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Topical herbal therapies for treating osteoarthritis

  1. Melainie Cameron1,*,
  2. Sigrun Chrubasik2

Editorial Group: Cochrane Musculoskeletal Group

Published Online: 31 MAY 2013

Assessed as up-to-date: 27 FEB 2013

DOI: 10.1002/14651858.CD010538

How to Cite

Cameron M, Chrubasik S. Topical herbal therapies for treating osteoarthritis. Cochrane Database of Systematic Reviews 2013, Issue 5. Art. No.: CD010538. DOI: 10.1002/14651858.CD010538.

Author Information

  1. 1

    University of the Sunshine Coast, School of Health and Sport Sciences, Maroochydore DC, QLD, Australia

  2. 2

    University of Freiburg, Freiburg, Germany

*Melainie Cameron, School of Health and Sport Sciences, University of the Sunshine Coast, Sippy Downs campus, Locked Bag 4, Maroochydore DC, QLD, 4558, Australia. mcameron@usc.edu.au.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 31 MAY 2013

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Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary

Background

Before extraction and synthetic chemistry were invented, musculoskeletal complaints were treated with preparations from medicinal plants. They were either administered orally or topically. In contrast to the oral medicinal plant products, topicals act in part as counterirritants or are toxic when given orally.

Objectives

To update the previous Cochrane review of herbal therapy for osteoarthritis from 2000 by evaluating the evidence on effectiveness for topical medicinal plant products.

Search methods

Databases for mainstream and complementary medicine were searched using terms to include all forms of arthritis combined with medicinal plant products. We searched electronic databases (Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, AMED, CINAHL, ISI Web of Science, World Health Organization Clinical Trials Registry Platform) to February 2013, unrestricted by language. We also searched the reference lists from retrieved trials.

Selection criteria

Randomised controlled trials of herbal interventions used topically, compared with inert (placebo) or active controls, in people with osteoarthritis were included.

Data collection and analysis

Two review authors independently selected trials for inclusion, assessed the risk of bias of included studies and extracted data.

Main results

Seven studies (seven different medicinal plant interventions; 785 participants) were included. Single studies (five studies, six interventions) and non-comparable studies (two studies, one intervention) precluded pooling of results.

Moderate evidence from a single study of 174 people with hand osteoarthritis indicated that treatment with Arnica extract gel probably results in similar benefits as treatment with ibuprofen (non-steroidal anti-inflammatory drug) with a similar number of adverse events. Mean pain in the ibuprofen group was 44.2 points on a 100 point scale; treatment with Arnica gel reduced the pain by 4 points after three weeks: mean difference (MD) -3.8 points (95% confidence intervals (CI) -10.1 to 2.5), absolute reduction 4% (10% reduction to 3% increase). Hand function was 7.5 points on a 30 point scale in the ibuprofen-treated group; treatment with Arnica gel reduced function by 0.4 points (MD -0.4, 95% CI -1.75 to 0.95), absolute improvement 1% (6% improvement to 3% decline)). Total adverse events were higher in the Arnica gel group (13% compared to 8% in the ibuprofen group): relative risk (RR) 1.65 (95% CI 0.72 to 3.76).

Moderate quality evidence from a single trial of 99 people with knee osteoarthritis indicated that compared with placebo, Capsicum extract gel probably does not improve pain or knee function, and is commonly associated with treatment-related adverse events including skin irritation and a burning sensation. At four weeks follow-up, mean pain in the placebo group was 46 points on a 100 point scale; treatment with Capsicum extract reduced pain by 1 point (MD -1, 95% CI -6.8 to 4.8), absolute reduction of 1% (7% reduction to 5% increase). Mean knee function in the placebo group was 34.8 points on a 96 point scale at four weeks; treatment with Capsicum extract improved function by a mean of 2.6 points (MD -2.6, 95% CI -9.5 to 4.2), an absolute improvement of 3% (10% improvement to 4% decline). Adverse event rates were greater in the Capsicum extract group (80% compared with 20% in the placebo group, rate ratio 4.12, 95% CI 3.30 to 5.17). The number needed to treat to result in adverse events was 2 (95% CI 1 to 2).

Moderate evidence from a single trial of 220 people with knee osteoarthritis suggested that comfrey extract gel probably improves pain without increasing adverse events. At three weeks, the mean pain in the placebo group was 83.5 points on a 100 point scale. Treatment with comfrey reduced pain by a mean of 41.5 points (MD -41.5, 95% CI -48 to -34), an absolute reduction of 42% (34% to 48% reduction). Function was not reported. Adverse events were similar: 6% (7/110) reported adverse events in the comfrey group compared with 14% (15/110) in the placebo group (RR 0.47, 95% CI 0.20 to 1.10).

Although evidence from a single trial indicated that adhesive patches containing Chinese herbal mixtures FNZG and SJG may improve pain and function, the clinical applicability of these findings are uncertain because participants were only treated and followed up for seven days. We are also uncertain if other topical herbal products (Marhame-Mafasel compress, stinging nettle leaf) improve osteoarthritis symptoms due to the very low quality evidence from single trials.

No serious side effects were reported.

Authors' conclusions

Although the mechanism of action of the topical medicinal plant products provides a rationale basis for their use in the treatment of osteoarthritis, the quality and quantity of current research studies of effectiveness are insufficient. Arnica gel probably improves symptoms as effectively as a gel containing non-steroidal anti-inflammatory drug, but with no better (and possibly worse) adverse event profile. Comfrey extract gel probably improves pain, and Capsicum extract gel probably will not improve pain or function at the doses examined in this review. Further high quality, fully powered studies are required to confirm the trends of effectiveness identifed in studies so far.

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary

Topical herbal therapy for treating osteoarthritis

This summary of a Cochrane review presents what we know from research about the effects of herbal therapies applied to the skin in people with osteoarthritis.

The review shows that in people with osteoarthritis:

Arnica gel probably improves pain and function as well as non-steroidal anti-inflammatory drugs do;

Capsicum extract gel probably will not improve pain or function more than placebo;

Comfrey extract gel probably improves pain more than placebo;

Chinese herbal patches probably improve pain and function slightly more than placebo.

Herbal therapies may cause side effects; however we do not have precise information about side effects and complications. This is particularly true for rare but serious side effects. Possible side effects may include skin irritations.

What is osteoarthritis and what is herbal therapy?

Osteoarthritis (OA) is a disease of the joints (commonly knee, hip, hands). When joints lose cartilage, bone grows to try to repair the damage. Instead of making things better, however, the bone grows abnormally and makes things worse. For example, the bone can become misshapen and make the joint painful and limit movement. OA can affect your physical function, particularly your ability to use your joints.

Herbal medicines are defined as finished, labeled medicinal products that contain as active ingredients aerial or underground parts of plants, other plant material, or combinations thereof, whether in the crude state or as plant preparations (for example oils, tinctures).

Best estimate of what happens to patients with osteoarthritis who apply Arnica extract gel:

Arnica gel was compared to ibuprofen (a non-steroidal anti-inflammatory).

Pain (higher scores mean more severe pain): people who applied Arnica rated their pain to be 3.8 points lower (10.1 points lower to 2.5 points higher) than people who applied ibuprofen. After 3 weeks of treatment, people who applied Arnica rated their pain to be 40.4 and people who applied ibufrofen rated their pain to be 44.2 on a scale of 0 to 100.

Physical function (lower scores mean better function): people who applied Arnica rated their physical function to be 0.4 points lower (1.75 points lower to 0.95 points higher) than people who applied ibuprofen. After 3 weeks of treatment, people who applied Arnica rated their physical function to be 7.1 on a scale of 0 to 30, and people who applied ibufrofen rated their physical function to be 7.5.

Side effects: a greater proportion of people who applied Arnica reported side effects than did those who applied ibuprofen. Fourteen out of 105 people reported side effects with Arnica, and 8 out of 99 people reported side effects with ibuprofen.

Best estimate of what happens to patients with osteoarthritis who apply Capsicum extract gel

Capsicum extract gel was compared to placebo.

Pain (higher scores mean more severe pain): people who applied Capsicum rated their pain to be 1.0 point lower (6.76 points lower to 4.76 points higher) than people who applied placebo. After 4 weeks of treatment, people who applied Capsicum rated their pain to be 44.6, and people who applied placebo rated their pain to be 45.6 on a scale of 0 to 100.

Physical function (lower scores mean better function): people who applied Capsicum rated their physical function to be 2.64 points lower (9.51 points lower to 4.23 points higher) on a 0 to 96 point scale than people who applied placebo. After 4 weeks of treatment, people who applied Capsicum rated their physical function to be 32.15 on a scale of 0 to 96, and people who applied ibufrofen rated their physical function to be 34.79.

Side effects: more adverse events were reported among people who applied Capsicum than for those who applied placebo. Of the 338 adverse events reported, 272 occurred in people who applied Capsicum and 66 occured in people who applied placebo.

Best estimate of what happens to patients with osteoarthritis who apply comfrey extract cream

Comfrey extract cream was compared to placebo.

Pain (higher scores mean more severe pain): people who applied comfrey rated their pain to be 16.3 points lower (20.08 to 12.58 points lower) than people who applied placebo. After 3 weeks of treatment, people who applied comfrey rated their pain to be lower by 20.9 points from baseline, and people who applied placebo rated their pain to be lower by 4.6 points from baseline on a scale of 0 to 100.

Side effects: a smaller proportion of people who applied comfrey reported side effects than did those who applied placebo. Seven out of 110 people reported side effects with comfrey, and 15 out of 110 people reported side effects with placebo.

Chinese herbal medicine patches

Adhesive patches containing the Chinese herbal mixtures FNZG and SJG were compared to placebo. We are uncertain whether Chinese herbal patches affect osteoarthritis because this intervention was tested over seven days only.

Pain (higher scores mean worse or more severe pain): people who applied FNZG rated their pain to be 1.44 points lower (9.28 points lower to 6.40 points higher) and people who applied SJG rated their pain to be 1.08 points lower (6.28 points lower to 8.40 points higher) than people who applied placebo. People who applied FNZG rated their pain to be lower by 19.20 points from baseline, people who applied SJG rated their pain to be lower by 16.04 points from baseline, and people who applied placebo rated their pain to be lower by 17.68 points from baseline on a scale of 0 to 100.

Physical function (lower scores mean better function): people who applied FNZG rated their function to be 2.61 points lower (9.50 points lower to 4.28 points higher) and people who applied SJG rated their function to be 2.97 points lower (9.60 points lower to 3.66 points higher) than people who applied placebo. People who applied FNZG rated their physical function to be lower (better) by 5.04 points from baseline, people who applied SJG rated their physical function to be lower (better) by 6.71 points from baseline, and people who applied placebo rated their physical function to be lower (better) by 6.10 points from baseline on a scale of 0 to 96.

Side effects: a greater proportion of people who applied herbal patches reported side effects than did those who applied placebo patches. Five out of 60 people reported side effects with FNZG, 4 out of 60 people reported side effects with SJG, and 0 out of 30 people reported side effects with placebo.

Other topical products

We are uncertain whether other topical herbal products affect osteoarthritis pain and function because the evidence available from these studies was of low to very low quality. FNZG patches were compared head-to-head with SJG patches. Marhame-Mafasel compress was compared to placebo. Stinging nettle leaf was compared with two placebos in two different studies of people with osteoarthritis of the thumb or of the knee.