Association between physical activity and sonographic features of the infrapatellar fat pad in older adults.

Abstract

Physical activity-related mechanical loading may alter the structural and mechanical properties of the infrapatellar fat pad (IFP), a pain-sensitive tissue. Echo intensity and stiffness reflect the mechanical properties of the IFP and are clinically relevant. This study aimed to investigate the associations between physical activity levels and ultrasound-derived properties of the IFP in older adults. Forty-six older adults participated in this cross-sectional study. Physical activity, including light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA), was measured using a triaxial accelerometer. Echo intensity and stiffness of the IFP were assessed using ultrasound imaging and shear wave elastography. Simple and multiple linear regression analyses were conducted to examine associations between physical activity levels and IFP characteristics. MVPA was significantly negatively correlated with IFP echo intensity (r = -0.32), and LPA was significantly negatively correlated with IFP stiffness (r = -0.29). In multiple regression analyses, the association between LPA and IFP stiffness remained significant after adjusting for demographic variables. These findings suggest that physical activity influences the biological and mechanical properties of the IFP in older adults. Increasing both LPA and MVPA may help maintain or improve IFP condition, potentially contributing to better knee joint health. UMIN000053230.