Background/Purpose: People with knee osteoarthritis (OA) often exhibit reduced physical activity levels and increased fall risk. Gait variability, specifically center of mass (COM) variability is a measure of balance and stability; characteristics that may be impaired with OA. Higher COM variability has been linked to better adaptability to environmental perturbations. It is plausible that more physically active people with OA will exhibit more typical levels of gait variability compared to less active individuals. The association between gait variability and physical activity measures in individuals with knee OA, nonetheless, remains unclear. The purpose of this study was to evaluate the associations between physical activity and COM variability during walking in people with knee OA. We hypothesized that greater amounts of physical activity will be associated with greater amounts of COM variability in people with knee OA.

Methods: We studied 25 people with knee OA (57 ± 8 years: 9 M, 16 W) using 3D gait analysis and physical activity monitoring. Physical activity was assessed through self-reported UCLA scores, and a wrist-worn Actigraph accelerometer. Using the UCLA Scale, Participants rated themselves from 1 (inactive) to 10 (highly active). Steps per day were calculated through Actigraph software. Participants walked on an instrumented treadmill collecting kinetic data at 1200 Hz, synced to an 8-camera system set up collecting kinematic data at 120 Hz. A full-body modified Helen Hayes marker set was used for biomechanical analysis. Gait variability was quantified using the coefficient of variation of the vertical COM trajectory displacement, over ten consecutive steps. We used Pearson’s correlation to test for associations between COM variability and activity measures.

Results: Aligned with our hypotheses, higher COM was associated with higher levels of activity in both the self-reported (R=.500, p=.011) and objective activity measures (R=.476, p=.016). This suggests individuals with more physical activity may retain more robust gait patterns, evidenced by the association to higher COM variability. No significant association found between COM variability and intensity measures such as total MVPA (R=-1.92, p=.358) or percentage in MVPA (R=-.200, p=.337), indicating that global activity levels may be more relevant than intensity.

Conclusion: People with knee OA face a lack of physical activity due to multifactorial influences. Our previous work has indicated that kinesiophobia can be a potential explanatory factor of physical inactivity in the population. Center of mass variability may also provide insight into the physical inactivity people with knee OA face. Increased gait variability has been linked to improved efficiency in responding to environmental perturbations. It known that individuals with knee OA have a greater fall prevalence, balance/stability deficits, and lower amounts of physical activity. Findings from this study illustrated a positive correlation between increased amounts of physical activity, and gait variability. This study illustrates how better understanding gait variability can provide insight into novel physical activity and fall interventions trainings for this population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/increased-gait-variability-at-preferred-walking-speeds-is-associated-with-increased-physical-activity-measures-in-people-with-knee-osteoarthritis/