My father was a chiropractor who graduated from the Palmer School of Chiropractic in Davenport, Iowa, in 1920. Following in my father’s footsteps, I enrolled as a student at Lincoln Chiropractic College in Indianapolis, Indiana, in 1952. Like my father, I believed that chiropractic manipulation or “adjustment” of the spine could be used to treat organic disease by correcting misaligned or “subluxated” vertebrae to remove pressure on spinal nerves. After a few years of mixing basic science study with chiropractic philosophy, however, it became apparent to me that the chiropractic vertebral subluxation theory was a tenuous belief ─ a belief formulated in 1895 by D.D. Palmer, a grocer who was also a magnetic healer. Palmer developed his theory that 95 percent of diseases are caused by displaced vertebrae after claiming that he had cured deafness by “racking” a thoracic vertebra back into place (Wardwell 1992). There is good reason to question Palmer’s claim. The acoustic nerve, with an auditory branch that supplies the function of hearing, is a cranial nerve that connects the brain with the inner ear, following pathways inside the skull, far removed from the 4th thoracic vertebra “racked” by Palmer.

I learned from reading anatomy and physiology books that the body’s organs are innervated by autonomic nerve ganglia and plexuses located outside the spinal column (some of which receive preganglionic autonomic fibers from the thoracic and upper lumbar portion of the spinal cord) and by autonomic cranial and sacral nerves that pass through solid bony openings, unaffected by misalignment of a vertebra. (The 10th cranial vagus nerves pass down from an opening on each side of the base of the skull to supply thoracic and abdominal viscera. Pelvic organs are supplied by autonomic sacral nerves.) Overlapping autonomic nerve supply from multiple sources, along with hormones and other factors, assure involuntary function of the body’s organs independent of spinal nerves that are designed primarily to supply skin and the voluntary function of musculoskeletal structures. This is why the body’s organs continue to function when a spinal cord injury in the neck paralyzes musculoskeletal structures from the neck down. Compression of a spinal nerve results in loss of sensory and motor functions only in the musculoskeletal area supplied by the affected nerve.

Although autonomic nerves are involved in regulating the function of organs, a transplanted organ, supplied by blood flow, can function fairly well without reconnection of severed nerves.

A search for truth

While still a student at Lincoln College, convinced that spinal manipulation (spinal adjustment) was not the panacea portrayed by chiropractors, I visited a nearby medical school library where I found text books written by orthopedic and physical medicine specialists who supported use of spinal manipulation as an option in the treatment of mechanical-type neck and back pain, an option that was not then readily available in departments of physical medicine. Physical therapy was not taught at the chiropractic school I attended, so I studied Bierman and Licht’s Physical Medicine in General Practice, a leading medical text book that described physical treatment methods, including use of spinal manipulation (Bierman 1952). I relied heavily upon the work of James Mennell, M.D., a physical medicine specialist who authored The Science and Art of Joint Manipulation: The Spinal Column (Mennell 1952). I continued this extracurricular study until the day of my graduation from Lincoln College.

When I began my practice as a chiropractor in Panama City, Florida, in 1956, I placed a small ad in the local newspaper announcing that my office offered specialized treatment for back pain, combining spinal manipulation with physical therapy modalities. There was little response to the ad. Although local chiropractors were quite busy treating the gamut of human ailments by adjusting vertebrae, most people thought of chiropractic as a form of quackery. Chiropractic theory that disease could be cured by manipulating the spine to relieve pressure on spinal nerves, however, was appealing to a portion of the population. An advertisement promising cures not provided by the medical profession was sure to attract a number of chronically ill patients.

After a few years of struggle as a “back specialist,” competing with subluxation-based chiropractors, I concluded that chiropractic as a method of treating organic disease was deserving of public suspicion and criticism by mainstream healthcare providers. I could not find any credible evidence to support the theory that a vertebral subluxation can affect general health. While spinal manipulation might temporarily disrupt the signals of receptors responsible for the perception of back pain (nociceptors), there appears to be no reason to believe that the temporary physiological effects of spinal manipulation can have a significant effect on general health. I felt a need to express my views criticizing the controversial aspects of chiropractic care in order to protect public health as well as to promote reform of my profession and to support appropriate use of spinal manipulation.

Opposing subluxation theory

When my book Bonesetting, Chiropractic, and Cultism was published in 1963 (Homola 1963), renouncing chiropractic vertebral subluxation theory and recommending that chiropractic be developed as a specialty in the treatment of mechanical-type back pain, the chiropractic profession refused to acknowledge or review the book. My book was, however, reviewed by the Library Journal, which concluded, in part, that:

A large amount of information from many sources has been brought together. Chiropractic is shown to be a cult without any scientific basis or substance…In view of the absence of any extensive histories of chiropractic, this book has a place in medical collections and reference libraries. (Meyerhoff 1964)

Following publication of my Bonesetting book, the American Chiropractic Association, without explanation, refused to renew my membership and my malpractice insurance:

In regard to your recent application for membership in the American Chiropractic Association and insurance in the National Chiropractic Insurance Company, please be advised that the ACA membership committee has rejected your application. (H.W. Pruitt, D.C., Executive Secretary, American Chiropractic Association, May 17, 1965)

I continued to express my views of chiropractic in articles published in popular magazines and journals, opposing subluxation theory while supporting appropriate use of spinal manipulation (Homola 1992). My published work invariably resulted in negative feedback from members of the chiropractic profession. One of my articles in a 1995 issue of Scholastic Coach and Athletic Director, titled “Sense and Nonsense in Chiropractic Care of the Back” (Homola 1995), resulted in threats to have my license revoked. A “Dear colleague” letter, circulated by a chiropractor, concluded with this appeal:

I believe this chiropractor is more harmful to our profession today than he was 30 years ago. I would personally appreciate any insight that you may have. Please contact me personally at [telephone number] if you feel this is worthy of any concern with respect to the future of the chiropractic profession.

Apparently, there was fear among some of my colleagues that my views could topple the chiropractic profession. My primary concern, however, was to offer support for appropriate use of spinal manipulation apart from chiropractic subluxation theory, hopefully aiding the development of chiropractic as a science-based musculoskeletal specialty.

In my final year of practice, 1998, my article “Finding a Good Chiropractor” was published in Archives of Family Medicine, a journal of the American Medical Association. I had learned from experience that many physicians were receptive to appropriate use of spinal manipulation provided by a properly limited chiropractor who was willing to exchange office notes in caring for patients with mechanical-type back pain. Physicians receiving requests from patients who wanted to see a chiropractor could avoid the questionable care of subluxation-based chiropractors by referring to a carefully vetted “good chiropractor.”

In 1999, my book Inside Chiropractic, edited by Stephen Barrett, M.D., was published by Prometheus Books. The jacket blurb describes the book as useful to physicians and lay persons alike:

Inside Chiropractic makes an important and unique contribution to the literature on chiropractic. Until chiropractic is properly specialized and regulated, consumers will have to learn how to make an informed choice in finding a good practitioner. This book is a must for readers who are considering chiropractic care, and a valuable reference for healthcare professionals who want to know what chiropractic is all about.

In April of 2001, the online edition of Medscape General Medicine published my article “Is the Chiropractic Subluxation Theory a Threat to Public Health?” The article had been previously published in the January 2001 issue of Scientific Review of Alternative Medicine and Aberrant Medical Practices. I received a flood of email and letters. I was praised by mainstream healthcare professionals (and a few chiropractors), but the bulk of my mail came from chiropractors who castigated me for my views. The president of the American Chiropractic Association described my article as “outdated and inaccurate” and asked Medscape to remove the article from their web site.

In September of 2005, Clinical Orthopaedics and Related Research, a leading peer-reviewed journal for orthopedic surgeons, published my article “Chiropractic: History and Overview of Theories and Methods“, a review exploring the incongruity underlying the practice of chiropractic based on subluxation theory. Chiropractic was (and is) a profession with the confusing image of a back specialty capable of treating a broad scope of health problems. Despite a plethora of chiropractic publications touting subluxation theory, I could not find any credible evidence supporting claims that a chiropractic subluxation or a joint dysfunction can affect general health.

A 2009 study by three academic chiropractors concluded that chiropractic subluxation theory is unsupported speculation:

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. This lack of supportive evidence suggests the subluxation construct has no valid clinical applicability.

A 2014 Position Statement on Clinical and Professional Chiropractic Education issued by the World Federation of Chiropractic (representing nine European, South African, and Australian chiropractic colleges) advised that subluxation theory is unsupported by evidence:

The teaching of vertebral subluxation complex as a vitalistic construct that claims that it is the cause of disease is unsupported by evidence. Its inclusion in a modern chiropractic curriculum in anything other than an historical context is therefore inappropriate and unnecessary.

Appropriate use of spinal manipulation as a treatment for back pain can be helpful in some cases, but spinal manipulation based on subluxation theory, which encompasses a broad scope of health problems, can cause harm by delaying appropriate treatment based on a correct diagnosis. Risk of stroke caused by injury to cervical arteries outweighs any known benefit when upper neck manipulation is used as a treatment to correct a putative chiropractic subluxation.

Perpetuation of chiropractic as a belief system

Today, after 43 years of practice as a chiropractor, 62 years after graduating from a chiropractic college, the definition of chiropractic in the United States, still based on subluxation theory, has changed little. In keeping with the paradigm of the Association of Chiropractic Colleges (in North America) which states that “Chiropractic is concerned with the preservation and restoration of health, and focuses particular attention on the subluxation” (Christensen 2015), the National Board of Chiropractic Examiners defines chiropractic as a practice focused on the subluxation:

The specific focus of chiropractic practice is known as the chiropractic subluxation or joint dysfunction. A subluxation is a health concern that manifests in the skeletal joints, and, through complex anatomical and physiologic relationships, affects the nervous system and may lead to reduced function, disability, or illness. (Christensen 2015)

The American Chiropractic Association (ACA) defines chiropractic as a method of dealing with musculoskeletal and nervous system disorders that affect general health ─ an ambiguous description that seems to leave the door open for chiropractors who use spinal manipulation as a treatment for health problems:

Chiropractic is a health care profession that focuses on disorders of the musculoskeletal system and the nervous system, and the effects of these disorders on general health.

The International Chiropractic Association (ICA), the smaller of the two American-based associations, is clearly dedicated to use of spinal adjustments based on the subluxation theory of chiropractic’s founding father:

The ICA is dedicated to the growth and development of the chiropractic profession based on Dr. Palmer’s fundamental belief in the principles and philosophy of chiropractic as a unique, distinct and drugless health care profession.

Chiropractors are better educated today, and most students enrolling in chiropractic colleges have undergraduate degrees. But despite increasing educational requirements for enrollment in a chiropractic college and for licensure of chiropractors, state laws and most chiropractic colleges continue to embrace subluxation theory. Without representation by a science-based majority, there will be little incentive for development of chiropractic as a properly limited specialty based on the guidelines of science.

Identifying science-based chiropractors

A subluxation-based chiropractor, as opposed to a science-based chiropractor, subscribes to a nonfalsifiable subluxation theory that cannot be verified by the scientific consensus and cannot be supported by the science of anatomy and physiology. Currently, there is no reliable way to distinguish a science-based chiropractor from a subluxation-based chiropractor in the marketplace. Without an academic degree identifying science-based chiropractors, it will continue to be difficult to find a properly limited chiropractor, and medical professionals will continue to avoid referring patients to chiropractors.

It goes without saying that a chiropractic program would not be acceptable in science-based academia until the chiropractic profession is totally divorced from subluxation theory, requiring changes in the mission of chiropractic colleges as well as changes in state laws that define and govern the practice of chiropractic. Such changes would result in programs similar to those already being used to train physical therapists. Increasing use of spinal manipulation by physical therapists and orthopedic manual therapists provides access to appropriate use of spinal manipulation for consumers who are not inclined or able to search for a science-based chiropractor.

When the Florida State Legislature allotted funds to establish a chiropractic college within Florida State University (FSU) in 2003, the proposal was rejected by FSU faculty members and alumni. Chiropractic subluxation theory, as defined by Florida state law and by chiropractic catalogues, was considered to be implausible and unscientific. Florida’s Board of Governors, which oversees state universities, voted against including a college of chiropractic at FSU.

At the present time, there are no U.S. public or state-funded universities that offer a program for a doctorate in chiropractic. The University of Bridgeport, D’Youville College, and Keiser University, all private institutions, have included chiropractic degree programs in their curriculum.

A 2011 review of chiropractic college catalogues revealed that the term “subluxation” is still found within the curriculum of most North American Chiropractic Colleges. All but three of 18 chiropractic colleges mentioned subluxation in their catalogues. Most chiropractic colleges guided by subluxation theory include instruction in adjunctive treatment methods, but a few “straight” schools, adhering to subluxation theory, depend almost entirely upon use of spinal adjustments as a treatment for most ailments. As privately controlled institutions, the mission of chiropractic colleges may vary from one institution to another.

It may not be enough for a chiropractic college to abandon subluxation theory if the college proposes to graduate primary-care physicians who use alternative “natural healing methods” as a treatment for a broad scope of health problems. A chiropractic college that limits instruction to care of musculoskeletal problems would certainly be more acceptable in mainstream health care than a chiropractic college dedicated to subluxation theory or alternative medicine, or a chiropractic college that mixes chiropractic philosophy with manual therapy.

Chiropractic, alternative medicine, and primary care

There are no indications that the chiropractic profession in America has plans to change course and make the changes needed to become a specialty or subspecialty capable of a reciprocal relationship with mainstream healthcare providers. Chiropractors are seeking status as primary care physicians in order to maintain their independence as an alternative to conventional medical care. According to the National University of Health Sciences (formerly the National College of Chiropractic, considered to be one of the best U.S. chiropractic colleges), “National University prepares students to become first-contact, primary care physicians fully qualified to diagnose, treat, and manage a wide range of conditions” (from 2017). As a “leader in the growing field of integrative medicine,” National University offers degree programs in chiropractic medicine, naturopathic medicine, Oriental medicine, acupuncture, and massage. National does not mention subluxations in its chiropractic catalogue.

Evidenced-based natural healing methods such as exercise or nutrition are essential for good health and might occasionally be an effective treatment for some conditions or can be helpful as complementary procedures over a broad scope, but they should not be mixed with subluxation correction and other alternative healing methods that preclude conventional medical care. Inclusion of such practices as homeopathy, naturopathy, acupuncture, or functional medicine in any treatment program, often under the banner of “integrative medicine,” should be viewed with skepticism.

In support of chiropractic care as a form of alternative medicine using natural healing methods, the American Chiropractic Association (ACA) recognizes 11 different chiropractic specialties, in fields including acupuncture, neurology, orthopedics, internal disorders, and pediatrics. A Chiropractic Internist “has training to diagnose a wide spectrum of conditions along with an education to use natural treatment options.” According to the ACA Council on Diagnosis and Internal Disorders, “Every year, more and more patients are choosing DABCIs [Diplomate of the American Board of Chiropractic Internists] as the first doctor they visit when they are sick or are having health problems”.

A diplomate in a chiropractic specialty requires 300 hours of post-graduate classroom work. Such abbreviated classroom instruction cannot compare with a full-time residency program in a hospital setting that lasts 3 to 7 years after graduation from medical school before a physician can be board certified as a specialist. An additional 1 to 3 years of training is required for a highly specialized subspecialty. There are more than 120 specialties and subspecialties that make up the practice of medicine.

Clearly, a chiropractic specialty, subluxation based or not, should not be considered to be a viable alternative to a board-certified medical specialty.

Making an informed career choice

Although there are some good chiropractors who use spinal manipulation appropriately and who do a good job treating mechanical-type neck and back pain, chiropractic in general, defined by subluxation theory, continues to be rejected by the scientific community. Physical therapy, on the other hand, is uncontested as a branch of science-based physical medicine. Since physical therapy is often compared with chiropractic, it is important to understand the difference between the two professions before selecting one or the other as a career.

Aside from aspirations to help the sick and disabled, financial security should be a primary consideration when choosing a profession. The chiropractic profession, identified as a form of alternative medicine, remains outside the mainstream of health care, providing few opportunities for employment outside of private practice. As a result, graduates of chiropractic schools have a much higher student loan default rate than graduates from other schools that train healthcare professionals.

A high student loan debt and the high cost of starting a practice and maintaining an office, coupled with little or no referrals from other health-care professionals, makes it difficult to build a private chiropractic practice from scratch. Many struggling newly-graduated chiropractors resort to self-marketing programs offered by practice-building firms. A 2010 investigation revealed that the 10-year attrition rate for chiropractors licensed in California between 1992 and 1998 was 20-25%.

The high failure rate of chiropractors who enter private practice, facing societal suspicion and rejection by the scientific community, may represent risk that outweighs the security promised by 3 to 4 years of undergraduate study and the 4 years of chiropractic college required to hang out a chiropractic shingle. (Some chiropractic colleges offer a dual-degree program for a bachelor degree and a Doctor of Chiropractic degree to applicants who have completed at least 3 years of undergraduate study for a Bachelor of Science degree in biology; some offer an abbreviated program for a D.C. degree if applicants have a Bachelor of Science degree.)

Most chiropractic colleges require 3 years of undergraduate study for enrollment in a chiropractic program; some require a bachelor’s degree. A few states require a bachelor’s degree along with a chiropractic degree for licensure as a chiropractor.

Persons interested in studying manipulative therapy should consider going for a Doctor of Physical Therapy (DPT) degree that would allow interaction with the scientific community in researching and performing manual therapy without the stigma associated with chiropractic. At the present time, all states, the District of Columbia, and the U.S. Virgin Islands now permit direct access to services provided by physical therapists, allowing private practice that fits in with mainstream health care, with ample opportunity for employment in hospitals and healthcare facilities.

Admission requirements for a physical therapy program may vary but most schools require a 4-year undergraduate degree in such subjects as exercise science, biology, and kinesiology, followed by a 3-year program for a DPT degree. Some physical therapy schools offer a 3+3 curricular format in which 3 years of specific pre-professional courses will allow enrollment for a 3-year DPT program.

Since undergraduate requirements to enter a program for a doctorate in chiropractic or a program for a doctorate in physical therapy are about the same, persons who are contemplating a career in chiropractic should research both professions before making a decision.

The bottom line

A chiropractic spinal adjustment claimed to restore and maintain health by adjusting specific vertebrae to remove nerve interference should not to be equated with generic spinal manipulation used to relieve pain and restore mobility. The former is unproven alternative medicine, the latter a scientifically acceptable modality.

Spinal nerves are commonly affected by disc herniation, osteophytes, and orthopedic subluxations caused by injury or degenerative changes, resulting in neuromusculoskeletal symptoms. But such segmental dysfunctions in the spine have never been associated with organic disease. Vertebral misalignment caused by structural deviations from normal is common and usually harmless. A chiropractic vertebral subluxation alleged to be a cause of health problems, now referred to as a “vertebral subluxation complex,” has not been proven to exist and is not the same as an orthopedic subluxation that causes musculoskeletal symptoms.

Patients and providers who are looking for a good chiropractor should seek out a practitioner who has renounced chiropractic vertebral subluxation theory and who has chosen to limit care to treatment of mechanical-type neck and back pain and related musculoskeletal problems, offering spinal manipulation as a treatment option along with physical therapy modalities. Such services are now being provided by physiatrists and orthopedic manual therapists in departments of physical medicine and rehabilitation ─ much like the service I was providing when I published my Bonesetting book in 1963.

While spinal manipulation is an acceptable option in the armamentarium of physical medicine as a method of relieving pain and restoring mobility, often buying the time needed to allow recovery without use of drugs, injections, or surgery, some studies indicate that spinal manipulation may not be any more effective than other forms of physical treatment. And there is reason to believe that certain upper-neck manipulative techniques can cause stroke by injuring vertebrobasilar arteries. There may be occasions, however, when spinal manipulation would be the treatment of choice in restoring mobility in joints locked by muscle spasm, binding facets, post-traumatic adhesions, impingement of synovial or cartilaginous tissue, or for reasons not yet determined. Many people simply enjoy a hands-on back-cracking back rub.

Unfortunately, appropriate use of spinal manipulation has been shaded by the promotion of such treatment as a method of restoring and maintaining health. Cavitation (a pop produced by slight separation of joint surfaces during manipulation) is often interpreted as evidence that a chiropractic subluxation has been corrected. This perception may have a powerful placebo effect, giving the false impression that spinal manipulation or a “spinal adjustment” is an effective treatment for the ailment being treated.

Surveys indicate that neck pain and back pain are the most common complaints encountered by chiropractors. Back pain and musculoskeletal problems are the first and second most common causes of disability worldwide. Although most people think of chiropractors as “back doctors,” it appears that the chiropractic profession, in its mission to provide primary care in the form of alternative medicine, may have missed the opportunity to make the changes needed to fill a niche in physical medicine as a conservative back-care specialty.


  • Bierman W, S Licht. 1952. Physical Medicine in General Practice, 3rd Ed. Paul B. Hoeber, Inc. (Harper & Brothers). New York, NY.
  • Christensen MG, JK Hyland, CM Goertz, et al. 2015. Practice Analysis of Chiropractic 2015. Pages 5, 127. National Board of Chiropractic Examiners. Greeley, CO.
  • Homola S. 1963. Bonesetting, Chiropractic, and Cultism. Critique Books. Panama City, FL.
  • Homola S. 1992. Seeking a common denominator in the use of spinal manipulation. Chiropractic Technique. 4(2):61-63.
  • Homola S. 1995. Sense and Nonsense in Chiropractic Care of the Back. Scholastic Coach and Athletic Director. March; 64(8): 32-34.
  • Homola S., Barrett S. 1999. Inside Chiropractic. Prometheus Books. Amherst, NY.
  • Mennell J. 1952. The Science and Art of Joint Manipulation: Volume 11, The Spinal Column. The Blakiston Company. New York,NY.
  • Meyerhoff E. 1964. Homola, Samuel. Library Journal. Page 643. February 1: 89(8).
  • Wardwell WI. 1992. Chiropractic: History and Evolution of a New Profession. Mosby-Year Book. St. Louis, MO.


  • Samuel Homola is a retired chiropractor who has been expressing his views about the benefits of appropriate use of spinal manipulation (as opposed to use of such treatment based on chiropractic subluxation theory) since publication of his book Bonesetting, Chiropractic, and Cultism in 1963. He retired from private practice in 1998. His 15 published books include Inside Chiropractic, published by Prometheus Books in 1999.

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Posted by Sam Homola

Samuel Homola is a retired chiropractor who has been expressing his views about the benefits of appropriate use of spinal manipulation (as opposed to use of such treatment based on chiropractic subluxation theory) since publication of his book Bonesetting, Chiropractic, and Cultism in 1963. He retired from private practice in 1998. His 15 published books include Inside Chiropractic, published by Prometheus Books in 1999.