To assess the effect of pulsed electromagnetic fields on joint pain and other symptoms due to osteoarthritis.

MEDLINE (from 1985 to 2001) EMBASE (from 1982 to 2001) and CINAHL (from 1980 to 2001) were searched for reports published in the English language; the keywords were stated. Only full reports were eligible.

Study designs of evaluations included in the review

Controlled trials were eligible for inclusion. The included studies were randomised controlled trials (RCTs), non-randomised controlled trials and non-controlled studies with retrospective data collection.

Specific interventions included in the review

Studies of the application of pulsed electromagnetic fields were eligible for inclusion. The included studies compared pulsed electromagnetic fields with placebo.

Participants included in the review

Studies of people with disability due to osteoarthritis were eligible for inclusion. The included studies were of men and women with osteoarthritis (knee, cervical and lumbar spine), soft tissue injuries, osteonecrosis, persistent rotator cuff tendinitis, chronic lateral humeral epicondylitis or acute whiplash injury, post-polio patients, and patients who had tibial or femoral osteotomy for the treatment of osteoarthritic joints or lumbar fusion surgery.

Outcomes assessed in the review

The inclusion criteria were not explicitly defined in terms of the outcomes. The review reported results for pain, function, 'responders' and radiographs. The included studies assessed pain using visual analogue scales, and assessed function using Lequesne's algofunctional index and activities of daily living.

How were decisions on the relevance of primary studies made?

The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.

RCTs of pulsed electromagnetic treatments for osteoarthritis were assessed according to criteria described by van der Heijden (see Other Publications of Related Interest). These criteria included: homogeneous group of participants defined by explicit inclusion criteria; adequate method of randomisation; baseline similarity of the treatment groups; less than 10% withdrawal and equal withdrawal rates across the treatment groups; less than 10% missing values at assessment; and standardised cointerventions and blinding of the interventions and assessments. The authors did not state how the papers were assessed for validity, or how many reviewers performed the validity assessment.

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. The following information were tabulated for some studies: sample size, characteristics of the participants, study design, intervention and the measures used to assess the outcomes.

How were the studies combined?

A narrative synthesis of the studies was undertaken.

How were differences between studies investigated?

Differences between the studies were not investigated.

Details of 6 studies were presented in tabular format: 5 RCTs (306 people) and one retrospective study (45 people) in people with osteoarthritis or soft tissue injuries. Other 'related' clinical studies were also included.

The results from studies that were presented in tabular format are reported below.

One retrospective study (45 people with osteoarthritis plus 35 people with soft tissue injuries) found that electromagnetic fields improved self-reported pain, compared with baseline levels, at 6 weeks and 6 months. No data were presented in the review.

One RCT (27 people with osteoarthritis of the knee) found that low-frequency pulsed waves improved pain and activities of daily living compared with placebo control. The review reported that the treated group improved by 23 to 61%, compared with improvements of 2 to 18% in the control group; no other details were reported.

One RCT (86 people with knee and 81 people with cervical osteoarthritis) found that pulsed electromagnetic fields improved pain and activities of daily living, compared with placebo control, both post-treatment and at 1 month. No data were presented in the review.

One RCT (40 people) found an increased proportion of responders at 1 month, and improved pain and function in the treated group 3 months after treatment, compared with placebo (P<0.05). This RCT was published as an abstract and the results were not discussed in the text, although they were listed in the data extraction table.

One RCT (32 patients having femoral inter-trochanteric osteotomy for arthritis) found that pulsed electromagnetic fields significantly improved healing (assessed radiologically) at 3 months in comparison with no fields (P<0.01).

One RCT (40 patients having valgus tibial osteotomy for knee arthritis) found that pulsed electromagnetic fields significantly improved healing (assessed radiologically) at 60 days in comparison with no fields.

Three controlled studies assessed pulsed electromagnetic fields in other inflammatory conditions (persistent rotator cuff tendonitis, chronic lateral humeral epicondylitis, and whiplash injury). These studies were described in the text of the review.

Further research into the effect of pulsed electromagnetic fields on pain, function and joint repair processes in osteoarthritic joints is required.

The review question was reasonably clear in terms of the study design, intervention and participants, although the inclusion criteria were not defined in terms of the outcomes. However, evidence from studies not meeting the inclusion criteria for the study design and participants were also reported in the 'Results' section. Three relevant sources were searched and the search terms were stated. Limiting the included studies to reports published in English may have omitted some relevant studies. The authors stated that only full reports were eligible, but some studies published only in abstract form were also included in the review. No attempt was made to locate unpublished studies, thus raising the possibility of publication bias. The methods used to select the studies, assess validity and extract the data were not described; hence, any efforts made to reduce errors and bias cannot be judged. The validity was assessed using established criteria and methodological limitations in some, but not all, of the included studies were discussed in the text of the review.

Relevant information on some of the included studies was tabulated, but insufficient details of the study results were presented. It was unclear whether the reporting of the results in the original studies was adequate. In addition, it was not stated whether the measures used to assess the outcomes in the individual studies had been validated. Given the small number of studies, the studies were appropriately grouped in a narrative synthesis. However, the results in the review were not structured or reported clearly. The authors' conclusion that more research is required appeared reasonable given the evidence presented.

Practice: The authors did not report any implications for practice.

Research: The authors stated that well-designed double-blind controlled trials with larger groups of diverse patients are required to assess the effect of pulsed electromagnetic fields on osteoarthritis. The authors further stated that the research should include three treatment arms: one with active stimulation, one with sham stimulation and one usual intervention. In addition, it should assess overall function, quality of life and the requirement for medication, and determine the optimum wave form characteristics.

Van der Heijden, GJ, van der Windt DA, de Winter AF. Physiotherapy for patients with soft tissue shoulder disorders: a systematic review of randomised clinical trials. BMJ 1997;315:25-30.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.