Pulsed Electromagnetic Field Therapy in People with Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

Background and Objectives: Knee osteoarthritis (KOA) is a major cause of global disability. The efficacy of a non-invasive treatment, pulsed electromagnetic field (PEMF) therapy, remains debated. This systematic review and meta-analysis evaluate PEMF's effectiveness on KOA, exploring the influence of device parameters. Materials and Methods: We systematically searched PubMed, Embase, and the Cochrane Library for randomized controlled trials (RCTs) from 2015 to 2025. Nine RCTs with a total of 457 patients were included. Primary outcomes were pain (Visual Analog Scale-VAS) and function (Western Ontario and McMaster Universities Osteoarthritis Index-WOMAC). Data were pooled using a random-effects model with subgroup analyses based on PEMF amplitude and frequency. Results: No significant improvement in VAS pain or total WOMAC scores was found at one month. However, time-dependent effects were observed. WOMAC-pain improved significantly at 18-21 days (MD = -1.63, 95% CI: -2.43 to -0.82, I2 = 28%) but not at one month. Conversely, WOMAC-stiffness (MD = -1.11, 95% CI: -1.386 to -0.85, I2 = 0%) and daily activity (MD = -3.39, 95% CI: -4.81 to -1.97, I2 = 0%) improved significantly only at the one-month. Objective functional measures did not improve, and the overall risk of bias across studies was high. The efficacy of PEMF is also influenced by the amplitude and frequency. Conclusions: PEMF efficacy for KOA is nuanced, with benefits dependent on timing and device parameters. High frequency gives fast pain relief; high amplitude builds function. Though statistically significant, these improvements may not reach thresholds for clinical meaningfulness. Significant heterogeneity in treatment protocols is a major barrier to clear conclusions. Standardized, large-scale RCTs are needed to determine optimal parameters and confirm PEMF's clinical role.