Predicting Scapula Orientation in Wheelchair Propulsion

Alicia M. Koontz MS, ATP, Michael L. Boninger MD, Rory Cooper PhD, Brian T. Fay MS, Jim Dietzer

Human Engineering Research Laboratories - VAMCCenter of Excellence in Wheelchairs & Related Technology
University of Pittsburgh
University of Pittsburgh Medical Center

Slide 1
Predicting Scapula Orientation in Wheelchair Propulsion

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Alicia M. Koontz MS, ATP, Michael L. Boninger MD, Rory Cooper PhD, Brian T. Fay MS, Jim Dietzer

Human Engineering Research Laboratories - VAMC

Center of Excellence in Wheelchairs & Related Technology

University of Pittsburgh

University of Pittsburgh Medical Center

Slide 2
Introduction
Background

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Shoulder pain and injury is a common and persistent problem among manual wheelchair users

Seems to be related to increased physical demands and overuse

Descriptions of the shoulder during weight-bearing activities have been limited to glenohumeral joint mechanics

Slide 3
Introduction
Shoulder Joint Complex

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Slide 4
Introduction
Research Objective

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Inherit problems with measuring dynamic scapula movement in-vivo

Glenohumeral motion related to scapulothoracic motion during arm elevation (Bagg et al., 1988)

Determine the relationship between scapular, humerus and torso orientation in a simulated push

Slide 5
Methods
Subjects

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8 men / 2 women with T2 level or below SCI

Experienced wheelchair users: 16.9 + 8.6 yrs

Adults: Mean age: 40.7 + 9.2 yrs

Average Mass: 80.6 + 13.7 kg

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Slide 6
Methods
Experimental Setup

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Slide 7
Methods
Digitizing Stylus

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Custom-fabrication using FeatureCAM and CNC mill

Three IRED markers on either side

D position of the tip

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Slide 8
Methods
Scalpula Palpation

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AA: Angulus Acromialis
TS: Trigonum Spinae
AI: Angulus Inferior

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Slide 9
Methods
Protocol

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Five randomized hand positions:

-30°, -15°, 0°, +15°, +30°

Recorded all IRED markers and scapula landmarks in each position

Left side analysis

Slide 10
Data Analysis
Local Coordinate Systems (LCS)

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LCS at the scapula, humerus and chest

Rotation matrices defined orientations relative to GCS

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Slide 11
Data Analysis
Scapula Orientation

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Slide 12
Data Analysis
Humeral Orientation

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ZXY Rotation Sequence:

First rotation (Hz): sagittal flexion/extension

Second rotation (Hx): abduction/adduction

Third rotation (Hy): internal/external rotation

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Slide 13
Data Analysis
Statistics

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Tested relationships between mean torso flexion, scapula and upper arm angles using Pierson r correlations (alpha < 0.05)

Significant variables entered into a stepwise multiple regression procedure

Slide 14
Results
Correlations

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Up/down rotation related to:

Torso flexion

Shoulder abduction

Shoulder flexion/extension

Tip angle related to:

Torso flexion

Shoulder flexion/extension

Protraction angle related to:

Torso flexion

Slide 15
Results
Multiple Regression Results

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Slide 16
Discussion

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Current modeling efforts assume the humerus rotates relative to a “fixed” scapula

Scapula position determined indirectly by humerus and thorax orientation

Arm has fewer degrees of freedom

Static vs. dynamic

Slide 17
Discussion

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Effect of load in scapular motion is small (Veeger et al., 1993)

Sliding was neglected

May increase the power of prediction for scapular protraction

Further research is necessary to assess the value in adding scapula kinematics to the models

Slide 18
Acknowledgements

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National Institutes of Health

(Project P01-HD33989)

Eastern Paralyzed Veterans of America

Veterans Affairs Pre-Doctoral Fellowship in Rehabilitation Science

Slide 19
Thank You

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For more information please contact:
Alicia Koontz

VA Pittsburgh HealthCare System
7180 Highland Dr.
Pittsburgh, PA 15206

TEL: 412-365-4858

Email: amkst63@pitt.edu

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The End

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Updated: February 26, 2002

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Please note: This information is provided a archival information from the Rehabilitation Engineering Research Center on Wheeled Mobility from 1993 to 2002.

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