The purpose of this research is to develop and test the feasibility of an exercise intervention for persons with painful knee osteoarthritis involving the patella (kneecap). Participants in the patellofemoral osteoarthritis (PFOA) group will be treated with a 6-week supervised exercise program that targets strengthening the hip and trunk core muscles. Painfree control participants will attend one session to gather biomechanical, strength, and function data for use in comparison to the patellofemoral osteoarthritis group. Feasibility outcomes include adherence to the treatment program, recruitment, and retention. It is hypothesized that PFOA group participants will change score on a knee pain and function questionnaire by the minimum clinically important difference score for positive improvement at the end of the 6-week intervention program.