Article

Individuals with leg amputations who use passive prostheses have
greater metabolic demands than non-amputees likely due to limited net positive
work compared to a biological ankle. New powered ankle-foot prostheses can
perform net positive mechanical work to aid push-off capabilities, which may
reduce metabolic demands. OBJECTIVES: Compare step-to-step transition work and
metabolic demand during level and inclined walking using passive and powered
ankle-foot prostheses. STUDY DESIGN: Repeated measures. METHODS: Six individuals
with transtibial amputation and six able-bodied controls walked at a standardized
speed across level ground and up a 5 degrees incline. Calculated measures
included mechanical work during step-to-step transitions from the trailing
prosthetic to leading intact limb, steady state metabolic rate, and ankle joint
kinetics and kinematics. RESULTS: The powered prosthesis generated 63% greater
trailing limb step-to-step transition work than the passive during level walking
only (p = 0.004). Metabolic rate was lower with the powered prosthesis during
level (p = 0.006) but not inclined walking (p = 0.281).
The powered prosthesis
increased ankle power compared to the passive, to the extent that power was
normalized to controls during inclined walking and greater than controls during
level walking. CONCLUSION:
The powered prosthesis improved ankle power, metabolic
rate, and step-to-step transition work on level ground, with few negative
consequences on inclines. These results may be used to guide the development and
use of actively powered prosthetic devices in high-functioning individuals.
CLINICAL RELEVANCE: Overall, powered devices offer biomechanical and metabolic
benefits over passive energy storage and return designs on level ground and
perform as well as a passive model on inclines. The lower metabolic demand when
using the powered device may delay fatigue for individuals with transtibial
amputation when walking over level ground.
CI - (c) The International Society for Prosthetics and Orthotics 2015.

Langue : ANGLAIS