Association Between Average Daily Activity Counts and Knee Osteoarthritis Progression

OBJECTIVE: The aim of the study was to explore the relationship between daily activity counts and knee osteoarthritis progression. DESIGN: A cohort study using Osteoarthritis Initiative data included 610 participants aged 45-79 yrs with knee osteoarthritis or at risk. Daily activity counts were measured using ActiGraph GT1M accelerometers. Osteoarthritis progression was assessed via Kellgren-Lawrence grade and joint space narrowing scores over 2 yrs. Cox proportional hazard and restricted cubic spline models identified the dose-response relationship and optimal activity threshold. RESULTS: The average age of participants was 63.7 yrs, with 44.8% male. A U-shaped relationship was observed between daily activity counts and osteoarthritis progression. Moderate activity levels could be associated with a reduced risk of Kellgren-Lawrence-grade (adjusted hazard ratio: 0.33; 95% confidence interval: 0.24-0.44) and joint space narrowing-score progression (hazard ratio: 0.31; 95% confidence interval: 0.25-0.38) for activity below 3263.3 counts/min. However, higher activity levels may increase Kellgren-Lawrence-grade (hazard ratio: 1.57; 95% confidence interval: 1.40-2.75) and joint space narrowing-score progression risk (hazard ratio: 1.27; 95% confidence interval: 1.13-1.43). CONCLUSIONS: Moderate activity may protect against knee osteoarthritis progression, while low and high levels may increase risk. Tailored activity recommendations are needed for individuals with or at risk for osteoarthritis. Future research should investigate the mechanisms and refine activity thresholds for osteoarthritis management.