Addition of Transcranial Direct Current Stimulation and Transcutaneous Electrical Nerve Stimulation to an Education and Exercise Program in Subjects With Chronic Pain Due to Knee Osteoarthritis

Inclusion Criteria: * Adults over fifty years of age with a diagnosis of knee osteoarthritis by radiography. * Chronic pain of more than six months, compliance with the diagnostic criteria for knee osteoarthritis according to the Osteoarthritis Research Society International (OARSI) guideline: * Pain in Analog Visual Scale more than 4/10 * Matutinal less than 30 minutes * Absence of hyperthermia upon palpation in the joint * Alteration of the bone image * Crepitus Exclusion Criteria: * Patients who can provide low-quality or biased information discriminated by the Mini-Mental State Examination (Score less than 24). * Severe hearing, visual or sensory impairment or comorbidities that prevent the correct completion of the questionnaires and mobility activities. * Patients who have undergone knee replacement surgery on the contralateral knee. * Patients who have received intervention (infiltration, blockages, etc...) in the last 6 weeks. * Pain due to tendinopathy, knee fracture, low back pain radiating to the knee, or fibromyalgia. * Patients who decline to participate out of fear or denial of therapy. * Severe heart disease that prevent exercise. * Body Mass Index above 45. * Patients with neuropsychiatric disorders (schizophrenia, epilepsy or bipolar disorders) or taking medication for these conditions (antiepileptic drugs). * Patients with metallic implants in the area (skull or knee).