Effects of Electrical Stimulation on Osteoarthritis of the Knee

Inclusion Criteria: * 50 years of age or older * Diagnosis of primary osteoarthritis of the knee (as defined by American College of Rheumatology criteria) * Knee pain of at least six months duration * Moderate or greater knee pain (defined as a score of 3 or greater on an 11 point numeric pain rating scale) for most days in the last month * Willing to abide by protocol and treatment schedule. Exclusion Criteria: * Implants, such as pacemaker, TENS, or insulin pump, incompatible with electrical stimulation * Uncontrolled concomitant disease affecting the knee, such as: rheumatoid arthritis, systemic lupus erythema, psoriatic arthritis * Pregnant or breast-feeding * Intra-articular corticosteroid or hyaluronic acid injection into the knee within 3 months preceding study * Arthroscopy of the knee within the past year * Significant injury to the knee within the past 6 months * Use of assistive devices other than a cane or knee brace * Disease of spine or other lower extremity joints of sufficient degree to affect assessment of the knee