Abstract

Low movement variability has been associated with chronic injury. Accordingly, variability in repeated movements may act as a protective mechanism against repeated tissue stress. Invariable joint-loading during gait may be an influence on the progressive development of knee osteoarthritis (OA); however, few studies have investigated this relationship. The purpose of this investigation was to compare the intra-subject variability of measures related to knee-joint loading among groups of contrasting knee OA severities. Seventeen individuals with no self-reported knee OA, 17 individuals with Kellgren-Lawrence (KL) grade II knee OA, and 14 individuals with KL grade IV knee OA were recruited for this study. Five walking trials at self-selected speeds were recorded using a three-dimensional motion analysis system and force plate. Variables of interest included the following: the variability of the internal knee abduction moment throughout stance phase, the variability of vertical and mediolateral ground reaction forces (GRF) throughout stance phase, the variability of the peak internal knee abduction moment, and the variability of the knee flexion angle at the instant of peak internal knee abduction moment. A series of one-way ANOVAs were used to test for differences (p<0.05) between groups. No significant differences were evident between groups for the variables of interest. For instance, the stance phase variability of the internal knee abduction moment was not different between groups (No OA = 0.00208 ± 0.0064 Nm/BW/ht, Grade II = 0.00224 ± 0.0080 Nm/BW/ht, Grade IV = 0.00238 ± 0.00056 Nm/BW/ht). Similarly, no group differences were evident regarding the variability of the peak internal knee abduction moment (No OA 0.00215 ± 0.0065 Nm/BW/ht, Grade II = 0.00279 ± 0.0122 Nm/BW/ht, Grade IV = 0.00219 ± 0.00106 Nm/BW/ht). These results suggest no differences in knee joint loading variability among individuals with contrasting OA severities. Movement variability may not play a significant role in the onset and progression of knee OA.