Ankle mechanics during sidestep cutting implicates need for 2-degrees of freedom powered ankle-foot prostheses

Evandro M. Ficanha, Mohammad Rastgaar, Kenton R. Kaufman

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


The ankle joint of currently available powered prostheses is capable of controlling one degree of freedom (DOF), focusing on improved mobility in the sagittal plane. To increase agility, the requirements of turning in prosthesis design need to be considered. Ankle kinematics and kinetics were studied during sidestep cutting and straight walking. There were no significant differences between the ankle sagittal plane mechanics when comparing sidestep cutting and straight walking; however, significant differences were observed in ankle frontal plane mechanics. During straight walking, the inversion-eversion (IE) angles were smaller than with sidestep cutting. The ankle that initiated the sidestep cutting showed progressively increasing inversion from 2 to 13 degrees while the following contralateral step showed progressively decreasing inversion from 8 to 4 degrees during normal walking speed. The changes in IE kinematics were the most significant during sidestep cutting compared with straight walking. The IE moments of the step that initiated the sidestep cutting were always in eversion, acting as a braking moment opposing the inverting motion. This suggests that an ankle-foot prosthesis with active DOFs in the sagittal and frontal planes will increase the agility of gait for patients with limb loss.

Original languageEnglish (US)
Pages (from-to)97-112
Number of pages16
JournalJournal of Rehabilitation Research and Development
Issue number1
StatePublished - 2015


  • Ankle kinematics
  • Ankle kinetics
  • Ankle moments
  • Degrees of freedom
  • Gait analysis
  • Human ankle impedance
  • Human ankle mechanics
  • Prosthetic
  • Sidestep cutting
  • Turning maneuvers

ASJC Scopus subject areas

  • Rehabilitation


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