Photobiomodulation in Chronic Knee Pain in Patients Who Are in PreRehabilitation for Bariatric Surgery

Inclusion Criteria: * Obese patients with indication for bariatric surgery performed in routine follow-up at the Gastric Surgery Outpatient Clinic of HC-UFG; * Patients with chronic pain (\> 3 months) in the knees bilaterally. Patients will be asked in the initial evaluation if they feel pain located in the topography of the knees that has been compromising their functionality both in daily activities and at work, and that lasts for more than or equal to 3 months. This pain may be reported as continuous or intermittent; * Sign the Informed Consent Term approved by the HC-UFG Ethics Committee. Exclusion Criteria: * \- Loss of follow-up in the outpatient clinic of origin and in the Physiotherapy sector, even though the use of laser therapy was maintained according to the study protocol; * Any reported adverse effects from the use of FBM reported; * Patients in whom there are changes in the medications being used for chronic pain during the study protocol will be excluded from this study. Minimal changes in the dosages of medications already in use can be tolerated, as long as there are no changes in the type of medication, but only in the prescribed dose. These modifications throughout the study, if they occur, will be described. * Death * Withdrawal of the informed consent by the participant * If the patient, for any reason, is excluded from the indication of bariatric surgery * Emergence during the study of any of the non-inclusion criteria, like: . * Patients with other rheumatologic diseases and/or systemic inflammatory diseases (rheumatoid arthritis, Reiter's arthritis, ankylosing spondylitis, generalized polyarthritis) or previous musculoskeletal diseases in the knees; * Clinical manifestations or complaints of knee arthralgia related to diseases other than obesity. * Previous use in the last 90 days of treatment with the use of Phototherapy for the same or another indication; * Clinical signs of neuropathy, including radiculopathies and peripheral nerve injuries; * Pain in the lower limb, originating from the lumbar spine (lombosciatalgia) * Use of corticosteroids at an immunosuppressive dose (20mg daily of prednisone or equivalent for at least 14 days); * Infection or tumor at the site of therapy application; * Current chronic infections such as tuberculosis or chronic hepatitis treated or not. * Blood clotting disorders (including thrombosis) at the application site. * Diagnosis of fibromyalgia; * Serious psychiatric disorders that require psychiatric care; * Systemic injections and/or joint injections of corticosteroids or hyaluronic acid during the last 48 hours prior to the initial assessment of the study; * Psychoaffective disorder that compromises adherence to treatment; * Any history of sensitivity to light or phototherapies.