Symptom assessment in knee osteoarthritis needs to account for physical activity level

Grace H. Lo, Timothy E. McAlindon, Gillian A. Hawker, Jeffrey B. Driban, Lori Lyn Price, Jing Song, Charles B. Eaton, Marc C. Hochberg, Rebecca D. Jackson, C. Kent Kwoh, Michael C. Nevitt, Dorothy D. Dunlop