Article

The purpose of this study was to investigate whether the increased energy cost of
amputee gait could be accounted for by an increase in the mechanical work
dissipated during the step-to-step transition in walking. Eleven transtibial
amputees (AMP) and 11 age-matched controls (CO) walked at both comfortable (CWS)
and fixed (FWS, 1.3m/s) walking speed, while external mechanical work of each
separate leg and metabolic energy consumption were measured. At FWS the metabolic
energy consumption (E(met)) was significantly higher in AMP compared to CO (3.34
Jkg(-1)s(-1) vs. 2.73 Jkg(-1)s(-1)). At CWS, no difference in energy consumption
was found (3.56 Jkg(-1)s(-1) vs. 3.58 Jkg(-1)s(-1)) but CWS was significantly
lower in AMP compared to CO (1.35 ms(-1) vs. 1.52 ms(-1)). In conjunction with
the higher E(met) at FWS, the negative work generated by the intact leading leg
for the step-to-step transition in double support was significantly higher for
AMP than CO at FWS. A moderate though significant correlation was found between
negative mechanical power generated during the step-to-step transition and
metabolic power (CWS: r=-0.56, p=0.007; FWS: r=-0.50, p=0.019). Despite the
difference in negative work during the step-to-step transition, the total
absolute mechanical work over a stride did not differ between groups. This could
possibly be attributed to exchange of internal positive and negative work during
single support, which remains unnoticed in the external work calculations. It was
concluded that the increased mechanical work for the step-to-step transition from
prosthetic to intact limb contributes to the increased metabolic energy cost of
amputee walking.

Langue : ANGLAIS