This trial will test if walking or bicycling exercise is effective as a non-surgical treatment option for patients with knee osteoarthritis.

Traditional, conservative medical treatment of osteoarthritis has been directed at improving functional status through reducing joint pain and inflammation and maintaining or restoring joint function. Exercise is an adjunct therapy in the clinical management of patients with osteoarthritis of the knee. However, it is not uniformly accepted. The central hypothesis of this work is that the Surgeon General's exercise guidelines can be successfully implemented as an effective nonsurgical option for treatment of patients with early stages of knee osteoarthritis.

Patients with knee osteoarthritis will be randomized into a control group, a walking exercise group, and a stationary cycling exercise group. The individuals in the exercise groups will be required to exercise three times per week for one year using emerging public health recommendations for aerobic exercise in the adult and aging population. Patient outcome will be assessed using objective gait analysis measurements, knee radiographs to quantify joint space narrowing, magnetic resonance imaging, a general health questionnaire (SF-36), a disease/site specific questionnaire (WOMAC), and a visual-analog pain scale. All subjects will be studied at 0 and 52 weeks.

Inclusion Criteria

• Current symptoms of chronic (6 months), stable pain and/or stiffness in one or both knees during weight-bearing activities
• Involved joint is primary factor limiting physical or functional activity
• Radiographic signs of mild or moderate arthritis
• Mild joint space narrowing (at least 2mm remaining)

Exclusion Criteria

• Current participation in a regular exercise program
• Existing medical condition that would preclude increased physical activity
• Subjective complaint of instability (giving way)
• Ligamentous instability greater than Grade I
• Knee flexion contracture greater than 15 degrees
• Asymptomatic osteoarthritis of both knees, incapacitating arthritis, or inflammatory arthritis
• Major reconstructive surgery on a lower extremity joint
• Multiple major joint involvement
• Any condition which severely limits local ambulation, such as amputation or stroke
• Gait aids used majority of time for ambulation
• Cannot use step-over-step techniques in either ascending or descending stair conditions
• Not able to undergo MRI scan (e.g., cardiac pacemaker)
• Dementia or inability to give informed consent as determined by a Folstein Mini Mental score greater than 24