Realtime Visual Feedback Diminishes Energy Consumption of Amputee Subjects During Treadmill Locomotion

Abstract

Approximately 173,000 people in the United States are using lower limb prostheses. Although the design and use of prostheses have improved during the past 10 years, problems with energy expenditure still affect the gait of amputee patients. Realtime visual feedback (RTVF) has been shown to have an immediate effect on gait symmetry, although the effect on energy consumption was not measured. The aim of this study was to test the hypothesis that as amputees walk more symmetrically with the aid of RTVF, there will be a reduction in their oxygen consumption. Eleven amputee patients (mean age, 46 years; range, 36–58 years) participated. Three subjects were transfemoral amputee patients. Five tests were conducted for each subject: tests 1 and 5 were tests with no visual feedback, whereas tests 2, 3, and 4 involved walking while watching a computer screen that showed (1) left and right stance/swing ratios, (2) left versus right peak push-off forces and (3) a graph in which vertical and anteroposterior shear forces under each foot are plotted as vectors alongside each other, forming a so-called butterfly plot. As expected, there was a significant negative correlation between residual limb length and energy consumption during gait. In terms of possible future rehabilitation strategies, it was found that with each form of visual feedback there were significant improvements in both heart rate and oxygen consumption. In addition, the actual symmetry for the three forms of feedback improved across all subjects, indicating that the statistically significant improvements were not attributable to a placebo-type effect. The conclusion from these data is that RTVF not only results in an immediate improvement in symmetry, but there are also concomitant reductions in heart rate and oxygen consumption while walking at a steady pace on a treadmill. This implies that RTVF may serve as a useful aid in the successful rehabilitation of amputee patients.