Characterizing Center Of Mass Trajectory Variability In People With And Without Hip Osteoarthritis

INTRODUCTION: Incidence of falls in people with hip osteoarthritis (OA) is higher than in people without hip OA. Increased fall risk persists even post total hip arthroplasty (THA). Characterizing center of mass (COM) trajectory during walking in this population may provide insight into balance and stability impairment in people with hip OA. Previous literature has supported quantifying walking stability and maintaining balance by determining the dynamic stability of the center of mass. We hypothesize that people with hip OA have greater variability in COM trajectories compared to healthy control, and that variability decreases post THA. PURPOSE: To characterize COM trajectory variability in people with hip OA. METHODS: We used a publicly available gait analysis dataset, that included whole body vertical COM trajectory for 172 participants (Table 1) for at least 3 overground walking trials at a self-selected pace. We quantified COM variability for each participant using the coefficient of variation (CV). The CV was calculated with the formula CV = (Standard Deviation/Sample Mean) * 100. We used unpaired t-tests to compare COM CV between the control group and the pre-THA group, and paired t-tests to identify pre-to-post THA differences. RESULTS: The COM CV for all participants ranged from 0.43% to 13.3%. COM CV was higher for the control group compared to the pre-THA group (1.140% ± 1.439% vs. 0.807% ± 0.286% respectively; p = 0.045, d = 0.332). There was no significant pre-to-post difference in COM CV (post THA 0.949% ± 0.693%, p = 0.061, d = 0.267) for the full THA group but, when data was separated by sex, there was a significant increase of COM CV in women post THA (p = 0.016, d = 0.383). CONCLUSION: COM CV was significantly lower in people with hip OA compared to control participants but significantly increased in women pre-to-post THA. Future research should further evaluate sex differences in how hip OA influences balance and stability during gait.