Electromagnetic fields for treating osteoarthritis

  • Review
  • Intervention

Authors


Abstract

Background

This is an update of a Cochrane review first published in 2002. Osteoarthritis is a disease that affects the synovial joints, causing degeneration and destruction of hyaline cartilage and subchondral bone. Electromagnetic field therapy is currently used by physiotherapists and may promote growth and repair of bone and cartilage. It is based on principles of physics which include Wolff's law, the piezoelectric effect and the concept of streaming potentials.

Objectives

To assess the benefits and harms of electromagnetic fields for the treatment of osteoarthritis as compared to placebo or sham.

Search methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), PreMEDLINE for trials published before 1966, MEDLINE from 1966 to October 2013, CINAHL and PEDro up to and including October 2013. Electronic searches were complemented by handsearches.

Selection criteria

Randomised controlled trials of electromagnetic fields in osteoarthritis, with four or more weeks treatment duration. We included papers in any language.

Data collection and analysis

Two review authors independently assessed studies for inclusion in the review and resolved differences by consensus with a third review author. We extracted data using pre-developed data extraction forms. The same review authors assessed the risk of bias of the trials independently using the Cochrane 'Risk of bias' tool. We extracted outcomes for osteoarthritis from the publications according to Outcome Measures in Rheumatology Clinical Trials (OMERACT) guidelines. We expressed results for continuous outcome measures as mean difference (MD) or standardised mean difference (SMD) with 95% confidence interval (CI). We pooled dichotomous outcome measures using risk ratio (RR) and calculated the number needed to treat (NNT).

Main results

Nine studies with a total of 636 participants with osteoarthritis were included, six of which were added in this update of the review. Selective outcome reporting was unclear in all nine included studies due to inadequate reporting of study design and conduct, and there was high risk of bias for incomplete outcome data in three studies. The overall risk of bias across the nine studies was low for the other domains.

Participants who were randomised to electromagnetic field treatment rated their pain relief 15.10 points more on a scale of 0 to 100 (MD 15.10, 95% CI 9.08 to 21.13; absolute improvement 15%) after 4 to 26 weeks' treatment compared with placebo. Electromagnetic field treatment had no statistically significant effect on physical function (MD 4.55, 95% CI -2.23 to 11.32; absolute improvement 4.55%) based on the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) scale from 0 to 100 after 12 to 26 weeks' treatment. We also found no statistically significant difference in quality of life on a scale from 0 to 100 (SMD 0.09, 95% CI -0.36 to 0.54; absolute improvement 0.09%) after four to six weeks' treatment, based on the SF-36. No data were available for analysis of radiographic changes. Safety was evaluated in four trials including up to 288 participants: there was no difference in the experience of any adverse event after 4 to 12 weeks of treatment compared with placebo (RR 1.17, 95% CI 0.72 to 1.92). There was no difference in participants who withdrew because of adverse events (measured in one trial) after four weeks of treatment (RR 0.90, 95% CI 0.06 to 13.92). No participants experienced any serious adverse events.

Authors' conclusions

Current evidence suggests that electromagnetic field treatment may provide moderate benefit for osteoarthritis sufferers in terms of pain relief. Further studies are required to confirm whether this treatment confers clinically important benefits in terms of physical function and quality of life. Our conclusions are unchanged from the previous review conducted in 2002.

アブストラクト

変形性関節炎治療における電磁場療法

背景

本システマティック・レビューは2002年発表のレビューの更新である。変形性関節炎は滑膜関節に影響を与える疾患で、硝子軟骨および軟骨下骨に変成や崩壊を引き起こす。電磁場療法は、現在では理学療法士によって行われており、骨および軟骨の成長や修復を促進する可能性がある。これは、ウォルフの法則、圧電効果、および流動電位の概念などの物理学の原則に基づいている。

目的

変形性関節炎の治療に対する電磁場の有効性および有害性を、プラセボまたはシャムと比較して評価すること。

検索戦略

Cochrane Central Register of Controlled Trials(CENTRAL)(コクラン・ライブラリ 2013年9号)、PreMEDLINE(1966年以前に発表された試験)、MEDLINE(1966年~2013年10月)、CINAHLおよびPEDro(2013年10月まで)を検索した。電子検索を補うためハンドサーチによる検索も行った。

選択基準

変形性関節炎に対する電磁場について調べたランダム化比較試験(RCT)で、治療期間が4週間以上のもの。あらゆる言語の論文を対象とした。

データ収集と分析

2名のレビュー著者が独立して本レビューで扱った研究を評価し、意見の相違については3人目の著者との合意により解決した。事前に開発したデータ抽出フォームを用いて、データを抽出した。同じレビュー著者らが、コクランのバイアスのリスクツールを用いて、試験のバイアスのリスクを独立して評価した。Rheumatology Clinical Trials(OMERACT)ガイドラインのアウトカム指標に基づき、変形性関節炎に関するアウトカムを出版物から入手した。連続的なアウトカム指標の結果を、95%信頼区間(CI)を伴う平均差(MD)または標準化平均差(SMD)として表した。リスク比(RR)を用いて二値アウトカム指標を統合し、治療必要数(NNT)を算出した。

主な結果

合計636例の変形性関節炎を伴う参加者を対象とした9件の研究を選択し、このうち6件を本レビューの更新に追記した。研究のデザインと実施に関する報告が不十分であるため、全9件の研究で選択的なアウトカム報告が不明であった。また、3件の研究ではアウトカムデータが不完全であるため、バイアスのリスクが高かった。その他の分野に関して、9件の研究の総バイアスのリスクは低かった。

4~26週間の治療後に、0~100点で疼痛を評価したところ、プラセボ群と比較して電磁場療法にランダム化された参加者では、15.10点分多く疼痛緩和がみられた(MD 15.10、95% CI 9.08~21.13;絶対改善度15%)。12~26週間の治療後に、Western Ontario and McMaster Universities osteoarthritis index(WOMAC)を用いて0~100点で身体機能を評価したところ、電磁場療法は統計学的に有意な効果を示さなかった(MD 4.55、 95% CI -2.23~11.32;絶対改善度4.55%)。また、4~6週間の治療後に、SF-36を用いて0~100点でQOLを評価したところ、統計学的な有意差はみられなかった(SMD 0.09、 95% CI -0.36~0.54;絶対改善度0.09%)。X線像の変化の解析に利用できるデータはなかった。288例に上る参加者を対象にした4件の試験で安全性を評価した。4~12週間の治療後で、プラセボと比較して有害事象の発生に差はなかった(RR 1.17、95% CI 0.72~1.92)。4週間の治療後で、有害事象により試験を中止した参加者数(1件の試験で測定)に差はなかった(RR 0.90、95% CI 0.06~13.92)。重篤な有害事象を発現した参加者はいなかった。

著者の結論

現在のエビデンスでは、電磁場療法が変形性関節炎における疼痛緩和に中等度の効果をもたらす可能性があることを示唆している。本療法が身体機能とQOLに関して臨床的に重要な効果をもたらすのかを裏付けるには、さらなる研究が必要である。2002年に実施した前回のレビューから変化はないと結論づける。

訳注

《実施組織》厚生労働省「「統合医療」に係る情報発信等推進事業」(eJIM:http://www.ejim.ncgg.go.jp/)[2015.12.29]《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。

Plain language summary

Electromagnetic fields for the treatment of osteoarthritis

Review question

We conducted a review of the effect of electromagnetic fields on osteoarthritis. We found nine studies with 636 people.

Background: what is osteoarthritis and what are electromagnetic fields?

Osteoarthritis is the most common form of arthritis that can affect the hands, hips, shoulders and knees. In osteoarthritis, the cartilage that protects the ends of the bones breaks down and causes pain and swelling.

An electromagnetic field is the invisible force that attracts things to magnets. This invisible attraction can be created using an electrical current that may affect the cartilage around the joints. In osteoarthritis, electromagnetic fields are a kind of therapy using electrical currents applied to the skin around the joints. Small machines or mats can be used to deliver electromagnetic fields to the whole body or to certain joints. A doctor or physiotherapist can perform the therapy and some machines can be used at home.

Study characteristics

After searching for all relevant studies up to October 2013, we found nine studies that reviewed the effect of electromagnetic field treatment compared to a sham or fake treatment in 636 adults with osteoarthritis for a duration of 4 to 26 weeks.

Key results

Pain (on a 0 to 100 scale; higher scores mean worse or more severe pain)

- Electromagnetic fields probably relieve pain in osteoarthritis.

- People who received electromagnetic field treatment experienced pain relief of 15 points more compared with people who received fake treatment (15% improvement).

- People who received electromagnetic field treatment rated their pain to be 26 points lower on a scale of 0 to 100.

- People who received fake treatment rated their pain to be 11 points lower on a scale of 0 to 100.

Physical function

- Electromagnetic fields may improve physical function but this may have happened by chance.

Overall health and well-being

- Electromagnetic fields probably make no difference to overall health and well-being.

Side effects

- Electromagnetic fields probably make no difference to whether people have side effects or stop taking the treatment because of side effects, but this may have happened by chance.

We do not have precise information about side effects and complications. This is particularly true for rare but serious side effects. Possible side effects could include skin rash and aggravated pain.

X-ray changes

There was no information available on whether electromagnetic fields show any improvement to a joint with osteoarthritis on an X-ray.

Quality of the evidence

- Electromagnetic fields probably improve pain and make no difference to overall health and well-being and side effects. This may change with further research.

- Electromagnetic fields may improve physical function. This is very likely to change with further research.

平易な要約

変形性関節炎治療における電磁場療法

レビューの論点

本レビューでは変形性関節炎に対する電磁場の効果を対象とした。636例を対象とした9件の研究を見出した。

背景:変形性関節炎や電磁場とは何か?

変形性関節炎はもっともよくみられる関節炎で、手、腰、肩、および膝に影響がみられることがある。変形性関節炎では、骨の両端を保護する軟骨が崩壊し、痛みや腫れを引き起こす。

電磁場は物を磁石に引きつける目に見えない力である。この目に見えない引力は電流を使って発生させることができ、関節周囲の軟骨に作用する可能性がある。変形性関節炎において、電磁場は電流を用いる療法の一種であり、関節周囲の皮膚に当てる。小型の機械やマットを使用して、全身または関節に電磁場を照射する。本療法は医師や理学療法士が実施することもあるが、自宅で機械を使って行うこともできる。

研究の特性

2013年10月までの関連性のあるあらゆる研究を検索し、変形性関節炎の成人636例を対象として、4~26週間にわたり、シャム治療(偽治療)と比較して電磁場療法の効果を調査した9件の研究を見出した。

主な結果

痛み(0~100点;点数が高いほど痛みが強いまたは激しい)

-電磁場はおそらく変形性関節炎の痛みを和らげると考えられる。

-電磁場療法を受けた人では、偽の治療を受けた人と比較して15点分多く痛みが緩和した(15%の改善)。

-電磁場療法を受けた人では、痛みの評価が26点(スケール:0-100)低くなった。

-偽の治療を受けた人では、痛みの評価が11点(スケール:0-100)低くなった。

身体機能

-電磁場は身体機能を改善する可能性があるが、偶然起きる場合もある。

総合的な健康とウェルビーイング(幸福)

-電磁場は、おそらく総合的な健康とウェルビーイング(幸福)に影響を与えない。

副作用

-おそらく、電磁場が副作用を与えたり、副作用で本療法を中止したりすることはないと考えられるが、こうしたことが偶然起きる場合もある。

副作用や合併症に関する正確な情報はない。特に、まれではあるが重篤な副作用に関する情報がない。起こりうる副作用は皮膚発疹と痛みの悪化である。

X線の変化

電磁場による変形性関節炎の改善がX線で認められるかについては、情報が得られなかった。

エビデンスの質

-電磁場は、おそらく痛みを改善し、総合的な健康とウェルビーイング(幸福)や、副作用には影響を与えないと考えられる。この見解はさらなる研究によって変わることもある。

-電磁場は身体機能を改善する可能性がある。この見解はさらなる研究によって変わる可能性が非常に高い。

訳注

《実施組織》厚生労働省「「統合医療」に係る情報発信等推進事業」(eJIM:http://www.ejim.ncgg.go.jp/)[2015.12.29]《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。

Laički sažetak

Elektromagnetska polja za liječenje osteoartritisa

Istraživačko pitanje

Ovaj Cochrane sustavni pregled literature analizirao je dokaze iz kliničkih pokusa na ljudima o djelovanju elektromagnetskih polja na osteoartritis (OA). Pronađeno je 9 studija s ukupno 636 ispitanika.

Dosadašnje spoznaje: Što je osteoartritis i što su elektromagnetska polja? 

Osteoartritis je najčešći oblik artritisa koji može zahvatiti zglobove ruku, kuka, ramena i koljena. Kod osteoartritisa se oštećuje hrskavica koja štiti krajnje dijelove kostiju te uzrokuje bol i oticanje.

Elektromagnetsko polje je nevidljiva sila koja privlači stvari poput magneta. Ova nevidljiva privlačna sila može se dobiti pomoću električnog naboja koji djeluje na hrskavicu oko zglobova. U liječenju osteoartritisa, elektromagnetska polja su vrsta terapije koja koristi električni naboj usmjeren na kožu oko zglobova. Mali uređaji i zavojnice mogu se koristiti za stvaranje elektromagnetskih polja na cijelo tijelo ili pojedine zglobove. Liječnik ili fizioterapeut može obavljati terapiju, a pojedini uređaji se mogu koristiti i kod kuće.

Značajke istraživanja

Nakon pretraživanja svih relevantnih studija do listopada 2013. godine, pronađeno je devet studija koje su istražile učinak liječenja elektromagnetskim poljem u usporedbi s placebom ili lažnim liječenjem bez primjene elektromagnetskog polja u 636 odraslih osoba s osteoartritisom. Studije su trajale od 4 do 26 tjedana.

Ključni rezultati

Bol (na ljestvici 0 do 100, gdje viši rezultati označavaju pogoršanje boli ili pojavu intenzivnije boli)

- Elektromagnetska polja vjerojatno djeluju na smanjenje boli kod osteoartritisa. 

- Ljudi koji su primili terapiju elektromagnetskim poljem osjetili su smanjenje boli u razlici od 15 bodova na ljestvici u odnosu na ispitanike koji su primili placebo tretman (poboljšanje od 15%).

- Ljudi koji su primili terapiju elektromagnetskim poljem ocijenili su svoju bol za 26 bodova manjom na ljestvici od 0 do 100.

- Ljudi koji su primili placebo tretman ocijenili su svoju bol za 11 bodova manjom na ljestvici od 0 do 100.

Tjelesna funkcija

- Elektromagnetska polja mogu poboljšati tjelesnu funkciju, ali taj rezultat može biti i posljedica slučajnosti.

Cjelokupno zdravlje i zadovoljstvo

- Elektromagnetska polja vjerojatno nemaju utjecaja na cjelokupno zdravlje i zadovoljstvo pacijenta.

Nuspojave

- Elektromagnetska polja, vjerojatno nema utjecaja na to da li su ispitanici imali nuspojave ili na to da su prestali provoditi terapiju zbog nuspojava, ali taj rezultat može biti i posljedica slučajnosti.

Nemamo precizne informacije o nuspojavama i komplikacijama. To posebno vrijedi za rijetke, ali ozbiljne nuspojave. Moguće nuspojave mogu biti osip na koži i nesnosna bol.

Promjene na rendgenskim slikama

Nema dostupnih podataka o tome da li elektromagnetska polja imaju ikakav učinak na zglobnu strukturu zahvaćenu osteoartritisom na rendgenskoj snimci.

Kvaliteta dokaza

- Elektromagnetska polja vjerojatno imaju učinka na smanjenje boli i ne čine razliku u ukupnom zdravstvenom stanju te nuspoajvama. Taj se rezultat može promijeniti s daljnjim istraživanjima.

- Elektromagnetska polja mogu poboljšati tjelesnu funkciju. Taj rezultat će se vrlo vjerojatno promijeniti s daljnjim istraživanjima.

Bilješke prijevoda

Hrvatski Cochrane
Prevela: Tea Jurić
Ovaj sažetak preveden je u okviru volonterskog projekta prevođenja Cochrane sažetaka. Uključite se u projekt i pomozite nam u prevođenju brojnih preostalih Cochrane sažetaka koji su još uvijek dostupni samo na engleskom jeziku. Kontakt: cochrane_croatia@mefst.hr

எளியமொழிச் சுருக்கம்

கீல்வாதத்திற்கான மின்காந்தமண்டலம் சிகிச்சைகள்

திறனாய்வு கேள்வி

கீல் வாதத்திற்கு மின்காந்தமண்டலத்தின் விளைவுகள் பற்றி அறிய இந்த திறனாய்வை நாங்கள் மேற்கொண்டோம். 636 பேர் கொண்ட ஒன்பது ஆய்வுகளை நாங்கள் கண்டறிந்தோம்.

பின் புலம்: கீல்வாதம் என்றால் என்ன மற்றும் மின்காந்தமண்டலம் என்றால் என்ன?

கீல்வாதம் என்பது, கைகள், இடுப்பு, தோள்கள் மற்றும் முழங்கால்களை பாதிக்கும் மிகவும் பொதுவான வாத வடிவம் ஆகும். மூட்டுவாதத்தில் மூட்டுஅமைப்பில் ஈடுபடும் எலும்புகளின் முனைகளை பாதுகாக்கும் குருத்தெலும்பு (Cartilage) சேதமடைந்து வலி மற்றும் வீக்கத்தை உண்டுபண்ணுகின்றது.

மின்காந்த மண்டலம் என்பது காந்தங்களின்பால் பொருள்களை ஈர்க்கும்தன்மையுடைய கண்ணுக்கு தெரியாத சக்தியாகும். இந்த கண்ணுக்கு தெரியாத ஈர்ப்பு சக்தியை, மூட்டுகளை சுற்றி உள்ள குருத்தெலும்பு பாதிக்கதக்க அளவில் மின் ஓட்டத்தை பயன்படுத்தி உருவாக்கலாம். கீல்வாதத்தில் மின்காந்தமண்டலங்கள் என்பது மூட்டினை சுத்தி உள்ள தோலில் மின்ஓட்டத்தை செலுத்தி செய்யப்படும் ஒருவகை சிகிச்சை முறையாகும். சிறிய இயந்திரங்கள் அல்லது மின்விரிப்புகள் (mats) மூலம் உடல் முழுவதும் அல்லது ஓரு சில மூட்டுகளில் மின்காந்தமண்டலம் அளிக்கப்படும். மருத்துவர் அல்லது இயன்முறை மருத்துவர் இந்த சிகிச்சையை செய்வார். சில இயந்திரங்கள் வீட்டிலேயே பயன்படுத்ததக்கவை.

ஆய்வு பண்புகள்

அக்டோபர் 2013 வரை இதனுடன் தொடர்புடைய அனைத்து ஆய்வுகளையும் தேடிய பிறகு, நாங்கள் 4 முதல் 26 வாரங்கள் மின்காந்த சிகிச்சையின் விளைவுகளை போலி சிகிச்சையோடு ஒப்பிட்ட , 636 கீல் வாதம் உள்ள பெரியவர்கள் பங்குபெற்ற ஒன்பது ஆய்வுகளை மீளாய்வு செய்தோம்.

முக்கிய முடிவுகள்

வலி (0-100 புள்ளிகள் கொண்ட அளவீட்டில் ; அதிக புள்ளிகள் என்றால் கடுமையான அல்லது மோசமான வலி):

கீல்வாதத்திற்கான மின்காந்தமண்டல சிகிச்சைகள் வலியை குறைக்கலாம்.

- மின்காந்த சிகிச்சை பெற்றுக்கொண்டுள்ளவர்கள் போலி சிகிச்சை பெற்றவர்களோடு ஒப்பிடுகையில் வலிநிவாரணத்தில் 15 புள்ளிகள் அதிகம் பெற்றார்கள் (15% முன்னேற்றம்).

- மின்காந்தமண்டல சிகிச்சை பெற்றவர்கள், 0 முதல் 100 புள்ளிகள் வரையிலான ஒரு அளவீட்டில், அவர்களின் வலியை, 26 புள்ளிகள் குறைவாக பதிவிட்டனர்.

- போலிசிகிச்சை பெற்றவர்கள், 0 முதல் 100 புள்ளிகள் வரையிலான ஒரு அளவீட்டில், அவர்களின் வலியை, 11 புள்ளிகள் குறைவாக பதிவிட்டனர்.

உடல் செயல்பாடு

-மின்காந்தமண்டலம் உடற்சார்ந்த செயல்பாட்டு திறனை அதிகரிக்க வாய்ப்பு உள்ளது, ஆனால் அது எதேச்சையாக நடந்திற்க கூடும்.

ஒட்டுமொத்த உடல்நலம் மற்றும் நல்வாழ்வு

- மின்காந்தமண்டலம் அநேகமாக ஒட்டுமொத்த உடல்நலம்,மற்றும் நல்வாழ்வில் எந்த மாற்றத்தையும் உண்டுபண்ணாது.

பக்க விளைவுகள்

பக்க விளைவுகள் அல்லது பக்க விளைவுகளால் சிகிச்சையை நிறுத்துவது போன்றவற்றில் மின்காந்தமண்டலம் சிகிச்சை எடுத்துக்கொண்டவர்களில் பொதுவாக எந்த வேறுபாடும் இல்லை. இருப்பினும் இது எதேச்சையாக நடந்திருக்கக் கூடும்.

பக்க விளைவுகள் மற்றும் சிக்கல்கள் பற்றிய துல்லியமான தகவல்கள் எங்களுக்கு கிட்டவில்லை. இது குறிப்பாக, அரிதான ஆனால் தீவிர பக்க விளைவுகளில் உண்மையாகிறது. தோல் எரிச்சல் மற்றும் வலி மேலும் மோசமடைதல் போன்ற பக்க விளைவுகள் ஏற்படலாம்.

எக்ஸ்-ரே மாற்றங்கள்

எக்ஸ்-ரேயில் கீல்வாதம் உள்ள மூட்டில் மின்காந்தமண்டலம் சிகிச்சையினால் எதாவது முன்னேற்றம் இருக்குமா என்பதை பற்றி எந்த தகவலும் இல்லை.

சான்றின் தரம்

- மின்காந்தமண்டலம் அநேகமாக வலியை குறைக்கலாம் மற்றும் ஒட்டுமொத்த உடல்நலம், நல்வாழ்வு மற்றும் பக்கவிளைவுகளில் எந்த மாற்றத்தையும்உண்டுபன்ணாது. மேற்கொண்டு செய்யப்படும் ஆராய்ச்சிகளில் இது மாறலாம்.

- மின்காந்தமண்டலம் சிகிச்சைகள் செயல்பாட்டு திறனை அதிகரிக்க வாய்ப்பு உள்ளது. ஆனால் மேலும் செய்யப்படும் ஆராய்ச்சிகள் மாற்றத்தை உண்டுபண்ணலாம்.

மொழிபெயர்ப்பு குறிப்புகள்

மொழிபெயர்ப்பு: சி.இ. பி.என்.அர்

Summary of findings(Explanation)

Summary of findings for the main comparison. Electromagnetic field treatment compared to placebo for the treatment of osteoarthritis
  1. 1Downgraded for moderate heterogeneity (I2 = 55%); unclear risk for random sequence generation (Zizic 1995), allocation concealment (Zizic 1995), blinding of outcome assessors (Fary 2011; Nelson 2013; Zizic 1995), selective reporting (all six studies) and high risk for incomplete outcome data (Zizic 1995).
    2Downgraded for considerable heterogeneity (I2 = 84%); Zizic 1995: unclear risk for random sequence generation, allocation concealment, blinding of outcome assessors, selective reporting and high risk for incomplete outcome data. Fary 2011: unclear risk for blinding of outcome assessors and selective reporting. Garland 2007: unclear risk for selective reporting.
    3 Fary 2011: unclear risk for blinding of outcome assessors and selective reporting. Pipitone 2001: high risk for incomplete outcome data.
    4Unclear risk for random sequence generation (Thamsborg 2005; Zizic 1995), allocation concealment (Zizic 1995), blinding of outcome assessors (Thamsborg 2005; Zizic 1995), selective reporting (all four studies) and high risk for incomplete outcome data (Garland 2007; Thamsborg 2005; Zizic 1995).
    5Only Zizic 1995 reported this outcome. Downgraded for imprecision (wide confidence interval and few events); unclear risk for random sequence generation, allocation concealment, blinding of outcome assessors and selective reporting and high risk for incomplete outcome data.

Electromagnetic field treatment compared to placebo for the treatment of osteoarthritis
Patient or population: patients with osteoarthritis
Settings: out-patients recruited from healthcare facilities in Australia, Denmark, UK and the US
Intervention: electromagnetic field treatment
Comparison: placebo
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Placebo Electromagnetic field treatment

Pain
100 mm VAS

Scale from: 0 to 100

(Higher scores mean worse pain)
Follow-up: mean 6 weeks

The mean change in pain in the control groups was 10.7The mean change in pain in the intervention groups was
15.10lower
(9.08 to 21.13 lower)
 434
(6 studies)
⊕⊕⊕⊝
moderate1

MD 15.10 (95% CI 9.08 to 21.13)

Absolute risk difference: 15% (95% CI 9.08% to 21.13%)

Relative per cent change: 21.03% (95% CI 12.65% to 29.43%)

NNT: 2 (95% CI 1 to 6)

Physical function

WOMAC function

Scale from: 0 to 100

(Higher scores mean more severe limitation)
Follow-up: mean 3 months

The mean change in physical function in the control groups was
1.7
The mean change in physical function in the intervention groups was
4.55lower
(2.23 lower to 11.32 higher)
 197
(3 studies)
⊕⊕⊝⊝
low2

MD 4.55 (95% CI -2.23 to 11.32)

Absolute risk difference: 4.55% (95% CI -2.23% to 11.32%)

Relative per cent change: 268% (95% CI -131% to 666%)

NNT: not statistically significant

Quality of life

SF-36 item

Scale from: 0 to 100

(Lower scores mean worse quality)

Follow-up: mean 16 weeks

The mean change in quality of life in the control groups was
2.4
The mean change in quality of life in the intervention groups was
0.09 lower
(0.36 lower to 0.54 higher)
 145
(2 studies)
⊕⊕⊕⊝
moderate3

SMD 0.09 (95% CI -0.36 to 0.54)

Absolute risk difference: 1% (95% CI -2.92% to 4.37%)

Relative per cent change: 30.38% (95% CI -121.5% to 182.25%)

NNT: not statistically significant

Radiographic progression

Bone scintigraphic examinations

Follow-up: mean 2.5 months

See commentSee commentNot estimable78
(1 study)
See commentNo related data were available

Number of patients experiencing any adverse event

Follow-up: mean 1 month

167 per 1000 195 per 1000
(120 to 320)
RR 1.17
(0.72 to 1.92)
288
(4 studies)
⊕⊕⊕⊝
moderate4

Absolute risk difference: 3% (95% CI -6% to 12%)

Relative per cent change:

17% (95% CI -28% to 92%)

NNT: not statistically significant

Number of patients who withdrew because of adverse events

Follow-up: mean 6 months

27 per 1000

24 per 1000

(2 to 376)

RR 0.90

(0.06 to 13.92)

78
(1 study)
⊕⊕⊝⊝
low5
Only 1 study: 1 participant withdrew from each group because of adverse skin reactions unrelated to the therapy
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; MD: mean difference; NNT: number needed to treat; RR: risk ratio; VAS: visual analogue scale;WOMAC: Western Ontario and McMaster Universities osteoarthritis index
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Background

Description of the condition

Osteoarthritis is a progressive rheumatic disease which occurs most commonly in older populations. It is becoming increasingly common due to the ageing population in many societies. The degeneration and eventual loss of articular cartilage causes changes in periarticular bone, synovial tissue and other periarticular soft tissue structures such as ligaments and muscles. This causes the pain, swelling, tenderness and stiffness that characterise osteoarthritis, especially in the weight-bearing joints of the lower extremities.

Description of the intervention

Current osteoarthritis treatment options include pharmacological and non-pharmacological procedures to decrease progression and treat the pain associated with this condition. They include:

  1. oral pharmacological medications: analgesics such as acetaminophen, aspirin, non-steroidal anti-inflammatory drugs (NSAIDs); symptomatic slow-acting drugs for osteoarthritis (SYSADOA) such as glucosamine sulphate (Towheed 2005), diacerein (Fidelix 2006) and the non-saponifiable oils of avocado and soya; and the newer disease-modifying osteoarthritis drugs (DMOAD);

  2. topical therapies (applied as gels or creams), including NSAIDs and capsaicin;

  3. intra-articular therapies, including corticosteroid and hyaluronic acid injections (Bellamy 2006a; Bellamy 2006b);

  4. non-pharmacological therapies, including aquatic exercise therapy (Bartels 2007), balneotherapy (Verhagen 2007), physical therapy (Rutjes 2010), occupational therapy, strengthening exercises (Fransen 2008; Fransen 2009), wedged insoles and braces and orthoses (Brouwer 2005); and

  5. surgical treatment: joint replacement (Singh 2013a; Singh 2013b) and arthroscopic debridement (Laupattarakasem 2008) of the affected joint.

Management of osteoarthritis of the knee aims to relieve pain, maintain or improve mobility, and minimise disability. However, these goals are seldom achieved through drug therapy alone, as many treatments are ineffective or lead to serious adverse effects, including the potentially lethal complications encountered with selective NSAIDS (Blower 1996). Different modalities in physiotherapy have been shown to help improve clinical symptoms and function in knee osteoarthritis, generally with fewer adverse effects than medical treatment (Brosseau 2003; Rutjes 2010). Electromagnetic fields are among these non-invasive therapies, already considered a proven adjunct therapy for delayed union fractures (Bassett 1974). Interest in electromagnetic field stimulation began after observing that physical stress on bone causes the appearance of tiny electric currents called piezoelectric potentials that are thought to act as the transduction signals to promote bone formation. In vitro studies showed that chondrocyte proliferation and matrix synthesis are significantly enhanced by pulsed electromagnetic field stimulation (De Mattei 2001; De Mattei 2003; De Mattei 2004; Fioravanti 2002; Pezzetti 1999). A number of multicentric randomised and double-blind clinical trials have been carried out with promising results (Fini 2005).

Electromagnetic fields can be delivered to biological systems by the direct placement of an electrode or non-invasively by two means:

  • capacitive coupling, in which opposing electrodes are placed within a conducting medium, that is, in contact with the skin surface overlying a target tissue (e.g. bone, joint, wound);

  • inductive coupling, in which a time-varying pulsed electromagnetic field induces an electrical current in the target tissue. This technique does not require direct contact with the skin or biological system.

Although the former relies on direct application of an electrical field rather than creating induced current through magnetic impulses, they act by the same mechanism. Thus both pulsed electromagnetic fields and pulsed electrical stimulation are considered electromagnetic field interventions in this update.

How the intervention might work

Three basic principles of physics are proposed to explain how electromagnetic fields may promote the growth and repair of bone and cartilage: Wolff's Law, the piezoelectric effect and the concept of streaming potentials (Shupak 2003).

Electromagnetic field stimulation first garnered interest as treatment for osteoarthritis following the discovery of evidence that stimulation of chondrocytes increased the synthesis of the major component of the cartilage matrix, known as proteoglycans (Aaron 1993). Experimental studies suggest that electromagnetic fields may interact with ligands on the chondrocyte cell surface membrane, potentially leading to changes in internal calcium concentrations which trigger proteoglycan synthesis (Graziana 1990; Lee 1993).

Electromagnetic field treatments might also help to preserve extracellular matrix integrity in the early stages of osteoarthritis by down-regulating proteoglycan production and degradation (Ciombor 2001; Liu 1997) and by increasing chondrocyte DNA replication and cell proliferation (Pezzetti 1999; Rodan 1978).

Through these improvements in bone and cartilage maintenance and repair, pulsed electromagnetic field stimulation could influence the osteoarthritic disease process by decreasing inflammation and providing temporary relief from pain (Darendeliler 1997; Lee 1997; Trock 2000).

Why it is important to do this review

Electromagnetic field therapy is already being widely used for the management of joint pain associated with osteoarthritis and has a promising theoretical basis for clinical application. Clinical trials evaluating its therapeutic effectiveness have been conducted recently, but with inconsistent results. A 2002 Cochrane review suggested that pulsed electromagnetic field therapy led to improvements in all measurements for knee osteoarthritis, but concluded that further studies were required to confirm whether the statistically significant results shown in these trials conferred important benefits to patients (Hulme 2002). The optimal frequency, duration and intensity of electromagnetic fields for osteoarthritis were also yet to be determined. This update of the 2002 review will include new clinical studies which have since been published.

Objectives

To assess the benefits and harms of electromagnetic fields for the treatment of osteoarthritis as compared to placebo or sham.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials or quasi-randomised trials which examined the effects of electromagnetic fields for treating osteoarthritis, with four or more weeks treatment duration.

Types of participants

Participants over 18 years of age, with clinical or radiological confirmation of the diagnosis (or both) were considered. The diagnosis of osteoarthritis was defined using the American College of Rheumatology (ACR) criteria for classification of osteoarthritis (Altman 1986; Altman 1997). We excluded trials where participants had received any previous surgical intervention for the treatment of osteoarthritis.

Types of interventions

All types of pulsed electromagnetic fields and pulsed electrical stimulation were included. Trials that compared the intervention group using electromagnetic fields to usual care were included, as well as placebo-controlled studies.

Types of outcome measures

The primary measure of effectiveness was pain relief, as suggested by the third Outcome Measures in Rheumatology (OMERACT) conference (Bellamy 1997). We included the other outcomes from this conference for analysis. According to OMERACT 3 (Bellamy 1997) (last reviewed in OMERACT 6) (Pham 2003) standardised, validated instruments, such as visual analogue scales (VAS) (Carlsson 1983) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) scale for pain (Bellamy 1988) and the Lequesne Functional Severity Index (Lequesne 1987), should be used to evaluate these outcomes.

Major outcomes
  1. Pain

  2. Physical function

  3. Health-related quality of life measure

  4. Radiographic joint structure changes

  5. Number of patients experiencing any adverse event

  6. Patients who withdrew because of adverse events

  7. Patients experiencing any serious adverse event

Search methods for identification of studies

Electronic searches

We identified relevant studies by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), PreMEDLINE for trials published before 1966, MEDLINE from 1966 to October 2013, CINAHL and PEDro up to and including October 2013. We used the search strategies recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Details of the search strategy can be found in the following appendices: MEDLINE (Appendix 1), CINAHL (Appendix 2), EMBASE (Appendix 3), CENTRAL (Appendix 4) and PEDro (Appendix 5).

Searching other resources

We complemented the electronic searches with handsearching:

  • bibliographic references; and

  • abstracts published in special issues of specialised journals or in conference proceedings (American Orthopaedic Physicians Annual Meeting; Asia-Pacific Orthopedic Society for Sports Medicine Meeting).

We contacted the Trial Search Co-ordinators of the Cochrane Rehabilitation and Related Therapies Field and the Cochrane Musculoskeletal Group.

We manually searched conference proceedings, used the Science Citation Index to retrieve reports citing relevant articles, contacted content experts and trialists, and screened the references of all articles obtained, including related reviews. We did not use abstracts if additional data could not be obtained.

Finally, we searched several clinical trial registries (www.clinicaltrials.gov, http://www.controlled-trials.com, http://www.anzctr.org.au/, www.umin.ac.jp/ctr) to identify ongoing trials.

The last update of the manual search was conducted on 3 October 2013.

Data collection and analysis

Selection of studies

Two review authors (SL and BY) independently screened the abstract, keywords and publication type of all publications obtained from the searches described. We obtained all studies which might be eligible RCTs, or quasi-RCTs, in full and independently assessed these. The two review authors independently selected trials according to the selection criteria.

When necessary, we sought information from the authors of the primary studies.

Data extraction and management

Two review authors (SL, BY) extracted data using a standard, pre-developed form that we pilot-tested. We extracted details of trial design, patient characteristics, treatment duration and the mechanics of the electromagnetic field device used, and established baseline and end of study outcomes. We resolved differences in data extraction by referring back to the original article and by establishing consensus. A third review author (CH or JH) was consulted to help resolve differences. Where the method of randomisation or allocation concealment was not clearly described, or where data were missing, we contacted the authors of the study to clarify the issues.

Assessment of risk of bias in included studies

The review authors assessed the risk of bias in the included studies using The Cochrane Collaboration 'Risk of bias' tool (Higgins 2011). We considered six domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessors, selective outcome reporting and incomplete outcome reporting. We expressed the judgements simply as 'low risk', 'high risk' or 'unclear risk' of bias.

We assessed two components of randomisation: generation of allocation sequence and concealment of allocation. We considered the generation of sequence adequate if it resulted in an unpredictable allocation schedule; mechanisms considered adequate included random number tables, computer-generated random numbers, minimisation, coin tossing, shuffling cards and drawing lots. We considered trials using an unpredictable allocation sequence to be randomised. We considered trials using potentially predictable allocation mechanisms, such as alternation or the allocation of patients according to date of birth, to be quasi-randomised.

We considered concealment of allocation adequate if both the patients and the investigators responsible for patient selection were unable to predict allocation to treatment or placebo groups. Adequate concealment included central randomisation and sequentially numbered, sealed, opaque envelopes.

Since the primary measure of effectiveness was patient-reported pain relief, we considered blinding of patients adequate if experimental and control preparations were explicitly described as indistinguishable or if a double-dummy technique was used.

We considered analyses adequate if all randomised patients were included in the analysis according to the intention-to-treat principle. We further assessed the reporting of major outcomes.

Measures of treatment effect

For continuous data, we presented results as a mean difference (MD). However, where different scales were used to measure the same concept or outcome, we used standardised mean difference (SMD). For dichotomous data, we used risk ratio (RR) (Hennekens 1987; Petitti 2000). Only if a comparison resulted in a statistically significant difference and baseline values were reported did we calculate the clinical relevance, i.e. the number need to treat to benefit (NNTB) or harm (NNTH).

Unit of analysis issues

If we identified cross-over trials presenting continuous outcome data which precluded paired analysis, we did not plan to include these data in a meta-analysis to avoid unit of analysis error. Where carry-over effects were thought to exist, and sufficient data existed, we planned to include only data from the first period in the analysis (Higgins 2011).

Dealing with missing data

We contacted the study investigators for missing data via email. Where possible, the analyses were based on intention-to-treat data from individual clinical trials.

Assessment of heterogeneity

We assessed statistical heterogeneity by examining the I2 statistic (Higgins 2011), a quantity that describes approximately the proportion of variation in point estimates due to heterogeneity rather than sampling error. If considerable between-group statistical heterogeneity was detected (i.e. an I2 value of more than 75%), we explored the causes of heterogeneity (Higgins 2011). In addition, we employed the Chi2 test of homogeneity to determine the strength of evidence that the heterogeneity is genuine. We considered heterogeneity significant when the probability (P value) was < 0.10.

Assessment of reporting biases

We planned to assess reporting bias by screening the clinical trials register at the International Clinical Trials Registry Platform of the World Health Organization (http://apps.who.int/trialsearch/) (De Angelis 2004) to determine whether the protocol for each RCT was published before recruitment of patients for the study was started. Furthermore, we planned a comparison between the fixed-effect estimate and the random-effects estimate, as well as a funnel plot if data were available, in order to assess for the possible presence of small sample bias and reporting bias, respectively.

Data synthesis

We planned to pool clinically homogeneous studies using the fixed-effect model for meta-analysis. When there was important heterogeneity (I2 > 25%), we pooled studies using the random-effects model for meta-analysis.

Subgroup analysis and investigation of heterogeneity

We planned to conduct subgroup analysis to examine the efficacy of electromagnetic fields with different application methods and modalities, including frequency, length of treatment and different techniques, if data were available.

Sensitivity analysis

We conducted a sensitivity analysis based on the methodological quality of each trial. We undertook sensitivity analyses to explore the impact of studies with poor ratings for domains described in the 'Risk of bias' table. We planned a priori sensitivity analyses for:

  1. concealment of allocation;

  2. blinding of outcome assessors;

  3. extent of drop-outs (we considered 20% as a cut-point).

'Summary of findings' table

We presented key findings in a 'Summary of findings' table. These included the magnitude of effect of the interventions examined, the sum of available data on the main outcomes and the quality of the evidence.

For dichotomous outcomes, we calculated the absolute risk difference using the risk difference (RD) statistic in RevMan (RevMan 2012) (RR - 1 calculated the weighted relative per cent change). We calculated the number needed to treat to benefit (NNTB) or to harm (NNTH) from the control group event rate (unless the population event rate was known) and the risk ratio using the Visual Rx NNT calculator (Cates 2004).

For continuous outcomes, we calculated the absolute benefit as the improvement in the treatment group (follow-up mean minus baseline mean) less the improvement in the control group (follow-up mean minus baseline mean). We calculated the relative difference in the change from baseline as the absolute benefit divided by the baseline mean of the control group. We calculated NNTB or NNTH using the Wells calculator software available at the CMSG editorial office. We determined the minimal clinically important difference (MCID) for each outcome for input into the calculator.

We used GRADE to describe the quality of the overall body of evidence (Guyatt 2008; Higgins 2011), defined as the extent of confidence in the estimates of treatment benefits and harms. The GRADE approach specifies four levels of quality (high, moderate, low and very low).

Results

Description of studies

Results of the search

The search strategies retrieved 2037 articles (Figure 1). The literature search identified 25 potentially relevant articles. Of these, only nine studies met the inclusion criteria (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Pipitone 2001; Thamsborg 2005; Trock 1993; Trock 1994; Zizic 1995) (see Characteristics of included studies table). Sixteen studies were excluded for the reasons given in the Characteristics of excluded studies table (Alcidi 2007; Ay 2009; Battisti 2004; Danao-Camara 2001; Fischer 2005; Fischer 2006; Hinman 2002; Jack 2006; Jacobson 2001; Kulcu 2009; Liu 2004; Ozgüçlü 2010; Pavlović 2012; Rigato 2002; Sutbeyaz 2006; Tomruk 2007).

Figure 1.

Study flow diagram.

Included studies

The eligible RCTs collectively involved 327 participants in active electromagnetic field treatment groups and 309 participants in placebo groups.

Six trials used pulsed electromagnetic fields (Nelson 2013; Nicolakis 2002; Pipitone 2001; Thamsborg 2005; Trock 1993; Trock 1994) while three studies (Fary 2011; Garland 2007; Zizic 1995) used pulsed electrical stimulation.

One study used a pulsed electromagnetic field signal consisting of a 7 ms burst of 6.8 MHz sinusoidal waves repeating at one burst/s and delivering a peak induced electrical field of 34 ± 8 V/m in the knee from a portable battery-operated device (Palermo, Ivivi Health Sciences, LLC, San Francisco, CA). Patients were treated for 15 minutes twice daily for 42 days (Nelson 2013).

Another study reviewed a pulsed electromagnetic field device (Medicur) that generates pulses of magnetic energy via a soft iron core treated with 62 trace elements. Pulses are selected at base frequencies of 3 Hz, 7.8 Hz and 20 Hz and have a rise time of 1 μs, a low magnetic output (< 0.5 gauss) and a range of activity of up to 30 cm around the unit. The Medicur device runs on batteries, requires no wires or electrodes, and only needs to be held close to the area to be treated. Patients were treated for 30 minutes per session three times a day for six weeks (Pipitone 2001).

In one study a pulsed electromagnetic field was administered to the whole body using a mat which produced a field from 1 Hz to 3000 Hz with a mean intensity of 40 μT (wave ranger professional, program 12, Mediscan GmbH, Bad Haller Straße34, 4500 Kremsmünster, Austria). The frequency of the pulsed electromagnetic field ranged from 1 Hz to 3000 Hz. Patients lay on the mat for 30 minutes per session twice a day for six weeks (Nicolakis 2002).

A fourth study measured the effect of a pulse generator that yields G50V in 50 Hz pulses, changing voltage at 3 ms intervals. This results in a maximal electrical gradient of 1 to 100 mV/cm as sensed by charged particles in the tissue, depending on the distance from the coils. As a result of this current, the coils become slightly warmer than the surroundings after 30 minutes (28 to 35 °C). Treatment was given for two hours daily, five days per week for six weeks (Thamsborg 2005).

Two other trials used a non-contact device that delivered three signals in a stepwise fashion, ranging from 5 Hz to 12 Hz frequency at 10 G to 25 G of magnetic energy (Trock 1993; Trock 1994). These studies exposed the affected knee to nine hours of stimulation over a one-month period.

In one study a commercially available TENS stimulator (Metron Digi-10s) was modified by a biomedical engineer to deliver pulsed electrical stimulation current parameters as follows: pulsed, asymmetrically biphasic, exponentially decreasing waveform with a frequency of 100 Hz and pulse width of 4 ms. Current was delivered via 120 mm x 80 mm multiple-use conductive silicone electrodes inserted into larger calico pockets. The participants were asked to wear the device seven hours daily, preferably overnight, for 26 weeks (Fary 2011).

Two other pulsed electrical stimulation studies used a pulsed electrical device to deliver a 100 Hz low-amplitude signal to the knee joint via skin surface electrodes. The patients were exposed for 6 to 14 hours a day for three months and 6 to 10 hours a day for four weeks, respectively (Garland 2007; Zizic 1995).

All studies reported on patients with knee osteoarthritis and Trock 1994 also included patients with cervical osteoarthritis, with their results reported separately. The main outcome measures related to pain (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Pipitone 2001; Thamsborg 2005; Trock 1993; Trock 1994; Zizic 1995). The major outcomes were assessed using the WOMAC osteoarthritis index: severity of joint pain, stiffness and limitation of physical function (Garland 2007; Nicolakis 2002; Pipitone 2001; Thamsborg 2005), ability to conduct activities of daily living (ADL) in terms of pain or difficulty (Trock 1993; Trock 1994), joint pain on motion (Trock 1993; Trock 1994), patient's overall assessment (Garland 2007; Trock 1994), patient evaluation of function (Zizic 1995) and physician's global assessment (Trock 1993; Trock 1994; Zizic 1995). The UK 36-item short form of the Medical Outcomes Study (SF-36) and the EuroQol (Euro-Quality of Life, EQ-5D) were also considered (Pipitone 2001).

Excluded studies

We excluded nine RCTs with a shorter duration than four weeks since this time frame may be too short to assess harms and benefits based on biological plausibility (Alcidi 2007; Ay 2009; Battisti 2004; Jacobson 2001; Kulcu 2009; Liu 2004; Ozgüçlü 2010; Pavlović 2012; Sutbeyaz 2006;Tomruk 2007). We excluded one RCT because it included patients with cervical spondylosis and shoulder periarthritis without separately reporting results and we could not extract data on cervical osteoarthritis (Rigato 2002). We excluded four other studies because they were not RCTs (Danao-Camara 2001; Fischer 2005; Fischer 2006; Jack 2006). We excluded one study because the aim of the study was to assess the effect of static magnetic fields for chronic knee pain but not specifically for osteoarthritis (Hinman 2002). We excluded one study because the treatment period was only 10 days (Pavlović 2012).

Risk of bias in included studies

Two review authors (SL, BY) assessed risk of bias independently. Differences were resolved by consensus with a third review author (DZ).

The overall assessment of the methodological quality of the trials in this review was as follows: we judged seven studies (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Pipitone 2001; Trock 1993; Trock 1994) to be at a low risk of bias for random sequence generation, and two studies omitted a description of the randomisation process (Thamsborg 2005; Zizic 1995).

Nine of the included studies met the allocation concealment criterion (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Pipitone 2001; Thamsborg 2005; Trock 1993; Trock 1994).

Seven trials (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Pipitone 2001; Trock 1993; Zizic 1995) had appropriate, well-described placebo treatments and we assessed them as low risk of bias for blinding.

We assessed seven studies (Fary 2011; Garland 2007; Nelson 2013; Nicolakis 2002; Thamsborg 2005; Trock 1994; Zizic 1995) as low risk of bias for incomplete outcome data; six trials reported loss to follow-up ranging from 5% to 20% (Garland 2007; Nicolakis 2002; Thamsborg 2005; Trock 1993; Trock 1994; Zizic 1995), balanced across compared groups, while one trial did not report the loss to follow-up (Pipitone 2001).

No information on selective outcome reporting was found in any study.

See the 'Risk of bias' graph (Figure 2) and 'Risk of bias' summary (Figure 3).

Figure 2.

'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Figure 3.

'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.

Effects of interventions

See: Summary of findings for the main comparison Electromagnetic field treatment compared to placebo for the treatment of osteoarthritis

In the nine controlled trials included in the analysis, a total of 636 participants were randomised: 327 participants to electromagnetic field treatment and 309 to a placebo device. The pulsed electromagnetic field treatment trials lasted approximately four to six weeks, with treatment duration ranging from 27 hours to 60 hours (Nelson 2013; Nicolakis 2002; Pipitone 2001; Thamsborg 2005; Trock 1993; Trock 1994). The treatments in three other pulsed electrical stimulation trials were more intensive, involving 26 weeks of seven hours treatment daily (Fary 2011), four weeks of six hours per day treatment (Zizic 1995) and three months of 6 to 14 hours per day, respectively (Garland 2007). These trials did not provide the statistical details required for inclusion in meta-analysis, therefore the analysis of the relative effects of treatment times, frequencies and modes of treatment delivery was limited (see Summary of findings for the main comparison).

Electromagnetic field treatment versus placebo for osteoarthritis

Pain

The combined results from the six included studies of electromagnetic field treatment which measured pain as an outcome (Fary 2011; Garland 2007; Nelson 2013; Trock 1993; Trock 1994; Zizic 1995) showed a statistically significant beneficial effect for patient pain relief (mean difference (MD) 15.10, 95% confidence interval (CI) 9.08 to 21.13). People who received electromagnetic field treatment rated their pain to be 15.10 points lower on a scale of 0 to 100 (15.10% absolute improvement and 21.03% relative improvement) (Analysis 1.1).

Physical function

Three studies including 107 patients in the electromagnetic field treatment group and 90 patients in the placebo group measured function as an outcome (Fary 2011; Garland 2007; Pipitone 2001). Improvement of function was not statistically significant in electromagnetic field-treated patients compared to control group patients (MD 4.55, 95% CI -2.33 to 11.32; 4.55% absolute effect and 10.13% relative effect) (Analysis 1.2).

Health-related quality of life measure

Two studies including 68 patients in the electromagnetic field treatment group and 71 patients in the placebo group measured quality of life as an outcome (Fary 2011). Improvement in quality of life was not statistically significant in electromagnetic field-treated patients compared to control group patients (SMD 0.09, 95% CI -0.36 to 0.54; 9% absolute effect and 100.8% relative effect) (Analysis 1.3).

Radiographic joint structure changes

Only two studies (Thamsborg 2005; Trock 1993) mentioned radiographic joint structure change but no data were available.

Number of patients experiencing any adverse event

Adverse events were presented in four studies with 156 participants in the intervention group and 132 participants in the control group (Garland 2007; Pipitone 2001; Thamsborg 2005; Zizic 1995), although specific definitions of adverse events were not provided in any study. The total number of adverse events was not statistically significantly increased in electromagnetic field-treated patients (19.9%) compared to 16.7% of placebo-treated patients, after six weeks (RR 1.17, 95% CI 0.72 to 1.92) (Analysis 1.4).

Patients who withdrew because of adverse events

Specific reasons for withdrawals were unrelated to the therapy except in the case of adverse skin reactions which were encountered in Zizic 1995 and occurred in patients receiving both placebo and active electrical stimulation treatment. There was no significant difference between groups (RR 0.90, 95% CI 0.06 to 13.92) (Analysis 1.5), suggesting that there is no difference between the active treatment and placebo in terms of adverse effects.

Patients experiencing any serious adverse event

No study reported any serious adverse events.

Subgroup analyses

We did not conduct the pre-planned subgroup analyses of the most effective means of delivering therapy due to the small number of trials and insufficient data.

Sensitivity analyses

We undertook sensitivity analyses to explore the impact of studies with poor ratings for concealment of allocation, blinding of outcome asessors and extent of drop-out and there was no change in the direction and significance of the effect sizes (results not shown).

Discussion

Summary of main results

Osteoarthritis is the most common of the rheumatic diseases. With an estimated 40,000 new cases of osteoarthritis diagnosed each year, it is the third leading cause of life-years lost due to disability and is associated with high morbidity and healthcare utilisation (March 2004; Towheed 2004). The range of treatments for osteoarthritis is continually increasing as conventional therapies, such as pharmaceutical management, physiotherapy and joint replacement surgery, are coupled with emerging and established complementary therapies.

Osteoarthritis results from a failure of chondrocytes within the joint to synthesise a good-quality matrix and to maintain a balance between synthesis and degradation of the extracellular matrix. The change in the quality of the matrix is mainly the result of dedifferentiation of chondrocytes, whereas the imbalance between synthesis and degradation of the extracellular matrix is caused by increased synthesis of proteinases and decreased anabolic effects of growth factors, mainly from chondrocytes but also from synovial tissue and subchondral bone. The biochemical reasoning behind the electrical stimulation of cartilage has been clearly demonstrated in vitro; its value in the treatment of delayed union fracture has been proven over two decades of use and it has been established as a standard of care (Aaron 1989; Baker 1974; Bassett 1974). The question remains as to whether it provides a financially accessible, clinically significant alternative to current therapies for osteoarthritis. The purpose of this systematic review was to evaluate the effectiveness of electrical stimulation treatment. However, its major limitation is the small number of contributing studies that could be included; this also prevented the planned subgroup analysis of variations in treatment.

All of the studies' participants had osteoarthritis of one or both knees, or cervical osteoarthritis, diagnosed by clinical symptoms and radiographic evidence, and the osteoarthritis was painful despite medical treatment.

The protocols for pulsed electrical stimulation or pulsed electromagnetic field device setting and application varied widely between studies, as did the outcome measures. Some pulsed electrical stimulation devices delivered a low-frequency (100 Hz), low-amplitude, voltage sourced (mean = 6.2 peak volts), monophasic, spiked signal to the knee via skin surface electrodes (Fary 2011; Garland 2007; Zizic 1995). In Nelson 2013 a pulsed electromagnetic field signal consisting of a 7 ms burst of 6.8 MHz sinusoidal waves repeating at one burst/s delivered a peak induced electrical field of 34 ± 8 V/m to the knee from a portable battery-operated device. Other devices used in the included trials generated a pulsating electromagnetic field with a mean intensity of 40 μT (the frequency of the pulsed magnetic field ranged: 1 Hz to 3000 Hz) (Nicolakis 2002); or generated pulses of magnetic energy via a soft iron core with base frequencies (3 Hz, 7.8 Hz and 20 Hz) (Pipitone 2001), G50V in 50 Hz pulses changing voltage in 3 ms intervals (Thamsborg 2005) and extremely low-frequency pulsed waves at 5 Hz, 10 to 15 gauss for 10 minutes, 10 Hz 15 to 25 gauss for 10 minutes and 12 Hz 15 to 25 gauss for 10 minutes (Trock 1993; Trock 1994). Characteristics of the devices, such as electromagnetic field modes, and application characteristics, such as duration, could not be evaluated in this systematic review due to the small number of trials.

Pain relief was measured using visual analogue scales (VAS). We pooled this outcome from six trials and found a significant difference between the electromagnetic field and placebo-treated groups (Fary 2011; Garland 2007; Nelson 2013; Trock 1993; Trock 1994; Zizic 1995). All were randomised controlled trials with appropriate blinding and they had appropriate, well-described placebo treatments (see Characteristics of included studies). There was moderate heterogeneity in the results. The intervention and its duration also differed between the studies.

The improvement in physical function in patients with knee osteoarthritis treated with pulsed electromagnetic fields was not statistically significant (Fary 2011; Garland 2007; Pipitone 2001). There was high heterogeneity in the results. This might be due to the different measurement tools used in the included studies. Two studies (Fary 2011; Garland 2007) used WOMAC physical function (on a 100 mm VAS) to measure the efficacy variable, while one study (Pipitone 2001) used the WOMAC disability score on a 20 cm VAS of the EuroQol. The intervention duration also differed among these studies.

Quality of life was not statistically significantly different between the treatment and placebo groups (Fary 2011; Pipitone 2001). This might be explained by the small sample sizes of the included studies measuring these outcomes, the wide variation in electromagnetic field devices and application protocols, or the inadequate intervention periods.

There were no life-threatening events reported among participants exposed to electromagnetic fields.

Overall completeness and applicability of evidence

A comprehensive search of the literature revealed a number of studies of electromagnetic field interventions for osteoarthritis. Although the studies presented differences between placebo and active treatment for osteoarthritis for some outcomes, these effects did not meet the generally accepted criteria for clinical importance. There are currently insufficient data to draw conclusions about the efficacy of electromagnetic field interventions in the management of osteoarthritis, thus highlighting the need for larger independent studies that focus on the OMERACT core outcomes with complete documentation of results.

In summary, electromagnetic field treatment has a moderate benefit for patients' pain relief. There is inconclusive evidence that electromagnetic field treatment improves physical function, quality of life or radiographic joint structure. No serious adverse effects of electromagnetic field treatment were reported in the included trials. This might be because of the relative safety of electromagnetic fields compared to physiotherapy, which could be an advantage. This meta-analysis did not reveal clinically important results overall and the analysis was limited by the paucity of literature on electromagnetic fields for osteoarthritis. However, the statistically significant benefits seen here do support the undertaking of further large-scale studies to allow definite conclusions to be drawn.

Quality of the evidence

The quality of the evidence of all included trials was moderate or low. Six trials described generation of allocation sequence or concealment of allocation, or reported whether primary outcomes were specified a priori. All trials described double-blinding of patients and physicians or assessors. Four of the trials were analysed according to the intention-to-treat principle. We also downgraded for heterogeneity and imprecision.

Potential biases in the review process

We believe that we identified all relevant studies. We devised a thorough search strategy and searched all major databases for relevant studies, and we applied no language restrictions. Two review authors independently assessed the trials for inclusion in the review and for risk of bias, with a third review author adjudicating if there was any discrepancy. The biggest limitation of the review process was the heterogeneity between the trials and the lack of data in a form that could be extracted for meta-analysis.

Agreements and disagreements with other studies or reviews

A systematic review has assessed the effectiveness of pulsed electromagnetic fields compared with placebo in the management of osteoarthritis of the knee (Vavken 2009). Nine studies, including 483 patients, were pooled. They reported that pulsed electromagnetic field treatment improved clinical scores and function in patients with osteoarthritis of the knee and that it should be considered as an adjuvant therapy in the management of these patients. However, there is still equipoise regarding the evidence in the literature for an effect on pain.

Authors' conclusions

Implications for practice

The current, limited evidence shows a moderate clinically important benefit of electromagnetic field treatment for the relief of pain in the treatment of knee or cervical osteoarthritis.

Implications for research

More trials are needed in this field. New trials should compare different treatments and provide an accurate description of the length of treatment, dosage and the frequency of the applications. Larger trials are needed to confirm whether the statistically significant results shown in the trials included in this review confer clinically important benefits.

Acknowledgements

The authors wish to thank Louise Falzon (CMSG Trial Search Co-ordinator) for developing the search strategy. Thanks also to the Cochrane Musculoskeletal Group (CMSG) editorial team and Elizabeth Tanjong Ghogomu (Assistant Managing Editor, Cochrane Musculoskeletal Group) for their helpful comments and suggestions for revisions. The authors also thank Professor Taixiang Wu and Guanjian Liu (Chinese Cochrane Centre, China) for their helpful comments and guidelines on the preparation of this review. We acknowledge the work of the author team for the first version of the review.

Data and analyses

Download statistical data

Comparison 1. Electromagnetic fields versus placebo for osteoarthritis
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Pain6434Mean Difference (IV, Random, 95% CI)15.10 [9.08, 21.13]
2 Physical function3197Mean Difference (IV, Random, 95% CI)4.55 [-2.23, 11.32]
3 Quality of life2139Std. Mean Difference (IV, Random, 95% CI)0.09 [-0.36, 0.54]
4 Number of patients experiencing any adverse event4288Risk Ratio (M-H, Fixed, 95% CI)1.17 [0.72, 1.92]
5 Number of patients who withdrew because of adverse events1 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
Analysis 1.1.

Comparison 1 Electromagnetic fields versus placebo for osteoarthritis, Outcome 1 Pain.

Analysis 1.2.

Comparison 1 Electromagnetic fields versus placebo for osteoarthritis, Outcome 2 Physical function.

Analysis 1.3.

Comparison 1 Electromagnetic fields versus placebo for osteoarthritis, Outcome 3 Quality of life.

Analysis 1.4.

Comparison 1 Electromagnetic fields versus placebo for osteoarthritis, Outcome 4 Number of patients experiencing any adverse event.

Analysis 1.5.

Comparison 1 Electromagnetic fields versus placebo for osteoarthritis, Outcome 5 Number of patients who withdrew because of adverse events.

Appendices

Appendix 1. MEDLINE search strategy

MEDLINE updated to 3 October 2013

1. exp osteoarthritis/

2. osteoarthr$.tw.

3. (degenerative adj2 arthritis).tw.

4. arthrosis.tw.

5. or/1-4

6. Electromagnetic Fields/

7. electromagnetic$.tw.

8. exp Electric Stimulation Therapy/

9. pulsed.tw.

10. (electric$ adj3 stimulat$).tw.

11. (alternat$ adj3 electric$).tw.

12. physical therapy modalities/

13. (physical adj therap$).tw.

14. physiotherap$.tw.

15. or/6-14

16. 5 and 15

17. randomized controlled trial.pt.

18. controlled clinical trial.pt.

19. randomized.ab.

20. placebo.ab.

21. drug therapy.fs.

22. randomly.ab.

23. trial.ab.

24. groups.ab.

25. or/17-24

26. (animals not (humans and animals)).sh.

27. 25 not 26

28. 16 and 27

Appendix 2. CINAHL search strategy

CINAHL updated to 3 October 2013

S30 S16 and S29

S29 S17 or S18 or S19 or S20 or S21 or S22 or S23 or S24 or S25 or S26 or S27 or S28

S28 TI Allocat* random* or AB Allocat* random*

S27 (MH "Quantitative Studies")

S26 (MH "Placebos")

S25 TI Placebo* or AB Placebo*

S24 TI Random* allocat* or AB Random* allocat* Search S23 (MH "Random Assignment")

S22 TI Randomi?ed control* trial* or AB Randomi?ed control* trial*

S21 AB singl* blind* or AB singl* mask* or AB doub* blind* or AB doubl* mask* or AB trebl* blind* or AB trebl* mask* or AB

tripl* blind* or AB tripl* mask*

S20 TI singl* blind* or TI singl* mask* or TI doub* blind* or TI doubl* mask* or TI trebl* blind* or TI trebl* mask* or TI tripl*

blind* or TI tripl* mask*

S19 TI clinical* trial* or AB clinical* trial*

S18 PT clinical trial

S17 (MH "Clinical Trials+")

S16 S5 and S15

S15 S6 or S7 or S8 or S9 or S10 or S11 or S12 or S13 or S14

S14 ti physiotherap* or ab physiotherap*

S13 ti physical therap* or ab physical therap* Search

S12 (MH "Physical Therapy+")

S11 ti alternat* N3 electric* or ab alternat* N3 electric*

S10 ti electric$* N3 stimulat* or ab electric$* N3 stimulat*

S9 ti pulsed or ab pulsed

S8 (MH "Electric Stimulation+")

S7 ti electromagnetic* or ab electromagnetic*

S6 (MH "Electromagnetic Fields")

S5 S1 or S2 or S3 or S4

S4 ti arthrosis or ab arthrosis

S3 ti degenerative N2 arthritis or ab degenerative N2 arthritis

S2 ti osteoarthr* or ab osteoarthr*

S1 (MH "Osteoarthritis+")

Appendix 3. EMBASE search strategy

EMBASE updated to 3 October 2013

1. exp osteoarthritis/

2. osteoarthr$.tw.

3. (degenerative adj2 arthritis).tw.

4. arthrosis.tw.

5. or/1-4

6. electromagnetic field/

7. electromagnetic$.tw.

8. exp electrostimulation therapy/

9. pulsed.tw.

10. (electric$ adj3 stimulat$).tw.

11. (alternat$ adj3 electric$).tw.

12. exp physiotherapy/

13. (physical adj therap$).tw.

14. physiotherap$.tw.

15. or/6-14

16. 5 and 15

17. (random$ or placebo$).ti,ab.

18. ((single$ or double$ or triple$ or treble$) and (blind$ or mask$)).ti,ab.

19. controlled clinical trial$.ti,ab.

20. RETRACTED ARTICLE/

21. or/17-20

22. (animal$ not human$).sh,hw.

23. 21 not 22

24. 16 and 23

Appendix 4. CENTRAL search strategy

CENTRAL updated to Issue 9, 2013

#1 MeSH descriptor Osteoarthritis explode all trees

#2 degenerative near/2 arthritis

#3 osteoarthr*

#4 arthrosis:ti,ab

#5 (#1 OR #2 OR #3 OR #4)

#6 MeSH descriptor Electromagnetic Fields explode all trees

#7 electromagnetic*:ti,ab

#8 MeSH descriptor Electric Stimulation Therapy explode all trees

#9 pulsed:ti,ab

#10 electric* near/3 stimulat*:ti,ab

#11 alternat* near/3 electric*:ti,ab

#12 MeSH descriptor Physical Therapy Modalities explode all trees

#13 physical next therap*:ti,ab

#14 physiotherap*:ti,ab

#15 (#6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14)

#16 (#5 AND #15)

Appendix 5. PEDro search strategy

PEDro updated to 3 October 2013

Abstract and title: electro

Subdiscipline: musculoskeletal

Abstract and title: osteoarthritis

Therapy: electrotherapies, heat and cold

What's new

DateEventDescription
3 October 2013New search has been performedNew search with six new studies.
3 October 2013New citation required but conclusions have not changedNew authors.

History

Review first published: Issue 1, 2002

DateEventDescription
8 May 2008AmendedCMSG ID: C031-R.

Contributions of authors

Dr. Shasha Li and Bo Yu performed the bibliographic searches, identified the studies, assessed their methodological quality, extracted the data and produced the first draft of the review. Dr. Chengqi He and Dr. Dong Zhou assessed the methodological quality of the studies, checked the extracted data and commented on all the draft manuscripts. Jennifer Hulme and Dr. Qi Zhuo helped to perform the bibliographic searches, identified the studies, assessed their methodological quality and extracted the data.

Declarations of interest

None known.

Sources of support

Internal sources

  • Chinese Cochrane Centre, Chinese EBM Centre, INCLEN CERTC in West China Hospital, Sichuan University, China.

External sources

  • No sources of support supplied

Differences between protocol and review

The major outcomes were changed to pain, physical function, radiographic joint structure changes, health-related quality of life measure, number of patients experiencing any adverse event, patients who withdrew because of adverse events and patients experiencing any serious adverse events on the recommendation of the CMSG. 'Risk of bias' assessment, 'Summary of findings' table and GRADE quality assessment were presented.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Fary 2011

MethodsRandomised, double-blind, placebo-controlled trial
Sample size at entry: 70 patients (34 in the active and 36 in the placebo group)
Withdrawals: 3 participants (2 in the active and 1 in the placebo group)
Treatment duration: 7 hours daily, preferably overnight, for 26 weeks
Follow-up: 26 weeks
Participants

Inclusion criteria: diagnosis of osteoarthritis of the knee was in accordance with the American College of Rheumatology modified clinical classification system. Plain radiographs available for 64 participants confirmed the diagnosis. Persistent and stable pain (defined as not getting worse or better overall despite short-term fluctuations) for a minimum of 3 months prior to study entry was confirmed in all participants by telephone interview.
Exclusion criteria: co-existing inflammatory arthropathies, contraindications to electrical stimulation, skin disorders in the
vicinity of the knee to be treated, total knee replacement scheduled during the study period, and/or insufficient English
to follow instructions and complete forms
Number of patients who finished this study: 67
Male/female: 17/17; 20/16
Mean age in years (range): 70.7 ± 8.9; 68.9 ± 11.4

Intervention group number: 34

Control/sham group number: 36

Interventions

Active group: a commercially available TENS stimulator (Metron Digi-10s) was modified by a biomedical engineer to deliver pulsed electrical stimulation current parameters as follows: pulsed, asymmetrically biphasic, exponentially decreasing waveform with a frequency of 100 Hz and pulse width of 4 ms
Placebo group: placebo devices
Current was delivered via 120 mm x 80 mm multiple-use conductive silicone electrodes inserted into larger calico pockets (175 mm x 100 mm) to increase the contact surface area and reduce current density

The placebo device was identical in appearance and method of use; however, the current flow was programmed to turn off after 3 minutes. Since this was a sub-sensory treatment, this change was not detectable by participants
Patients were advised to use the instrument for 7 hours daily, preferably overnight, for 26 weeks

Outcomes

Primary outcomes:
(1) Pain: change in pain score over 26 weeks measured on a 100 mm VAS
(2) Physical function (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Likert format 3.1)
(3) Patient's global assessment of disease activity (on a 100 mm VAS)

Secondary outcomes:
(1) Quality of life (the 36-item Medical Outcomes Study Short-Form 36 version 2 (SF-36 v. 2) health survey)
(2) Joint stiffness (WOMAC 3.1)
(3) Physical activity (Human Activity Profile and Actigraph GT1M accelerometers worn for 7 consecutive days)
(4) An 11-point global perceived effect scale

NotesSupported by an Arthritis Australia and State & Territory Affiliate Grant and a Physiotherapy Research Foundation Research Seeding grant, and by a Curtin University School of Physiotherapy Early Career Researcher grant to Dr. Fary. Dr. Fary was the recipient of an Australian Government Postgraduate PhD scholarship and a Curtin University School of Physiotherapy Movement Through Life Top-Up scholarship
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "using computer-generated randomization in blocks of 6."
Allocation concealment (selection bias)Low riskQuote: "Allocation, stratified by sex, age (60 years, 60–75 years, and 75 years), and baseline VAS pain scores (25–40 mm, 41–60 mm, and 61–100 mm), was performed independently by an administrator, not otherwise involved in the study"
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "This process ensured that all study investigators and participants remained blinded to allocation until analysis was complete."
Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "This process ensured that all study investigators and participants remained blinded to allocation until analysis was complete."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Unclear riskNo information provided
Incomplete outcome data (attrition bias)
All outcomes
Low risk

4 weeks: 1/34 missing from active group (failed to return week 4 data)

16 weeks: 1/34 missing from active group (device uncomfortable to wear) but participant who completed week 4 data returned; 1/36 missing from placebo group (protocol too onerous)

26 weeks: 1/ 34 missing from active group (failed to attend final appointment)

Selective reporting (reporting bias)Unclear riskNo information provided

Garland 2007

MethodsRandomised, double-blind, placebo-controlled trial
Sample size at entry: 58 patients (39 in the active and 19 in the placebo group)
Withdrawals: 2 patients
Treatment duration: 6 to 14 hours per day during the 3-month treatment period
Follow-up: 3 months
Participants

Inclusion criteria: age 18 years or greater, the intellectual ability to understand and sign an informed consent and complete the study questionnaire, and willingness to maintain stable doses of analgesics and NSAIDs for 1 month prior to study entry and during the 3-month double-blind period
Exclusion criteria: knee instability and/or valgus or varus deformities of > 20; pregnancy; infectious arthritis; implantable electronic devices; a diagnosis of gout; recurrent inflammatory episodes of pseudogout; malignancy (other than basal cell carcinoma) in the prior 3 years; inflammatory arthritis such as rheumatoid arthritis; psoriatic arthritis; Reiter's syndrome; haemochromatosis; inflammatory bowel disease, etc.
Number of patients who finished this study: 58
Male/female: 12/27; 8/11
Mean age in years (range): 64.3 ± 10.2; 69.9 ± 11.4

Intervention group number: 39

Control/sham group number: 19

InterventionsActive group: pulsed electrical stimulation (BioniCare Medical Technologies, Inc., Sparks, Maryland)
Placebo group: placebo devices
100 Hz, negative pulsed signal, 0 and 12 V, active treatment remained imperceptible and indistinguishable from placebo. The placebo devices shut off after the amplitude was reduced. All active and placebo devices contain a timer that recorded the cumulative hours when the device was in use
Patients were advised to use the instrument for 6 to 14 hours/day during the 3-month treatment period
OutcomesPrimary outcomes:
(1) Per cent change from baseline on a 0 to 100 VAS measuring patient global evaluation of arthritis symptoms in the treated knee
(2) Per cent change from baseline on a 0 to 100 VAS measuring pain and other symptoms in the treated knee
(3) Per cent change from baseline on the Western Ontario and McMaster Universities (WOMAC) pain (0 to 500), stiffness (0 to 200) and function (0 to 850) sub-scales as measured on a 100 mm VAS
Secondary outcomes: the percentage of patients that experienced 50% improvement in patient global evaluation, pain and symptoms in the treated knee, and in the 3 WOMAC outcome scale measures
The occurrence of rashes and other adverse device effects was solicited and recorded at each visit
NotesSupported by a grant from BioniCare Medical Technologies, Inc
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Each placebo and active device was assigned a unique number."
Allocation concealment (selection bias)Low riskQuote: "A master random number chart was generated and maintained by an independent observer who had no interaction with the sponsors pendent observer who had no interaction with the sponsors"; "The number coincided with active or placebo units according to the dictates of the random number table."
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "A master random number chart was generated and maintained by an independent observer who had no interaction with the sponsors pendent observer who had no interaction with the sponsors."
Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "A master random number chart was generated and maintained by an independent observer who had no interaction with the sponsors pendent observer who had no interaction with the sponsors"; "The clinical investigators had no influence on the assignment of any specific patient to an active or placebo device. The blind has never been revealed to any of the authors except the statistician."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Low riskQuote: "A master random number chart was generated and maintained by an independent observer who had no interaction with the sponsors pendent observer who had no interaction with the sponsors"; "The clinical investigators had no influence on the assignment of any specific patient to an active or placebo device. The blind has never been revealed to any of the authors except the statistician."
Incomplete outcome data (attrition bias)
All outcomes
Low risk1/39 missing from active group (discontinued study participation before the second month follow-up visit); 1/19 missing from placebo group (discontinued study participation before the second month follow-up visit)
Selective reporting (reporting bias)Unclear riskNo information provided

Nelson 2013

MethodsDouble-blind, placebo-controlled, randomised pilot study
Sample size at entry: 34 patients (15 in the active and 19 in the sham group)
Withdrawals: 10 participants (3 in the active and 7 in the sham group)
Treatment duration: 15 minutes twice daily, for 42 days
Follow-up: 42 days
Participants

Inclusion criteria: patient selection required that participants had knee pain for at least 3 months with an imaging study that confirmed articular cartilage loss, an initial VAS score ≥ 4, and at least 2 hours of daily standing activity in a physical occupation

Exclusion criteria: patients with rheumatoid arthritis, gout and pregnancy; cortisone injections, surgery or an effective visco supplementation series within the past 6 months; implanted electronic devices. Patients on disability or with third party claims were excluded

Male/female: 5/10, 5/14
Mean age in years (range): 55.5 ± 2.5, 58.4 ± 2.5

Intervention group number: 15

Control/sham group number: 19

Interventions

Active group: a pulsed electromagnetic field signal consisting of a 7 ms burst of 6.8 MHz sinusoidal waves repeating at 1 burst/s delivering a peak induced electrical field of 34 ± 8 V/m in the knee from the portable battery operated device (Palermo, Ivivi Health Sciences, LLC, San Francisco, CA)

Sham group: sham devices were activated with a switch, same as active devices, and both sham and active units had blinking indicator lights. The pulsed electromagnetic field signal from these devices did not produce heat or cause any other sensation in tissue

Once manually activated, treatment was automatically applied for 15 minutes. Device was used for 15 minutes twice daily for 42 days

OutcomesPrimary outcomes: pain: self report maximum daily VAS pain scores on an unmarked horizontal 10 cm line (0 is no pain and 10 is worst possible pain)
NotesPartially supported by the Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit Michigan, and Ivivi Health Sciences, LLC, San Francisco, CA, who manufactured the pulsed electromagnetic field devices utilised in this study
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Randomization was performed by the blinded assignment of devices according to their serial numbers."
Allocation concealment (selection bias)Low riskQuote: "Device randomization was performed by the manufacturer (Ivivi Health Sciences, LLC) and all devices with the randomization code were sent to the Epidemiology Dept at Henry Ford Hospital, from which assignment to patients was controlled. General unblinding occurred after all data were collected."
Blinding (performance bias and detection bias)
Blinding of patients?
Low risk

Quote: "PEMF signal employed in this study is at least 1,000-fold below the ambient magnetic field and cannot be detected using standard Gauss meters. Therefore, only measurements with specialized laboratory equipment, not readily available to the patient or health care practitioner, could determine whether a device was active. General unblinding occurred after all data were collected."

Comment: probably done.

Blinding (performance bias and detection bias)
Blinding of physicians?
Low risk

Quote: ""PEMF signal employed in this study is at least 1,000-fold below the ambient magnetic field and cannot be detected using standard Gauss meters. Therefore, only measurements with specialized laboratory equipment, not readily available to the patient or health care practitioner, could determine whether a device was active. General unblinding occurred after all data were collected."

Comment: probably done.

Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Unclear riskNo information provided
Incomplete outcome data (attrition bias)
All outcomes
High riskDay 42: 3/15 missing from active group (lack of perceived benefit as the reason, confirmed by VAS scores); 7/19 missing from sham group (lack of perceived benefit as the reason, confirmed by VAS scores)
Selective reporting (reporting bias)Unclear riskNo information provided

Nicolakis 2002

MethodsRandomised, double-blind, controlled trial
Sample size at entry: 36 patients
Withdrawals: 4 patients
Treatment duration: 30 minutes per session twice a day for 6 weeks
Follow-up: 2 months
Participants

Inclusion criteria: patients with symptomatic osteoarthritis of the knee. All patients had radiographic signs of osteoarthritis according to the classification of Kellgren, grade 2 or 3
Exclusion criteria: included clinical evidence of meniscal tears, polyarthritis, cardiovascular, pulmonary or neurological disorders, cardiac pacemakers or malignancies
Number of patients who finished this study: 36
All patients were on long-term intra-articular steroid injections every 2.6 ± 0.8 (verum) and 2.4 ± 1.1 (sham) weeks (mean ± SD) before inclusion into the study
Male/female: 11/4, 8/9
Mean age in years (range): 69 ± 5, 67 ± 7

Intervention group number: 15

Control/sham group number: 17

InterventionsTreatment group: PMF
Sham group: PMF devices had disconnected coils and a shunt resistor in the mat, so they did not produce a PMF. PMF was administered to the whole body using a mat 1.7 m x 0.65 m in size. The mat produced a pulsating electromagnetic field with a mean intensity of 40 μT (wave ranger professional, program 12, Mediscan GmbH, Bad Haller StraBe34, 4500 Kremsmünster, Austria). The frequency of the PMF ranged from 1 Hz to 3000 Hz
During the treatment the patients lay on the mat for 30 minutes per session twice a day for 6 weeks
Outcomes1) Primary outcomes: change between baseline and the end of treatment in the 240-point WOMAC Osteoarthritis Index: pain score (maximum score, 50), stiffness score (maximum score, 20) and physical function score (maximum score, 170)
2) Secondary outcomes included objective and subjective measures: gait test, isokinetic dynamometry strength tests
NotesThe study was supported by a grant from the "Institut zurwissenschaftlichen Evaluierung alternativer Heilmethoden" (Institute for Research in Complementary Medicine), Rokitan-skygasse 40/8, 1170 Vienna, Austria
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "The study coordinator assigned the devices on a random basis to patient according to a list created by randomization function (Matlab, Mathworks Incor-poration, Natick, Massachusetts)."
Allocation concealment (selection bias)Low riskQuote: "All devices were numbered; only the study coordinator was aware of the code."
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "The persons involved in patient administration, the evaluator, as well as the person instructing the patients in the use of the device and giving technical support if required, were blinded. At the end of the study the code was broken."
Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "The persons involved in patient administration, the evaluator, as well as the person instructing the patients in the use of the device and giving technical support if required, were blinded. At the end of the study the code was broken."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Low riskQuote: "The persons involved in patient administration, the evaluator, as well as the person instructing the patients in the use of the device and giving technical support if required, were blinded. At the end of the study the code was broken."
Incomplete outcome data (attrition bias)
All outcomes
Low risk3/18 missing from treatment group (1 did not complete treatment, 2 further patients had to be excluded from the statistical analysis as they did not use the device properly); 1/18 missing from the sham group (withdrew because of excessive pain)
Selective reporting (reporting bias)Unclear riskNo information provided

Pipitone 2001

MethodsRandomised, double-blind, placebo-controlled trial
Sample size at entry: 75 patients
Withdrawals: 16 patients
Treatment duration: 3 times a day for 30 minutes of 6 weeks duration
Follow-up: not clear
Participants

Inclusion criteria: patients had radiographic signs and symptoms of osteoarthritis as judged by the criteria of the ACR
Exclusion criteria: pregnancy, use of pacemaker, insulin pump or of any implanted electrical device, etc.
Number of patients who finished this study: 69
Male/female: 22/12, 28/7
Mean age in years (range): 40 to 84, 48 to 84

Intervention group number: 39

Control/sham group number: 36

(6 patients failed to attend after the screening visit and were excluded from the analysis)

InterventionsActive group: pulsed electromagnetic fields (Snowden Healthcare Ltd., Nottingham, UK)
Sham group: sham devices
Pulsed electromagnetic field devices that generate pulses of magnetic energy via a soft iron core treated with 62 trace elements. Pulses are selected at their base frequencies (3 Hz, 7.8 Hz and 20 Hz). They have a rise time of 1 μs, a low magnetic output (< 0.5 gauss) and a range of activity of up to 30 cm around the unit. Medicur devices run on 9 V batteries and switch off automatically after a 10-minute period
Patients were instructed not to change their basic therapeutic regimen
Number of sessions: 30 minutes per session 3 times a day for 6 weeks
Outcomes1) Primary outcomes: reduction in overall pain assessed on a 4-point Likert scale ranging from none to severe
2) Secondary outcomes: Lequesne Index; WOMAC Osteoarthritis Index (Likert scale); UK 36-item short form of the Medical Outcomes Study (SF-36) and the EuroQol (Euro-Quality of Life, EQ-5D)
NotesThis study was supported by an educational grant from Snowden Healthcare
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Patients fulfilling the study criteria were randomised on study entry to receive active pulsed electromagnetic fields treatment with the Medicur magnetic devices or placebo using a 12 * 12 randomisation table."
Allocation concealment (selection bias)Low riskQuote: "Neither the patients nor the medical assessor were aware of the treatment group". "The code numbers were not broken until all patients had complete the study."
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "Neither the patients nor the medical assessor were aware of the treatment group". "The code numbers were not broken until all patients had complete the study."
Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "Neither the patients nor the medical assessor were aware of the treatment group". "The code numbers were not broken until all patients had complete the study."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Low riskQuote: "Neither the patients nor the medical assessor were aware of the treatment group". "The code numbers were not broken until all patients had complete the study."
Incomplete outcome data (attrition bias)
All outcomes
High risk10/39 missing from active group (5 attended only for screening and were excluded from the analysis, 5 withdrew before completing treatment); 6/36 missing from sham group (1 attended only for screening and was excluded from the analysis, 5 withdrew before completing treatment)
Selective reporting (reporting bias)Unclear riskNo information provided

Thamsborg 2005

MethodsRandomised, double-blind, placebo-controlled trial
Sample size at entry: 90 patients (pulsed electromagnetic field 45, placebo 45)
Withdrawals: 7 patients
Treatment duration: 2 hours daily treatment 5 days per week for 6 weeks
Follow-up: 6 weeks
Participants

Inclusion criteria: patients older than 45 years with painful knee osteoarthritis of the femorotibial compartment fulfilling the combined clinical and radiological criteria of the American College of Rheumatology were included
Exclusion criteria: inflammatory joint disease, acromegaly, Charcot's arthropathy, haemochromatosis, Wilson's disease, ochronosis, terminal illnesses/malignancies, pregnancy or lack of contraception use in women of childbearing age, and use of pacemaker or any implanted electrical device
Number of patients who finished this study: 83
Male/female: 23/20, 16/25
Mean age in years (range): 60.4 ± 8.7, 59.6 ± 8.6

Intervention group number: 45

Control/sham group number: 45

InterventionsActive group: pulsed electromagnetic fields (Biofields Aps, Copenhagen, Denmark)
Sham group: sham devices
A pulse generator yields G50V in 50 Hz pulses changing voltage in 3 ms intervals. The current in the coils that create the pulsed electromagnetic fields causes the coils to become slightly warmer than the surroundings after 30 minutes (28 to 35). For the group of patients not receiving active treatment, direct current (DC) was applied to the coils yielding a permanent magnetic field that does not evoke changing electrical potentials in tissue
Treatment duration: 2 hours daily treatment 5 days per week for 6 weeks
Outcomes1) Primary outcomes: WOMAC osteoarthritis index: a questionnaire addressing the severity of joint pain (5 questions), stiffness (2 questions) and limitation of physical function (17 questions)
2) Secondary outcome measures: WOMAC sub-score of joint pain (0 to 25); WOMAC sub-scores of stiffness (0 to 10); activities of daily living (ADL) (0 to 85) and scintigraphic results
NotesEconomic support from IMK Almene Fond and from Københavns Amts Erhvervskontor
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskQuote: "This was a 1:1 randomized, controlled, double-blind add-on study." No further information provided
Allocation concealment (selection bias)Low risk

Quote: "This was a 1:1 randomized, controlled, double-blind add-on study." "Blinding was maintained until the final database was cleaned and locked."

Comment: probably done

Blinding (performance bias and detection bias)
Blinding of patients?
Unclear riskQuote: "This was a 1:1 randomized, controlled, double-blind add-on study." No further information provided
Blinding (performance bias and detection bias)
Blinding of physicians?
Unclear riskQuote: "This was a 1:1 randomized, controlled, double-blind add-on study." No further information provided
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Unclear riskQuote: "This was a 1:1 randomized, controlled, double-blind add-on study." No further information provided
Incomplete outcome data (attrition bias)
All outcomes
Low risk3/45 missing from active group; 4/45 missing from sham group
Selective reporting (reporting bias)Unclear riskNo information provided

Trock 1993

MethodsRandomised, placebo-controlled trial
Sample size at entry: 27 patients (pulsed electromagnetic field 15, placebo 12)
Withdrawals: 7 patients
Treatment duration: 18 half-hour periods of exposure over about 1 month
Follow-up: 2 months
Participants

Inclusion criteria: all patients met the criteria for the diagnosis of osteoarthritis published by Altman. Patients with osteoarthritis, primarily of the knee with symptoms for greater than 1 year, who had not started any new treatment within 1 month of study
Exclusion criteria: pregnancy or lack of contraception use in women of childbearing age, and use of pacemaker or the presence of any serious unstable medical illness
Number of patients who finished this study: 25
Male/female: unclear
Age: at least 18 years

Intervention group number: 15

Control/sham group number: 12

InterventionsActive group: pulsed electromagnetic fields (MFG)
Sham group: sham devices
Magnetic therapy system with extremely low-frequency (ELF) pulsed waves consisting of a magnetic field generator with an electronic interface to freely moving air coil. Separate systems for peripheral joints and the axis skeleton. Placebo therapy applied by not energising the air coil
Treatment duration: 18 half-hour periods of exposure over about 1 month
OutcomesSeverity of pain, difficulty performing activities of daily living (ADL), pain performing ADL, worst discomfort in previous week, pain on joint motion by MD exam, joint tenderness by MD exam, assessment of improvement by MDs
NotesFunded by Bio-Magnetic Therapy Systems, Inc.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "Patients were randomized to receive active pulsed electromagnetic fields or placebo using a table of 1000 random digits."
Allocation concealment (selection bias)Low riskQuote: "A code master record sheet was kept by an office administrator."
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "Both the patients and the examining physician remained blinded as to whether active pulsed electromagnetic fields or placebo was given."
Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "Both the patients and the examining physician remained blinded as to whether active pulsed electromagnetic fields or placebo was given."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Low riskQuote: "A code master record sheet was kept by an office administrator."
Incomplete outcome data (attrition bias)
All outcomes
High risk5/15 missing from active group; 2/12 missing from sham group
Selective reporting (reporting bias)Unclear riskNo information provided

Trock 1994

MethodsRandomised, double-blind, multicentre controlled trial
Sample size at entry: 86 patients with osteoarthritis of the knee and 81 patients with osteoarthritis of the cervical spine
Withdrawals: 11 patients withdrew from the double-blind trial of knee osteoarthritis and 11 patients from the trial of osteoarthritis of the cervical spine before completing treatment
Treatment duration: treatments were given for 30-minute periods, 3 to 5 times a week for 18 treatments
Follow-up: 1 month
Participants

Inclusion criteria: patients with osteoarthritis of the knee who met the criteria published by Altman. 11 patients with cervical spine pain were admitted to the study if radiographs showed evidence of disk space narrowing with osteocyte formation and/or subchondral sclerosis in 1 or more locations; osteophyte formation and subchondral sclerosis of facet joints were also accepted as evidence of osteoarthritis, with local symptoms such as pain and stiffness of at least 1 year duration. Patients were instructed not to change their basic therapeutic regimen, including drugs and physical therapy, during the period of treatment and observation
Exclusion criteria: patients who had changed their therapeutic regimen within 1 month before evaluation were excluded

Number of patients who finished this study: 86 knee osteoarthritis and 81 cervical osteoarthritis
Male/female: unclear
Age: at least 35 years

Intervention group number: 86

Control/sham group number: 86

InterventionsActive group: pulsed electromagnetic fields (M-T System)
Sham group: sham devices
Magnetic therapy system with extremely low-frequency (ELF) pulsed waves consisting of 3 integrated components: a magnetic field generator, an electronic interface and a segmented single toroid coil with annular windings that produced pulsed DC elliptical magnetic fields
Wave form: quasi-rectangular with abruptly rising and deteriorating wave form: pulse burst duty cycle of up to 0.8. The number of pulsed bursts is determined by the frequency: the maximum was 20
Frequency: the following energy characteristics were applied stepwise to the area of the joint being treated: 5 Hz 10 to 15 gauss for 10 minutes; 10 Hz 15 to 25 gauss for 10 minutes; and 12 Hz 15 to 25 gauss for 10 minutes
Intensity and voltage control: coil current of < 2 A with 120 V
Placebo therapy applied by not energising the air coil
Treatment duration: 30 minutes
Number of sessions: 3 to 5 times a week for 18 treatments
Outcomes1) The physician recorded the degree of pain on motion (none, slight, moderate or severe) and tenderness using the Ritchie Scale as described for patients with osteoarthritis by Doyle. For both of these observations the score for 'none' was assigned as 0, 'slight' as 1, 'moderate' as 2 and 'severe' as 3
2) At each of the evaluations after the baseline, the patient was asked to quantify any improvement by marking a 10 cm VAS
3) At the end of treatment and the 1-month follow-up evaluation the observing physician was asked to record a global assessment of overall improvement using a 4-point scale (0 = none, 1 = slight, 2 = good and 3 = excellent)
NotesSupported by Bio-Magnetic Therapy Systems, Inc.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskQuote: "One research associate kept the list of 1000 random numbers, divided into pairs, the higher of which was to receive treatment and the lower placebo."
Allocation concealment (selection bias)Low riskQuote: "Separate lists of random numbers were kept for the patients."
Blinding (performance bias and detection bias)
Blinding of patients?
Low riskQuote: "Neither patient in the trial nor any patient in the center, nor any other staff could tell which patients were receiving active treatment."
Blinding (performance bias and detection bias)
Blinding of physicians?
High riskQuote: "Only the therapy technician at the treatment center was informed, by means of a code."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Low riskQuote: "Neither patient in the trial nor any patient in the center, nor any other staff could tell which patients were receiving active treatment." "Only the therapy technician at the treatment center was informed, by means of a code."
Incomplete outcome data (attrition bias)
All outcomes
Low riskDouble-blind trial of knee osteoarthritis: 5/42 missing from active group; 5/44 missing from sham group
Trial of osteoarthritis of the cervical spine: 4/42 missing from active group; 7/39 missing from sham group
Selective reporting (reporting bias)Unclear riskNo information provided

Zizic 1995

  1. a

    ACR: American College of Rheumatology
    DC: direct current
    MD: medical doctor
    NSAID: non-steroidal anti-inflammatory drug
    PMF: pulsed magnetic field
    TENS: transcutaneous electrical nerve stimulation
    VAS: visual analogue scale

MethodsRandomised, multicentre,double-blind, placebo-controlled trial
Sample size at entry: 78 patients (41 in the active and 37 in the placebo group)
Withdrawals: 7 patients
Treatment duration: 6 to 10 hours per day during the 4-week treatment period
Follow-up: 6 months
Participants

Patients older than 20 years with painful knee osteoarthritis of the femorotibial compartment fulfilling the combined clinical
and radiological criteria
Number of patients who finished this study: 71
Male/female: 20/18, 18/15
Age: over 20 years

Intervention group number: 41

Control/sham group number: 37

InterventionsActive group: pulsed electrical stimulation
Control group: sham devices
The electrical impulse was generated by a portable, battery-operated device that delivers a low-frequency (100 Hz), low-amplitude, voltage sourced (mean = 6.2 peak volts), monophasic, spiked signal to the knee via skin surface electrodes. The voltage of the placebo device was adjusted to the subthreshold level using the same procedure as the active device. Patients were advised to use the instrument for 6 to 10 hours/day during the 4-week treatment period
Outcomes1) Primary efficacy outcomes: physician's global evaluation, patient's evaluation of pain, patient's evaluation of function of the treated knee
2) Secondary efficacy outcomes: patient estimate of the duration of morning stiffness in the affected knee, measured in minutes; range of motion of the knee, determined by goniometric measurement of flexion and extension; tenderness; swelling; knee circumference; 50-foot walking time
NotesThis study was supported by Murray Electronics
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "Patients were randomized to receive an active device or an identical appearing placebo device."

Comment: no further information provided

Allocation concealment (selection bias)Unclear risk

Quote: "Patients were randomized to receive an active device or an identical appearing placebo device."

Comment: no further information provided

Blinding (performance bias and detection bias)
Blinding of patients?
Low risk

Quote: "...in a multicenter, prospective, randomized, placebo controlled, double blind study"

Comment: probably done

Blinding (performance bias and detection bias)
Blinding of physicians?
Low riskQuote: "A nurse coordinator instructed patients in the proper use of the device."
Blinding (performance bias and detection bias)
Blinding of outcome assessors?
Unclear riskNo further information provided
Incomplete outcome data (attrition bias)
All outcomes
Low risk3/41 missing from active group; 4/37 missing from sham group
Selective reporting (reporting bias)Unclear riskNo information provided

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
  1. a

    PEMF: pulsed electromagnetic field therapy
    RCT: randomised controlled trial

Alcidi 2007The duration of treatment was only 5 days (once daily). Efficacy requires at least 4 weeks' treatment duration (suggestion of several physiotherapists)
Ay 2009All patients participated in the therapy programmes for 3 weeks (15 sessions). Pulsed electromagnetic field therapy for 30 minutes per day and combined hot-pack and transcutaneous electrical nerve stimulation (TENS)
Battisti 2004Treatments were given for 30 minutes for 15 days. The treatment duration did not match the inclusion criteria of this review
Danao-Camara 2001Primary report, not a RCT
Fischer 2005Randomisation was not mentioned. Li SS sent an email to Dr. Pelka, the corresponding author of the paper, on 10 December 2007, with 2 questions as follows: 1. Was the randomisation of the allocation procedure adequate? 2. Was the allocation concealment properly done? The author did not reply, so, we considered this a cohort study rather than a RCT
Fischer 2006The second version of Fischer 2005
Hinman 2002The aim of this article was to assess the effect of static magnetic fields for chronic knee pain but not osteoarthritis
Jack 2006Prospective, cohort study and not a RCT
Jacobson 2001Treatment duration: 48 minutes per treatment session 8 times in 2 weeks. This time frame may be too short to assess safety and efficacy based on biological plausibility
Kulcu 2009A therapy session lasted for 35 minutes and 15 sessions were performed during 3 weeks (5 sessions/week)
Liu 2004Randomisation was mentioned but not described in detail. Li SS telephone interviewed the original author, Wencai Liu, on 3 December 2007. The author could not remember how the randomisation was designed. Therefore we considered the study not to be a RCT
Ozgüçlü 2010Both the pulsed electromagnetic fields and sham PEMF treatments being evaluated were 55 minutes/session, 5 sessions per week for 2 weeks. The treatment duration did not match the inclusion criteria of this review
Pavlović 2012The treatment period was only 10 days. The treatment duration did not match the inclusion criteria of this review
Rigato 2002The study included patients with cervical spondylosis and shoulder periarthritis without separately reported results and we could not extract data on cervical osteoarthritis
Sutbeyaz 2006Treatment duration: twice a day for 30 minutes of 3 weeks duration. The duration did not match the inclusion criteria of this review
Tomruk 2007Both the pulsed electromagnetic field group (n = 16) and the control group (n = 16) participated in therapy, 30 minutes per session twice a day for 3 weeks. The treatment duration did not match the inclusion criteria of this review

Ancillary