The Effect of Knee Osteoarthritis on the Variability and Fractal Dynamics of Human Gait
Knee osteoarthritis (OA) is the most common joint disease seen in the older adult population, and has a greater influence on gait compared to the effects of aging alone. Spatiotemporal parameters can be used to quantify age-related changes in gait, however gait variability (i.e., the magnitude of stride-to-stride fluctuations with respect to time) and the fractal-scaling index (FSI) (i.e., correlated self-similar patterns of gait) can provide better information about the rhythmicity of the gait cycle over time. Recent studies have shown a relationship between knee OA and gait variability for certain spatiotemporal parameters, but the evidence is still preliminary and requires further investigation. Therefore, the purpose of this study was to investigate the relationship between bilateral knee OA and the temporal aspects of gait variability in a group of older adults, and to compare these results to a healthy, age- and sex-matched control group. Each participant completed a ten-minute walking test at a self-selected speed with a triaxial accelerometer placed on his or her lower back. The device collected the vertical, mediolateral, and anteroposterior accelerations associated with gait, which were then used to analyze the stride time and step time of each gait cycle. Gait variability was assessed by calculating the standard deviation of each participant’s stride time and step time. As well, the FSI (α scaling component) of the entire series of stride times was calculated for each participant. The degree of bilateral asymmetry for step time and step time SD for each participant was also calculated using an asymmetry index (ASI). While significant differences were found between groups for stride time and step time, no significant differences were found for any of the gait variability parameters, stride time FSI, or bilateral asymmetry measurements. Although the differences in this study were not statistically significant, knee OA does appear to increase gait variability, decrease stride time FSI and increase the bilateral asymmetry of gait variability compared to age and sex-matched older adults with healthy knees. This study also demonstrated the effectiveness of a tri-axial accelerometer as a non-invasive measurement device to analyze gait variability in older adults with and without bilateral knee OA.
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Faculty of Graduate Studies and Research, University of Regina