Analysis of the weight-transfer mechanism through forward velocity of the combined center of pressure during the loading response in individuals with unilateral transtibial amputation.

Abstract

The dynamic stability during forward propulsion in the stance phase of prosthetic gait can be quantified using the center of pressure (COP). Although previous studies focused primarily on the single-limb support phase, COP movement during the double-limb support phase remains unclear. This study quantitatively analyzed the weight-transfer mechanism during gait by examining the forward velocity of the combined COP and the duration of the loading response (LR) on the prosthetic and intact sides. This study conducted experiments involving 6 individuals with unilateral transtibial amputation and 11 able-bodied individuals. The participants were instructed to walk at 3 different speeds, and data were collected under each condition, using a 3D motion capture system. The peak value and timing of the forward velocity of combined COP in the LR were compared between the prosthetic and intact sides. Regarding the forward velocity of the combined COP in the prosthetic-side LR, the peak value was smaller at slow walking speeds and the peak timing tended to be delayed under all walking-speed conditions compared with the intact-side LR. These parameters during the prosthetic-side LR were similar to those of able-bodied individuals. Analysis of the LR duration revealed no consistent trend in the relative durations of the prosthetic-side LR and intact-side LR. The results of this study suggest that individuals with unilateral transtibial amputation may employ a characteristic movement strategy during intact-side LR while the prosthetic side is in the pre-swing phase.