Individual Differences in Gait and Osteoarthritis Pain

Inclusion Criteria: * Knee pain for greater than 6 months. * Moderate-to-severe knee pain (\>3/10) due to osteoarthritis, as defined by American College of Rheumatology and EULAR diagnostic criteria, on \>50% of days in the past month. * KL grade 2-4 indicating significant degenerative changes on knee X-ray. * 45-80 years old Exclusion Criteria: * Inflammatory arthritis (e.g. rheumatoid arthritis). * More intense pain due to another chronic pain syndrome (e.g. fibromyalgia, hip osteoarthritis) * Significant pain or weakness in the lower extremities due to a neurological condition (e.g. lumbar radiculopathy, paresis due to stroke) * Acute pain that is more intense than knee osteoarthritis pain * Current routine use of more than 15 mg oral morphine equivalents per day (use of \<15 mg OME does not exclude the participant). * Recent new medication, exercise, behavioral, or complementary and integrative treatment started in the last month. Stable use of these treatments for greater than 1 month does not exclude the participant. * Recent intra-articular injection of steroid or other agent (greater than 1 month does not exclude the participant) * Recent knee radiofrequency ablation (greater than 3 months does not exclude the participant) * Recent knee arthroscopic surgery (greater than 3 months does not exclude the participant) * History of knee replacement or open knee surgery on the index knee, defined as the more painful knee on average over the last month. * Inability to walk or climb stairs without significant assistance (e.g. a one-person assist, use a wheel chair; however, the use of a cane does not exclude the participant). * Inability to participate in study procedures (e.g. cognitive impairment limiting ability to understand directions, inability to understand and read English) * Uncontrolled or unstable medical disorder preventing participation in study procedures * History of brain surgery * Tattoos on sensory testing sites * Pregnancy * Breastfeeding * Inability to under knee MRI scan due to incompatible devices or foreign bodies.