Project Overview Overview | Relevance | Design Goals | Signal Acquisition | Signal Processing |...

Project Overview

Overview | Relevance | Design Goals | Signal Acquisition | Signal Processing | Future Work

Our product: • Rehabilitation device Recumbent stationary bicycle• Electromyography of quadriceps muscles Feedback• User-friendly interface Autonomous recovery

Our customers: • Post-ACL repair patients

Phase II and III of rehabilitation Assist in at-home exercises

1) EMG signals differ between patellofemoral pain syndrome patients and control

Cowan SM, et al. Arch Phys Med Rehabil. (2001) 82:183-189.

2) Literature on EMG acquisition on bicycles Garrett WE, Kirkendall DT. Exercise and Sport Science. Lippincott Williams & Wilkins.

(2000)

3) Quadricep EMG signals differ between ACL patients and control when cycling

Hunt MA, et al. Clinical Biomechanics. (2003) 18: 393-400.

Clinical Relevance


I. Signal Acquisition

A. Collect EMG data while cyclingB. Correlate crank angle with EMG signal

II. Signal Processing

A. Filtering noise B. Algorithms to analyze signalC. Developing user-friendly interface

III. Testing

A. Protocol optimizationB. Proof of concept

Design Goals


Components and Setup


EMG Electrode Placement



Electrode placement on the quadriceps

muscles

Hall Effect Sensor


Difference in timing between up and down stroke

400

425

450

475

500

1

Tim

e (

ms)

Downstroke time (180 degrees)Updstroke time (180 degrees)

90o

180o

270o

0o

Magnets

Volt

age (

volt

s)EMG Acquisition


Time (ms)

VMO, ~50 rpm, Hall effect sensor at 180o

Volt

age (

volt

s)EMG Acquisition


Time (ms)

VMO, ~40 rpm, Hall effect sensor at 0o and 180o

The Butterworth Filter


Unfiltered Data


Filtered Data



Magnitude of VMO Muscle Activation (7 cycles)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 90 180 270 360

Crank Angle (degrees)

EM

G (

norm

alize

d)

Integrated Data


Garrett WE, Kirkendall DT. Exercise and Sport Science. Lippincott Williams & Wilkins. (2000)

Experiments


Experiment TestMinimum muscle warm-up time for repeatable EMG signals

With warm-up prescribed from Cowan SM, et al. (2001) vs. no warmup

Effect of changing electrode position on EMG signal

Change electrode placement at set distances

Effect of individual differences on EMG signals for non-injured volunteers

Measure EMG signals amongst several people

Minimum resistance/speed for even pedaling AND VMO/VL stimulation

Increase the resistance (e.g. low, medium, high settings)

1. Develop a user-friendly GUI

2. Correlate position with crank angle more precisely

3. More signal processing for de-noising

4. Process the signal and plot as a function of crank angle or time

5. Proof of concept studies with current recovering ACL patients

Future Work


Bloopers


Acknowledgements


Dr. William MacaulayOrthopedic Surgeon, Columbia University Medical CenterDirector of Center for Hip and Knee Replacement

Dr. Ranjan GuptaDepartment Chair of Orthopaedic Surgery, UC Irvine Professor of Orthopaedics, Anatomy & Neurobiology, and BME

James GossettAssociate Athletic Director, Columbia University

Dr. Evan JohnsonDirector of Physical Therapy at the Spine CenterAdministrative Director of the Spine Center

Julianne CostaOccupational Therapist RegisteredPhysical Therapist

Dr. Tim WrightOrthopaedic Biomechanics and Biomaterials Hospital of Special Surgery

Dr. Clark HungAssociate Professor of Biomedical Engineering

Dr. Gordana Vunjak-NovakovicProfessor of Biomedical Engineering

Dr. Paul SajdaAssociate Professor of Biomedical Engineering

Dr. Elizabeth HillmanAssistant Professor of Biomedical Engineering

Keith YeagerSenior Staff Associate, Laboratory Manager

Sean BurgessTeaching Assistant

Robert MaidhofTeaching Assistant

Viktor GamarnikBME Senior, SMArtView

Project Overview Overview | Relevance | Design Goals | Signal Acquisition | Signal Processing |...

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