The Efficacy of Homeopathic Arnica as Treatment for Musculoskeletal Injury

Lori Zucker

Introduction

Dr. Samuel Hahnemann began the formal practice of homeopathic medicine approximately 200 years ago (Schroyens, 2001). In 1810, after many years of observation, case studies, and personal experience, Hahnemann published The Organon, a reference book that describes the concept of using like cures and extremely dilute remedies to cure illness. The Law of Similars, described by Hahnemann in Latin as "similia similibus curentus", states that if a specific substance can cause symptoms in a healthy person, small amounts of that same substance can cure a sick person (Tedesco, 2001). Modern homeopathic practice uses minute amounts of specific substances to treat illnesses or injuries.

The principle of potentization refers to how a remedy is made and the belief that the more dilute the medicine, the more potent the remedy (Tedesco, 2001). In homeopathic practice, a 30C remedy is more dilute and therefore more potent than a 6C remedy (Schmidt, 1996). Traditional western medicine does not recognize homeopathic remedies as containing any active ingredient (Ernst, 1998; Reilly, 1994).

The practice of homeopathy in the United States began in 1825 and progressed steadily for the next 75 years. During those years, there were 22 homeopathic colleges and 100 homeopathic hospitals. Alexander Flexners’ critical report on the state of medical schools within the U.S., published in 1910, precipitated the closure of many homeopathic institutions (National Center for homeopathy, 2001; Schroyens, 2001; Tedesco, 2001). Over the next several decades, although the practice of homeopathic medicine flourished in Europe, medicine in the United States strongly favored allopathic treatment. By the 1940’s, there were no schools or courses of homeopathy in the U.S.

Current research (Eisenberg, 1998; Eisenberg, 1993; Kessler, 2001; National Center for Complementary and Alternative Medicine, 2001) has shown that there is a burgeoning interest and use of homeopathic medicine. Prevalence and long-term trend studies of complementary and alternative treatment demonstrate that in 1990, patients visited practitioners of unconventional medicine more times than primary care physicians (Eisenberg, 1993; Kessler, 2001).During that same time, expenditures associated with those visits approximated 13 billion dollars (Eisenberg, 1998; Eisenberg, 1993). These numbers require health care professionals, insurance companies, pharmaceutical companies, and consumers to re-examine attitudes toward alternative forms of medicine including homeopathy.

Arnica, one of the most common homeopathic remedies, is often prescribed for musculoskeletal injuries (Ernst, 1998; Lockie, 2000; Tedesco, 2001). Arnica is made from the arnica montana plant. It can be purchased in pill or cream form in most health food stores, pharmacies, specialty grocery stores, and over the Internet. Because homeopathic remedies are extremely dilute, they do not require a physician’s prescription and have not been associated with toxicity, overdose, or severe side effects (Homeopathic Pharmocopoeia of the United States, 1998; Ullman, 1992; Wollschlaeger, 1999). Thus, it is reported that individuals choose arnica as a remedy for the bangs and buises of everyday life without apparent concern of drug interaction and the side effects common with standard medicines (Lockie, 2000; Schroyens, 2001; Tedesco, 2001). If arnica is effective in reducing the pain associated with musculoskeletal injuries, it could provide a safer, cost effective alternative to traditional pain medication and enhance a patient’s tolerance of musculoskeletal pain (Lockie, 2000; Tedesco, 2001).

The author will review the readily available research on homeopathic arnica and musculoskeletal injury.

Methods

This author conducted a computerized search of Medline (1966-2001), CINAHL, the Cochrane Review, Ovid HealthSTAR, Alt-HealthWatch, and the Glasgow Homeopathic Library. The terms homeopathic and arnica were mapped and then combined for the database searches. Additionally, an Internet search was done using the Google search engine to identify sites containing the terms "homeopathic" and "arnica." Multiple commercial, organizational, and educational sites were scanned for related literature and research trials. Finally, the bibliography of all articles read was scrutinized for potential sources of information.

The results of this search strategy gleaned 204 possible references. The inclusion criterion for this literature review focused mainly on experimental trials of homeopathic arnica. The review included only experimental or quasi-experimental trials reported in English and those readily available on-line, through a medical library, or, at no additional cost, through an inter-library loan service. Eight articles fulfilled the inclusion criteria; one systematic review of randomized controlled clinical trials, one meta-analysis of placebo-controlled clinical trials, and six clinical trials.

The studies included in this paper represent primary clinical trials or secondary research synthesizing data from clinical trials. Strictly based on a hierarchy, this type of research is at the apex of the pyramid of evidence (Markinson, 2001). A systematic review or meta-analysis is given more substantial weighting than an individual research finding. In addition, trends noted across several papers are grouped together and given more regard than a trend noted in only one research project.

Context and Background

For medical decision makers, the lack of literature supporting the use of homeopathy is a problem. Physicians and third party payers want rigorous research conducted to identify a cause and effect relationship between a homeopathic remedy and the condition it is presumed to alleviate. Consumers want more broad information and typically are satisfied in their decision making process with case studies or trends. In the last decade, the public clearly has embraced the use of homeopathy more quickly than the research community has been able to provide evidence of the effectiveness of specific remedies (Eisenberg, 1998; Eisenberg, 1993). Recently, more federal funding has been made available for research into alternative therapies in response to the public interest in this approach to medicine. (National Center for Complementary and Alternative Medicine, 2001) Much of the present research on the effectiveness of arnica on musculoskeletal symptoms is methodologically poor or has too few subjects to be conclusive.

Nevertheless, there is a prevailing public sentiment that arnica gel and arnica tablets are a first line defense in musculoskeletal injury literature (Ernst, 1998; Lockie, 2000; Tedesco, 2001). This sentiment is evidenced in the literature (Ernst, 1998; Lockie, 2000; Tedesco, 2001), by the abundance of consumer products that include arnica as an ingredient, and the ease with which the average consumer can purchase retail arnica products. Accordingly, it is appropriate, timely, and medically responsible to evaluate the research available to clinicians on the subject of homeopathic arnica.

Review of the Literature

The most substantial paper on the effectiveness of homeopathic arnica in general is a systematic review published in 1998 by Ernst and Pittler. The authors conducted an exhaustive search of available databases to identify all placebo-controlled clinical trials of homeopathic arnica. The authors reviewed several hundred papers and evaluated them against predetermined inclusion/exclusion criteria. The screening yielded eight studies that satisfied their standards for a randomized controlled trial, which were then grouped into positive and negative findings.

The authors present a generally negative conclusion on the efficacy of arnica. A Cochrane review (2000) of the Ernst and Pittler (1998) study states that the conclusions appear to follow from the results. However, the reliability of the conclusions cannot be confirmed as the paper contains insufficient information. Of the eight studies included in the Ernst and Pittler (1998) review, two had positive statistical outcomes for arnica, four had negative outcomes, and two had positive trends but included no statistical results. A closer look at the eight studies included in Ernst and Pittler’s (1998) paper reveal trials of arnica use for post operative ileus, dental work, acute trauma, delayed onset muscle soreness, and acute stroke. Because this review focuses solely on the effectiveness of arnica in treating musculoskeletal symptoms, the broad approach taken by Ernst and Pittler (1998) was deemed only indirectly applicable. Instead, only the relevant primary research literature was further addressed.

Three studies of similar design specifically address the effectiveness of arnica on muscle soreness after running. Two early studies done by Tveiten, Bruset, Borchgrevink, and Lohne (1991) and Tveiten, Bruset, Borchgrevink, and Norseth (1998) suggest positive benefits. A larger study modeled after both of Tveiten’s (1991, 1998) work suggests that arnica is ineffective in allaying the muscle soreness after a long distance run. Tveiten, et al. (1991, 1998) conducted two randomized, double-blind, placebo-controlled trials on marathon runners. The original article (Tveiten, 1991) detailing the first study was printed in Norwegian in 1991 but an English abstract is available through the Glasgow homeopathic library.

Tveiten, et al. (1991) led with 36 participants and found a positive trend between arnica and muscle soreness. These results led the researchers to expand the trial to include more subjects and more outcome measures. In a second study, involving 46 subjects, blood tests and a visual analog scale (VAS) were used to assess muscle soreness after the Oslo marathon. The 1995 study by Tveiten, et al. (1998) showed a statistical significance in favor of arnica in the VAS (p=0.017) scores. Although the sample size was small, the study was well designed and the authors included ideas for future research.

Other investigators, Vickers, Fischer, Smith, Wyllie, and Rees (1998), modeled their study on the earlier work by Tveiten, et al. (1998). . They studied 400 volunteers who self reported concerns about muscle soreness after participating in a recreational run. The design used by the researchers effectively controlled many of the scientific aspects in this trial. The randomization, blinding, power calculations, and prospective nature of the design were stringent and bolstered the finding that arnica was no more effective than the placebo in decreasing perceived soreness after a long distance run. Unfortunately, this study differs from the Oslo (Tveiten, 1998) studies in that the subjects participated in recreational runs anywhere from 2 to 26 miles.

There are four concerns with Vickers, et al. (1998) research. First, the sampling process is such that a subject self-reported concerns with delayed onset muscle soreness. Second, the varying lengths of each subject’s run present a conflict of internal validity. Third, the evaluation and diagnosis process for delayed onset muscle soreness (DOMS) is not well defined. And fourth, the dosing of arnica for the diagnosis of DOMS is not substantiated. All four of these issues present possible threats to validity . Based on the statistical findings, the authors state that arnica is ineffective in preventing or treating muscle soreness. This conclusion is too global based on the information presented in the original article; the problem arises from the dosages utilized. Although Vickers used the same dosages as in the Oslo trials (Tveiten, 1991; Tveiten, 1998) the research is devoid of any data substantiating the appropriateness of the dosages selected.

The conclusions would be more generalizable if Vickers, et al. (1998) had established some efficacy regarding potency and the dosing procedure. In its present state, the only affirmative conclusion a reader can draw from the study is that arnica is ineffective when used in this specific manner. Nevertheless, Vickers, et al. study is weighted the most compelling on the subject of effectiveness of arnica for muscle soreness as it has the most rigorous research design.

In a separate double blind, placebo-controlled trial, Schmidt (1996) evaluated the use of topical arnica cream versus a topical placebo cream after a three and a half mile run. One hundred and forty-one people volunteered to participate in a 72 hour study following completion of a recreational run. Using descriptive statistics and graphical representations of the outcomes, Schmidt reports a positive finding in favor of arnica over the placebo. The author does not report any randomization sequence during the recruiting of the subjects or randomization between treatment and control groups. Although randomization may have occurred in the sampling and/or assignment, the reader cannot assume that the randomization was done properly. The study did not include any true statistical tests to ensure that the treatment and control groups began the study as equal samples. Had this been established, the results might be more substantial even without statistical tests to support a treatment effect from the arnica remedy.

Jawara, Lewith, Vickers, Mullee, and Smith (1997) present a randomized, double-blind, placebo-controlled pilot study looking at the effect of arnica and rhus toxicodendron on DOMS. This study with 50 subjects randomized into a treatment and control group, is well orchestrated and scientifically appropriate. In this study, unlike Vickers et al.(1998) DOMS is described and a standardized method of producing and diagnosing DOMS is used. The outcome measures are not statistically significant. The authors, however, repeatedly comment that the data indicate a positive trend and they are planning on using this preliminary pilot study to design a more powerful trial. Jawara et al. report that post hoc power calculations suggest 170 subjects would be needed to properly assess significant differences between the treatment and control groups. This study also misses an opportunity to define the dosing procedure. Jawara, et al. is weighted more meaningfully than the study done by Schmidt (1996) based on its adherence to scientific design.

In a different approach to the use of arnica in musculoskeletal injury, Gibson, Haslam, Laurenson, Newman, Pitt, and Robins (1991) conducted a clinical trial with 20 hospitalized patients. This double blind study involves patients who recently experienced an acute trauma. The nursing staff identified possible subjects, who then consented to participate in the study. There was no mention of random assignment to treatment versus control group but there was an attempt to blind the subject and the testers to group assignment. A pre-test, post-test design was used to measure the effects of arnica on blood pressure, pulse, respiratory rate, and perception of pain and stiffness using a VAS. The report indicates that some of the data is missing due to the nurse’s schedule and failure to record information.

The results of Gibson, et al. (1991) are reported as not statistically significant but, similar to the Jawara et al. (1997) study, the authors present a positive view of arnica for acute musculoskeletal injury. Some unplanned post hoc analyses are reported to be strongly in favor of arnica although these statistics are highly questionable and could appear to be a search mission for positive results. Given the flaws in research design, Gibson et al. must be considered the weakest trial reviewed in this paper.

It is clear from a review of the above literature that a definitive statement cannot be made regarding the effectiveness of homeopathic arnica on musculoskeletal symptoms. The most scientifically sound trial (Vickers, 1998) finds arnica to be no different than a placebo; however, its design raises some internal validity issues and the sampling method limits generalizability. The authors of the remaining papers suggest positive effects of arnica but the conclusions are flawed for one of several reasons: either the results are not statistically significant, they are reported positive but they are not tested with statistical analyses, or the study was too small to make a definitive statement.

Implications

There are some positive statistical findings in the data reviewed for this paper. Unfortunately, there is also a primary credibility lapse in the form of author bias. In four out of the six papers reviewed, the authors suggest positive trends in their research, despite a lack of statistical support. For example, one trial hailing positively for arnica reports only the median, the mode and graphical representations of the outcome measures but does not report any further analysis, leaving the statistical significance undeterminable (Schmidt, 1996). Another research trial reports negative results yet the authors present the data with a positive slant (Jawara, 1997). If this bias arose only in one research paper, it would not make a trend and the reader merely could put that article aside in favor of others with less bias. In the homeopathic body of literature, a consistent trend toward positive reporting of data exists even when the trend information is not consistent with the statistical results of the study. It is possible that the reader would be making an error to discard all the research in this category in favor of those with only rigid adherence to scientific interpretation. For example, on a strictly factual basis, there is only one trial reviewed here with enough power in its statistical analysis and enough attention to scientific methodology to make a definitive statement regarding arnica and muscle soreness (Vickers, 1998). Based on the results of this study the evidence would deem homeopathic arnica ineffective. Unfortunately, this study has methodological flaws and is not representative of all uses of arnica. Nevertheless, it is not usually a sound medical principle to base decision-making on one research article. A 1997 study by Linde, Clausius, Ramirez, Melchart, Gitel Hedges, and Jonas posed the question of whether the clinical effects of homeopathy are placebo effects. The authors followed stringent criteria for identifying and including trials and followed rigorous methodologies for analysis. The pooled results across the 89 placebo-controlled trials favor homeopathy over a placebo. The authors clearly state that these findings are not specific to one remedy and generalizations to an individual remedy cannot be made. However, the results of Linde, et al. support the positive trends of homeopathic arnica reported by many of the authors.

The literature reviewed for this paper reveals the inadequate state of homeopathic research. The dearth of sophisticated research available to a typical clinician leaves unanswered the question of a cause and effect relationship between arnica and alleviating musculoskeletal symptoms.

This literature review could be used to assist a practicing clinician about the poor quality of research in the use of arnica. To the extent that patients rely on healthcare practitioners for guidance in medication and overall health, this information is meaningful. Given the research reviewed here, a practitioner can only give a client anecdotal advice regarding the use of arnica for muscle soreness. This literature review can also be used to motivate researchers to develop more comprehensive trials using the rigorous methodology needed to answer an experimental question.

A major concern for the future of homeopathic research is the question about dosages. Unlike that of allopathic medicine, in the practice of homeopathy, dosing procedures are highly individualized (Lockie, 2000). Clinical trials demand the same medicinal intervention for all members of the group in order to properly run statistical tests. Prior to embarking on bigger and better studies on the efficacy of arnica, it may be prudent to do research to establish potency guidelines. These studies could be done as they are for any new drug being introduced to the consumer market. Another option would be to conduct consensus studies across a pool of experts to establish a typically accepted dose of arnica in a specified injured state. These findings and the application of these findings would strengthen future studies that attempt to evaluate the effectiveness of arnica on muscle soreness.

Finally, if more comprehensive and more rigorous studies are not readily achievable due to sampling techniques, funding, clinical time, or dosage, smaller studies need to be conducted with similar enough methodologies to allow for a meta-analysis. The one meta-analysis that evaluates the question of placebo effect is very well done and comprehensive (Linde, 1997). Unfortunately, the authors bundled all homeopathic treatments that were tested against a placebo into the pooled outcome data. The sample sizes were too small to make any claims for individual remedies. This limits the clinical use of the research. For the question of homeopathic arnica, there would need to be several studies that allow for pooling of data to make a meta-analysis possible.

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