J Manipulative Physiol Ther 2000 (Mar); 23 (3): 202207 ~ FULL TEXT
Carl D. Nelson, DC, Daniel Redwood, DC,
David L. McMillin, MA,
Douglas G. Richards, PhD, Eric A. Mein, MD
Carl D. Nelson, DC,
1849 Old Donation Parkway, Suite 1,
Virginia Beach, VA 23454, (757) 496-6009
Chiropractic has made significant strides in establishing itself as a leading contender for integration in the emerging health care system. However, recent articles in prominent medical journals illustrate key issues that must be resolved for chiropractic to fully establish itself within the new health care model. Manual therapy diversity and the corollary question of whether chiropractic care should be defined solely in terms of the high velocity-low amplitude (HVLA) adjustment, are issues in need of urgent attention and analysis. Other problematic areas affecting chiropractic's integration into the health care mainstream include research methodology issues, treatment of visceral disorders, and professional relationships.
Chiropractic has met many challenges in its development
as a healing art. Throughout most of its existence, the chiropractic
profession has battled opposition from organized medicine, suffered financially
as a result of exclusion from health insurance reimbursement, and been
widely regarded as a marginal profession . Despite these obstacles,
chiropractic has flourished, becoming the third largest of the learned
health care professions . Although the quality and quantity of
chiropractic research during the early years of the profession left much
to be desired , modern research has contributed significantly to the
success and acceptance of chiropractic.
With the rapidly changing political and economic
aspects of health care delivery, chiropractic is well situated to make
important contributions to the emerging health care paradigm. However,
to fully participate in this revolution, key issues must be addressed with
regard to manual therapy diversity, research methodology, the treatment
of systemic dysfunction, and professional relations.
MANUAL THERAPY DIVERSITY
Chiropractic is one of the main branches of manual
therapy. Historically, one of the major challenges of chiropractic has
been to define and maintain its unique identity among the various manual
therapy professions. This has often resulted in a competitive stance toward
other forms of manual therapy. Notably, the rift between chiropractic
and osteopathy goes back to the founders of the professions, who openly
debated the conceptual and clinical differences of their respective approaches
. Osteopathy has integrated a wide variety of modalities, most
notably the practice of medicine, while chiropractic has remained primarily
focused in the application of manual therapy. While the role of manual
therapy in osteopathy (osteopathic manipulative treatment or OMT) has decreased,
the diversity of techniques practiced by osteopaths has increased. The
minority of osteopaths who practice OMT utilize a broad spectrum of techniques
including inhibitive pressure, soft tissue manipulation, and cranial/sacral
In chiropractic as well, the short lever high velocity/low
amplitude (HVLA) thrust adjustment (typically associated with an audible
cavitation or "cracking" sound) has been supplemented by a wide range of
non-cavitating methods including flexion-distraction, sacro-occipital,
Thompson, Activator, Applied Kinesiology, directional non-force, and dozens
of others. Defining chiropractic strictly in terms of the HVLA adjustment
fails to accurately describe the practice of contemporary chiropractic.
Historically, chiropractic has struggled with the
dilemma of therapeutic diversity in a number of ways. To some extent,
the battle between "purists" and "mixers" continues to this day .
Some chiropractors offer a blend of diverse manual therapy techniques in
addition to complementary and alternative medicine (CAM) options including
nutrition, herbal medicine, energy medicine, and physiotherapy. These
DCs view themselves as chiropractic physicians qualified to address a broad
range of disorders, including systemic dysfunction and visceral disease.
Many of these clinicians use methods from the full spectrum of manual therapy,
including soft tissue manipulation. Other chiropractors limit their therapeutic
methods to the hands-on adjustment but apply this method to both somatic
and visceral complaints. Still others feel strongly that the role of chiropractic
should be limited to treating somatic dysfunction, primarily back and neck
Manual therapy diversity is more than an historical
or academic issue. Structuring research to reflect this diversity
poses a significant methodological problem and, if recent, well-publicized
studies are a harbinger of things to come, represents a potential major
stumbling block to chiropractic's full integration into the mainstream
of health care.
ISSUES IN RESEARCH METHODOLOGY
Two studies reported in leading medical journals
illustrate the potential methodological problems confronting chiropractic
researchers. In the New England Journal of Medicine, Balon
et al.  compared "active" and "simulated" chiropractic manipulation
as adjunctive treatment for childhood asthma.
The active treatment consisted of "manual contact
with spinal or pelvic joints followed by low-amplitude, high velocity directional
push often associated with joint opening, creating a cavitation, or pop.
This treatment is a standard direct technique used by a wide variety of
manual therapy practitioners, primarily chiropractors and osteopaths.
The simulated treatment involved:
"soft-tissue massage and gentle palpation" to the spine, paraspinal
muscles, and shoulders
"turning the subject's head from one side to the other"
"a nondirectional push, or impulse" to the gluteal area with the
subject lying on one side and then the other
with the subject in the prone position, "a similar impulse was applied
bilaterally to the scapulae"
the subject in a supine position "with the head rotated slightly
to each side, and an impulse applied to the external occipital protuberance"
"low-amplitude, low-velocity impulses were applied in all these nontherapeutic
contacts, with adequate joint slack so that no joint opening or cavitation
Jongeward  questioned the appropriateness of the
simulated treatment, noting that that standard chiropractic practice commonly
includes soft tissue work. Furthermore, the sham treatment in the Balon
et al. study bears a marked similarity to a traditional general osteopathic
treatment . The Early American Manual Therapy website
provides easy access to several such examples from the traditional manual
therapy literature .
The authors of the Balon et al. study summarized
the simulated treatment by stating, "Hence, the comparison of treatments
was between active spinal manipulation as routinely performed by chiropractors
and hands-on procedures without adjustments or manipulation." Apparently,
these investigators were unaware of the early osteopathic works addressing
asthma  and more recent literature on OMT for respiratory problems
in general, particularly as cited in Osteopathic Considerations in Systemic
Dysfunction . The methodological limitations of the Balon et al. study
with regard to manual therapy were noted by Richards et al. . Balon
et al.  responded that they were unconvinced by the evidence supporting
the efficacy of the simulated treatment.
The results as reported by the researchers were,
"Symptoms of asthma and use of ß-agonists decreased and the quality
of life increased in both groups, with no significant differences between
the groups." Based on this equality of improvement, the authors concluded,
"the addition of chiropractic spinal manipulation to usual medical care
provided no benefit," . In our view, this is unfortunate, because the
data clearly indicate that the subjects in both groups improved after being
treated by diverse forms of manual therapy.
Another article, reported in the Journal of the
American Medical Association, also fails to accurately portray and
interpret manual therapy diversity. In certain respects, "Spinal
Manipulation in the Treatment of Episodic Tension-Type Headache"  duplicates
the questionable methodological choices in the Balon et al. study.
The researchers compared two forms of manual therapy for the treatment
of tension headache. The experimental treatment consisted of HVLA
chiropractic adjustments and deep friction massage plus trigger point therapy
(if indicated). The subjects receiving this intervention were designated
as the "manipulation" group. The "active control" group received
deep friction massage plus low-power laser light (considered not to be
efficacious for tension headache). Thus, as in the asthma study,
one form of manual intervention was compared to another.
The researchers observed that "by week 7, each group experienced significant
reductions in mean daily headache hours" and mean number of analgesics
per day." But because both groups benefited equally from the diverse forms
of manual therapy, the authors concluded that, "as an isolated intervention,
spinal manipulation does not seem to have a positive effect on episodic
tension-type headaches." [15, p. 1576]. Unlike the Balon study, this carefully
worded conclusion is technically correct, though it would also have been
technically correct to conclude that both massage and manipulation plus
massage resulted in measurable improvements for tension headache sufferers.
Both the headache and the asthma studies were widely
reported in the mass media as demonstrating that chiropractic fails to
help patients with childhood asthma and tension headache. In our view,
a more informative conclusion is that diverse forms of manual therapy appear
to be at least mildly helpful for these conditions. Although the favorable
outcomes could have resulted from chance or placebo effects, a reasonable
person might also justifiably conclude that various forms of manual medicine
can be helpful for these conditions. The diversity and potential validity
of the full spectrum of manual therapy applications significantly confounds
Although less publicized, Nilsson  used the same methodology in an earlier study on cervicogenic headache (n=39). Standard chiropractic (HVLA spinal manipulation) was compared to deep massage, trigger point therapy and light therapy (control treatment). The subjects in both the experimental and control groups showed notable improvement.
There was no statistical difference in the outcomes between the two groups. Ironically and disconcertingly, Nilsson specifically noted in this earlier article that, "the control group in the present study (massage/trigger points) is normally assumed to have some effect on this group of headaches." He further noted the inherent methodological shortcomings of using such a group as a control: "Future studies need necessarily include higher numbers of experimental subjects, but should take care to use an absolutely inert control treatment (for example, low-level laser only)." [16, p. 440] One can only wonder why Nilsson elected not to follow his own clearly stated recommendation, and instead used the same admittedly questionable methodology in the later tension-headache study.
Future research must seriously consider the full spectrum of diverse manual therapy options rather than assuming that some
forms are ineffective and can therefore be used as sham treatments. Legitimate alternative methodologies exist, particularly direct comparisons of chiropractic procedures (allowing the full range of methods typically used by chiropractors
in real-world practice settings) versus standard medical care. Some comparative studies  have shown chiropractic equal or superior to conventional medical procedures, with fewer side effects. If fairly constructed, future studies of this type will yield data that allow health practitioners and the general public to place manual therapy procedures in proper context. Comparing manual therapy to highly questionable placebos confuses the issue, and delays the advent of a level playing field .
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