Association Between Average Daily Activity Counts and Knee Osteoarthritis Progression.

Objective: To explore the relationship between daily activity counts and knee osteoarthritis (OA) progression.

Design: A cohort study using Osteoarthritis Initiative (OAI) data included 610 participants aged 45-79 years with knee OA or at risk. Daily activity counts were measured using ActiGraph GT1M accelerometers. OA progression was assessed via Kellgren-Lawrence (KL) grade and joint space narrowing (JSN) scores over two years. 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 years, with 44.8% male. A U-shaped relationship was observed between daily activity counts and OA progression. Moderate activity levels could be associated with a reduced risk of KL-grade (adjusted HR: 0.33; 95% CI: 0.24-0.44) and JSN-score progression (HR: 0.31; 95% CI: 0.25-0.38) for activity below 3263.3 counts/min. However, higher activity levels may increase KL-grade (HR: 1.57; 95% CI: 1.40-2.75) and JSN-score progression risk (HR: 1.27; 95% CI: 1.13-1.43).

Conclusion: Moderate activity may protect against knee OA progression, while low and high levels may increase risk. Tailored activity recommendations are needed for individuals with or at risk for OA. Future research should investigate the mechanisms and refine activity thresholds for OA management.