Electromagnetic fields for treating osteoarthritis.

Electromagnetic fields for treating osteoarthritis (Review) Li S, Yu B, Zhou D, He C, Zhuo Q, Hulme JM

This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library 2013, Issue 12 http://www.thecochranelibrary.com

Electromagnetic fields for treating osteoarthritis (Review) Copyright © 2013 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

TABLE OF CONTENTS HEADER . . . . . . . . . . . . . . . . . . . . ABSTRACT . . . . . . . . . . . . . . . . . . . PLAIN LANGUAGE SUMMARY . . . . . . . . . . . SUMMARY OF FINDINGS FOR THE MAIN COMPARISON BACKGROUND . . . . . . . . . . . . . . . . . OBJECTIVES . . . . . . . . . . . . . . . . . . METHODS . . . . . . . . . . . . . . . . . . . RESULTS . . . . . . . . . . . . . . . . . . . . Figure 1. . . . . . . . . . . . . . . . . . . Figure 2. . . . . . . . . . . . . . . . . . . Figure 3. . . . . . . . . . . . . . . . . . . DISCUSSION . . . . . . . . . . . . . . . . . . AUTHORS’ CONCLUSIONS . . . . . . . . . . . . ACKNOWLEDGEMENTS . . . . . . . . . . . . . REFERENCES . . . . . . . . . . . . . . . . . . CHARACTERISTICS OF STUDIES . . . . . . . . . . DATA AND ANALYSES . . . . . . . . . . . . . . . WHAT’S NEW . . . . . . . . . . . . . . . . . . HISTORY . . . . . . . . . . . . . . . . . . . . CONTRIBUTIONS OF AUTHORS . . . . . . . . . . DECLARATIONS OF INTEREST . . . . . . . . . . . SOURCES OF SUPPORT . . . . . . . . . . . . . . DIFFERENCES BETWEEN PROTOCOL AND REVIEW . . INDEX TERMS . . . . . . . . . . . . . . . . .

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[Intervention Review]

Electromagnetic fields for treating osteoarthritis Shasha Li1 , Bo Yu2 , Dong Zhou3 , Chengqi He1 , Qi Zhuo4 , Jennifer M Hulme5 1 Department

of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China. 2 Department of Paediatrics, Sichuan Provincial Hospital for Women and Children, Chengdu, China. 3 Department of Neurology, West China Hospital, Sichuan University, Chengdu, China. 4 Department of Orthopaedic Surgery, Chinese PLA General Hospital, Beijing, China. 5 Class of 2012, McGill University School of Medicine, Montreal, Canada Contact address: Chengqi He, Department of Rehabilitation Medicine, West China Hospital, Sichuan University, No.37 Guo-xuexiang Street, Chengdu, Sichuan Province, 610041, China. [email protected]. Editorial group: Cochrane Musculoskeletal Group. Publication status and date: New search for studies and content updated (no change to conclusions), published in Issue 12, 2013. Review content assessed as up-to-date: 3 October 2013. Citation: Li S, Yu B, Zhou D, He C, Zhuo Q, Hulme JM. Electromagnetic fields for treating osteoarthritis. Cochrane Database of Systematic Reviews 2013, Issue 12. Art. No.: CD003523. DOI: 10.1002/14651858.CD003523.pub2. Copyright © 2013 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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). Electromagnetic fields for treating osteoarthritis (Review) Copyright © 2013 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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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.

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. Electromagnetic fields for treating osteoarthritis (Review) Copyright © 2013 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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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 Xray. 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.


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S U M M A R Y O F F I N D I N G S F O R T H E M A I N C O M P A R I S O N [Explanation]

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 Outcomes

Illustrative comparative risks* (95% CI)

No of participants (studies)

Quality of the evidence (GRADE)

Comments

The 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)

The mean change in The mean change in physical function in the physical function in the control groups was intervention groups was 1.7 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

Assumed risk

Corresponding risk

Placebo

Electromagnetic treatment

Pain The mean change in pain 100 mm VAS in the control groups was Scale from: 0 to 100 10.7 (Higher scores mean worse pain) Follow-up: mean 6 weeks

Physical function WOMAC function Scale from: 0 to 100 (Higher scores mean more severe limitation) Follow-up: mean 3 months

Relative effect (95% CI)

field

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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 progres- See comment sion Bone scintigraphic examinations Follow-up: mean 2.5 months

See comment

Not estimable

78 (1 study)

See comment

No related data were available

Number of patients ex- 167 per 1000 periencing any adverse event Follow-up: mean 1 month

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 27 per 1000 withdrew because of adverse events Follow-up: mean 6 months

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 5


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. 1 Downgraded

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). 2 Downgraded 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. 4 Unclear 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). 5 Only 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.

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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


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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.

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

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

1. 2. 3. 4. 5. 6. 7.

Pain Physical function Health-related quality of life measure Radiographic joint structure changes Number of patients experiencing any adverse event Patients who withdrew because of adverse events Patients experiencing any serious adverse event

METHODS

Search methods for identification of studies

Criteria for considering studies for this review

Electronic searches

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.

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


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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, predeveloped 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.

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

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 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.


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Assessment of reporting biases

Subgroup analysis and investigation of heterogeneity

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 (followup 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).

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.

RESULTS

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 randomeffects model for meta-analysis.

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

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; Pavlovi 2012; Rigato 2002; Sutbeyaz 2006; Tomruk 2007).


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Figure 1. Study flow diagram.


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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 fre-

quency 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 (EuroQuality 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; Pavlovi 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 (Pavlovi 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).


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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.


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Figure 3. ’Risk of bias’ summary: review authors’ judgements about each risk of bias item for each included study.


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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 metaanalysis, 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).

quality of life as an outcome (Fary 2011). Improvement in quality of life was not statistically significant in electromagnetic fieldtreated 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. 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).

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 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

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).


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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), lowamplitude, 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, qual-


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ity 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.

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 Quality of the evidence

Implications for practice

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.

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.

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

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.

REFERENCES

References to studies included in this review Fary 2011 {published data only} Fary RE, Carroll GJ, Briffa TG, Briffa NK. The effectiveness of pulsed electrical stimulation in the management of osteoarthritis of the knee: results of a double-blind, randomized, placebo-controlled, repeated-measures trial. Arthritis and Rheumatism 2011;63(5):1333–42. Garland 2007 {published data only} Garland D, Holt P, Harrington JT, Caldwell J, Zizic T,

Cholewczynski J. A 3-month, randomized, double-blind, placebo-controlled study to evaluate the safety and efficacy of a highly optimized, capacitively coupled, pulsed electrical stimulator in patients with osteoarthritis of the knee. Osteoarthritis and Cartilage 2007;15(6):630–7. Nelson 2013 {published data only} Nelson FR, Zvirbulis R, Pilla AA. Non-invasive electromagnetic field therapy produces rapid and substantial pain reduction in early knee osteoarthritis: a randomized double-blind pilot study. Rheumatology International 2012;


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33(8):2169–73. Nicolakis 2002 {published data only} Nicolakis P, Kollmitzer J, Crevenna R, Bittner C, Erdogmus CB, Nicolakis J. Pulsed magnetic field therapy for osteoarthritis of the knee - a double-blind sham-controlled trial. Wiener Klinische Wochenschrift 2002;114(15-6): 678–84. Pipitone 2001 {published data only} Pipitone N, Scott DL. Magnetic pulse treatment for knee osteoarthritis: a randomised, double-blind, placebocontrolled study. Current Medical Research and Opinion 2001;17(3):190–6. Thamsborg 2005 {published data only} Thamsborg G, Florescu A, Oturai P, Fallentin E, Tritsaris K, Dissing S. Treatment of knee osteoarthritis with pulsed electromagnetic fields: a randomized, double-blind, placebo-controlled study. Osteoarthritis and Cartilage 2005; 13(7):575–81. Trock 1993 {published data only} Trock DH, Bollet AJ, Dyer RH Jr, Fielding LP, Miner WK, Markoll R. A double-blind trial of the clinical effects of pulsed electromagnetic fields in osteoarthritis. Journal of Rheumatology 1993;20(3):456–60. Trock 1994 {published data only} Trock DH, Bollet AJ, Markoll R. The effect of pulsed electromagnetic fields in the treatment of osteoarthritis of the knee and cervical spine. Report of randomized, double blind, placebo controlled trials. Journal of Rheumatology 1994;21(10):1903–11. Zizic 1995 {published data only} Zizic TM, Hoffman KC, Holt PA, Hungerford DS, O’Dell JR, Jacobs MA, et al.The treatment of osteoarthritis of the knee with pulsed electrical stimulation. Journal of Rheumatology 1995;22(9):1757–61.

References to studies excluded from this review Alcidi 2007 {published data only} Alcidi L, Beneforti E, Maresca M, Santosuosso U, Zoppi M. Low power radiofrequency electromagnetic radiation for the treatment of pain due to osteoarthritis of the knee. Reumatismo 2007;59(2):140–5. Ay 2009 {published data only} Ay S, Evcik D. The effects of pulsed electromagnetic fields in the treatment of knee osteoarthritis: a randomized, placebo-controlled trial. Rheumatology International 2009; 29(6):663–6. Battisti 2004 {published data only} Battisti E, Piazza E, Rigato M, Nuti R, Bianciardi L, Scribano A, et al.Efficacy and safety of a musically modulated electromagnetic field (TAMMEF) in patients affected by knee osteoarthritis. Clinical and Experimental Rheumatology 2004;22(5):568–72. Danao-Camara 2001 {published data only} Danao-Camara T, Tabrah FL. The use of pulsed electromagnetic fields (PEMF) in osteoarthritis (OA) of the

knee preliminary report. Hawaii Medical Journal 2001;60 (11):288,300. Fischer 2005 {published data only} Fischer G, Pelka RB, Barovic J. Adjuvant treatment of osteoarthritis of the knee with weak pulsing magnetic fields. Results of a prospective, placebo controlled trial [Adjuvante Behandlung der Gonarthrose mit schwachen pulsierenden Magnetfeldern Ergebnisse einer prospektiven, plazebo–kontrollierten vergleichenden Therapiestudie]. Zeitschrift fur Orthopadie und Ihre Grenzgebiete 2005;143 (5):544–50. Fischer 2006 {published data only} Fischer G, Pelka RB, Barovic J. Adjuvant treatment of osteoarthritis of the knee with weak pulsing magnetic fields - results of a prospective, placebo controlled trial [Adjuvante Behandlung der Gonarthrose mit schwachen pulsierenden Magnetfeldern Ergebnisse einer prospektiven, plazebo–kontrollierten vergleichenden Therapiestudie]. Aktuelle Rheumatologie 2006;31:226–33. Hinman 2002 {published data only} Hinman MR, Ford J, Heyl H. Effects of static magnets on chronic knee pain and physical function: a double-blind study. Alternative Therapies in Health and Medicine 2002;8 (4):50–5. Jack 2006 {published data only} Farr J, Mont MA, Garland D, Caldwell JR, Zizic TM. Pulsed electrical stimulation in patients with osteoarthritis of the knee: follow up in 288 patients who had failed nonoperative therapy. Surgical Technology International 2006; 15:227–33. Jacobson 2001 {published data only} Jacobson JI, Gorman R, Yamanashi WS, Saxena BB, Clayton L. Low-amplitude, extremely low frequency magnetic fields for the treatment of osteoarthritic knees: a double-blind clinical study. Alternative Therapies in Health and Medicine 2001;7(5):54-64, 66-9. Kulcu 2009 {published data only} Kulcu DG, Guslen G, Altunok E. Short-term efficacy of pulsed electromagnetic field therapy on pain and functional level in knee osteoarthritis: a randomized controlled study. Turkish Journal of Rheumatology 2009;24(3):144–8. Liu 2004 {published data only} Liu WC, Liu Y, Zhang J. Effect of electromagnetic field on treating knee osteoarthritis. Proceedings of Clinical Medicine Journal 2004;13(4):281–2. Ozgüçlü 2010 {published data only} Ozgüçlü E, Cetin A, Cetin M, Calp E. Additional effect of pulsed electromagnetic field therapy on knee osteoarthritis treatment: a randomized, placebo-controlled study. Clinical Rheumatology 2010;29(8):927–31. Pavlovi 2012 {published data only} Pavlovi AS, Djurasi LM. The effect of low frequency pulsing electromagnetic field in treatment of patients with knee joint osteoarthritis. Acta Chirurgica Iugoslavica 2012; 59(3):81–3.


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Rigato 2002 {published data only} Rigato M, Battisti E, Fortunato M, Giordano N. Comparison between the analgesic and therapeutic effects of a musically modulated electromagnetic field (TAMMEF) and those of a 100 Hz electromagnetic field: blind experiment on patients suffering from cervical spondylosis or shoulder periarthritis. Journal of Medical Engineering & Technology 2002;26(6):253–8.

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Sutbeyaz 2006 {published data only} Sutbeyaz ST, Sezer N, Koseoglu BF. The effect of pulsed electromagnetic fields in the treatment of cervical osteoarthritis: a randomized, double-blind, sham-controlled trial. Rheumatology International 2006;26(4):320–4.

Bellamy 1997 Bellamy N, Kirwan J, Boers M, Brooks P, Strand V, Tugwell P, et al.Recommendations for a core set of outcome measures for future phase III clinical trials in knee, hip, and hand osteoarthritis. Consensus Development at OMERACT III. Journal of Rheumatology 1997;24(4):799–802.

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De Angelis 2004 De Angelis C, Drazen JM, Frizelle FA, Haug C, Hoey J, Horton R, et al.Clinical trial registration: a statement from the International Committee of Medical Journal Editors. Annals of Internal Medicine 2004;141(6):477–8. De Mattei 2001 De Mattei M, Caruso A, Pezzetti F, Pellati A, Stabellini G, SollazzoV, et al.Effects of pulsed electromagnetic fields on human articular chondrocyte proliferation. Connective Tissue Research 2001;42(2):1–11. De Mattei 2003 De Mattei M, Pasello M, Pellati A, Stabellini G, Massari L, Gemmati D, et al.Effects of electromagnetic fields on proteoglycan metabolism of bovine articular cartilage explants. Connective Tissue Research 2003;44(3-4):54–9. De Mattei 2004 De Mattei M, Pellati A, Pasello M, Ongaro A, Setti S, Massari L, et al.Effects of physical stimulation with electromagnetic field and insulin growth factor-I treatment on proteoglycan synthesis of bovine articular cartilage. Osteoarthritis and Cartilage 2004;12(10):793–800. Fidelix 2006 Fidelix TS, Soares BG, Trevisani VF. Diacerein for osteoarthritis. Cochrane Database of Systematic Reviews 2006, Issue 1. [DOI: 10.1002/14651858.CD005117.pub2] Fini 2005 Fini M, Giavaresi G, Carpi A, Nicolini A, Setti S, Giardino R. Effects of pulsed electromagnetic fields on articular hyaline cartilage: review of experimental and clinical studies. Biomedicine and Pharmacotherapy 2005;59(7):388–94. Fioravanti 2002 Fioravanti A, Nerucci F, Collodel G, Markoll R, Marcolongo R. Biochemical and morphological study of human articular chondrocytes cultivated in the presence of pulsed signal therapy. Annals of the Rheumatic Diseases 2002;61(11): 1032–3. Fransen 2008 Fransen M, McConnell S. Exercise for osteoarthritis of the knee. Cochrane Database of Systematic Reviews 2008, Issue 4. [DOI: 10.1002/14651858.CD004376.pub2] Fransen 2009 Fransen M, McConnell S, Hernandez-Molina G, Reichenbach S. Exercise for osteoarthritis of the hip. Cochrane Database of Systematic Reviews 2009, Issue 3. [DOI: 10.1002/14651858.CD007912] Graziana 1990 Graziana A, Ranjeva R, Teissié J. External electric fields stimulate the electrogenic calcium/sodium exchange in plant protoplasts. Biochemistry 1990;29(36):8313–8. Guyatt 2008 Guyatt G, Oxman AD, Vist GE, Kunz R, Falck-Ytter Y, Alonso-Coello P, et al.GRADE Working Group. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 2008;336(7650): 924–6.

Hennekens 1987 Hennekens CH, Buring JE. Measures of Disease Frequency and Association. Boston: Little, Brown and Co., 1987. Higgins 2011 Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org. Hulme 2002 Hulme J, Robinson V, DeBie R, Wells G, Judd M, Tugwell P. Electromagnetic fields for the treatment of osteoarthritis. Cochrane Database of Systematic Reviews 2002, Issue 1. [DOI: 10.1002/14651858.CD003523] Laupattarakasem 2008 Laupattarakasem W, Laopaiboon M, Laupattarakasem P, Sumananont C. Arthroscopic debridement for knee osteoarthritis. Cochrane Database of Systematic Reviews 2008, Issue 1. [DOI: 10.1002/14651858.CD005118.pub2] Lee 1993 Lee RC, Canaday DJ, Doong H. Review of the biophysical basis for the clinical application of electric fields in softtissue repair. Journal of Burn Care Rehabilitation 1993;54 (14):319–35. Lee 1997 Lee EW, Maffulli N, Li CK, Chan KM. Pulsed magnetic and electromagnetic fields in experimental achilles tendonitis in the rat: a prospective randomised study. Archives of Physical Medicine and Rehabilitation 1997;78(4):399–404. Lequesne 1987 Lequesne MG, Mery C, Samson M, Gerard P. Indexes of severity for osteoarthritis of the hip and knee. Validation - value in comparison with other assessment tests. Scandinavian Journal of Rheumatology. Supplement 1987;65: 85–9. Liu 1997 Liu H, Lees P, Abbott J, Bee JA. Pulsed electromagnetic fields preserve proteoglycan composition of extracellular matrix in embryonic chick cartilage. Biochimica et Biophysica Acta 1997;1336(2):303–14. March 2004 March LM, Bagga H. Epidemiology of osteoarthritis in Australia. Medical Journal of Australia 2004;180(5 Suppl): S1–10. Petitti 2000 Petitti DB. Meta-analysis, Decision analysis, and Costeffectiveness Analysis: Method for Quantitative Synthesis in Medicine. Oxford: Oxford University Press, 2000. Pezzetti 1999 Pezzetti F, De Mattei M, Caruso A, Cadossi R, Zucchini P, Carinci F, et al.Effects of pulsed electromagnetic fields on human chondrocytes: an in vitro study. Calcified Tissue International 1999;65(5):396–401. Pham 2003 Pham T, Van Der Heijde D, Lassere M, Altman RD, Anderson JJ, Bellamy N, et al.OMERACT-OARSI.


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Outcome variables for osteoarthritis clinical trials: the OMERACT-OARSI set of responder criteria. Journal of Rheumatology 2003;30(7):1648–54. RevMan 2012 The Nordic Cochrane Centre, The Cochrane Collaboration. Review Manager (RevMan). 5.1. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2012. Rodan 1978 Rodan GA, Bourret LA, Norton LA. DNA synthesis in cartilage cells is stimulated by oscillating electric fields. Science 1978;54(199):690–2. Rutjes 2010 Rutjes AWS, Nüesch E, Sterchi R, Jüni P. Therapeutic ultrasound for osteoarthritis of the knee or hip. Cochrane Database of Systematic Reviews 2010, Issue 1. [DOI: 10.1002/14651858.CD003132.pub2] Shupak 2003 Shupak NM. Therapeutic uses of pulsed magnetic-field exposure: a review. The Radio Science Bulletin 2003;12 (307):9–32. Singh 2013a Singh JA, Kundukulam JA, Kalore NV. Total hip replacement surgery versus conservative care for hip osteoarthritis and other non-traumatic diseases. Cochrane Database of Systematic Reviews 2013, Issue 9. [DOI: 10.1002/14651858.CD010731] Singh 2013b Singh JA, Dohm M, Borkhoff C. Total joint replacement surgery versus conservative care for knee osteoarthritis

and other non-traumatic diseases. Cochrane Database of Systematic Reviews 2013, Issue 9. [DOI: 10.1002/ 14651858.CD010732] Towheed 2004 Towheed T, Judd M, Hochberg M, Wells G. Acetaminophen for osteoarthritis. Cochrane Database of Systematic Reviews 2004, Issue 3. [DOI: 10.1002/ 14651858.CD004257.pub2] Towheed 2005 Towheed TE, Maxwell L, Anastassiades TP, Shea B, Houpt J, Robinson V, et al.Glucosamine therapy for treating osteoarthritis. Cochrane Database of Systematic Reviews 2005, Issue 2. [DOI: 10.1002/14651858.CD002946.pub2] Trock 2000 Trock DH. Electromagnetic fields and magnets. Investigational treatment for musculoskeletal disorders. Rheumatic Diseases Clinics of North America 2000;26(1): 51–62. Vavken 2009 Vavken P, Arrich F, Schuhfried O, Dorotka R. Effectiveness of pulsed electromagnetic field therapy in the management of osteoarthritis of the knee: a meta-analysis of randomized controlled trials. Journal of Rehabilitation Medicine 2009;41 (6):406–11. Verhagen 2007 Verhagen AP, Bierma-Zeinstra SM, Boers M, Cardoso JR, Lambeck J, de Bie R, et al.Balneotherapy for osteoarthritis. Cochrane Database of Systematic Reviews 2007, Issue 4. [DOI: 10.1002/14651858.CD006864] ∗ Indicates the major publication for the study


21

CHARACTERISTICS OF STUDIES

Characteristics of included studies [ordered by study ID] Fary 2011 Methods

Randomised, 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-


22

Fary 2011

(Continued)

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 Notes

Supported 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 Bias

Authors’ judgement

Support for judgement

Random sequence generation (selection Low risk bias)

Quote: “using computer-generated randomization in blocks of 6.”

Allocation concealment (selection bias)

Low risk

Quote: “Allocation, stratified by sex, age (60 years, 60-75 years, and 75 years), and baseline VAS pain scores (25-40 mm, 4160 mm, and 61-100 mm), was performed independently by an administrator, not otherwise involved in the study”

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

Quote: “This process ensured that all study investigators and participants remained blinded to allocation until analysis was complete.”

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

Quote: “This process ensured that all study investigators and participants remained blinded to allocation until analysis was complete.”

Blinding (performance bias and detection Unclear risk bias) Blinding of outcome assessors?

No information provided

Incomplete outcome data (attrition bias) All outcomes

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

Low risk


23

Fary 2011

(Continued)

(failed to attend final appointment) Selective reporting (reporting bias)

Unclear risk


Garland 2007 Methods

Randomised, 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

Interventions

Active 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

Outcomes

Primary 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


24

Garland 2007

(Continued)

The occurrence of rashes and other adverse device effects was solicited and recorded at each visit Notes

Supported by a grant from BioniCare Medical Technologies, Inc

Risk of bias Bias




Quote: “Each placebo and active device was assigned a unique number.”


Low risk

Quote: “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.”


Quote: “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.”


Quote: “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 Low risk bias) Blinding of outcome assessors?

Quote: “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.”


25

Garland 2007

(Continued)


Low risk

1/39 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 risk


Nelson 2013 Methods

Double-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

Outcomes

Primary 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)

Notes

Partially 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


26

Nelson 2013

(Continued)

Bias




Quote: ”Randomization was performed by the blinded assignment of devices according to their serial numbers.“


Low risk

Quote: ”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.“


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.


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.




Day 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)

High risk


27

Nelson 2013

(Continued)


Unclear risk


Nicolakis 2002 Methods

Randomised, 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

Interventions

Treatment 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

Outcomes

1) Primary outcomes: change between baseline and the end of treatment in the 240point 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

Notes

The 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 Bias




28

Nicolakis 2002

(Continued)


Quote: “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).”


Low risk

Quote: “All devices were numbered; only the study coordinator was aware of the code.”


Quote: “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.”






Low risk

3/18 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)


Unclear risk



29

Pipitone 2001 Methods

Randomised, 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)

Interventions

Active 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

Outcomes

1) 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)

Notes

This study was supported by an educational grant from Snowden Healthcare

Risk of bias Bias




Support for judgement Quote: “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.”

30

Pipitone 2001

(Continued)


Low risk

Quote: “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.”








High risk

10/39 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)


Unclear risk


Thamsborg 2005 Methods

Randomised, 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, preg-


31

Thamsborg 2005

(Continued)

nancy 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 Interventions

Active 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

Outcomes

1) 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

Notes

Economic support from IMK Almene Fond and from Københavns Amts Erhvervskontor

Risk of bias Bias



Random sequence generation (selection Unclear risk bias)

Quote: “This was a 1:1 randomized, controlled, double-blind add-on study.” No further information provided


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

Low risk

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


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



32

Thamsborg 2005

(Continued)




Low risk

3/45 missing from active group; 4/45 missing from sham group


Unclear risk


Trock 1993 Methods

Randomised, 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

Interventions

Active 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

Outcomes

Severity 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

Notes

Funded by Bio-Magnetic Therapy Systems, Inc.

Risk of bias Bias




33

Trock 1993

(Continued)


Quote: “Patients were randomized to receive active pulsed electromagnetic fields or placebo using a table of 1000 random digits.”


Low risk

Quote: “A code master record sheet was kept by an office administrator.”


Quote: “Both the patients and the examining physician remained blinded as to whether active pulsed electromagnetic fields or placebo was given.”


Quote: “Both the patients and the examining physician remained blinded as to whether active pulsed electromagnetic fields or placebo was given.”


Quote: “A code master record sheet was kept by an office administrator.”


High risk



Unclear risk


Trock 1994 Methods

Randomised, 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


34

Trock 1994

(Continued)

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 Interventions

Active 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

Outcomes

1) 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)

Notes

Supported by Bio-Magnetic Therapy Systems, Inc.

Risk of bias Bias




Quote: “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.”


Quote: “Separate lists of random numbers were kept for the patients.”

Low risk


35

Trock 1994

(Continued)


Quote: “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 High risk bias) Blinding of physicians?

Quote: “Only the therapy technician at the treatment center was informed, by means of a code.”


Quote: “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.”


Low risk

Double-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


Unclear risk


Zizic 1995 Methods

Randomised, 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

Interventions

Active 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


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Zizic 1995

(Continued)

active device. Patients were advised to use the instrument for 6 to 10 hours/day during the 4-week treatment period Outcomes

1) 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

Notes

This study was supported by Murray Electronics

Risk of bias Bias



Random sequence generation (selection Unclear risk bias)

Quote: “Patients were randomized to receive an active device or an identical appearing placebo device.” Comment: no further information provided


Quote: “Patients were randomized to receive an active device or an identical appearing placebo device.” Comment: no further information provided

Unclear risk


Quote: “...in a multicenter, prospective, randomized, placebo controlled, double blind study” Comment: probably done


Quote: “A nurse coordinator instructed patients in the proper use of the device.”


No further information provided


Low risk



Unclear risk


ACR: American College of Rheumatology DC: direct current Electromagnetic fields for treating osteoarthritis (Review) Copyright © 2013 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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MD: medical doctor NSAID: non-steroidal anti-inflammatory drug PMF: pulsed magnetic field TENS: transcutaneous electrical nerve stimulation VAS: visual analogue scale

Characteristics of excluded studies [ordered by study ID]

Study

Reason for exclusion

Alcidi 2007

The duration of treatment was only 5 days (once daily). Efficacy requires at least 4 weeks’ treatment duration (suggestion of several physiotherapists)

Ay 2009

All 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 2004

Treatments were given for 30 minutes for 15 days. The treatment duration did not match the inclusion criteria of this review

Danao-Camara 2001

Primary report, not a RCT

Fischer 2005

Randomisation 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 2006

The second version of Fischer 2005

Hinman 2002

The aim of this article was to assess the effect of static magnetic fields for chronic knee pain but not osteoarthritis

Jack 2006

Prospective, cohort study and not a RCT

Jacobson 2001

Treatment 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 2009

A therapy session lasted for 35 minutes and 15 sessions were performed during 3 weeks (5 sessions/week)

Liu 2004

Randomisation 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 2010

Both 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

Pavlovi 2012

The treatment period was only 10 days. The treatment duration did not match the inclusion criteria of this review


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(Continued)

Rigato 2002

The study included patients with cervical spondylosis and shoulder periarthritis without separately reported results and we could not extract data on cervical osteoarthritis

Sutbeyaz 2006

Treatment duration: twice a day for 30 minutes of 3 weeks duration. The duration did not match the inclusion criteria of this review

Tomruk 2007

Both 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

PEMF: pulsed electromagnetic field therapy RCT: randomised controlled trial


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DATA AND ANALYSES

Comparison 1. Electromagnetic fields versus placebo for osteoarthritis

Outcome or subgroup title 1 Pain 2 Physical function 3 Quality of life 4 Number of patients experiencing any adverse event 5 Number of patients who withdrew because of adverse events

No. of studies

No. of participants

Statistical method

Effect size

6 3 2 4

434 197 139 288

Mean Difference (IV, Random, 95% CI) Mean Difference (IV, Random, 95% CI) Std. Mean Difference (IV, Random, 95% CI) Risk Ratio (M-H, Fixed, 95% CI)

15.10 [9.08, 21.13] 4.55 [-2.23, 11.32] 0.09 [-0.36, 0.54] 1.17 [0.72, 1.92]

Risk Ratio (M-H, Fixed, 95% CI)

Totals not selected

1

WHAT’S NEW Last assessed as up-to-date: 3 October 2013.

Date

Event

Description

3 October 2013

New search has been performed

New search with six new studies.

3 October 2013

New citation required but conclusions have not changed New authors.

HISTORY Review first published: Issue 1, 2002

Date

Event

Description

8 May 2008

Amended

CMSG ID: C031-R.


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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.

INDEX TERMS Medical Subject Headings (MeSH) ∗ Electric

Stimulation Therapy; Clinical Trials as Topic; Electromagnetic Fields; Osteoarthritis [∗ therapy]

MeSH check words Humans


41

Health and electromagnetic fields.

Osteotomy for treating knee osteoarthritis.

Symptomatic Early Osteoarthritis of the Knee Treated With Pulsed Electromagnetic Fields: Two-Year Follow-up.

[Health effects of electromagnetic fields].

Health effects of electromagnetic fields.

[Illness caused by electromagnetic fields].

Health effects of electromagnetic fields.

Oral herbal therapies for treating osteoarthritis.

Electromagnetic Fields for the Regulation of Neural Stem Cells.

Electromagnetic fields and male breast cancer.

Efficient semi-analytical propagation techniques for electromagnetic fields.

Epidemiologic studies on electromagnetic fields and cancer.

Biological effects of low frequency electromagnetic fields.

Viscosupplementation for treating osteoarthritis in the military population.

Mesenchymal Stem Cells for Treating Articular Cartilage Defects and Osteoarthritis.

Stem cell therapies for treating osteoarthritis: prescient or premature?

Braces and orthoses for treating osteoarthritis of the knee.

Visualizing electromagnetic fields at the nanoscale by single molecule localization.

Effects of Electromagnetic Fields on Automated Blood Cell Measurements.

[Radiation doses in radiology and exposure to electromagnetic fields. Presentation].

Effects of electromagnetic fields on the motion of Euglena gracilis.

Extremely low frequency electromagnetic fields and cancer: the epidemiologic evidence.

Electromagnetic fields and cancer--media and public attention affect research.

Extremely low frequency (ELF) electromagnetic fields and leukaemia in children.