Influence of Noxious Electrical Stimulation on Chronic Pain From Knee Osteoarthritis

Knee osteoarthritis (OA) is the most common lower extremity joint pain condition, and it is estimated that 15 million people in the US are living with symptomatic knee OA and that more than half (8 million) are under 65 years of age. To that end, the Centers for Disease Control and Prevention strongly recommends non-pharmacological treatments for chronic pain including physical therapy and weight loss; however, these interventions have significant barriers that can prevent their success. An intervention that targets pain specifically is transcutaneous electrical nerve stimulation (TENS), which is a low-cost intervention with evidence to support pain reduction. As used in the majority of research to date, the intervention called "TENS" refers to the application of electricity across the skin that produces a tingling sensation that is strong but comfortable. However, electricity is applied at a noxious level is thought to result in strong activation of the endogenous pain modulation system, thus producing longer-lasting pain inhibition. However, noxious electrical stimulation (NxES) has rarely been investigated as a treatment intervention. Recent studies, including our own, demonstrate that NxES produces immediate and potentially greater pain relief. Despite some promising research, the clinical use of NxES is sparse and more research is necessary to demonstrate its effects on resting pain, movement-related pain, physical function, and quality of life. The investigators hypothesize that the application of NxES will activate pain modulation mechanisms and change the pain modulation profile toward an anti-nociceptive state in adults with chronic knee osteoarthritis (OA) pain, and thereby decrease pain (at rest and with movement), improve physical function, and improve quality of life. The investigators expect individual differences; therefore, participants will be classified at baseline and their response to the intervention tracked using psychophysical tests and clinic