In previous posts (The Silent Killer - part 1 and part 2) I discussed the irrationality of the chiropractic premise of vertebral subluxation. I also presented reasons given by subluxation-based chiropractors -— the majority of those practicing, according to data cited in part 1 — for regarding the hypothesis as gospel truth. In doing research for these posts, I contacted one of the foremost advocates for subluxation-based chiropractic and asked him to provide me with a summary of scientific evidence to support his conviction. The email correspondence I received from him was something less than scholarly. It was not the tone I would expect from someone who purports to represent his profession, who served as a professor at a chiropractic college with the title of Director of Research, who was liaison to a national medical NGO and a journal editor (albeit not a journal indexed by the National Library of Medicine, which does catalog some of the leading chiropractic publications), among his other bona fides. But his emails, which I have reprinted below, appear to be representative of the attitudes of subluxation-based chiropractors who scoff at the more reasoned heads in the chiropractic community. (For example, see the website Subluxation Deniers, which perversely compares those who attempt to refute the subluxation hypothesis with Flat Earthers.) I have refrained from mentioning this chiropractor's name for the same reason that I don't attend Trump rallies waving a peace flag and handing out Vote for Biden literature.
Here is the request I sent:
I am writing a book about the chiropractic profession. Presently I'm focused on the vertebral subluxation theory. Can you provide me with published research of the best evidence for the chiropractic subluxation concept? What is the best evidence that supports chiropractic claims for the existence and correction of subluxations? Thank you for your help.
In response to my request for scientific evidence, I received this reply:
I have devoted my entire career to this concept. For starters you may want to subscribe as we are the only group of research journals devoted exclusively to vertebral subluxation.
The email included a link to a website that promotes several purportedly scholarly journals as well as a link to the Foundation for Vertebral Subluxation. The latter site contains a link to research that leads to a page on chiropractic and immunity.
I wrote back to this doctor with the following:
Thank you for your response. I will look through the material on the two sites you recommended. In the meantime, is there a single document you can send to me that contains references for the strongest evidence supporting the vertebral subluxation theory, perhaps a summary of the research? That would be very helpful.
Here's the answer I received:
I notice you are not a subscriber to the journals or a donor to the Foundation yet you ask for me to spend my time helping you. How does that work?
So I wrote:
I'm writing a book about chiropractic. I'm looking for answers to my questions about subluxations. I am not a believer in the subluxation hypothesis, at least not yet. If you are an advocate for what you so firmly believe in, I would think you would jump at any opportunity to freely spread your message more widely rather than asking for something in return. The majority of articles you sent me are case studies. The plural of anecdote is not data. Properly performed RCTs [randomized control trials] are the gold standard in clinical research. Are there any such studies that support the subluxation hypothesis?
Thank you for your time and consideration. I'm grateful for the information you sent.
And here is the distinguished doctor's response, after which I wrote no further:
Dr. Burke - I have better things to do with my time than waste it trying to teach a pig to sing. What’s sad is that you made it this far and never learned how to search the literature, gather it and critically evaluate it. Go find someone who wants to waste their time trying to convert a Denier. I haven’t the time nor the patience.
At least he addressed me as Doctor.
This doctor's attitude about the subluxation and its deniers is reminiscent of the fable of the Emperor's New Clothes. Recall that anyone who couldn't see the magnificent raiments was either stupid or unfit for their job.
A more erudite discussion of subluxation can be found in the article Subluxation: Dogma or Science?  Published in 2005, many of its criticisms and recommendations are apropos today. Here's the article's abstract:
Subluxation syndrome is a legitimate, potentially testable, theoretical construct for which there is little experimental evidence. Acceptable as hypothesis, the widespread assertion of the clinical meaningfulness of this notion brings ridicule from the scientific and health care communities and confusion within the chiropractic profession. We believe that an evidence-orientation among chiropractors requires that we distinguish between subluxation dogma vs. subluxation as the potential focus of clinical research. We lament efforts to generate unity within the profession through consensus statements concerning subluxation dogma, and believe that cultural authority will continue to elude us so long as we assert dogma as though it were validated clinical theory.
Keating et al discuss the Association of Chiropractic Colleges' consensus statement on subluxation, which was published in 1996.  I don't know if the ACC's position remains the same after all these years, but it is still posted on their website.
Chiropractic is concerned with the preservation and restoration of health, and focuses particular attention on the subluxation.
A subluxation is a complex of functional and/or structural and/or pathological articular changes that compromise neural integrity and may influence organ system function and general health.
A subluxation is evaluated, diagnosed, and managed through the use of chiropractic procedures based on the best available rational and empirical evidence.
The uncertainty of this statement is striking. Between the and-ors and the "may influence," one is compelled to ask if any science went into it or if it was created more for political expediency. Keating et al quote Dr. Craig Nelson's observation that "clinical studies of the effectiveness of spinal manipulation are conducted and reported without reference to the presence or absence or even the existence of subluxations."  In other words, research has not focused on defining and identifying the vertebral subluxation. This mischievous sprite does not exist in the same sense that a bacterium or virus - or a chemical compound or a subatomic particle, for that matter - are known to exist. Thus, clinical studies designed to purportedly prove the notion that the presence of vertebral subluxations leads to disease and that their correction by spinal adjustments improves and maintains health neglect the fundamentals necessary to perform the research in the first place. In order to do research, the definition of subluxation must be reduced to something that can at least be recognized and mutually agreed upon by researchers and clinicians alike such as pain produced by spinal palpation (i.e., manual examination), muscle spasm, x-rays demonstrating vertebral misalignments, and vertebral motion restrictions. (Among these and other findings, only palpatory pain has a sufficiently high degree of interexaminer reliability, i.e., agreement between examiners.) These factors could comprise some elements of a subluxation, but to state that they singularly or in combination indicate the presence of subluxation brings to mind the parable of the blind men and the elephant, each one examining a different part and claiming knowledge of the whole. 
I can't say it any better than the authors of Subluxation: Dogma or Science? so I'll conclude with another quote:
The dogma of subluxation is perhaps the greatest single barrier to professional development for chiropractors. It skews the practice of the art in directions that bring ridicule from the scientific community and uncertainty among the public. Failure to challenge subluxation dogma perpetuates a marketing tradition that inevitably prompts charges of quackery. Subluxation dogma leads to legal and political strategies that may amount to a house of cards and warp the profession's sense of self and of mission. Commitment to this dogma undermines the motivation for scientific investigation of subluxation as hypothesis, and so perpetuates the cycle.
The phrase "uncertainty among the public" in the above quote raises one last question, one I will not answer in this post. That question is this: Does anyone but a chiropractor — and I'm referring specifically to patients and the general public — really care about vertebral subluxations? If you are planning to see a chiropractor, does it really matter to you if she is a subluxation-based chiropractor or one who sees herself as providing manual therapies for musculoskeletal problems, or some other variation on the theme?
I would really like to know your thoughts on this, so please write a comment below or email me at michaelburkesbackissues [at] gmail.com. If you send email, please state if your comment is for publication or not.
Keating, Joseph C., et al. "Subluxation: Dogma or Science?." Chiropractic & Osteopathy 13.1 (2005): 1-10. This excellent review of the subluxation concept and ideology can be found here. Also worth reading is An epidemiological examination of the subluxation construct using Hill's criteria of causation. back
Association of Chiropractic Colleges: Position paper #1. J Manipulative Physiol Ther 1996, 19(9):634-7. back
Nelson CF: The subluxation question. J Chiropr Humanities 1997, 7:46-55. back
My thanks to Dr. Mitch Haas, former Dean of Research at University of Western States, for providing me with his assessment of this problem, however, its description is my own. back