We performed a similar search strategy to that used by Hulme et al 2001 [5] with the following criteria for inclusion in the review.
Types of studies
1. Randomised controlled trials
2. Controlled clinical trials
Trials were not included if they measured bone and cartilage repair from electromagnetic therapy following a specific treatment for osteoarthritis, which would then no longer be applicable to all knee OA patients.
Types of participants
Those trials with subjects over 18 years of age, with clinical and radiological confirmation of the diagnosis were considered.
Types of intervention
All types of PEMF and Pulsed Electrical Stimulation trials were included. Although the latter relies on direct application of an electrical field rather than creating induced current through magnetic impulses, they act by the same mechanism. Trials that compared the intervention group using PEMF to a standard treatment were included, as well as placebo-controlled studies.
Outcomes
The main outcomes of interest were pain and functional disability as recorded by validated self report instruments such as the Western Ontario and McMasters University Osteoarthritis Index WOMAC [6], EuroQol [7], Arthritis Impact Measurement Scale AIMS[8] or SF-36 [9]. Studies that did not utilise validated outcome measures of pain and function were excluded.
We searched MEDLINE, AMED, EMBASE, HealthSTAR, CINAHL, PEDro, and SPORTDiscus and the Cochrane Controlled Trials Register (CCTR) from January 1966 to September 2005. The electronic search was complemented by the following hand searches of bibliographic references and abstracts published in special issues of specialized journals or in Conference Proceedings. Reference lists were hand-search for further identification of published work, presentations at scientific meetings and personal communications. Abstracts were not used if additional data could not be obtained. The publication bias could not be assessed due to the small number of included studies.
Search strategy
1 exp osteoarthritis/or osteoarthritis.tw.
2 electromagnetics.mp. or electromagnetic fields/[mp = title, abstract, registry number word, mesh subject heading]
3 electromagnetic$.tw.
4 exp electric stimulation therapy/
5 electrical stimulation.tw.
6 or/2–5
7 1 and 6
Assessing quality
Abstracts were read to make the final decision on selection of the full paper for review. The quality of the papers was assessed by two reviewers independently using a validated criteria checklist[10]. The maximum total score achievable was 5. Any differences were resolved by discussion between the reviewers. Differences unresolved in this manner were resolved in discussion with a third reviewer.
Statistical analysis
For pain and functional outcomes, weighted mean differences and standardised mean differences, with 95% confidence intervals, were calculated. Due to differences in follow up assessment timings, data were analysed from the immediate post-intervention assessments. A priori it was decided that an effect size difference in post treatment scores of greater than 0.2 was required to represent a clinically important difference. Effect sizes were calculated by dividing the difference in post-treatment group mean scores by the pooled standard deviation of both baseline scores.
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