injuryupdate
17-12-2004, 11:52 AM
In quite a big journal, with a good study, an effect on pain in osteoarthritis of the hip and knee has been shown by strong magnets:
http://bmj.bmjjournals.com/cgi/content/full/329/7480/1450?ehom
Abstract and some discussion, references:
BMJ 2004;329:1450-1454 (18 December), doi:10.1136/bmj.329.7480.1450
Osteoarthritis
The limits of medicine
Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee
Tim Harlow, general practitioner1, Colin Greaves, research fellow2, Adrian White, senior research fellow3, Liz Brown, research assistant4, Anna Hart, statistician5, Edzard Ernst, professor of complementary medicine4
1 College Surgery, Cullompton, Devon EX15 1TG, 2 Peninsula Medical School (Primary Care), Exeter EX2 5DW, 3 Peninsula Medical School, Tamar Science Park, Plymouth PL6 8BX, 4 Peninsula Medical School (Complementary Medicine), Exeter EX2 4NT, 5 Lancashire School of Health and Postgraduate Medicine, University of Central Lancashire, Preston PR1 2HE
Correspondence to: T Harlow, Hospiscare, Dryden Road, Exeter EX2 5JJ timharlow@eclipse.co.uk
Abstract
Objective To determine the effectiveness of commercially available magnetic bracelets for pain control in osteoarthritis of the hip and knee.
Design Randomised, placebo controlled trial with three parallel groups.
Setting Five rural general practices.
Participants 194 men and women aged 45-80 years with osteoarthritis of the hip or knee.
Intervention Wearing a standard strength static bipolar magnetic bracelet, a weak magnetic bracelet, or a non-magnetic (dummy) bracelet for 12 weeks.
Main outcome measures Change in the Western Ontario and McMaster Universities osteoarthritis lower limb pain scale (WOMAC A) after 12 weeks, with the primary comparison between the standard and dummy groups. Secondary outcomes included changes in WOMAC B and C scales and a visual analogue scale for pain.
Results Mean pain scores were reduced more in the standard magnet group than in the dummy group (mean difference 1.3 points, 95% confidence interval 0.05 to 2.55). Self reported blinding status did not affect the results. The scores for secondary outcome measures were consistent with the WOMAC A scores.
Conclusion Pain from osteoarthritis of the hip and knee decreases when wearing magnetic bracelets. It is uncertain whether this response is due to specific or non-specific (placebo) effects.
Manufacturers of permanent static magnet devices claim that they reduce pain in various conditions, including osteoarthritis.1 Worldwide sales were estimated at $5bn (£2.6bn, 3.8bn) in 1999.2 Osteoarthritis affects around 760 000 people in the United Kingdom, producing an estimated 3.02 million general practice consultations in 2000.3 If magnets were effective they would offer a cheap and probably safe treatment option.
Some studies of permanent static magnets have found significant pain reduction2 4-9 whereas others reported no effect.10-12 Major differences exist in the type and strength of magnets used, the conditions treated, and treatment times. There are also methodological concerns about small sample size and difficulties in maintaining blinding.2 We therefore aimed to conduct an adequately powered trial testing the hypothesis that magnetic bracelets, as used in the consumer market, reduce pain in osteoarthritis of the hip and knee.
We found evidence of a beneficial effect of magnetic wrist bracelets on the pain of osteoarthritis of the hip and knee. Self reported unblinding to treatment group did not substantially affect the results. Although there were problems with the weak magnets, a per-specification analysis suggested (but could not confirm) a specific effect of magnetic bracelets over and above placebo. Other reasons for suspecting a specific effect are that the data on belief show a low level of unblinding in the dummy group and the data on individual responses (table 4) show that more people achieve high levels of improvement in the standard magnet group. The results for two of the secondary outcome measures (WOMAC C and visual analogue pain scores) were consistent with this pattern. No change was seen in WOMAC B score, but this measure has been found to lack sensitivity.18
The findings are consistent with previous studies on magnetic therapies and pain. Studies that have failed to show an effect on pain10 12 generally used weaker magnets (19 to 50 mTesla). Studies that have shown an effect used stronger magnets (47 to 180 mTesla), which were comparable with our standard strength magnets.2 4-8 Together these findings suggest that field strength is important.
Refs 1-8:
Ecoflow. Single module magnetic bracelets. www.ecoflow.plc.uk/uk/PeopleandAnimals/people_prod_sin_mod.htm (accessed 24 Feb 2004).
Weintraub M. Magnetic Bio-stimulation in painful diabetic peripheral neuropathy: a novel intervention-a randomized, double-placebo crossover study. Am J Pain Manage 1999;9: 8-17.
Arthritis Research Campaign. Arthritis: the big picture. Chesterfield: ARC, 2002.
Hinman R, Ford J, Heyl H. Effects of static magnets on chronic knee pain and physical function: A double-blind study. Altern Ther 2002;8(4): 50-4.[CrossRef]
Alfano AP, Taylor AG, Foresman PA, Dunkl PR, McConnell GG, Conaway MR, et al. Static magnetic fields for treatment of fibromyalgia: a randomized controlled trial. J Altern Complement Med 2001;7: 53-4.[ISI][Medline]
Man D, Man B, Plosker H. The influence of permanent magnetic field therapy on wound healing in suction lipectomy patients: a double-blind study. Plast Reconstr Surg 1999;104: 2267-8.[ISI]
Brown CS, Ling FW, Wan JY, Pilla AA. Efficacy of static magnetic field therapy in chronic pelvic pain: a double-blind pilot study. Am J Obstet Gynecol 2002;187: 1581-7.[CrossRef][ISI][Medline]
Wolsko PM, Eisenberg DM, Simon LS, Davis RB, Wallaczek J, Mayo-Smith M, et al. Double-blind placebo-controlled trial of static magnets for the treatment of osteoarthritis of the knee: results of a pilot study. Altern Ther 2004;10: 36-43.[ISI]
http://bmj.bmjjournals.com/cgi/content/full/329/7480/1450?ehom
Abstract and some discussion, references:
BMJ 2004;329:1450-1454 (18 December), doi:10.1136/bmj.329.7480.1450
Osteoarthritis
The limits of medicine
Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee
Tim Harlow, general practitioner1, Colin Greaves, research fellow2, Adrian White, senior research fellow3, Liz Brown, research assistant4, Anna Hart, statistician5, Edzard Ernst, professor of complementary medicine4
1 College Surgery, Cullompton, Devon EX15 1TG, 2 Peninsula Medical School (Primary Care), Exeter EX2 5DW, 3 Peninsula Medical School, Tamar Science Park, Plymouth PL6 8BX, 4 Peninsula Medical School (Complementary Medicine), Exeter EX2 4NT, 5 Lancashire School of Health and Postgraduate Medicine, University of Central Lancashire, Preston PR1 2HE
Correspondence to: T Harlow, Hospiscare, Dryden Road, Exeter EX2 5JJ timharlow@eclipse.co.uk
Abstract
Objective To determine the effectiveness of commercially available magnetic bracelets for pain control in osteoarthritis of the hip and knee.
Design Randomised, placebo controlled trial with three parallel groups.
Setting Five rural general practices.
Participants 194 men and women aged 45-80 years with osteoarthritis of the hip or knee.
Intervention Wearing a standard strength static bipolar magnetic bracelet, a weak magnetic bracelet, or a non-magnetic (dummy) bracelet for 12 weeks.
Main outcome measures Change in the Western Ontario and McMaster Universities osteoarthritis lower limb pain scale (WOMAC A) after 12 weeks, with the primary comparison between the standard and dummy groups. Secondary outcomes included changes in WOMAC B and C scales and a visual analogue scale for pain.
Results Mean pain scores were reduced more in the standard magnet group than in the dummy group (mean difference 1.3 points, 95% confidence interval 0.05 to 2.55). Self reported blinding status did not affect the results. The scores for secondary outcome measures were consistent with the WOMAC A scores.
Conclusion Pain from osteoarthritis of the hip and knee decreases when wearing magnetic bracelets. It is uncertain whether this response is due to specific or non-specific (placebo) effects.
Manufacturers of permanent static magnet devices claim that they reduce pain in various conditions, including osteoarthritis.1 Worldwide sales were estimated at $5bn (£2.6bn, 3.8bn) in 1999.2 Osteoarthritis affects around 760 000 people in the United Kingdom, producing an estimated 3.02 million general practice consultations in 2000.3 If magnets were effective they would offer a cheap and probably safe treatment option.
Some studies of permanent static magnets have found significant pain reduction2 4-9 whereas others reported no effect.10-12 Major differences exist in the type and strength of magnets used, the conditions treated, and treatment times. There are also methodological concerns about small sample size and difficulties in maintaining blinding.2 We therefore aimed to conduct an adequately powered trial testing the hypothesis that magnetic bracelets, as used in the consumer market, reduce pain in osteoarthritis of the hip and knee.
We found evidence of a beneficial effect of magnetic wrist bracelets on the pain of osteoarthritis of the hip and knee. Self reported unblinding to treatment group did not substantially affect the results. Although there were problems with the weak magnets, a per-specification analysis suggested (but could not confirm) a specific effect of magnetic bracelets over and above placebo. Other reasons for suspecting a specific effect are that the data on belief show a low level of unblinding in the dummy group and the data on individual responses (table 4) show that more people achieve high levels of improvement in the standard magnet group. The results for two of the secondary outcome measures (WOMAC C and visual analogue pain scores) were consistent with this pattern. No change was seen in WOMAC B score, but this measure has been found to lack sensitivity.18
The findings are consistent with previous studies on magnetic therapies and pain. Studies that have failed to show an effect on pain10 12 generally used weaker magnets (19 to 50 mTesla). Studies that have shown an effect used stronger magnets (47 to 180 mTesla), which were comparable with our standard strength magnets.2 4-8 Together these findings suggest that field strength is important.
Refs 1-8:
Ecoflow. Single module magnetic bracelets. www.ecoflow.plc.uk/uk/PeopleandAnimals/people_prod_sin_mod.htm (accessed 24 Feb 2004).
Weintraub M. Magnetic Bio-stimulation in painful diabetic peripheral neuropathy: a novel intervention-a randomized, double-placebo crossover study. Am J Pain Manage 1999;9: 8-17.
Arthritis Research Campaign. Arthritis: the big picture. Chesterfield: ARC, 2002.
Hinman R, Ford J, Heyl H. Effects of static magnets on chronic knee pain and physical function: A double-blind study. Altern Ther 2002;8(4): 50-4.[CrossRef]
Alfano AP, Taylor AG, Foresman PA, Dunkl PR, McConnell GG, Conaway MR, et al. Static magnetic fields for treatment of fibromyalgia: a randomized controlled trial. J Altern Complement Med 2001;7: 53-4.[ISI][Medline]
Man D, Man B, Plosker H. The influence of permanent magnetic field therapy on wound healing in suction lipectomy patients: a double-blind study. Plast Reconstr Surg 1999;104: 2267-8.[ISI]
Brown CS, Ling FW, Wan JY, Pilla AA. Efficacy of static magnetic field therapy in chronic pelvic pain: a double-blind pilot study. Am J Obstet Gynecol 2002;187: 1581-7.[CrossRef][ISI][Medline]
Wolsko PM, Eisenberg DM, Simon LS, Davis RB, Wallaczek J, Mayo-Smith M, et al. Double-blind placebo-controlled trial of static magnets for the treatment of osteoarthritis of the knee: results of a pilot study. Altern Ther 2004;10: 36-43.[ISI]