Effects of photobiomodulation therapy combined with static magnetic field on pain and function in patients with lateral epicondylitis: a multicentre, randomised, placebo-controlled trial

Introduction Photobiomodulation therapy (PBMT), particularly when combined with a static magnetic field (PBMT-sMF), is a promising non-pharmacological approach for managing musculoskeletal disorders. However, high-quality evidence for its efficacy in lateral epicondylitis remains limited. Objectives The study aims to investigate the effectiveness of PBMT-sMF vs placebo in reducing pain, improving function and modulating inflammatory markers in individuals with lateral epicondylitis. Design Multicentre, randomised, triple-blinded, placebo-controlled trial. Setting Three outpatient physiotherapy clinics in Brazil. Participants 50 adults (18–50 years) with unilateral lateral epicondylitis and baseline pain ≥50 on the visual analogue scale (VAS). Interventions Participants received either active PBMT-sMF (n=25) or placebo (n=25), 2 times per week for 3 weeks. PBMT-sMF involved multi-wavelength irradiation at 4 epicondyle sites (60 s; 27.1 J/site). The placebo group underwent the same procedure without active irradiation. Primary and secondary outcome measures The primary outcome was degree of pain rating (VAS). Secondary outcomes included forearm disability (Patient-Rated Tennis Elbow Evaluation, PRTEE), grip strength, serum tumour necrosis factor-alpha (TNF-α) levels and treatment satisfaction. Assessments were conducted at baseline, post-treatment (3 weeks) and at 4-week follow-up. Results PBMT-sMF yielded a higher responder rate (defined as the proportion of participants achieving at least a 30% reduction in pain intensity relative to baseline) than placebo (72% vs 40%, p=0.045), with a clinically and statistically significant between-group difference. Compared with placebo, the PBMT-sMF group showed significantly greater reductions in pain intensity both at the end of treatment (51.4±19.8 vs 36.9±22.6; p=0.0223) and at follow-up (37.4±24.1 vs 20.3±21.2; p=0.0049). TNF-α levels also decreased significantly in the PBMT-sMF group compared with placebo at both time points (p<0.0001 and p=0.0019, respectively). No significant between-group differences were observed for PRTEE scores, grip strength or treatment satisfaction. No major adverse events were reported. Conclusions PBMT-sMF significantly reduced pain intensity and TNF-α levels, suggesting an anti-inflammatory mechanism. Although functional outcomes were not improved, PBMT-sMF may be a valuable short-term, non-invasive option for lateral epicondylitis pain management. Trial registration number NCT04829734 on ClinicalTrials.gov