Article

The fixed neutral position of conventional prosthetic feet causes difficulties
for transtibial amputees (TTAs) when walking on ramps. New
microprocessor-controlled prosthetic ankles such as the Proprio-Foot (Ossur) aim
to reduce these difficulties by modifying the prosthetic ankle angle according to
the gait condition. The purpose of the present investigation was to assess the
biomechanical effects of adaptation of the prosthetic ankle on ramp ambulation in
TTAs. Sixteen TTAs and 16 controls underwent a conventional 3D gait analysis
while walking up and down a ramp. TTAs walked with the prosthetic foot set to a
neutral mode angle and set to the adapted mode. Norm distance, sagittal
kinematics and kinetics were calculated for comparisons between TTAs and
controls. During ramp ascent, the dorsiflexion brought about by the adapted
prosthetic ankle reduced the increased knee extension noted on the TTAs' involved
side and the increased plantarflexion on their sound side. During ramp descent,
the plantarflexion of the adapted mode increased the adaptation mechanisms
observed in TTAs. These findings suggest that the adapted mode leads to more
physiologic kinematics and kinetics in the lower limbs in TTAs during ramp ascent
but not during ramp descent. However, in the adapted mode, patients reported
feeling safer during ramp descent, thus indicating that there might be other
safety related measures such as toe-clearance or coefficient of friction
influencing this perception.
CI - Copyright 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS