The potential of unstructured “physical activity” data for understanding relationships between movement-induced joint loading and osteoarthritis progression

Gait and exercise have been extensively studied in knee osteoarthritis (OA) as potential interventions to modify mechanical loading at the joint and, subsequently, influence biological processes and disease progression. However, this research has often failed to account for mechanical loading encountered in daily life outside structured activities. Wearable sensors help address this limitation by capturing movement as it occurs in daily life. Yet most analyses have relied on coarse summary measures (e.g., step count), overlooking biologically relevant variation in loading patterns across activities and time. Given that these sensors record millions of data points per day, there is an opportunity to move beyond summary measures and quantify within- and between-day variations in movement patterns. We propose that a deeper exploration of these rich datasets, guided by OA literature and related fields, may reveal how load-inducing human movement contributes to knee OA, informing the development of personalized, activity-based interventions.