he concept of evidence-based practice (EBP) is a recent innovation in health care that strives to combine the best available scientific evidence with the doctor’s clinical expertise, in line with the preferences of the patient, to improve treatment outcomes.1 Those who find EBP unpalatable are often the victims of its improper application by third-party payers or other independent auditors of clinical care, who may find it convenient to rely too heavily upon the research leg as they neglect the clinical expertise of the doctor or, worse, the preferences of the patient. As an example, if a patient is against surgical intervention and in favor of pursuing a chiropractic approach to resolving a condition, all of the research in the world in favor of surgery is irrelevant, and only the chiropractic data need be considered. If no such data exists, EBP standards then suggest the doctor’s clinical expertise is sufficient to justify the chosen approach. Since nearly half of all medical procedures currently in use appear to lack sufficient evidence to justify their use,2 quite often the clinical expertise of the doctor is the primary deciding factor in the judicious application of care. When used properly, EBP “facilitates the process of practitioners finding solutions to their patients’ individual clinical problems.”3 For those who may have been unjustly injured by an improper application of EBP, I offer one ironic statistic in hopes of alleviating the bitterness. According to a study published by Straus et al. in the Canadian Medical Association Journal in 2000,4 the process of evidence-based practice itself has not been evaluated according to its own standards. So, although suggestive evidence exists in favor of this,5 we cannot claim with certainty that following these standards truly results in improved patient outcomes. Regardless of this fact, understanding the principles of EBP is fast becoming a necessity in the 21st century healthcare arena. Considering that most chiropractors do not possess an understanding of basic research principles,6 this should be a matter of serious concern for our profession. In this article, I aim to educate the clinical chiropractor about some of the basics of research methods and the proper application of EBP as it pertains to whole-body vibration (WBV) therapy, and to aid them in making the correct statements regarding the safety and effectiveness of this increasingly popular therapy.
First, it is important to understand that research terminology is often confusing in its exactitude
First, it is important to understand that research terminology is often confusing in its exactitude. The apparently contradictory nature of this statement can be resolved by considering two studies. The first is by Clinton Rubin,7 lead researcher whose department received funding from NASA to study the potential of WBV therapy to prevent bone and muscle loss in astronauts. This study showed that WBV therapy successfully prevented bone loss in postmenopausal women. Compare this to a randomized trial, which found no effect of WBV therapy in postmenopausal women.8 These two studies say the exact same thing — essentially, there was no change in bone mineral density (BMD) after WBV treatment — but one frames it as a success and the other as a failure. One key point to remember when evaluating research articles is this: No evidence of effect is not the same as evidence of no effect.9 To misquote F. Scott Fitzgerald, "The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function."
So, while we must recognize that the appropriate standards for the use of WBV therapy as a potential treatment for any condition have not yet been established or verified for any segment of the population,10 we should also realize that EBP is in favor of efforts to advance our understanding of WBV therapy and continues to justify its use under carefully controlled circumstances. However, this confusion is often exploited by marketers, so the responsible researcher is right to encourage caution and a “buyer beware” type mentality. Claims made by advertisers must be evaluated with great care, as the evidence is contradictory, even in the area where the greatest research on WBV therapy has been performed, namely osteoporosis. In regards to WBV therapy and osteoporosis, the honest man will tell you that some studies show good results, while others report no results, and hopefully opine that further research is needed to understand this apparent contradiction (in research circles, the technical term for this is “job security”). One of the reasons for the conflicting research has to do with the high number of variables involved with WBV therapy. Totosy de Zepetnek et al. quoted five factors that influence the response of the human skeletal system to WBV therapy (vibration direction, frequency, magnitude, duration, and body position),11 but this still leaves out the variables that occur within the population being studied. Prescription drug use,12 nutritional and hormonal status,8 gender, and age13 are just a few of these variables that could influence the results, and provide false information to the busy clinician who is ultimately seeking specific benefits for specific patients in the office. If all of the various types of WBV are placed together into one category without understanding how the involved variables can alter the critical effects experienced by the patient, this will confound the data and render it invalid.
The Bone and Joint Decade calculated that the financial burden borne by our society as a consequence of falls and fractures was $24.2 billion in 2004.14 This is not an insignificant finding, and, considering the recent concerns that the drugs being prescribed to mothers and grandmothers to promote their bone health may actually be causing bone death,15 non-drug efforts to reduce the societal cost of fractures are worth the effort of further research. As we endeavor to do so, however, we must always place the safety of our patients above all other concerns. As quoted by Wysocki et al. in a comparative effectiveness review by the Agency for Healthcare Research and Quality, questions such as the optimal population that could benefit from WBV therapy and the ideal treatment protocol for osteoporosis remain unanswered; as I stated earlier, EBP favors research into fields where it is needed. However, in their research, Wysocki et al. noted that “safety concerns emerged . . . including unknown long-term harms from the use of whole-body vibration therapy, and the potential inability of consumers to clearly distinguish low-intensity platforms intended for osteoporosis therapy from platforms intended for high intensity exercise.”16
A greater sustained research effort has been made about the potential negative effects of WBV therapy than has been done concerning its potential benefits. Because of the detailed research conducted by the International Standards Organization, OSHA, and others, we can state with confidence that the safety of WBV therapy has been validated, but only for specific frequencies, amplitudes, and durations, and under specific conditions.17 Exceeding these established safe levels is dangerous, just as exercising too much can be harmful to your health. For instance, there is no published research showing any negative effect to exposure to vibration at 30 Hz and 0.3 g, and the established guidelines for the safety of WBV exposure indicate that four hours of exposure to vibration at this level would be required to exceed safe levels.
Some chiropractors may be using WBV products in their offices which have the potential to harm their patients’ skeletal systems
When it comes to the safety of WBV, amplitude (measured in acceleration) is the most important factor in this regard. The human body is designed to operate in a 1.0 g environment, and we can safely withstand forces at this level or below it for long periods. We can also tolerate short exposures to g-forces in excess of this amount (when we jump and land, for instance, that’s a short-term exposure to increased g’s). It is important to recognize, then, that according to Clinton Rubin, “g-forces that greatly exceed 1.0 are the very basis of devices referred to as PowerPlate, Galileo, SoloFlex, Galaxy, Nemes, and others, and should be approached with extreme caution. Conditioned athletes, should they knowingly understand these dangers and still wish to put their body at risk is one thing, but to use interventions on the elderly, osteoporotic, or functionally impaired individuals is dubious, at best.”18 When Rubin’s statement is combined with the statement made by Wysocki et al. regarding “the potential inability of consumers to clearly distinguish low-intensity platforms intended for osteoporosis therapy from platforms intended for high intensity exercise,” it should be readily apparent that some chiropractors may be using WBV products in their offices which have the potential to harm the skeletal systems of their patients. What, then, is the difference between the chiropractor claiming to help elderly patients with osteoporosis by exposing them to dangerous levels of vibration, and the medical doctor who treats osteoporosis by prescribing drugs that may cause bone death?
A constant amplitude will change with increasing load; someone weighing 80 lbs is going to experience greater g-forces than someone weighing 180 lbs because increased weight will dampen the vibration. Amplitude can also vary depending upon foot placement, especially with oscillating platforms; the farther away your feet are from the axis of rotation, the greater the forces inputted into the body. While amplitude is the primary variable of interest, frequency also factors into the safety equation as well; for example, it’s easy to move your hand up and down three inches twice in one second. However, try moving your hand up and down three inches eighteen times in one second; this requires a great deal more exertion of force and the result is a higher amount of kinetic energy. So, in reviewing the literature, in order to have a safe product, you should ensure that the maximum amplitude never exceeds 1.0 g, and preferably remains closer to 0.2 or 0.3 g. This is an especially important concern with children, as their lighter weights will result in increased amplitude, and exposure to excessive vibratory forces could potentially affect the growth plates in a negative manner. If using an oscillating device, correct foot placement must be determined with care. In one report, a healthy athlete experienced hematuria (blood in the urine) after using an oscillating platform; the researchers suggested that something as simple as foot placement may have been at fault for the traumatic forces.19
I hope this article will serve as a warning to the chiropractic clinician who has purchased an unsafe vibration therapy product, and as an admonition to the manufacturers who are profiting without considering the true impact of their products upon those who use them. As the public becomes educated regarding the harmful effects of the misuse of WBV therapy, these individuals and organizations will increasingly render themselves vulnerable to the legal consequences of their decisions in the same manner that searching on the web for bisphosphonates and osteonecrosis brings up numerous articles written by attorneys.
- Sackett DL et al. Evidence-based medicine: What it is and what it isn’t. BMJ. 1996. 312(7023):71-2.
- Lewith G (cited by Cope J): Healthwriter. April 2007, p 2. Data retrieved from http://clinicalevidence.com/ceweb/about/knowledge/jsp visited 06-05- 07
- Haneline MT: Evidence-based Chiropractic Practice, Jones and Bartlett Publishers 2007, p. 7.
- Straus SE and McAlister FA: Evidence-based medicine: a commentary on common criticisms. CMAJ. 2000. 163(7):837-41.
- McGuirk B et al.: Safety, efficiency, and cost-effectiveness of evidence-based guidelines for the management of acute low back pain in primary care. Spine. 2001. 26(23):2615-22.
- Feise R: The evidence-based approach. J Amer Chiropr Assoc. 2002. 39(8):30-3.
- Rubin C, Recker R, Cullen D, Ryaby J, McCabe J, McLeod K: Prevention of postmenopausal bone loss by a low-magnitude, high-frequency mechanical stimuli: a clinical trial assessing compliance, efficacy, and safety. J. Bone Miner. Res. 19 (3) (2004), pp. 343–351.
- Slatkovska L, Alibhai SM, Beyene J, Hu H, Demaras A, Cheung AM: Effect of 12 months of whole-body vibration therapy on bone density and structure in postmenopausal women: a randomized trial. Ann Intern Med. 2011. Nov 15;155(10):668-79, W205.
- Tarnow-Mordi WO, Healy MJR: Distinguishing between “no evidence of effect” and “evidence of no effect” in randomized controlled trials and other comparisons. Arch Dis Child, 1999. 80(3):210-11.
- Prisby et al.: Effects of whole-body vibration on the skeleton and other organ systems in man and animal models: what we know and what we need to know. Ageing Research Reviews. 7, 2008, 319-329.
- Totosy de Zepetnek et al.: Whole-body vibration and the skeletal system. JRRD. 2009;46(4):529-542.
- Iwamoto et al: Effect of whole-body vibration exercise on lumbar bone mineral density, bone turnover, and chronic back pain in post-menopausal osteoporotic women treated with alendronate, Aging Clin. Exp. Res. 17 (2) (2005), pp. 157–163.
- Merriman et al: Systematically controlling for the influence of age, sex, hertz, and time post-whole-body-vibration exposure on four measures of physical performance in community- dwelling older adults: a randomized cross-over study. Curr Geront Geriat Res. 2011.
- The Burden of Musculoskeletal Diseases in the United States: Prevalence, Societal, and Economic Cost. United States Bone and Joint Decade. Chapter 5; p. 107.
- Sedghizadeh PP et al.: Oral bisphosphonate use and the prevalence of osteonecrosis of the jaw: an institutional inquiry. JADA. 2009 Jan;140(1):61-66.
- Wysocki et al.: Whole-body vibration therapy for osteoporosis [Internet]. AHRQ Comparative Effectiveness Reviews. Rockville (MD): Agency for Healthcare Research and Quality (US); 2011 Nov. Report No.: 11(12);EUC083-EF.
- ISO Guidelines Section 2631-1: Mechanical vibration and shock – Evaluation of human exposure to whole-body vibration.
- Rubin C: Contraindications and potential dangers of the use of vibration as a treatment for osteoporosis and other musculoskeletal diseases. April 2007.
- Franchignoni F et al.: Hematuria in a runner after treatment with whole body vibration: a case report. Scand J Med Sci Sports. 2012 May 17 [Epub ahead of print].