Association between infrapatellar fat pad stiffness and gait-related mechanical characteristics in women with knee osteoarthritis.

Abstract

Infrapatellar fat pad (IFP) stiffness is a biomechanical feature associated with the severity and symptoms of knee osteoarthritis. This study examined the relationship between IFP stiffness and gait-related mechanical characteristics in individuals with knee osteoarthritis. Sixty-seven women with symptomatic medial knee osteoarthritis classified as Kellgren-Lawrence grade (KL) ≥2 were included. Ultrasound shear wave elastography was used to evaluate IFP stiffness in the supine position with the knee at 10° flexion. Gait kinematics and kinetics were recorded using three-dimensional motion capture and force plates during comfortable-speed walking. Seventeen gait variables were analyzed, including ground reaction force-related parameters, knee joint angle variables, knee flexion excursion during stance and swing, and the first and second peaks of knee adduction and flexion moments. Gait variables were Z-standardized and analyzed using principal component analysis. Multiple linear regression was performed with IFP stiffness as the dependent variable, principal components as the independent variables, and age, body mass, KL grade, and knee symptoms as covariates. IFP stiffness was significantly associated with greater knee adduction moment (KAM)-related loading (β = 0.429, 95% CI: 0.139 to 0.719, P = 0.004) and smaller stance-phase knee excursion (β = 0.221, 95% CI: 0.036 to 0.406, P = 0.020). These findings suggest that IFP stiffness may be related to the mechanical environment of the knee during weight-bearing gait in patients with knee osteoarthritis.