Both toe-out (TO) and toe-in (TI) gaits decrease knee load during walking and stair ascent. However, few reports have focused on stair descent, which requires a higher load compared with walking. In this study from the Division of Rehabilitation at the Hyogo (Japan) University of Health Sciences, the researchers wanted to investigate the effect of foot progression angle (FPA) on knee joint load and related variables during stair descent.
They recruited 22 healthy young adults who performed a stair descent task (Figure) at a predefined speed of 90 steps/min with normal gait, TO gait (15°> normal), and TI gait (15°< normal). 3D motion analysis was conducted. In addition, the ground reaction force (GRF) with 3 components, center of pressure (COP) positions, and sagittal and frontal plane hip and knee joint kinematic and kinetic variables were recorded during stair descent.
Their findings showed that the medial GRF increased and the COP position was more lateral in TO gait compared with normal and TI gait during stair descent. TO gait exhibited a significant decrease in the peak knee adduction moment by ~20% compared with normal gait and by ~23% compared with TI gait. In addition, the knee flexion moment in TI gait significantly increased compared with normal and TO gait.
The researchers concluded that the FPA significantly affects hip and knee joint kinematics and kinetics during stair descent. TO gait significantly changes hip and knee adduction angles and COP position. Moreover, it successfully decreases the peak knee adduction moment compared with normal and TI gaits. In contrast, TI gait significantly increases the peak knee flexion moment compared with normal and TO gaits, which is related to the contact force in the medial compartment of the knee joint. TO gait is the most advantageous strategy for decreasing the medial knee load. In contrast, TI gait might pose a risk of promoting medial knee OA progression, so care must be taken during stair descent.
Source: Tsukagoshi R, et al. Toe-out gait decreases knee load during stair descent in healthy individuals. Journal of Cartilage & Joint Preservation. 2021;1(1):100002. doi.org/10.1016/j.jcjp.2021.100002.