Neurofeedback for Pain Sensitization in Knee Osteoarthritis

Inclusion Criteria: * Age 45 years or older * Symptomatic knee osteoarthritis meeting the clinical definition in the National Institute for Health and Care Excellence (NICE) guidelines: knee pain for more than 3 months and morning stiffness lasting less than 30 minutes * Able to speak and understand English * Able to attend all study visits at the study site in Boston, MA Exclusion Criteria: Stimulation safety * Pacemaker, implanted defibrillator, or other implanted electronic device * Metal implants in the head * Implants in the lower limb, including prior knee arthroplasty * History of seizures or epilepsy * Prior adverse reaction to transcranial magnetic stimulation * Frequent or severe headaches * Suspected or diagnosed cardiac disease * Pregnancy (self-reported) Neurological, psychiatric, and medical * Neurological disease, including multiple sclerosis * Currently active major depressive disorder, defined as a current clinical diagnosis of major depressive disorder or ongoing treatment for depression; a prior history that is neither active nor treated is not exclusionary * Insulin-dependent diabetes * Raynaud's phenomenon, cold urticaria, or other cold-induced reaction * Large ischaemic scars Pain and musculoskeletal * Lower extremity pain other than knee osteoarthritis Skin and sensation at stimulation sites * Altered skin sensation of the thigh * Swollen, infected, inflamed, or damaged skin of the thigh Substances * Use of medication known to alter pain perception or cortical excitability, including opioids, gabapentinoids, antidepressants (SSRIs, SNRIs, tricyclics), benzodiazepines, anti-seizure medications, muscle relaxants, prescription sleep medications, and cannabis or cannabinoids * Use of alcohol or recreational drugs within 12 hours before a study visit Radiographic confirmation is not required, consistent with current clinical recommendations for knee osteoarthritis diagnosis. Commonly used medications that do not alter pain perception or cortical excitability are permitted and recorded as covariates.