The science behind spinal manipulation, and why it seems to work for some people
Pain is a plague on the American populace. According to data from the CDC’s National Health Interview Survey, nearly 20% of U.S. adults experience pain most days or every day.
Back pain, neck pain, and headaches are three of the most common causes of persistent pain. And after factoring in lost productivity and work absences, these and other pain conditions cost the United States at least $560 billion annually, finds a 2012 analysis in the Journal of Pain. That’s greater than costs associated with heart disease and cancer combined.
While pain is the most common and costly medical condition in the United States, it’s also the one doctors struggle the most to treat. Prescription pain pills, including opioids, tend to provide inconsistent and often diminishing relief for people who experience chronic pain. Some of these drugs also come with significant risks for addiction, withdrawal, and other dangerous side effects. For these reasons, many national health authorities have begun to recommend non-pharmacological treatment options for common pain conditions. The American College of Physicians, one of the largest physician groups in the United States, now advises its members to treat most forms of low-back pain with massage, acupuncture, and other non-drug interventions. Among these, chiropractic spinal manipulation is one of the most widely used and research-supported forms of “alternative” pain therapy.
A central tenet of chiropractic medicine has always been that improper spine alignment is the root cause of many musculoskeletal ailments. By correcting misalignments, which some chiropractors call “subluxations,” spinal manipulation can purportedly treat a range of health complaints. The National Center for Complementary and Integrative Health (NCCIH), which is a branch of the National Institutes of Health, says that chiropractic “emphasizes the body’s ability to heal itself.”
Chiropractic was founded toward the end of the 19th century by a health enthusiast in Iowa with no formal medical training. It was controversial from the start, and it was widely derided for much of the 20th century in part because some of its early practitioners rejected the practice of immunization and refuted germ theory, the science-backed belief that bacteria, viruses, and other pathogenic microorganisms cause certain illnesses. While specific practices and philosophies vary widely among chiropractors today, most have abandoned those early and contentious positions in favor of evidence-backed approaches.
“Chiropractic was the original holistic health-care profession,” says Michael Schneider, a licensed chiropractor and associate professor in the Department of Physical Therapy at the University of Pittsburgh. “A deeply held belief among chiropractors is that you need to treat the whole person, not just the body part that hurts.”
Schneider says there’s good evidence supporting the use of chiropractic spinal manipulation for low-back and neck pain, and that it can also help treat conditions that stem from musculoskeletal issues, such as nerve pain and some types of headaches.
A 2017 research review in JAMA found that spinal manipulation was associated with modest improvements among people with acute low-back pain. While “modest” may not sound like a ringing endorsement, an editorial accompanying that JAMA review points out that when pitted against “conventional” medical care — namely, drugs or surgery — spinal manipulation works at least as well and comes with fewer risks. Also, a 2013 survey from Consumer Reports found that among patients with low-back pain, treatment satisfaction rates were almost twice as high for those who visited a chiropractor compared to those who met with a primary care physician.
The NCCIH says there’s evidence that spinal manipulation may be as helpful as or more helpful than drugs for the treatment of neck pain and migraine headaches, and that it may also help relieve sciatic nerve pain. The NCCIH also says spinal manipulation is safe when performed by a licensed chiropractor; while it’s common for people to experience muscle soreness or stiffness, or even a temporary increase in pain, serious side effects are “very rare,” the NCCIH states.
But a big question lingers: How does spinal manipulation work? One theory, Schneider says, is that adjusting the spine stimulates nerve activity in ways that change how the body perceives pain. “We’ve measured what happens to spinal joints during manipulation, and we do see a gaping of joints,” he says. This gaping may trigger “a very strong neurological reaction in the body,” which may result in the observed pain benefits, he adds. But all these findings are preliminary and require more study.
Some have argued that chiropractic’s benefits are attributable to the placebo effect. A 2016 study in the Journal of Chiropractic Medicine found some evidence, albeit inconsistent, that spinal manipulation outperformed a sham procedure for the treatment of low-back pain. But as with acupuncture and other alternative pain treatments, it’s difficult for researchers to design a convincing sham alternative to chiropractic spinal manipulation. This makes it tough for them to rule out the placebo effect. “We should be cautious of making strong inferences based on these results,” says Rachel Perry, first author of the study and a senior researcher at the University of Bristol in the U.K.
Also complicating matters is the fact that specific techniques and approaches vary from one chiropractor to the next. While some employ “thrust-type” procedures that lead to cracking or popping sounds and sensations, others use gentler methods to manipulate the bones of the spine, Schneider says. Still others treat patients using instruments that deliver small electric pulses or light therapy. Some use X-ray and other imaging technologies, while others mostly eschew these tools.
This mosaic of treatment approaches can make it hard to pin down chiropractic’s risks and benefits. Perry says thrust-type procedures may come with some additional risks. And the Mayo Clinic reports that, in rare cases, chiropractic adjustment has been associated with spinal disk injuries or stroke. The latter is thought to result from trauma to the arteries of the neck caused by “high-velocity” adjustments, although new research in the Annals of Medicine argues that the link between spinal manipulation and stroke is questionable.
Finally, Schneider says some chiropractors make exaggerated claims or attempt to treat conditions without the backing of sound science. “I know some claim they can treat autism and learning disabilities or conditions like diabetes or high blood pressure, and this is where a lot of the controversy comes in,” he says. “There is not good evidence that [chiropractic] can treat non-musculoskeletal conditions.”
To sum all this up, the evidence to date suggests chiropractic spinal manipulation may help some people find relief from back, neck, nerve, and headache pain. The lack of mechanistic evidence is a sticking point for some medical doctors, but many now endorse chiropractic methods for pain relief because there don’t seem to be better alternatives.
“We got most of our new patients from primary care physician referrals,” Schneider says. For people looking to give chiropractic a try, he says asking a trusted doctor for a chiropractor recommendation is a good tack. “There are good and bad practitioners in any profession,” he says. All chiropractors must be licensed, which requires a doctor of chiropractic (DC) degree. But asking around can help you find a good one, he says.
“I think the general public has gravitated toward non-pharmacologic and alternative treatments,” Schneider adds. “Ten or 15 years ago, this was still considered voodoo medicine, but the perception has changed.”