Photobiomodulation therapy combined with a static magnetic field for chronic non-specific knee pain: protocol for a multicentre, randomised, triple-blind, placebo-controlled trial
Ernesto Cesar Pinto Leal-Junior, Luana Barbosa Dias, Heliodora Leão Casalechi, Jociane Schardong, Older Manoel de Araújo-Silva, Rodrigo Della Méa Plentz, Douglas Scott Johnson, Shaiane Silva TomazoniIntroduction
Chronic non-specific knee pain represents a prevalent and disabling musculoskeletal condition that often lacks a clearly identifiable structural cause and evidence-based management strategies. Photobiomodulation therapy combined with a static magnetic field (PBMT-sMF) has been proposed as a non-invasive approach capable of modulating inflammation, reducing oxidative stress and promoting tissue repair. However, high-quality clinical evidence regarding its effectiveness in this population remains scarce. This trial aims to investigate the effects of PBMT-sMF on pain intensity, biochemical and functional outcomes and patient satisfaction in individuals with chronic non-specific knee pain.
Methods and analysis
This superiority, multicentre, randomised, placebo-controlled, triple-blind clinical trial will include 86 adults (aged 18–50 years) with chronic, unilateral, non-specific knee pain. Participants will be randomly allocated (1:1) to receive either active or placebo PBMT-sMF, applied three times per week for four consecutive weeks (12 sessions in total). The active intervention will be delivered using a Multi Radiance Medical Super Pulsed Laser device (905 nm laser, 850 nm infrared LEDs [light-emitting diodes], 640 nm red LEDs and an sMF), while the placebo device will be identical in appearance but emit biologically inactive energy. The primary outcome will be pain intensity measured by a 100 mm Visual Analogue Scale at the end of treatment. Secondary outcomes will include prostaglandin E₂ (PGE₂) concentrations, subjective knee function (International Knee Documentation Committee), patient satisfaction and safety (adverse events and co-interventions), all assessed at the end of treatment and reassessed 1 week postintervention. Pain intensity will also be measured at the 1-week follow-up. Statistical analyses will follow the intention-to-treat principle, with significance set at p<0.05.
Ethics and dissemination
This study was approved by the Research Ethics Committee of Irmandade da Santa Casa de Misericórdia de Porto Alegre and prospectively registered on ClinicalTrials.gov (
Trial registration number