Pulsed electromagnetic field therapy for knee osteoarthritis
Records identiffied through
database searching
(n=241)
Additional records identiffied
through other sources
(n=0)
Records after duplicates removed
(n=163)
Records excluded by title
and abstract (n=149)
Records screened
(n=163)
Full-text articles
assessed for eligibility
(n=14)
Studies included in
qualitative synthesis
(n=8)
Full-text articles
excluded, with reasons:
Not classical PEMF:1
Not knee OA separately:1
Data unextractable:4
(n=6)
Studies included in
quantitative synthesis
(meta-analysis)
(n=8)
Fig. 1. Study flow diagram of search results and study selection.
tent of the assessment consisted mainly of the following items:
random sequence generation, allocation concealment, blinding
of participants and personnel, blinding of outcome assessment,
incomplete outcome data, selective reporting, and other bias.
There were 3 evaluation options for each item: low risk, high
risk, and unclear, based on the original research. A third reviewer
participated in the assessment when differences could not be
resolved through discussion.
Statistical analysis
Weighted mean differences (WMD) and 95% CIs were used to
estimate the pooled effects for continuous outcomes, including
VAS for pain and WOMAC scores. In addition, Cochrane’s Q
823
test and the I 2 test were used to evaluate heterogeneity among
all studies. When the I 2 test value exceeded 50%, indicating
high heterogeneity, a meta-analysis was performed using a
random effects model, whereas a fixed effects model was chosen
when the I 2 test value was 50% or less. In addition, sensitivity
analysis was performed by eliminating each study in turn so as
to estimate the effect of a single study on overall heterogeneity
and pooled effects. Publication bias was not performed, due to
the limited number of studies (n < 10) included in this analysis.
p < 0.05 was defined as a significant difference, and all statistical
analyses were performed by RevMan version 5.3.
RESULTS
Search results
A total of 241 studies were retrieved through searching the
electronic databases listed (Fig. 1). No additional records were
identified from other sources. Seventy-eight duplicate studies
were excluded initially, and a further 149 studies were exclu-
ded after reading the title and abstract. This left 14 studies that
needed to be further screened by reading the full text. As a result,
6 studies were excluded due to unextractable data, non-classical
PEMF therapy, or knee OA not reported separately. A final total
of 8 studies was included in this meta-analysis (15–22).
Study characteristics
The baseline characteristics, PEMF therapy parame-
ters, and treatment regimen of the 8 included studies,
with a total sample size of 421 patients, are shown in
Table I. These studies were all randomized placebo-
controlled trials involving patients of similar age, sex
ratio, and body mass index, which were published
between 1994 and 2016. There were some differences
in the parameters and treatment regimen of PEMF
therapy among all studies. In addition, 3 studies re-
Table I. Baseline characteristics, PEMF parameters and treatment regimen of included studies
PEMF therapy group
Placebo group
Disease
BMI,
duration,
BMI,
Age, years Female, kg/m 2
years
Age, years Female, kg/m 2
n Mean (SD) n
Mean (SD) Mean (SD) n Mean (SD) n
Mean (SD) Disease
duration
Year
Treatment
Mean (SD) Frequency Intensity regimen
Bagnato et al.
2016 (15)
Wuschech et
al. 2015 (16)
Nelson et al.
2013 (17)
Ay & Evcik
2009 (18) 30 68.6 (11.9) 21 27.7 (4.6) 12.4 (9.1) 30 66.9 (10.0) 22 27.1 (4.1) 11.9 (7.4)
44 63.4 (12.1) 15 N/A N/A 13 55.5 (10.8) 5 N/A N/A
15 55.5 (2.5) N/A 33.5 (1.9) N/A 19 58.4 (2.5) N/A 34.7 (1.7) N/A
30 58.9 (8.8) 21 N/A 3.6 (4.6) 25 57.7 (6.5) 19 N/A 3.5 (4.1)
Thamsborg et
al. 2005 (19) 42 60.4 (8.7) 20 27.0 (4.0) 7.5 (5.2) 41 59.6 (8.6) 25 27.5 (5.7) 7.9 (7.7)
N/A N/A 17 67.0 (7.0) 8 N/A N/A
N/A N/A 35 64.0 7 N/A N/A
N/A 7.4 (6.7) 44 65.8 (11.7) 31 N/A 8.1 (8.0)
Study
Nicolakis et al. 15 69.0 (5.0) 11
2002 (20)
Pipitone &
34 62.0
12
Scott 2001
(21)
Trock et al.
42 69.2 (11.5) 29
1994 (22)
1 MHz 9.5 mT
12 h a day, daily, 4
weeks
4–12 Hz
105 mT
5 min twice a day,
daily, 18 days
6.8 MHz
34±8 V/m 15 min twice a
day, daily, 6 weeks
50 Hz
105 uT
30 min/session, 5
sessions/week, 3
weeks
50 Hz
10 mV/cm 2 h/session, 5
sessions/week, 6
weeks
1–3,000 Hz 40 uT
30 min twice a
day, daily, 6 weeks
3–7.8 Hz
50 uT
10 min 3 times a
day, daily, 6 weeks
5–12 Hz 1–2.5 mT 30 min/session,
3–5 sessions/
week, 18 sessions
SD: standard deviation; BMI: body mass index; N/A: Not applicable.
J Rehabil Med 51, 2019