Technical Briefs

Comparison of Strain-Gage and Fiber-Optic Goniometry for Measuring Knee Kinematics During Activities of Daily Living and Exercise

[+] Author and Article Information
Abeer A. Mohamed, Jennifer Baba

 Institute of Biomedical Engineering and Department of Mechanical Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada

James Beyea

 Institute of Biomedical Engineering and Faculty of Kinesiology, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada

John Landry, Andrew Sexton

 Institute of Biomedical Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada

Chris A. McGibbon1

Institute of Biomedical Engineering and Faculty of Kinesiology,  University of New Brunswick, Fredericton, NB, E3B 5A3 Canadacmcgibb@unb.ca

Although both DOF were recorded from the Egon we only used the sagittal plane angles for comparison to the Fgon.


Corresponding author.

J Biomech Eng 134(8), 084502 (Aug 06, 2012) (6 pages) doi:10.1115/1.4007094 History: Received December 19, 2011; Accepted June 01, 2012; Revised June 01, 2012; Posted July 06, 2012; Published August 06, 2012; Online August 06, 2012

There is increasing interest in wearable sensor technology as a tool for rehabilitation applications in community or home environments. Recent studies have focused on evaluating inertial based sensing (accelerometers, gyroscopes, etc.) that provide only indirect measures of joint motion. Measurement of joint kinematics using flexible goniometry is more direct, and still popular in laboratory environments, but has received little attention as a potential tool for wearable systems. The aim of this study was to compare two goniometric devices: a traditional strain-gauge flexible goniometer, and a fiberoptic flexible goniometer, for measuring dynamic knee flexion/extension angles during activity of daily living: chair rise, and gait; and exercise: deep knee bends, against joint angles computed from a “gold standard” Vicon motion tracking system. Six young adults were recruited to perform the above activities in the lab while wearing a goniometer on each knee, and reflective markers for motion tracking. Kinematic data were collected simultaneously from the goniometers (one on each leg) and the motion tracking system (both legs). The results indicate that both goniometers were within 2–5 degrees of the Vicon angles for gait and chair rise. For some deep knee bend trials, disagreement with Vicon angles exceeded ten degrees for both devices. We conclude that both goniometers can record ADL knee movement faithfully and accurately, but should be carefully considered when high (>120 deg) knee flexion angles are required.

Copyright © 2012 by American Society of Mechanical Engineers
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Figure 1

The two flexible goniometers used in the study. (a) Penny & Giles type flexible goniometer (Biometric’s Ltd) mounted on the right knee. (b) ShapeSensorTM fiber-optic goniometer (Measurand Inc.) mounted on the left knee. (c) Form-factor comparison of the two devices. (d) Plug-in Gait (lower extremity) marker attachment sites and joint center locations.

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Figure 2

(a) Goniometer linearity test results over 0 to 150 deg and 0 to −150 deg range. Measured goniometer values are shown on the vertical axis and reference goniometer values are shown on the horizontal axis. (b) Difference between measured goniometer readings and reference goniometer. Flexion ranges used for each goniometer in the experiments are indicated.

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Figure 3

Representative trials for study participants. Plots depict a close agreement for gait and chair rise, and illustrate the higher errors observed for deep knee bend trials. (a) Gait data for Participant #1. (b) Chair rise data for Participant #2. (c) Deep knee bend data for Participant #6.




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