Contribution of ankle-foot orthosis moment in regulating ankle and knee motions during gait in individuals post-stroke

Clin Biomech (Bristol, Avon). 2017 Jun;45:9-13. doi: 10.1016/j.clinbiomech.2017.04.002. Epub 2017 Apr 8.


Background: Ankle-foot orthosis moment resisting plantarflexion has systematic effects on ankle and knee joint motion in individuals post-stroke. However, it is not known how much ankle-foot orthosis moment is generated to regulate their motion. The aim of this study was to quantify the contribution of an articulated ankle-foot orthosis moment to regulate ankle and knee joint motion during gait in individuals post-stroke.

Methods: Gait data were collected from 10 individuals post-stroke using a Bertec split-belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant wore an articulated ankle-foot orthosis whose moment resisting plantarflexion was adjustable at four levels. Ankle-foot orthosis moment while walking was calculated under the four levels based on angle-moment relationship of the ankle-foot orthosis around the ankle joint measured by bench testing. The ankle-foot orthosis moment and the joint angular position (ankle and knee) relationship in a gait cycle was plotted to quantify the ankle-foot orthosis moment needed to regulate the joint motion.

Findings: Ankle and knee joint motion were regulated according to the amount of ankle-foot orthosis moment during gait. The ankle-foot orthosis maintained the ankle angular position in dorsiflexion and knee angular position in flexion throughout a gait cycle when it generated moment from -0.029 (0.011) to -0.062 (0.019) Nm/kg (moment resisting plantarflexion was defined as negative).

Interpretations: Quantifying the contribution of ankle-foot orthosis moment needed to regulate lower limb joints within a specific range of motion could provide valuable criteria to design an ankle-foot orthosis for individuals post-stroke.

Keywords: AFO; Gait; Hemiplegia; Orthotics; Stiffness.

MeSH terms

  • Adult
  • Aged
  • Ankle / physiopathology*
  • Ankle Joint / physiopathology
  • Biomechanical Phenomena
  • Female
  • Foot / physiopathology
  • Foot Orthoses*
  • Gait Disorders, Neurologic
  • Gait*
  • Humans
  • Knee / physiopathology
  • Knee Joint / physiopathology
  • Male
  • Middle Aged
  • Range of Motion, Articular*
  • Stress, Mechanical
  • Stroke
  • Stroke Rehabilitation / methods*
  • Walking / physiology