Chiropractic Overview

Chiropractic is one of the most widely used health services today. It has gained increasing acceptance as a treatment for back and neck pain, and it is covered by many health insurance plans. Millions of people would report that chiropractic spinal manipulation has brought them relief. Nonetheless, at present the research record for its effectiveness is inconclusive at best.

Daniel David Palmer founded chiropractic in 1895, after an experience in which he apparently believed he cured a man’s deafness by manipulating his back. He opened the Palmer School of Chiropractic and began teaching spinal manipulation. This college still exists today, with a fully accredited program.

One of Palmer’s first students was his son, Bartlett Joshua (B.J.) Palmer. It was B.J. Palmer who truly popularized the technique. Later, Willard Carver, an Oklahoma City lawyer, opened a competing school. He believed that chiropractic physicians needed to offer other methods of treatment in addition to spinal manipulation. This opened a schism in the chiropractic world that still exists today. Followers of Palmer and his methods focus only on spinal adjustments, an approach called "straight" chiropractic. Those who, like Carver, use various approaches to healing are called "mixers." Mixers may use vitamins, herbs, and any other treatment methods they find useful (and are allowed to practice by law).

Medical treatments in the 19th and early 20th centuries were not based on scientific evidence of effectiveness, and chiropractic treatment was no exception. It became a widespread technique long before there was any real evidence that it worked. Chiropractic schools utilized all of their profits and resources to further develop programs for training people in chiropractic techniques—not for verifying the theory and practice of chiropractic. However, in the 1970s, proper scientific research into chiropractic began to draw interest. In 1977, the Foundation for Chiropractic Education and Research (FCER) established a program to train chiropractic researchers. Since then, efforts have been made to fund scientific trials testing the effectiveness of chiropractic techniques and to establish a scientific foundation for the practice.

There are many different chiropractic techniques in use today, some with proprietary names such as the Gonstead and Maitland techniques. In general, most involve rapid (high-velocity) short (low-amplitude) thrusts. Manipulation may be purely manual or mechanically assisted. For example, some chiropractors use an "activator"—a small metal tool that applies a force directly to one vertebra.

In addition, some chiropractors use a related therapy called spinal mobilization. This method involves gentle, extended movements (low-velocity, high-amplitude), rather than the “back-cracking” of classic chiropractic spinal manipulation.

Since its origin, chiropractic theory has based itself on “subluxations,” or vertebrae that have shifted position in the spine. These subluxations are said to impede nerve outflow and cause disease in various organs. A chiropractic treatment is supposed to "put back in" these "popped out" vertebrae; for this reason, it is called an “adjustment.”

However, no real evidence has ever been presented showing that a given chiropractic treatment alters the position of any vertebrae. In addition, there is as yet no real evidence that impairment of nerve outflow is a major contributor to common illnesses, or that spinal manipulation changes nerve outflow in such a way as to affect organ function.

More recent theories suggest that chiropractic manipulation may relieve pain by “loosening” vertebrae that have become relatively immobile rather than by changing their position. In addition, the movements associated with manipulation may alter the response patterns of nerves in the central nervous system—including both the spine ¹ and brain— ² leading to pain relief.

Chiropractic spinal manipulation has been evaluated scientifically to determine its efficacy, as well as its costs comparative to other forms of health care. However, the evidence is not compelling in either case.

Efficacy

Although there is some evidence that chiropractic spinal manipulation may be helpful for various medical purposes, in general the evidence is not strong. There are several reasons for this, but one is fundamental: Even with the best of intentions, it is difficult to properly ascertain the effectiveness of a hands-on therapy like chiropractic.

Only one form of study can truly prove that a treatment is effective: the double-blind, placebo-controlled trial. (For more information on why such studies are so crucial, see Why Does This Database Rely on Double-blind Studies? ) However, it isn’t easy to fit chiropractic into a study design of this type. Consider the obstacles: What could researchers use for placebo chiropractic treatment? And how could they make sure that both participants and practitioners would be kept in the dark regarding who was receiving real chiropractic manipulation and who was receiving fake manipulation?

Because of these problems, all studies of chiropractic manipulation fall short of optimum design. Many have compared chiropractic treatment against no treatment. However, studies of this type cannot provide reliable evidence about the efficacy of a treatment. If a benefit is seen, there is no way to determine whether it was caused by chiropractic manipulation specifically, or just attention generally. (Attention alone will almost always produce some reported benefit.)

More meaningful trials used some sort of unrelated fake treatment for the control group, such as phony laser acupuncture. However, it is less than ideal to use a placebo treatment that is so very different in form from the treatment under study.

Better studies compare real chiropractic manipulation against sham forms of manipulation, such as light touch. Studies of this type are a definite step forward. However, it is quite likely that the practitioners at least unconsciously conveyed more enthusiasm and optimism when performing the real therapy than the fake therapy; this, too, could affect the outcome.

It has been suggested that the only way to get around this problem would be to compare the effectiveness of trained practitioners to actors trained only enough to provide a simulation of treatment; however, such studies have not been reported.

Still other studies have simply involved treating people with chiropractic spinal manipulation and seeing whether they improve. These trials are particularly meaningless; it has been long since proven that both participants and examining physicians will at least think that they observe improvement in people given a treatment, regardless of whether the treatment does anything on its own.

Finally, other trials have compared chiropractic manipulation to competing therapies, such as massage therapy or conventional physical therapy. However, neither of these therapies has been proven effective. When you compare unproven therapies to each other, the results cannot possibly prove that any of the tested treatments are effective.

Given these caveats, we discuss below what science knows about the effects of chiropractic.

Cost

Besides effectiveness, another important consideration is cost of care. There are many aspects to the cost of treatment, including number of visits to the chosen provider, cost of evaluation procedures such as x-rays, insurance reimbursement versus patient out-of-pocket expense, and costs for missed work time.

However, it is difficult to develop accurate cost-comparison figures because there are many complicating factors in research on the subject. For example, one approach is to simply identify people with similar injuries who choose one treatment or another and add up the total cost. Unfortunately, the results of such a study can be misleading. People with more or less severe back pain might tend to choose different forms of treatment; if those with more severe pain usually chose surgical treatment, this would tend to inflate the comparative costs of conventional care and make chiropractic seem less expensive.

Another potentially complicating factor is that, to a great extent, insurance companies control utilization of treatment. If they are less inclined to authorize chiropractic visits, people who choose chiropractic care might find their care cut off more rapidly than others who choose, say, physical therapy. This too would lead to artificially low costs of chiropractic treatment compared to physical therapy, skewing the results of the study.

These problems could be solved by conducting a study in which researchers randomly assign participants to certain treatments, with the length of treatment determined entirely by the treating physician. Unfortunately, studies of this type have not yet been conducted.

Back Pain

Chiropractic spinal manipulation is one of the most popular treatments for acute and chronic back pain in the US, and it may in fact provide at least modest benefit. However, as yet, research evidence has failed to find chiropractic manipulation convincingly more effective than standard medical care. ³ Chiropractic does seem to be more effective than placebo, if not by a great deal. For example, a single-blind controlled study of 84 people suffering from low back pain compared manipulation to treatment with a diathermy machine (a physical therapy machine that uses microwaves to create heat beneath the skin) that was not actually functioning. ⁴ The researchers asked the participants to assess their own pain levels within 15 minutes of the first treatment, then 3 and 7 days after treatment. The only statistically significant difference between the two groups was within 15 minutes of the manipulation. (Chiropractic had better results at that point.)

In another single-blind, placebo-controlled study, researchers assigned 209 participants to one of three groups: a high-velocity, low-amplitude (HVLA) spinal manipulation; a sham manipulation; or a back-education program. ⁵ Although this has been reported as a positive study, ⁶ most of the differences seen between the groups were not statistically significant. In addition, because almost half the participants dropped out of the study before the end, the results can't be regarded as meaningful.

Unimpressive results were also seen in a well-designed study of 321 people with back pain comparing chiropractic manipulation, a special form of physical therapy (the Mackenzie method), and the provision of an educational booklet in treating low back pain. ⁷ All groups improved to about the same extent.

Several studies evaluated the effectiveness of chiropractic manipulation combined with a different kind of treatment called mobilization, but they too found little to no benefit. ^{8 9} On a positive note, one study of 100 people with back pain and sciatica symptoms (pain down the leg due to disc protrusion) found that chiropractic manipulation was significantly more effective at relieving symptoms than sham chiropractic manipulation. ¹⁰ Several studies have found that chiropractic is at least as helpful as other commonly used therapies for low back pain, such as muscle relaxants, anti-inflammatory medication, soft-tissue massage , conventional medical care, and physical therapy. ¹¹ For example, a large, well-designed study found chiropractic manipulation more effective than general medical care and exercise therapy. ¹² Note: Physical therapy, the main conventional therapy for back pain, also lacks consistent supporting evidence. ¹³ For example, in one large study of people with back pain, a single session of advice proved equally effective as a full course of physical therapy for back pain. ¹⁴

Neck Pain

As with back pain, despite the widespread use of chiropractic spinal manipulation for neck pain, there is as yet no reliable evidence that it works. ¹⁵ Of the limited number of studies performed, most have failed to find manipulation (with or without mobilization or massage) convincingly more effective than placebo or no treatment. One large study (almost 200 participants) found that a special exercise program (MedX) was more effective than manipulation. ¹⁶ However, a study reported in 2006 found that a single high velocity, low-amplitude (eg, chiropractic-style) manipulation of the neck was more effective than a single mobilization procedure in improving range of motion and pain in people with neck pain. ¹⁷

Upper Extremity Pain

Patients often seek out chiropractic for painful conditions affecting their upper extremities (eg, shoulder, elbow, forearm, wrist, hand). A recent search and analysis of all published studies examining the effectiveness of chiropractic for these conditions revealed mostly case studies, an unreliable source of evidence. ¹⁸ The few uncovered controlled trials were of insufficient quality to draw any reliable conclusions about the effectiveness of chiropractic for painful conditions of the upper extremity.

Tension Headaches and Cervicogenic Headaches

Many people experience headaches caused by muscle tension, neck problems, or a combination of the two. Because these so-called tension headaches and cervicogenic headaches (caused by neck problems) overlap, we discuss them together here. Chiropractic spinal manipulation has shown some promise for these conditions, but the evidence remains incomplete and somewhat contradictory. In a controlled trial of 150 people, investigators compared spinal manipulation to the drug amitriptyline for the treatment of chronic tension-type headaches. ¹⁹ By the end of the 6-week treatment period, participants in both groups had improved similarly. However, 4 weeks after treatment was stopped, people who had received spinal manipulation showed greater reduction in headache intensity and frequency and over-the-counter medication usage than those who used the medication. The difference in the amount of improvement between the groups was statistically significant.

In another positive trial, 53 people with cervicogenic headaches received chiropractic spinal manipulation or laser acupuncture plus massage. ²⁰ Chiropractic manipulation was more effective. However, a similar study of 75 people with recurrent tension headaches found no difference between the two groups. ²¹ Other, smaller studies of spinal manipulation have been reported as well, with mixed results. ²² Finally, in a controlled trial, 200 people with cervicogenic headaches were randomly assigned to receive one of four therapies: manipulation, a special exercise technique, exercise plus manipulation, or no therapy. ²³ Each participant received at least 8 to 12 treatments over a period of 6 weeks. All three treatment approaches produced better results than no treatment, and approximately the same effect as each other. However, these results prove little because, as noted earlier, any treatment whatsoever will generally produce better results than no treatment.

Migraine Headaches

There is some evidence that chiropractic manipulation may provide both long- and short-term benefits for migraine headaches .

In a double-blind, placebo-controlled study, 123 participants suffering from migraine headaches were treated for 2 months with chiropractic manipulations or fake electrical therapy (electrodes placed on the body without electrical current sent between them) as placebo. ²⁴ The study lasted a total of 6 months: 2 months pre-treatment, 2 months of treatment, and 2 months post-treatment.

After 2 months of treatment, those receiving chiropractic manipulation showed statistically significant improvement in headache severity and frequency compared to the control group. Furthermore, these benefits persisted to a 2-month follow-up evaluation.

Chiropractic manipulation also produced relatively prolonged benefits in another trial as well. In this study, 218 people with migraine headaches were divided into three groups: manipulation, medication (amitriptyline), or manipulation plus medication. ²⁵ During the 4 weeks of treatment, all three groups experienced comparable benefits. During the follow-up 4-week period, however, people who had received manipulation alone experienced more benefit than those who had been in the other two groups.

However, a study of 85 people with migraines compared spinal manipulation against two other treatments: manipulation performed by a non-chiropractor and mobilization. ²⁶ The results showed no difference between groups.

Other Conditions

Chiropractic has been evaluated for many other conditions as well, but the results as yet provide little evidence of benefit.

Infantile Colic

Infantile colic is a common and frustrating problem. Although chiropractic manipulation has been promoted as a treatment for this condition, there is as yet little evidence that it offers specific benefits.

In a single-blind, placebo-controlled trial, a total of 86 infants either received three chiropractic treatments or were held for 10 minutes by a nurse. ²⁷ While a high percentage of infants improved, there was no significant difference between the two groups.

Another trial compared spinal manipulation to the drug dimethicone. ²⁸ While chiropractic proved more effective than the medication, dimethicone itself has never been proven effective for infantile colic, and the study did not use a placebo group. For this reason, the results of this study indicate little about the effectiveness of chiropractic treatment for infantile colic.

Premenstrual Syndrome

A small crossover trial of chiropractic for PMS symptoms found equivocal results. ²⁹

Phobias

A small trial compared real and sham Activator-style chiropractic treatment in people with phobias and found some evidence of benefit. ³⁰

Asthma

In two controlled studies comparing spinal manipulation to sham manipulation for treatment of people with asthma , the results showed equal improvement for participants in the two groups. ^{31 32} These results suggest that the benefits were most likely caused by the attention given by the chiropractor, and not due to the spinal manipulation itself. However, one of these studies has been sharply criticized for using as a sham treatment a chiropractic method perfectly capable of producing a therapeutic effect. ³³ This could hide real benefits of the tested form of chiropractic. (If the “placebo” treatment used in a study is actually better than placebo, and the tested treatment does no better than this “placebo,” the results would appear to indicate that the tested treatment is no better than placebo, and, hence, ineffective.)

Dysmenorrhea (Menstrual Pain)

A single-blind, placebo-controlled study of 138 women complaining of menstrual pain compared spinal manipulation to sham manipulation for four menstrual cycles and found no differences between the two groups. ³⁴

High Blood Pressure

In a study of 148 people with mild high blood pressure , use of chiropractic spinal manipulation plus dietary changes failed to prove more effective for reducing blood pressure than dietary changes alone. ³⁵

Bedwetting

A single-blind, placebo-controlled trial compared real and sham chiropractic (Activator technique) in 46 children with bedwetting problems, but failed to find a statistically significant difference between the groups. ³⁶

Scoliosis

Weak evidence hints that chiropractic could be somewhat helpful for adolescent idiopathic scoliosis (curvature of the spine that occurs for no clear reason in adolescents). ³⁷

Depending on the condition, chiropractic treatment is usually conducted two- or three times per week, for a month or more. Chiropractic is also sometimes used on an as-needed basis, or in a once- or twice-a-month maintenance form. For many chiropractors, x-rays are essential at the first visit and at some follow-up visits.

Each session involves hands-on manipulation following the methods of whatever manipulation technique the practitioner chooses to use. Sometimes other modalities may be used as well, such as massage or hot or cold packs.

Chiropractic physicians may also provide general wellness counseling and prescribe herbs or supplements .

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