Customized Photobiomodulation Modulates Pain and Alters Thermography Pattern in Patients with Knee Osteoarthritis: A Randomized Double-Blind Pilot Study

Background: Photobiomodulation therapy (PBMT) modulates a wide variety of biological processes, leading to anti-inflammatory and analgesic effects. Understanding the mechanisms underlying therapeutic effects of PBMT remains challenging due to varying outcomes observed between wavelengths, dosage, and site of application. Our research group has dedicated close attention to customization and individualization of dosimetry for PBMT protocols. Preliminary data showed that using an individualized treatment could solve contradictory results reported by previous studies. Based on literature and our preliminary data on light absorption, the goal of the present pilot is to determine whether our individualized dosimetry is a feasible method to assist osteoarthritis (OA) pain control. Methods: This parallel two-arm controlled-pilot study aimed to assess whether personalized PBMT can be effective in the treatment of painful chronic knee OA. Thirty-one patients were randomly allocated into treatment and placebo group (sham irradiation), and the treatment procedure was performed twice a week, for 5 weeks. The PBMT was applied using 850 nm with continuous wave and a total of 526-1402 J each session. Individualized dosimetry was chosen based on each patient's body mass index and skin color. Quality-of-life (QOL) questionnaires and serum/urine analyses were performed before and after treatment was over. Both examiners and participants were blinded to group allocation. Results: Pain scores were reduced significantly in the 4th, 5th, and 10th sessions and remained lower 6 weeks posttherapy in the treatment group when compared to the placebo group. Moreover, the treatment group's results were improved in QOL questionnaires score, dopamine level, and in microcirculation. Conclusions: The present results provide initial evidence that customized photobiomodulation (PBM) reduce pain levels in short- and medium-term in patients with symptomatic knee OA when compared to placebo group. Furthermore, we have provided evidence that customized PBM is able to improve the QOL of those patients.