0
Technical Briefs

A Mechanical Model of the Human Ankle in the Transverse Plane During Straight Walking: Implications for Prosthetic Design

[+] Author and Article Information
Brian C. Glaister1

Department of Mechanical Engineering, University of Washington, Seattle, WA 98195; VA Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle, WA 98108bglaiste@u.washington.edu

Jason A. Schoen

VA Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle, WA 98108

Michael S. Orendurff

Movement Science Laboratory, Texas Scottish Rite Hospital for Children, Dallas, TX 75219

Glenn K. Klute

Department of Mechanical Engineering, and Department of Electrical Engineering, University of Washington, Seattle, WA 98195; VA Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle, WA 98108

1

Corresponding author.

J Biomech Eng 131(3), 034501 (Dec 23, 2008) (5 pages) doi:10.1115/1.3005153 History: Received September 10, 2007; Revised July 14, 2008; Published December 23, 2008

In order to protect sensitive residual limb soft tissues, lower limb prostheses need to control torsional loads during gait. To assist with the design of a torsional prosthesis, this paper used simple mechanical elements to model the behavior of the human ankle in the transverse plane during straight walking. Motion capture data were collected from ten able-bodied subjects walking straight ahead at self-selected walking speeds. Gait cycle data were separated into four distinct states, and passive torsional springs and dampers were chosen to model the behavior in each state. Since prosthetic design is facilitated by simplicity, it was desirable to investigate if elastic behavior could account for the physiological ankle moment and include viscous behavior only if necessary to account for the inadequacies of the spring model. In all four states, a springlike behavior was able to account for most of the physiological ankle moments, rendering the use of a damper unnecessary. In State 1, a quadratic torsional spring was chosen to model the behavior, while linear torsional springs were chosen for States 2–4. A prosthetic system that actively changes stiffness could be able to replicate the physiological behavior of the human ankle in the transverse plane. The results of this study will contribute to the mechanical design and control of a biomimetic torsional prosthesis for lower limb amputees.

FIGURES IN THIS ARTICLE
<>
Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Marker placement locations. The tibia was defined by markers placed at the knee, tibia, and ankle, while the foot was defined by markers placed at the toe, ankle, and heel. Ankle joint angles were calculated based on the relative displacement of these two body segments.

Grahic Jump Location
Figure 2

Transverse plane ankle kinematics and kinetics. States were identified by zero-crossing values of the power curve. Heel strike occurred at 0% and 100%. A neutral ankle angle refers the case in which the toe and heel markers defining the foot line up with the sagittal plane.

Grahic Jump Location
Figure 4

Stiffness curve fits for all four states. A quadratic fit was found to be significant for State 1, while linear fits were found to be significant for States 2–4. Data points are equally spaced in time, while arrows mark the direction of the time series.

Grahic Jump Location
Figure 5

Residual moments and damping regression fits. A significant regression could not be found for State 1, but linear regressions were found to be significant for States 2–4. Data points are equally spaced in time, while arrows denote the direction of the time series.

Grahic Jump Location
Figure 3

Visual description of the sagittal ankle position during the states defined for the transverse plane

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In