Research: GRUBE and co-authors,

Listed in Issue 147


GRUBE and co-authors, Merck Selbstmedikation GmbH, Rosslerstrasse 96, 64293 Darmstadt, Germany, have carried out a randomized controlled trial of Comfrey root for arthritis.


The aim of this randomised, double-blind, placebo-controlled clinical trial was to investigate the effect of a comfrey root ointment in patients suffering from painful osteoarthritis of the knee.


The 220 patients examined consisted of 153 women and 67 men of an average age of 57.9 years with osteoarthritis of the knee of an average of 6.5 years’ standing. The treatment consisted of a daily application of 6g Kytta-Salbe f (3 x 2 g) or placebo ointment over a 3 week period.


In the course of the trial, the Pain total score (primary outcome measure) in the verum group dropped by 51.6 mm (54.7%) and in the placebo group by 10.1 mm (10.7%), corresponding to a significant difference between the groups of 41.5 mm or 44.0% (p<0.001). The Western Ontario and McMaster Universities total score (secondary outcome) also improved similarly: at the end of the trial, a reduction by 60.4 mm (58.0%) was recorded for the verum group and a reduction of 14.7 mm (14.1%) for the placebo group. The average group difference of 45.7 mm or 43.9% was significant (p<0.001). The difference between the treatment groups increased systematically and significantly, in parallel with the duration of the treatment. Thus, the superiority of the treatment with the comfrey ointment over that with the placebo was shown, even by means of the multi-factorial multivariate analysis for repetitive measurements. In respect of the explorative secondary outcome measures SF-36 (quality of life), angle measurement (mobility of the knee), CGI (clinical global impression) and global assessment of efficacy by the physician and the patient, a significant superiority (p<0.001 each) of the verum treatment over the placebo treatment was also demonstrated.


The results suggest that the comfrey root extract ointment is well suited for the treatment of osteoarthritis of the knee.


Grube B et al. Efficacy of a comfrey root (Symphyti offic. radix) extract ointment in the treatment of patients with painful osteoarthritis of the knee: results of a double-blind, randomised, bicenter, placebo-controlled trial. Phytomedicine 14 (1): 2-10, Jan 2007.

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