Do thigh circumference and mass changes alter knee biomechanics during walking?

Obese adults walk with different biomechanics compared to healthy weight adults. Previous studies have focused on knee biomechanics because they are associated with development and progression of osteoarthritis. Changes in thigh mass and circumference that occur as body weight increases may influence gait. The purpose of this study was to determine if increases in thigh mass and circumference alter gait biomechanics. For 20 healthy weight young adults (10 male and 10 female) knee kinematic, kinetic and gait temporospatial variables were collected using a three-dimensional motion capture system and a force platform during over ground walking. Data were collected during control, increased thigh mass, increased thigh circumference, and both increased mass and circumference conditions. Increases in thigh segment parameters reflected changes expected with a 10 point increase in body mass index. Step width was wider during the added circumference and combination conditions compared to the control condition. Increases in thigh circumference associated with obesity increase step width. This suggests the greater step width observed in obese adults compared to healthy weight adults is a result of the physical constraints introduced by their wider thigh segments. Peak knee flexion angle, peak knee extension moment, peak knee adduction angle, and peak knee abduction moment were similar in all conditions. Thus, acute changes in thigh segment parameters did not result in knee biomechanics suggestive of an increased risk of knee osteoarthritis.