Title: Photobiomodulation reduces pain in patients with shoulder Tendinopathy

Abstract

Objectives: Summary and discussion of a systematic review and meta-analysis on efficacy of low-level laser therapy (LLLT) for shoulder tendinopathy. Results: Positive effects reported in 11 of 17 (73%) studies. Six studies reported no significant effects but 4 were found to have inadequate dosage. Eleven of 15 studies addressing pain relief favored LLLT over no treatment, placebo, or other modalities. When only studies with adequate dosage based on World Association for PhotobiomoduLation Therapy (WALT) recommendations were used, 10 of 11 (90%) studies reported significant pain reduction. Discussion: Photobiomodulation (PBM) therapy entails the therapeutic use of light energy to affectphotophysical and photochemical mechanisms of endogenous chromophores. LLLT is one form of PBM used to inhibit pain and inflammation or stimulate wound healing and tissue regeneration. PBM therapy can be used as a monotherapy or as an adjunct with other interventions to reduce pain associated with shoulder tendinopathies.To obtain optimal outcomes, clinicians mustprovide adequate dosage energy in joules (J) to the tissue. Distance to the target tissue, pigmentation, makeup of tissue content, and size of the total tissue area (cm2) treated affects dosing. Dosage is related to the wavelength of light, number of diodes for each energy source, irradiation area point size (cm2) of the aperture, and the calibration of the PBM device. Power output is affected by the peak power (W), pulse rate or frequency (Hz), pulse width (s), and duty cycle (%) while energy (J) is affected by power (W) multiplied by treatment time (s). Dosage should be based onWALT minimum recommendations of an energy density of 2 to 4 J/cm2 or 2 to 8J of total energy. Conclusion: PBM can be an effective tool for treating shoulder tendinopathies if clinicians understand tissue considerations, unit settings, and follow WALT recommended dosage guidelines.