Influence of Obesity on Knee Joint Mechanics: A Subject-Specific Musculoskeletal Modeling Approach

Abstract

Obesity has been consistently linked to knee osteoarthritis (KOA), a debilitating joint disease. While prior work has shown that obese individuals often walk with altered biomechanics compared to normal-weight (NW) individuals, which may accelerate KOA progression, less is known about how these mechanics affect load distribution between the medial and lateral tibiofemoral (TF) compartments, particularly during higher-demand activities. This study developed subject-specific musculoskeletal models of five obese and five NW individuals, incorporating CT-based bone measurements and individualized joint contact points. Simulations were driven by six degree-of-freedom (6DOF) kinematics obtained from high-speed stereo radiography (HSSR) to predict TF loading and associated joint mechanics during gait, pivot, step-down, step-up, and lunge. Obese individuals exhibited higher normalized peak medial TF forces in lower flexion activities (e.g., +27% in step-down and +10% in pivot), whereas the NW group demonstrated greater normalized peak lateral compartment loading across all activities (e.g., +65% in step-up and +62% in lunge). Obese individuals also had significantly higher unnormalized medial compartment loads in gait, pivot, and step-down. This work emphasized the importance of subject-specific kinematics in predicting joint reaction forces and demonstrated that movement compensations in obesity lead to a medial shift in TF loading. Quantifying such measures may ultimately inform future implant design and treatment strategies for this historically underserved population.