not described in sufficient detail to allow replication.” But if NCCAM cannot produce the best quality studies of alternative medicine, who can? No organization has ever been better funded (or motivated) to validate alternative therapies.

    Ernst concludes: “It seems questionable whether such research is worthwhile.”

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  28. Hadler et al. A benefit of spinal manipulation as adjunctive therapy for acute low back pain: a stratified controlled trial. Spine. 1987. PubMed #2961085.

    From the abstract, “In the first week following [spinal] manipulation, these patients improved to a greater degree ... and more rapidly ....”

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  29. Hoehler et al. Spinal manipulation for low back pain. Journal of the American Medical Association. 1981.

    This study supports the usefulness of spinal adjustment for acute pain only. From the abstract: “Patients who received [spinal] manipulative treatment were much more likely to report immediate relief after the first treatment.” However, “at discharge there was no significant difference between the two groups because both showed substantial improvement.”

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  30. Vernon et al. Chronic mechanical neck pain in adults treated by manual therapy: a systematic review of change scores in randomized controlled trials of a single session. Journal of Manipulative & Physiological Therapeutics. 2008. PubMed #19119388.

    “There is moderate-to-high quality evidence that immediate clinically important improvements are obtained from a single session of spinal manipulation. The evidence for mobilization is less substantial, with fewer studies reporting smaller immediate changes.”

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  31. Swenson et al. Spinal manipulative therapy for low back pain. Journal of the American Academy of Orthopaedic Surgeons. 2003. PubMed #12889861.

    From the abstract: “Most reviews of these trials indicate that spinal manipulative therapy provides some short-term benefit to patients, especially with acute low back pain.”

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  32. Zaproudina et al. Effectiveness of traditional bone setting in chronic neck pain: randomized clinical trial. Journal of Manipulative & Physiological Therapeutics. 2007. PubMed #17693333.

    This seems to a straightforward “thumbs up” study showing that “traditional bone setting” (chiropractic adjustment, spinal manipulative therapy) has a good effect on chronic neck pain. I admit to being skeptical for no clear reasons. The conclusions seem too strong, too much at odds with a lot of other very mixed evidence on this topic. I certainly don’t reject it outright, but I think a careful reading of the whole paper would probably turn up concerns.

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  33. Senna et al. Does maintained Spinal manipulation therapy for chronic non-specific low back pain result in better long term outcome? Spine (Phila Pa 1976). 2011. PubMed #21245790. BACK TO TEXT
  34. Cherkin et al. A comparison of physical therapy, chiropractic manipulation, and provision of an educational booklet for the treatment of patients with low back pain. New England Journal of Medicine. 1998. BACK TO TEXT
  35. Bogduk. Spinal manipulation for neck pain does not work. Journal of Pain. 2003. I take Bogduk’s opinion very seriously, as he is one of a small group of elite pain scientists in the world today whose opinions are relentlessly well-informed and sensible (see Jackson for an intriguing example, or his short and readable editorial, “What's in a name? The labelling of back pain”). In spite of everything I know myself, when I encounter an opinion from someone like Dr. Bogduk, I’m inclined to just go with “what he said.” Of course, guess I can’t quite give up thinking for myself … :-) But seriously, this guy is smart, and if he says it doesn’t work, he’s got good reasons for it. BACK TO TEXT
  36. Bronfort et al. Spinal manipulation, medication, or home exercise with advice for acute and subacute neck pain: a randomized trial. Annals of Internal Medicine. 2012. PubMed #22213489.

    This reasonably well-designed, big, 12-week NCCAM trial of spinal manipulative therapy (SMT) for neck pain concludes with an important disclaimer: although SMT “won” and chiropractors cite this study as evidence that adjustment works, the authors acknowledge that just “a few instructional sessions of home exercise with advice resulted in similar outcomes at most time points.” And so SMT is damned, damned, damned with (extremely) faint praise yet again, as it always is, every time it gets studied: it costs vastly more and performs barely better than sending someone home to do a few simple exercises! Now that hurts.

    BACK TO TEXT
  37. Jüni et al. A randomised controlled trial of spinal manipulative therapy in acute low back pain. Annals of the Rheumatic Diseases. 2009. PubMed #18775942. BACK TO TEXT
  38. Hurwitz et al. Manipulation and mobilization of the cervical spine: A systematic review of the literature. Spine. 1996. PubMed #8855459. BACK TO TEXT
  39. Bronfort et al. Efficacy of spinal manipulation and mobilization for low back pain and neck pain: a systematic review and best evidence synthesis. Spine. 2004. BACK TO TEXT
  40. The complexity of this experiment’s results must be seen to be believed! Here’s a sampling:

    There is limited to moderate evidence that SMT is better than physical therapy and home back exercise in both the short and long term. There is limited evidence that SMT is superior to sham SMT in the short term and superior to chemonucleolysis for disc herniation in the short term. However, there is also limited evidence that mobilization is inferior to back exercise after disc herniation surgery. Mix of acute and chronic low back pain: SMT/mobilization provides either similar or better pain outcomes in the short and long term when compared with placebo and with other treatments, such as McKenzie therapy, medical care, management by physical therapists, soft tissue treatment and back school. Acute neck pain: There are few studies, and the evidence is currently inconclusive.

    Uh, yeah. That really clears things up! I’m not saying this is a bad review — I’m just saying it’s mired in the poor quality of the body of literature, and the complexity of the problem.

    BACK TO TEXT
  41. Gross et al. A Cochrane review of manipulation and mobilization for mechanical neck disorders. Spine. 2004. BACK TO TEXT
  42. That review did qualify that there was evidence that neck adjustments could work when combined with exercises, which doesn’t exactly make it sound like a miracle cure). Headaches are a closely related issue, so what if we look there? Does it get any better if the goal of neck adjustment is to relieve headache pain? Unfortunately, the problems are identical. BACK TO TEXT
  43. Fernandez-de-las-Penas et al. Methodological quality of randomized controlled trials of spinal manipulation and mobilization in tension-type headache, migraine, and cervicogenic headache. Journal of Orthopaedic & Sports Physical Therapy. 2006. BACK TO TEXT
  44. Lenssinck et al. The effectiveness of physiotherapy and manipulation in patients with tension-type headache: a systematic review. Pain. 2004. BACK TO TEXT
  45. Rubinstein et al. Spinal manipulative therapy for acute low-back pain. Cochrane Database of Systematic Reviews. 2012. PubMed #22972127. BACK TO TEXT
  46. The Cochrane Collaboration publishes comprehensive reviews of what the science can tell us so far about medical treatments, and they promote and facilitate evidence-based medicine. Although not perfect — in recent years their quality control has slipped a little, in my opinion — they still generally produce the most authoritative reviews available of pain and injury science.

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  47. Rubinstein et al “identified 26 randomised controlled trials (represented by 6070 participants) that assessed the effects of SMT in patients with chronic low-back pain. Treatment was delivered by a variety of practitioners, including chiropractors, manual therapists and osteopaths. Only nine trials were considered to have a low risk of bias. In other words, results in which we could put some confidence.” BACK TO TEXT
  48. Machado et al. Analgesic effects of treatments for non-specific low back pain: a meta-analysis of placebo-controlled randomized trials. Rheumatology (Oxford). 2009. PubMed #19109315.

    This is a meticulous, sensible, and readable analysis of the very best studies of back pain treatments that have ever been done: the greatest hits of back pain science. There is a great deal of back pain science to review, but authors Machado, Kamper, Herbert, Maher and McCauley found that shockingly little of it was worth their while: just 34 acceptable studies out of a 1031 candidates, and even among those “trial quality was highly variable.” Their conclusions are derived from only the best sort of scientific experiments: not just the gold-standard of randomized and placebo-controlled tests, but carefully choosing only the “right” kind of placebos (several kinds of placebos were grounds for disqualification, because of their known potential to skew the results). They do a good job of explaining exactly how and why they picked the studies they did, and pre-emptively defending it from a couple common concerns. The results were sad and predictable, robust evidence of absence: “The average effects of treatments … are not much greater those of placebos.”

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  49. This view is supported explicitly with regards to SMT and every other low back pain treatment by Machado et al. BACK TO TEXT
  50. Bronfort et al. Effectiveness of manual therapies: the UK evidence report. Chiropr Osteopat. 2010. PubMed #20184717.

    This review of manual therapies focusses on spinal manipulative therapy and massage therapy for low back and neck pain, with predictably underwhelming results: both are “effective” in some circumstances but certainly not impressively so, and generally no different from other therapies that help a little but haven’t exactly put a dent in the epidemic. For instance, the authors write that SMT is effective but “similar in effect to other commonly used efficacious therapies such as usual care, exercise, or back school.” Um, that’s nice. I’m thrilled for SMT that it can hold it’s own against “back school” — which, of course, is so legendary for curing low back pain!

    The conclusions about SMT in particular are silly. The data is consistent with what other major reviews have concluded, most notably the 2012 Cochrane review (Rubinstein et al).

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  51. Homola. Inside Chiropractic. 1999. amazon.com p150 BACK TO TEXT
  52. Carnes et al. Adverse events and manual therapy: a systematic review. Manual Therapy. 2010. PubMed #20097115.

    The sound bite in this study is that 20-40% of all manual therapy treatments — massage, chiropractic, physiotherapy — will cause some kind of unpleasantness, side effect or “adverse event” in medicalspeak.

    In a word: yikes!

    Perspective cuts both ways here. On the one hand, it’s not as bad as it sounds: these “events” are minor and moderate in severity; only 1 or 2 per thousand visits causes a serious problem; and drugs are actually relatively worse. That is, you are modestly more likely to have an “adverse event” if you are given a pill. This just refers to typical side effects, such as ibuprofen’s tendency to cause indigestion.

    But when you take a pill, the side effect is usually unrelated to the problem (i.e. it doesn’t make the problem you’re treating worse), you are generally trading those side effects for some pretty clear benefits, and it’s usually cheap. In manual therapy, most adverse events are backfires — that is, you go for a neck adjustment at the chiropractor, and you come out with more neck pain instead of less. Other data shows this is 25% more likely than if you did nothing at all (see Carlesso). And you pay through the nose for this! Manual therapy is much more expensive than most drug therapy.

    Manual therapists routinely claim that their services are much safer and more effective than drug therapies. Yet this data pretty clearly shows that the difference is really not great. Depending on how you look at it, drugs are only a little worse in some ways, or maybe a little better in other ways. But no matter how you slice it, 20-40% is a pretty unpleasant rate of harm — especially at $60–120/hour!

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  53. Carlesso et al. Adverse events associated with the use of cervical manipulation and mobilization for the treatment of neck pain in adults: A systematic review. Manual Therapy. 2010. PubMed #20227325. BACK TO TEXT
  54. I’m not sure I agree that a statistically insignificant number constitutes “strong evidence” of the absence of harms so much as just generally low confidence in the results. There are just too many ways the data could be missing the truth entirely here (see the other note about this, about statistical dragons). And Carlesso acknowledges this in the paper as well (practically in the next sentence: “However, the limitations of the Strunk study and the low GRADE rating remain, affecting confidence in the estimate.”) She’s also authored three other papers about how difficult it is to study this stuff! See 2010, 2011, 2013. BACK TO TEXT
  55. Spinal cracks and other chiropractic manipulations — like traction — are downright frightening to a significant portion of the population. Hardly a day goes by without a client telling me they are “freaked out” by the idea of being cracked, and many people with back pain are also uneasy about traction (another common chiropractic treatment method). BACK TO TEXT
  56. Chiropractors do this because many of them either subscribe to a belief that the whole spine is greatly affected by the condition of the cervical joints, particularly the top one. So chiropractors may well throw in a little neck adjusting, with varying degrees of conviction about its importance. But the idea is as controversial and questionable as any idea in all of chiropractic. BACK TO TEXT
  57. Chiropractors have an ethical duty to tell their patients about risks: A survey suggests fewer than half of chiropractors always discuss the risks of cervical manipulation with patients. The Guardian. July 12, 2011. Accessed July 14, 2011. BACK TO TEXT
  58. Swinkels et al. Upper cervical instability: fact or fiction? Journal of Manipulative & Physiological Therapeutics. 1996. PubMed #8728462.

    This 1996 paper found that “there is no correlation between the measure of hypermobility and the presence of clinical symptoms. Also, the validity of the upper-cervical stability tests is questionable.”

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  59. Here be statistical dragons. At first glance, the lack of a smoking gun might seem to indicate that such serious harms are unlikely — wouldn’t a problem show up if it were serious? And that is exactly how I would spin my analysis if I were a chiropractor! But that signal would show up only if the research were actually designed to detect it in the first place. These authors were simply going through data from many small studies of neck adjustment, in which some rotten reactions were noted, while many other studies were disqualified for not tracking harms at all and — this is interesting — for “notable ascertainment bias.” Translation: some of the studies were written by authors likely to ignore, deny and minimize evidence of harm

    In the end, only 32 studies could be analyzed. So it remains entirely possible that the phenomenon of severe neck injury from SMT is real but rare, and simply didn’t occur in any of those 32 studies, or wasn’t observed and tracked. Similarly, you could analyze dozens of studies of the health effects of hiking, but probably none of them would have data about bear attacks — yet bears do attack hikers! BACK TO TEXT

  60. Triano et al. Current Concepts: Spinal Manipulation and Cervical Arterial Incidents 2005. National Chiropractic Mutual Insurance Company. 2005.

    Like the infamous Cassidy et al paper, this document is often cited by chiropractors when they are trying to allay fears about serious complications of cervical adjustment. Although the athors make an effort to be scientifically sound, they obviously have a conflict of interest, stating outright that they wish to make the case that cervical manipulation is not dangerous. Consider this excerpt from the executive summary: “In addition, as part of our ongoing commitment to giving NCMIC doctors the best defense possible should the need arise, we are providing this information to our network of chiropractic defense attorneys. We expect this latest research will be an important tool for our defense attorneys to use in presenting the most contemporary findings from recent research and to help overcome common biases held by judges and juries.” So, whatever else this document might be, it’s not objective. Note: Allan Terrett originally wrote a monograph for the National Chiropractic Mutual Insurance Company in 2001. The 2005 version is not written by him, but by Triano and Kawchuk “with grateful appreciation” to him.

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  61. Cassidy et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. Spine. 2008. PubMed #18204390.

    Since its publication, “the Cassidy paper” has been the defensive citation used by chiropractors to respond to accusations that neck adjustments involve a risk of stroke, and therefore should not be conducted without proven benefit and informed consent. The abstract seems to strongly exonerate chiropractors: “We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.”

    “But abstracts are like movie trailers,” as Dr. Mark Crislip wrote. “They give a flavor of the movie, but often leave out many important plot devices and characters. … If you were to read this article in its entirety, you would not be so sanguine about the safety of chiropractic.” He goes on to explain exactly why in one of the earliest popular posts on ScienceBasedMedicine.org, Chiropractic and Stroke: Evaluation of One Paper.

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  62. Fabio. Manipulation of the cervical spine: risks and benefits. Physical Therapy. 1999. BACK TO TEXT
  63. Hurwitz et al. Frequency and clinical predictors of adverse reactions to chiropractic care in the UCLA neck pain study. Spine. 2005. PubMed #15990659. BACK TO TEXT
  64. Statement of Concern to the Canadian Public from Canadian Neurologists Regarding the Debilitating and Fatal Damage Manipulation of the Neck May Cause to the Nervous System. Neck911.com. 2009.

    We Canadian neurologists hereby express our strong concern and thereby issue this warning to Canadians. The public must be made aware that the neurological damage that can result subsequent to upper neck manipulation can be debilitating and fatal.

    We make the following recommendations for the attention of the Canadian public, the practitioners of manipulation, the medical community, the provincial Ministries of Health and the health care professional regulatory bodies.

    Our concerns are significant. Stroke and death due to neck manipulation has been reported in the scientific literature for over 50 years. New deaths, in the past few years, have been reported to the Canadian Stroke Consortium. The Canadian Stroke Consortium recently published a major prospective study. The latest data from the Stroke Consortium indicates that “more than 100 cases of dissection per year are associated with neck manipulation.” The resulting stroke and debilitation from such a large number is very significant.

    A recent study by the Institute of Clinical Evaluative Sciences (ICES Ontario) indicates that patients with posterior circulation strokes under the age of 45 are 5 times more likely than controls to have visited a chiropractor within one week of the event.

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  65. For many years now, I have been looking forward to getting around to writing an article all about this. Unfortunately, I have not yet made the time. Meanwhile, suffice it to say that the dominant theory of joint popping depends on the concept of “cavitation” — the rapid formation and explosive collapse of bubbles in a liquid due to pressure changes. The theory is full of holes and doesn’t begin to explain many features of joint popping, in particular the “recharge” phenomenon, wherein joints that supposedly cavitated nicely just a moment ago need to be left alone for seconds, minutes or hours before they can cavitate again. Also, the cavitation hypothesis does not explain why there is such significant variation between individuals and between joints. It is, in short, almost certainly wrong or incomplete. BACK TO TEXT
  66. SY Ingraham. The Sixth Sense: Proprioception, the vital but mysterious sensation of position and movement. SaveYourself.ca. 710 words. BACK TO TEXT
  67. Regardless of how you feel about being “adjusted”, the therapeutic “message” of a joint wiggle or crack can really only be repeated, not significantly modulated: a crack is a crack is a crack, and one traction or joint wiggle is pretty much like another. There is only so much novel sensory input these techniques can provide. If the body doesn’t “get it” after a few tries on a few different days, it’s probably not going to “get it” later. This may explains why the effectiveness of SMT treatment tends to lessen over time (a well-known characteristic of chiropractic therapy). By contrast, I have always been grateful for the large number of ways that massage therapy can be used to manipulate tissues in the low back, creating a rich variety of fresh sensory experiences for clients for an hour at a time, week after week. This is certainly one of the advantages of massage therapy as a therapy. BACK TO TEXT
  68. Homola. Finding a Good Chiropractor. Archives of Family Medicine. 1998. BACK TO TEXT
  69. Tseng et al. Predictors for the immediate responders to cervical manipulation in patients with neck pain. Manual Therapy. 2006.

    From the abstract: “The presence of four or more of these predictors increased the probability of success with manipulation to 89%. We concluded that using favourable predictors to identify treatment responders before administering cervical manipulations could significantly increase the probabilities of a successful treatment.”

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  70. On the one hand, according to this study, SMT is likely to be more effective for mild neck pain (and that’s a pretty reasonable idea). On the other hand, the milder the problem, the less you should want to take the risks of SMT for the neck! It’s a messy decision, no doubt about it. BACK TO TEXT
  71. A chiropractor who recommends anything more than a dozen appointments for back pain is probably pushing the limits. Remember that most cases of back pain resolve on their own within three weeks! However, only a dozen treatments is actually on the low end of what I’ve heard about chiropractic treatment recommendations. For instance, one of my clients was recently told by a chiropractor that he could only get relief from back pain if he made a commitment to two years of weekly appointments — at a cost of at least $2000! Another client faced down a chiropractor who was demanding that he sign a contract for a “two-year, $7,000 treatment plan.” Such prescriptions constitute a serious conflict of interest. Health care professionals are ethically obliged to be conservative in their treatment recommendations. Clients must be informed and presented with a range of options and allowed to make their choices with an absolute minimum of interference — not threatened with the consequences of failure to adhere to the most expensive therapeutic option available! Especially when the condition may be aggravated by the perception that it is problematic! These chiropractors were way out of line, and the chiropractic profession must take collective responsibility for such blatantly excessive treatment prescriptions. BACK TO TEXT
  72. Cleland et al. Short-term effects of thrust versus nonthrust mobilization/manipulation directed at the thoracic spine in patients with neck pain: a randomized clinical trial. Physical Therapy. 2007. BACK TO TEXT