Photobiomodulation Therapy to Reduce Pain and Inflammation in Patients With Gonarthrosis: a Multicenter Randomized, Double-blind, Placebo-controlled Clinical Trial

Osteoarthritis (OA) is one of the main causes of chronic pain and physical disability, which directly impacts the quality of life of patients. The prevalence of OA among adults over 60 years of age is approximately 13% in women and 10% in men. Knee OA (gonarthrosis) has as main risk factors, in addition to age, female gender and obesity. It can involve all three compartments of the knee and is clinically characterized by pain and progressive impairment of cartilage, bone, synovial membrane and ligaments. Pharmacological treatment of gonarthrosis is based on approaches to reduce symptoms and/or pain, with joint replacement (arthroplasty) being reserved for more advanced forms of the disease. In general, currently available treatments have only moderate effects and low satisfaction rates among patients. Photobiomodulation Therapy (TFBM) has been used for at least 50 years by health professionals to treat a variety of clinical conditions, especially those associated with chronic pain. TFBM is a treatment using a non-ionizing light source such as Low Intensity Laser (LBI) or Light Emitting Diodes (LED), with near-infrared wavelengths. The technique does not emit heat, is painless and non-invasive and does not have significant side effects, and can be used as an adjuvant therapy to control pain associated with gonarthrosis. The aim of this study is to evaluate the intensity of knee pain in the short and medium term after photobiomodulation therapy in patients with gonarthrosis. In this multicenter, randomized, placebo-controlled, double-blind clinical trial, 238 volunteers with gonarthrosis grades II and III according to the Kellgren-Lawrence classification will be recruited to be administered adjuvant treatment with TFBM. The TFBM will be performed in the knee region, twice a week, for five weeks, totaling 10 sessions. Volunteers will be allocated in the intervention group (n=119) or in the placebo group, which will be treated with 10 sessions of inert light (n=119). The evaluations will be made before and after TFBM or placebo and will consist of (i) measurement of pain intensity through the application of questionnaires; (ii) verify the functional mobility of the knee joint and the muscle strength of the lower limb through physical tests; (iii) evaluate the quality of life and levels of anxiety and depression through the application of questionnaires; and (iv) record the consumption of medication for analgesic purposes and the frequency of physical therapy during the trial period. The hypothesis is that the photobiomodulation therapy will have a positive impact, in the short and medium term, on improving pain, functionality and quality of life of patients with symptomatic gonarthrosis. It is also expected to observe a reduction in pain on the Visual Analog Scale of more than 20% after 10 treatment sessions.