Effect of Pulsed Electromagnetic Field and Microwave Therapy on Pain and Physical Function in Older Adults With Knee Osteoarthritis: A Randomized Clinical Trial.

Background and purpose: The objective was to examine the adjuvant effect of active pulsed electromagnetic field (PEMF) versus microwave (MW) therapy, as well as sham PEMF, in addressing pain and improving functionality for treating knee osteoarthritis (KOA).

Methods: This was a double-blind, placebo-controlled, randomized clinical trial. Individuals diagnosed with KOA were assigned to an intervention combining an exercise program (EX) with active PEMF, MW, or sham PEMF. The main outcomes were pain, reported on a visual analogue scale (VAS), and functionality, assessed using the Western Ontario and McMaster Universities Arthritis (WOMAC) questionnaire, and the Timed Up and Go test (TUG). The outcomes were measured preintervention, immediately postintervention, and at 1 and 4 months of follow-up (FU).

Results: Sixty individuals (n = 83 knees) were evaluated. Significant between-group differences were found in WOMAC stiffness (rmMANOVA (F(2,77) = 4.33, P = .017, partial η 2  = 0.10)). A notable interaction effect between group and time was found for the WOMAC pain score (rmMANOVA (F(2, 77) = 3.14, P = .049, partial η 2  = 0.07)). After 4 months, the PEMF + EX group demonstrated superior pain relief compared to the sham PEMF + EX (WOMAC pain "mean difference ± standard error between-groups": -3.2 ± 1.2, P = .028) and MW + EX (VAS pain: -2.1 ± 0.9, P = .042) groups. PEMF + EX perceived less stiffness than did the sham PEMF + EX in both the pre-FU (WOMAC stiffness: -1.6 ± 0.6, P = .047), 1-month FU (-1.7 ± 0.6, P = .015) and 4-month FU (-1.4 ± 0.6, P = .038), with no changes in the MW + EX group. WOMAC function score showed greater improvement in the PEMF + EX group compared to the MW + EX group at 4-month of FU (-9.0 ± 3.6, P = .039). Only PEMF + EX showed a positive effect on the TUG score at 1-month FU (-1.7 ± 0.5, P = <.001) and 4-month of FU (1.9 ± 0.5, P = .020).

Conclusions: The application of PEMF could be a useful adjuvant treatment to exercise programs to further decrease pain and improve knee stiffness and function in individuals with KOA in the medium term compared to MW and sham PEMF.