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Excessive and Variable Center of Mass Motion Characterizes Gait Instability In Women with Obese Knee Osteoarthritis

Authors :

Diba Chegini¹ Behzad Yasrebi² Siamak Haghipour³ Farhad Farhad Tabatabai Ghomsheh⁴ Aliakbar Pahlevanian⁵

1- ازاد تبریز 2- ازاد تبریز 3- ازاد تبریز 4- دانشگاه علوم توانبخشی و سلامت اجتماعی 5- دانشگاه توانبخشی سمنان

Keywords :

Gait Analysis،Knee Osteoarthritis،Obesity،Center of Mass،Postural Balance،Stability،Biomechanics

Abstract :

Abstract—Background: Elderly women with obese knee osteoarthritis (KOA) represent a population at high risk for impaired balance and falls. Quantifying the dynamic stability of their gait is crucial for understanding this risk and developing targeted interventions. Objective: This study aimed to compare gait stability and balance between healthy young women and elderly women with obese KOA through a comprehensive analysis of center of mass (COM) kinematics. Methods: Forty elderly women with obese KOA (70±4 yrs, 98.8±7.3 kg, 158.6±7.8 cm) and twenty healthy young women (29±5 yrs, 61.2±6.4 kg, 159.5±6.7 cm) underwent 3D gait analysis. A subject-specific OpenSim model was used to compute the COM trajectory for each participant. Key stability metrics—including path, range of motion (ROM), maximum displacement, standard deviation, and their velocity counterparts in the anteroposterior (AP), mediolateral (ML), and vertical (SI) directions—were calculated and normalized to body height. Results: The obese KOA group demonstrated significantly impaired stability across all COM metrics. Specifically, they exhibited a larger COM path, greater ROM, and increased maximum displacement (p<0.05), with the most pronounced differences observed in the ML direction. Furthermore, the obese KOA group showed significantly higher variability, evidenced by greater standard deviation of both COM position and velocity (p<0.05), indicating a less consistent and more unstable gait pattern. Conclusion: Elderly women with obese knee osteoarthritis walk with a gait pattern characterized by excessive and poorly controlled motion of the center of mass, particularly in the mediolateral direction. These objective biomechanical findings highlight a significant deficit in dynamic stability, which likely contributes to a heightened fall risk in this population. Rehabilitation strategies should focus on improving mediolateral balance control to mitigate this risk. Keywords-component; Gait Analysis; Knee Osteoarthritis; Obesity; Center of Mass; Postural Balance; Stability; Biomechanics