Background: Chronic musculoskeletal pain is a global health issue, affecting over 1.7 billion people, including 619 million with low back pain, a leading cause of disability. There is growing interest in non-invasive, safe, non-drug alternatives, such as magnetic therapies, for persistent musculoskeletal pain. The Powerinsole® device is an innovative and wearable flexible gel pad which incorporates a multipolar array of permanent magnets generating a spatially varying static magnetic field. The device is intended to support the alleviation of musculoskeletal pain in adults during daily activities (e.g. back, neck, knee, foot and heel regions). The trial was designed to determine whether daily use of the Powerinsole® device for 40 days reduces pain more effectively than a placebo. The trial also evaluated functional outcomes, analgesic use, and patient acceptance. For clarity, this corresponds to a spatially complex static magnetic field); due to body movement and flexible placement, local exposure may vary dynamically although the underlying field remains static.

Methods: Following the CONSORT guidelines, we conducted a prospective, double-blind, randomized, placebo-controlled crossover trial comparing the Powerinsole® device to a visually identical placebo device with a a non-magnetized insert in retail workers suffering from chronic musculoskeletal pain. Participants were instructed to wear the device for at least 4 hours per day on the designated body area. Adverse events and device-related complaints were recorded at each visit per protocol. Retail store employees were randomly assigned (1:1) to use either the active Powerinsole® or the placebo for 40 days. Participants and investigators were blinded to group assignment. Adults (N=117; 72 female, 45 male; average age 43.2 years) with chronic pain lasting at least 3 months and a baseline Numeric Rating Scale (NRS) pain score of 4 or higher were randomly assigned 1:1 to either Group A (active Powerinsole® or Group B (placebo for Days 0-20, then crossover to active from Day 21- 40). Assessments took place on Days 0, 10, 20, 30, and 40. The primary endpoint was the Pain NRS score at Day 20 (between-group comparison). Key secondary endpoints included work interference, sleep, mood, quality of life, analgesic use, satisfaction, and responders achieving the minimal clinically significant difference (MCID), defined as a reduction of 2 or more points on the Pain NRS from Day 0 to Day 20. Outcomes at Day 40 were predefined for secondary and longitudinal analyses only.

Results: At Day 20, active treatment resulted in lower Pain NRS scores than placebo between-group difference -2.21 NRS, 95% CI -2.79 to -1.63; p < 0.001. Work interference also favored the active group -2.53 NRS, 95% CI -3.06 to -2.00; p < 0.001. MCID responder rates at Day 20 were higher with active treatment compared to placebo (61.5% [32/52] vs 1.9% [1/54]; p < 0.001). After crossover, both groups were on active treatment; by Day 40, differences narrowed but still favored the initially active group for pain (-0.86, 95% CI -1.44 to -0.29; p = 0.004; d = 0.5) and work interference (−0.84, 95% CI -1.48 to -0.19; p = 0.012; d = 0.7). Day-40 responder rates were similar (66.7% [38/57] vs 59.3% [32/54]; p = 0.42). Secondary patient-reported outcomes (sleep, mood, quality of life) improved during active treatment in both arms, with divergence during the blinded phase and convergence after crossover. No serious adverse events were reported; the device was well tolerated, and satisfaction was high.

Conclusions: In a double-blind, placebo-controlled trial with crossover, the Powerinsole® device that generates a spatially complex static magnetic field produced clinically and statistically meaningful reductions in pain and work interference at Day 20 versus placebo, with substantial responder rates and favorable tolerability. Benefits persisted after crossover, with improvements across broader patient-reported outcomes. These findings support Powerinsole® as a non-pharmacologic, low-risk adjunct for chronic musculoskeletal pain and warrant confirmatory trials with baseline models and mechanistic endpoints.