Doctors of Chiropractic are physicians who consider man as an integrated being and give special attention to the physiological and biochemical aspects including structural, spinal, musculoskeletal, neurological, vascular, nutritional, emotional and environmental relationships." 

American Chiropractic Association

Let’s start with an overview, specifically with 1) background and context, 2) comparative safety and cost-effectiveness, and 3) mechanisms of action.


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BACKGROUND AND CONTEXT
Using the state of the sciences before the year 1910, chiropractic was founded with a profound appreciation of the integrated nature of health and the therapeutic focus was on spinal manipulation. In describing the chiropractic model of health, DD Palmer[1] wrote, “The human body represents the actions of three laws—spiritual, mechanical, and chemical—united as one triune. As long as there is perfect union of these three, there is health.” While the therapeutic focus of the profession has been spinal manipulation, from its inception the chiropractic profession has emphasized a holistic, integrative model of therapeutic intervention, health, and disease, and chiropractic was the first healthcare profession in America to specifically claim that the optimization of health requires attention to spiritual/emotional/psychological, mechanical/physical/structural, and biochemical/nutritional/hormonal/chemical considerations. Accordingly, these cornerstones are fundamental to the modern definition of the chiropractic profession recently articulated by the American Chiropractic Association[2]: “Doctors of Chiropractic are physicians who consider man as an integrated being and give special attention to the physiological and biochemical aspects including structural, spinal, musculoskeletal, neurological, vascular, nutritional, emotional and environmental relationships.”

As primary care providers with specialized training in musculoskeletal medicine, chiropractic physicians typically play a dual role in clinical practice on a daily basis, generally striving to accomplish two related goals simultaneously in each patient: 1) promoting overall wellness and professionally-supervised patient-implemented preventive healthcare, and 2) alleviating acute and chronic musculoskeletal pain. Both of these goals are tremendously important given the tremendous financial and social impact of musculoskeletal pain and the progressive deterioration of Americans’ health. At any given time, nearly thirty percent of the American population suffers from musculoskeletal pain, joint swelling, or limitation of movement[3], and approximately 1 of every 7 (14% of total) visits to a primary healthcare provider is for the treatment of musculoskeletal pain or dysfunction.[4] Resulting in more than $100 billion in US healthcare costs each year, back pain is the most prevalent medical problem in the US, is the leading cause of long-term disability, and the second leading cause of restricted activity and the use of prescription and non-prescription drugs.[5] Chiropractic wellness promotion is now more important than ever since the health of the American population is consistently and progressively declining: obesity and diabetes are “ever-growing” epidemics among children and adults[6] [7], infant mortality has recently increased for the first time in 40 years[8], and self-reported health status and health-related quality of life among adults are declining.[9] In the 25 years between 1975 and 2000, the incidence of cancer increased significantly, and the number of people diagnosed with cancer is expected to double in the next several decades.[10] Despite these negative health trends, America spends more on healthcare than does any other nation—an unprecedented $1.55 trillion, which is roughly 15% of the US gross domestic product.[11]

COMPARATIVE SAFETY AND COST-EFFECTIVENESS
Chiropractic and naturopathic physicians receive extensive training in the outpatient management of musculoskeletal disorders during their course of graduate healthcare training, which typically lasts from 4-6 years. In accord with this extensive training in musculoskeletal management, numerous sources of evidence demonstrate that chiropractic management is much safer and less expensive than allopathic medical treatment, particularly for treatment of low-back pain. In a randomized trial involving 741 patients, Meade et al[12] showed, “Chiropractic treatment was more effective than hospital outpatient management, mainly for patients with chronic or severe back pain… The benefit of chiropractic treatment became more evident throughout the follow up period. Secondary outcome measures also showed that chiropractic was more beneficial.” A 3-year follow-up study by these same authors[13] in 1995 showed, “At three years the results confirm the findings of an earlier report that when chiropractic or hospital therapists treat patients with low back pain as they would in day to day practice those treated by chiropractic derive more benefit and long term satisfaction than those treated by hospitals.” In their extensive review of the literature, Manga et al[14] published in 1993 that chiropractic management of low-back pain is superior to allopathic medical management in terms of greater safety, greater effectiveness, and reduced cost; they concluded, "There is an overwhelming body of evidence indicating that chiropractic management of low-back pain is more cost-effective than medical management." and "There would be highly significant cost savings if more management of LBP was transferred from medical physicians to chiropractors." Most recently, in 2004 Legorreta et al[15] reported that the availability of chiropractic care was associated with significant cost savings among 700,000 patients with chiropractic coverage compared to 1 million patients whose insurance coverage was limited to allopathic medical treatments. Simple extrapolation of the average savings per patient in this study ($208 annual savings associated with chiropractic coverage) to the US population (295 million citizens in 2005[16]) suggests that, if fully implemented in a nation-wide basis, America could save $61,360,000,000 (more than $61 billion per year) in healthcare annual expenses by ensuring chiropractic for all citizens in contrast to failing to provide such coverage. Spinal manipulation appears safer than the use of NSAIDs in the treatment of neck pain.[17] Contrasting the rates of manipulation-associated cerebrovascular accidents to the dangers of medical and surgical treatments for spinal disorders, Rosner[18] noted, “These rates are 400 times lower than the death rates observed from gastrointestinal bleeding due to the use of nonsteroidal anti-inflammatory drugs and 700 times lower than the overall mortality rate for spinal surgery.” Similarly, in his review of the literature comparing the safety of chiropractic manipulation in patients with low-back pain associated with lumbar disc herniation, Oliphant[19] showed that, “The apparent safety of spinal manipulation, especially when compared with other "medically accepted" treatments for [lumbar disk herniation], should stimulate its use in the conservative treatment plan of [lumbar disk herniation].”



MECHANISMS OF ACTION
Applied to either the spine or peripheral joints, high-velocity low-amplitude joint manipulation appears to have numerous physical and physiological effects, including but not limited to the following: 1) releasing entrapped intraarticular menisci and synovial folds, 2) acutely reducing intradiscal pressure, thus promoting replacement of decentralized disc material, 3) stretching of deep periarticular muscles to break the cycle of chronic autonomous muscle contraction by lengthening the muscles and thereby releasing excessive actin-myosin binding, 4) restoring proper kinesthesia and proprioception, 5) promoting relaxation of paraspinal muscles by stretching facet joint capsules, 6) promoting relaxation of paraspinal muscles via “postactivation depression”, which is the temporary depletion of contractile neurotransmitters, 7) temporarily elevating plasma beta-endorphin, 8) temporarily elevating serum levels of substance P, 9) temporarily enhancing phagocytic ability of neutrophils, 10) activation of the diffuse descending pain inhibitory system located in the periaqueductal gray matter—this is an important aspect of nociceptive inhibition by intense sensory/mechanoreceptor stimulation, which will be discussed in a following section for its relevance to neurogenic inflammation. While this list of mechanisms-of-action is certainly not complete, for purposes of this paper it is sufficient to have established that, indeed, joint manipulation in general and spinal manipulation in particular have objective effects that correlate with their clinical benefits. Additional mechanistic details are provided in numerous published reviews and primary research[20] [21] [22] [23] [24] [25] and by Leach[26], whose extensive description of the mechanisms of action of spinal manipulative therapy is unsurpassed.

Adjunctive therapies such as post-isometric relaxation[27] and correction of myofascial dysfunction[28] can effect tremendous and rapid reductions in musculoskeletal pain without the hazards and expense associated with pharmaceutical drugs. Nonmusculoskeletal benefits of musculoskeletal/spinal manipulation include improved pulmonary function and/or quality of life in patients with asthma[29] [30] [31] [32] and improvement or restoration of vision in patients with post-traumatic visual loss.[33] [34] [35] [36] [37] [38] [39] [40] More research is required to quantify the potential benefits of spinal manipulation in patients with wide-ranging conditions such as epilepsy[41] [42], attention-deficit hyperactivity disorder[43] [44], and Parkinson’s disease.[45]

Research documenting the systemic and “nonmusculoskeletal” benefits of spinal manipulation mandates that our concept of “musculoskeletal” must be expanded to appreciate that musculoskeletal interventions benefit nonmusculoskeletal body systems and physiologic processes. This conceptual expansion applies also to soft tissue therapeutics such as massage, which can reduce adolescent aggression[46], improve outcome in preterm infants[47], alleviate premenstrual syndrome[48], and improve flexibility and reduce pain and increase serotonin and dopamine in patients with low back pain.[49]


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OK, so hopefully that is a good introduction. I've included about 50 citations below for additional reading.


Alex Vasquez DC ND







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[1] Palmer DD. The Science, Art, and Phiosophy, of Chiropractic. Portland, OR; Portland Printing House Company, 1910: 107

[2] American Chiropractic Association. What is Chiropractic? http://amerchiro.org/media/whatis/ Accessed January 9, 2005

[3] Woolf AD, Pfleger B. Burden of major musculoskeletal conditions. Bull World Health Organ. 2003;81(9):646-56

[4] American College of Rheumatology Ad Hoc Committee on Clinical Guidelines. Guidelines for the initial evaluation of the adult patient with acute musculoskeletal symptoms. Arthritis Rheum. 1996 Jan;39(1):1-8

[5] Legorreta AP, Metz RD, Nelson CF, Ray S, Chernicoff HO, Dinubile NA. Comparative analysis of individuals with and without chiropractic coverage: patient characteristics, utilization, and costs. Arch Intern Med. 2004;164:1985-92

[6] Bloomgarden ZT. Type 2 diabetes in the young: the evolving epidemic. Diabetes Care. 2004;27:998-1010

[7] Rizvi AA. Type 2 diabetes: epidemiologic trends, evolving pathogenic concepts, and recent changes in therapeutic approach. South Med J. 2004;97(11):1079-87

[8] Nelson R. US infant mortality shows first rise in 40 years. Lancet. 2004;363(9409):626

[9] Zack MM, Moriarty DG, Stroup DF, Ford ES, Mokdad AH. Worsening trends in adult health-related quality of life and self-rated health-United States, 1993-2001. Public Health Rep. 2004;119:493-505

[10] Weir HK, Thun MJ, Hankey BF, Ries LA, Howe HL, Wingo PA, Jemal A, Ward E, Anderson RN, Edwards BK. Annual report to the nation on the status of cancer, 1975-2000, featuring the uses of surveillance data for cancer prevention and control. J Natl Cancer Inst. 2003;95(17):1276-99

[11] US health care: a state lottery? Lancet. 2004 Nov 20;364(9448):1829-30

[12] Meade TW, Dyer S, Browne W, Townsend J, Frank AO. Low back pain of mechanical origin: randomised comparison of chiropractic and hospital outpatient treatment. BMJ. 1990;300(6737):1431-7

[13] Meade TW, Dyer S, Browne W, Frank AO. Randomised comparison of chiropractic and hospital outpatient management for low back pain: results from extended follow up. BMJ. 1995;311(7001):349-5

[14] Manga P, Angus D, Papadopoulos C, et al. The Effectiveness and Cost-Effectiveness of Chiropractic Management of Low-Back Pain. Richmond Hill, Ontario: Kenilworth Publishing; 1993

[15] Legorreta AP, Metz RD, Nelson CF, Ray S, Chernicoff HO, Dinubile NA. Comparative analysis of individuals with and without chiropractic coverage: patient characteristics, utilization, and costs. Arch Intern Med. 2004;164:1985-92

[16] US Census Bureau http://factfinder.census.gov/home/saff/main.html?_lang=en Accessed January 12, 2005

[17] Dabbs V, Lauretti WJ. A risk assessment of cervical manipulation vs. NSAIDs for the treatment of neck pain. J Manipulative Physiol Ther. 1995;18:530-6

[18] Rosner AL. Evidence-based clinical guidelines for the management of acute low back pain: response to the guidelines prepared for the Australian Medical Health and Research Council. J Manipulative Physiol Ther. 2001;24(3):214-20

[19] Oliphant D. Safety of spinal manipulation in the treatment of lumbar disk herniations: a systematic review and risk assessment. J Manipulative Physiol Ther. 2004;27:197-210

[20] Maigne JY, Vautravers P. Mechanism of action of spinal manipulative therapy. Joint Bone Spine. 2003;70(5):336-41

[21] Brennan PC, Triano JJ, McGregor M, Kokjohn K, Hondras MA, Brennan DC. Enhanced neutrophil respiratory burst as a biological marker for manipulation forces: duration of the effect and association with substance P and tumor necrosis factor. J Manipulative Physiol Ther. 1992 Feb;15(2):83-9

[22] Brennan PC, Kokjohn K, Kaltinger CJ, Lohr GE, Glendening C, Hondras MA, McGregor M, Triano JJ. Enhanced phagocytic cell respiratory burst induced by spinal manipulation: potential role of substance P. J Manipulative Physiol Ther. 1991 Sep;14(7):399-408

[23] Heikkila H, Johansson M, Wenngren BI. Effects of acupuncture, cervical manipulation and NSAID therapy on dizziness and impaired head repositioning of suspected cervical origin: a pilot study. Man Ther. 2000 Aug;5(3):151-7

[24] Rogers RG. The effects of spinal manipulation on cervical kinesthesia in patients with chronic neck pain: a pilot study. J Manipulative Physiol Ther. 1997;20(2):80-5

[25] Bergman, Peterson, Lawrence. Chiropractic Technique. New York: Churchill Livingstone 1993. An updated edition is now availabe published by Mosby.

[26] Leach RA. (ed). The Chiropractic Theories: A Textbook of Scientific Research, Fourth Edition. Baltimore: Lippincott, Williams & Wilkins, 2004

[27] Lewit K, Simons DG. Myofascial pain: relief by post-isometric relaxation. Arch Phys Med Rehabil. 1984;65(8):452-6

[28] Ingber RS. Iliopsoas myofascial dysfunction: a treatable cause of "failed" low back syndrome. Arch Phys Med Rehabil. 1989 May;70(5):382-6

[29] Nielson NH, Bronfort G, Bendix T, Madsen F, Wecke B. Chronic asthma and chiropractic spinal manipulation: a randomized clinical trial. Clin Exp Allergy 1995;25:80-8

[30] Mein EA, Greenman PE, McMillin DL, Richards DG, Nelson CD. Manual medicine diversity: research pitfalls and the emerging medical paradigm. J Am Osteopath Assoc. 2001 Aug;101(8):441-4

[31] “There were small increases (7 to 12 liters per minute) in peak expiratory flow in the morning and the evening in both treatment groups,… Symptoms of asthma and use of beta-agonists decreased and the quality of life increased in both groups, with no significant differences between the groups.” Balon J, Aker PD, Crowther ER, Danielson C, Cox PG, O'Shaughnessy D, Walker C, Goldsmith CH, Duku E, Sears MR. A comparison of active and simulated chiropractic manipulation as adjunctive treatment for childhood asthma. N Engl J Med. 1998 Oct 8;339(15):1013-20

[32] Bronfort G, Evans RL, Kubic P, Filkin P. Chronic pediatric asthma and chiropractic spinal manipulation: a prospective clinical series and randomized clinical pilot study. J Manipulative Physiol Ther. 2001 Jul-Aug;24(6):369-77

[33] Stephens D, Pollard H, Bilton D, Thomson P, Gorman F. Bilateral simultaneous optic nerve dysfunction after periorbital trauma: recovery of vision in association with chiropractic spinal manipulation therapy. J Manipulative Physiol Ther. 1999 Nov-Dec;22(9):615-21

[34] Stephens D, Gorman F, Bilton D. The step phenomenon in the recovery of vision with spinal manipulation: a report on two 13-yr-olds treated together. J Manipulative Physiol Ther. 1997 Nov-Dec;20(9):628-33

[35] Stephens D, Gorman F. The association between visual incompetence and spinal derangement: an instructive case history. J Manipulative Physiol Ther. 1997 Jun;20(5):343-50.

[36] Stephens D, Gorman RF. Does 'normal' vision improve with spinal manipulation? J Manipulative Physiol Ther. 1996 Jul-Aug;19(6):415-8

[37] Gorman RF. Monocular scotomata and spinal manipulation: the step phenomenon. J Manipulative Physiol Ther. 1996 Jun;19(5):344-9

[38] Gorman RF. Monocular visual loss after closed head trauma: immediate resolution associated with spinal manipulation. J Manipulative Physiol Ther. 1995 Jun;18(5):308-14

[39] Gorman RF. The treatment of presumptive optic nerve ischemia by spinal manipulation. J Manipulative Physiol Ther. 1995;18(3):172-7

[40] Gorman RF. Automated static perimetry in chiropractic. J Manipulative Physiol Ther. 1993 Sep;16(7):481-7

[41] Elster EL.Treatment of bipolar, seizure, and sleep disorders and migraine headaches utilizing a chiropractic technique. J Manipulative Physiol Ther. 2004 Mar-Apr;27(3):E5

[42] Alcantara J, Heschong R, Plaugher G, Alcantara J. Chiropractic management of a patient with subluxations, low back pain and epileptic seizures. J Manipulative Physiol Ther. 1998;21(6):410-8

[43] Giesen JM, Center DB, Leach RA. An evaluation of chiropractic manipulation as a treatment of hyperactivity in children. J Manipulative Physiol Ther. 1989 Oct;12(5):353-63

[44] Bastecki AV, Harrison DE, Haas JW. Cervical kyphosis is a possible link to attention-deficit/hyperactivity disorder. J Manipulative Physiol Ther. 2004 Oct;27(8):e14

[45] Elster EL. Upper cervical chiropractic management of a patient with Parkinson's disease: a case report. J Manipulative Physiol Ther. 2000 Oct;23(8):573-7

[46] Diego MA, Field T, Hernandez-Reif M, Shaw JA, Rothe EM, Castellanos D, Mesner L. Aggressive adolescents benefit from massage therapy. Adolescence 2002 Fall;37(147):597-607

[47] Mainous RO. Infant massage as a component of developmental care: past, present, and future. Holist Nurs Pract 2002 Oct;16(5):1-7

[48] Hernandez-Reif M, Martinez A, Field T, Quintero O, Hart S, Burman I. Premenstrual symptoms are relieved by massage therapy. J Psychosom Obstet Gynaecol 2000 Mar;21(1):9-15

[49] "RESULTS: By the end of the study, the massage therapy group, as compared to the relaxation group, reported experiencing less pain, depression, anxiety and improved sleep. They also showed improved trunk and pain flexion performance, and their serotonin and dopamine levels were higher." Hernandez-Reif M, Field T, Krasnegor J, Theakston H. Lower back pain is reduced and range of motion increased after massage therapy. Int J Neurosci 2001;106(3-4):131-45