Estimating the Mechanical Behavior of the Knee Joint during Crouch Gait: Implications for Real-Time Motor Control of Robotic Knee Orthoses

Zachary F. Lerner, Diane L. Damiano, Thomas C. Bulea

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Individuals with cerebral palsy frequently exhibit crouch gait, a pathological walking pattern characterized by excessive knee flexion. Knowledge of the knee joint moment during crouch gait is necessary for the design and control of assistive devices used for treatment. Our goal was to 1) develop statistical models to estimate knee joint moment extrema and dynamic stiffness during crouch gait, and 2) use the models to estimate the instantaneous joint moment during weight-Acceptance. We retrospectively computed knee moments from 10 children with crouch gait and used stepwise linear regression to develop statistical models describing the knee moment features. The models explained at least 90% of the response value variability: peak moment in early (99%) and late (90%) stance, and dynamic stiffness of weight-Acceptance flexion (94%) and extension (98%). We estimated knee extensor moment profiles from the predicted dynamic stiffness and instantaneous knee angle. This approach captured the timing and shape of the computed moment (root-mean-squared error: 2.64 Nm); including the predicted early-stance peak moment as a correction factor improved model performance (root-mean-squared error: 1.37 Nm). Our strategy provides a practical, accurate method to estimate the knee moment during crouch gait, and could be used for real-Time, adaptive control of robotic orthoses.

Original languageEnglish (US)
Article number7452627
Pages (from-to)621-629
Number of pages9
JournalIEEE Transactions on Neural Systems and Rehabilitation Engineering
Volume24
Issue number6
DOIs
StatePublished - Jun 2016
Externally publishedYes

Keywords

  • Cerebral palsy (CP)
  • control of wearable robotic devices
  • crouch gait
  • kinematic-kinetic joint coupling
  • knee joint moment
  • rehabilitation robotics

ASJC Scopus subject areas

  • Internal Medicine
  • Neuroscience(all)
  • Biomedical Engineering

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