Van Tulder, Koes, and Bouter (1997), researchers in the Netherlands funded by the Dutch Health Insurance Board, retrieved and evaluated evidence from 48 randomized controlled trials conducted worldwide that addressed the treatment of acute and chronic low-back pain. Researchers found "strong evidence" for the effectiveness of spinal manipulation in the treatment of chronic low-back pain.

Bronfort (1999) conducted a systematic review of literature concerning the efficacy of chiropractic treatment of low-back pain. The author found evidence "of short-term efficacy for SMT [spinal manipulative therapy] in the treatment of acute LBP [low-back pain]" (107). Additionally, the author found a combination of spinal manipulation and mobilization to be effective for chronic low-back pain "compared with placebo and commonly used therapies such as general medical practitioner management" (98).

In a study reported in 1992, Anderson et al. conducted a meta-analysis of twenty-three randomized controlled clinical trials of the effectiveness of spinal manipulation in the treatment of back pain. The researchers stated, "the trend for spinal manipulation to produce better results than any form of treatment to which it was compared was consistent and strong" (193). For 86% of the outcomes, spinal manipulation was more effective than any other treatment.

In a study conducted for the Ontario Ministry of Health, Manga et al. (1993) reported that spinal manipulation is the most effective treatment for low-back pain and that spinal manipulation is "safer than medical management of low-back pain" (11).

Following a 1993 study, researchers Cassidy, Thiel, and Kirkaldy-Willis of the Back Pain Clinic at the Royal University Hospital in Saskatchewan concluded that "the treatment of lumbar intervertebral disk herniation by side posture manipulation is both safe and effective" (102).

A study conducted by T.W. Meade, a medical doctor, and reported in the British Medical Journal concluded, after two years of patient monitoring, that "for patients with low-back pain in whom manipulation is not contraindicated, chiropractic almost certainly confers worthwhile, long-term benefit in comparison with hospital outpatient management" (Meade 1990, 1431).

A 1988 study of 10,652 Florida workers' compensation cases was conducted by Wolk and reported by the Foundation for Chiropractic Education and Research. According to Wolk, back injury patients treated by chiropractors versus medical doctors or osteopaths were less likely to develop compensable injuries (injuries resulting in time lost from work and therefore requiring compensation) and less likely to require hospitalization. The author explained that chiropractors are more effective in treating low-back injuries because "chiropractic treatment, in providing more services to the patient at the outset of injury, may produce more immediate therapeutic results and may reduce the amount of time lost from work" (56).

Hurwitz et al. (1996), a doctor of medicine and doctors of chiropractic from RAND and several academic institutions, conducted a review of literature on treatments for neck pain. The authors found manipulation to be more effective than mobilization or physical therapy in treating some subacute or chronic neck pain and noted that "all 3 treatments are probably superior to usual medical care" (1755).

Doctors of medicine and other professionals from the Netherlands conducted two randomized clinical trials comparing the outcomes of various treatments of chronic back and neck complaints. Spinal manipulative therapy was compared to physiotherapy, treatment by a general practitioner, and a placebo. The authors found faster and greater improvement in the spinal manipulation groups (Koes et al. 1992; Koes et al. 1992a).

Several studies (Howe, Newcombe, and Wade 1983; Verhoef, Page, & Waddell 1997) have found spinal manipulation to improve neck mobility and decrease neck pain. As Verhoef, Page, and Waddell (1997) concluded, "patients suffering from back and/or neck complaints experience chiropractic care as an effective means of resolving or ameliorating pain and functional impairments" (240).

A randomized controlled trial reported by medical doctors and doctors of chiropractic in Denmark found manipulation to have "a significant positive effect" on intensity and duration of cervicogenic headaches compared to "soft-tissue" therapy (Nilsson, Christensen, and Hartrigsen 1997).

Boline et al. (1995) conducted a study comparing manipulation to pain medication (amitriptyline) in the treatment of tension headaches. The authors found that pain medication had short-term effectiveness--although with side effects--while "four weeks after the end of intervention, the spinal manipulation group showed a 32% reduction in headache intensity, 42% [reduction] in headache frequency, 30% [reduction] in over-the-counter medication usage, and a 16% improvement in functional health status... The amitriptyline therapy group showed no improvement or slight worsening" (150).

In 1998, Hack et al. reported a new anatomical discovery: bridges of connective tissue establish a direct connection between neck muscles and the protective covering of the brain and spinal cord. This is a probable cause-and-effect connection between headaches and cervical spine dysfunction. The authors hypothesized that chiropractic treatment of muscle tension headaches is effective because it can "decrease muscle tension and thereby reduce or eliminate pain by reducing the potential forces exerted on the dura via the muscle-dura connection" (22).

In 1998, Mitchell, Humphreys, and O'Sullivan described previously unreported ligaments of the neck attached to the base of the skull. This discovery has implications for manual therapy and the treatment of cervicogenic headaches caused by damaged ligaments, mainly in cases of moderate to severe whiplash.

Davis et al. (1998) compared chiropractic treatment of carpal tunnel syndrome (CTS) to nonsurgical medical treatment. The chiropractic group used manipulation, ultrasound, and wrist supports while the medical group used wrist supports and ibuprofen. While both treatment groups improved significantly, the authors noted that chiropractic represents an alternative conservative treatment for CTS, especially for patients "who are unable to tolerate ibuprofen" (322).

Blunt, Rajwani, and Guerriero (1997) concluded that chiropractic treatment of fibromyalgia resulted in clinically significant improvement in flexibility and pain levels. The authors recommended that chiropractic treatment be included in a multidisciplinary treatment regimen for fibromyalgia.

Klougart, Nilsson, and Jacobsen (1989) reported a prospective study of 316 cases of infantile colic. The authors found that 94% of the infants appeared to be helped by chiropractic treatment "within 14 days from the start of treatment" (287). The infants included in the study had moderate to severe infantile colic and were otherwise healthy, averaged two weeks of age at the outset of colic, and averaged 5.7 weeks of age at the start of treatment.
The authors found that chiropractic treatment resulted in "both a reduction of the daily length of the colic periods and a reduction of the number of colic periods per day" (287). Because recovery began between 5.7 and 7.7 weeks of age, the authors maintained that this provided substantial evidence that the improvement could not be attributed strictly to "natural cessation of colic symptoms" (286).

In a 1999 study similar to the 1989 colic study noted above, Wiberg, Nordsteen, and Nilsson found that "spinal manipulation has a positive short-term effect on infantile colic" (520). Researchers randomly placed otherwise healthy, colicky infants into one of two treatment groups: chiropractic treatment and dimethicone medication. Parents kept a diary of symptoms and behaviors before the trial to establish baseline data and continued to keep a diary of symptoms during the trial. Both groups received two weeks of treatment. The infants in the chiropractic group exhibited "a reduction of 67% on day 12" of daily hours with colic, which was nearly identical to the results of the first study. The "dimethicone group only had a reduction in daily hours with colic of 38% by day 12" (520).
The dimethicone group had several subjects drop out of the study because their symptoms worsened. These subjects and their corresponding data were excluded from the results, creating better overall improvement statistics for the dimethicone group than actually occurred. Yet, the chiropractic subjects still exhibited twice as much improvement at the end of the trials when compared to the dimethicone group.


The authors noted that "[s]pinal manipulation is normally used in the treatment of musculoskeletal disorders, and the results of this trial leave open 2 possible interpretations. Either spinal manipulation is effective in the treatment of the visceral disorder infantile colic or infantile colic is, in fact, a musculoskeletal disorder, and not, as normally assumed, visceral" (520).

In an opinion article by respected researchers on the use of chiropractic manipulation in lumbar rehabilitation, Triano, McGregor, and Skogsbergh (1997) stated that the symptom relief and improved flexibility provided by chiropractic care make it a "valuable tool," assisting and easing patients into necessary rehabilitative programs. According to the authors, not only can chiropractic treatment relieve symptoms that interrupt therapy, but it restores patients' confidence in movement, discourages chronicity, and encourages patients to continue rehabilitation.

Validation of chiropractic treatment through evidence presented in the legal system evolved from an antitrust suit filed by four members of the chiropractic profession against the American Medical Association (AMA) and a number of other health care organizations in the U.S. (Wilk et al. v. AMA et al. 1990).
Following eleven years of litigation, a federal appellate court judge upheld a U.S. District Court ruling that the AMA had engaged in a boycott designed to restrict cooperation between MDs and chiropractors in order to eliminate the profession of chiropractic as a competitor in the U.S. health care system.

The U.S. District Court Judge rejected the AMA's patient care defense and cited specific studies which showed that "chiropractors are twice as effective as medical physicians and physical therapists in the care and alleviation of neuro mechanical problems" ("Chiropractors File Supreme Court Response" 1990, 1). The court determined that chiropractic care was therapeutic based on evidence that "chiropractors are particularly effective in relieving long term chronic and severe pain syndromes, headaches, and stress and strain problems associated with pregnancy" (1-2).

Mosley, Cohen, and Arnold (1996) concluded that for patients who had back or neck pain, "chiropractic care was substantially more cost effective than conventional care" (281).

Stano and Smith (1996) found that "[f]or both total payments and total outpatient payments, the mean cost of chiropractic first episodes ($518 and $477 respectively) is substantially and significantly lower than medical episodes ($1,020 and $598) with much of the difference in total costs because of inpatient costs" (198).

An earlier cost comparison study by Stano (1993) involved 395,641 patients with neuromusculoskeletal conditions. Results over a two-year period showed that patients who received chiropractic care incurred significantly lower health care costs than did patients treated solely by medical or osteopathic physicians.

In a 1998 study, Manga and Angus urged the Ontario government to lower chiropractic co-payments, which would grant access to more proper and prompt care for those who need it most yet can least afford it: poor and elderly patients. Once the government improves public access to chiropractic care, "direct savings to Ontario's health care system may be as much as $770 million, will very likely be $548 million, and will be at least $380 million. The corresponding savings in indirect costs--made up of the short and long term costs of disability--are $3.775 billion, $1.849 billion and $1.225 billion" (3).

In a study of work-related back pain claims in Australia, Ebrall (1992) found that the percentage of cases managed by chiropractors that required compensation days was half that of cases managed by medical doctors. The likelihood of a claim progressing to 90-day, or chronic, status was three times more likely with medical management than with chiropractic management.

A 1992 review of data from over 2,000,000 users of chiropractic care in the U.S., reported in the Journal of American Health Policy, stated that "chiropractic users tend to have substantially lower total health care costs," and "chiropractic care reduces the use of both physician and hospital care" (Stano, Ehrhart, and Allenburg 1992, 43).