Knee Osteoarthritis Worsening Across the Disease Spectrum and Future Knee Pain, Symptoms, and Functioning: A Multisite Prospective Cohort Study

K/L worsening over a 1-year period is prognostically important over the short term for all baseline K/L grades, and for knees with baseline K/L grades of 2 or 3 worsening continues over the following year.