Patient Population:

All adult patients with knee OA. Reported median age was 63 years (range = 60 – 73). Median proportion of female participants enrolled was 72.3 (range = 50-88.1). The K-L radiological score of participants ranged from 2.3 – 3.3 (median = 2.7).

Intervention:

Pulsed Electro-Magnetic Field (PEMF). Reported details of the PEMF regimen varied substantially (in the detail and content of what was reported). Machine operating frequency, pulse length, electrical field strength, mean power, total energy/day were all details that were reported infrequently by trial authors. Although ICNIRP reference levels, magnetic flux levels and pulse frequency were reported more often, there was little consistency. Pulse Frequency: several trials (3) reported 50 Hz, 6 trials reported differing ranges. Length of treatment used: most common duration identified was 6 weeks.

Comparison:

PEMF was compared to a placebo. Type of placebo used:  PEMF switched off, PEMF switched on but with no output, PEMF of near zero intensity and PEMF with a constant (non-pulsed) current).  5 trials did not provide a full description of the placebo condition used. 14 trials were identified for inclusion in the present review. Five trials were classified as high quality based on PEDro scoring. 13/14 trials were small – with less than 50 participants allocated to each condition. 482 patients, in total, received PEMF and 448 were allocated to control/placebo conditions. Egger’s test and funnel plots revealed no evidence of publication bias.

Outcome:

1. Pain: PEMF vs. placebo – no significant difference at 4, 8, 12 or 16 weeks.
2. Function: PEMF vs. placebo – no significant difference at 4, 12 or 16 weeks.
3. Function: PEMF vs. placebo (5 studies) – significant difference in favour of PEMF at 8 weeks (SMD=0.30; 95% CI 0.07 to 0.53, I2=0%).