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
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
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
Graphic description:
Slide 4
Introduction
Research Objective
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
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
Graphic description:
Slide 6
Methods
Experimental Setup
Graphic description:
Slide 7
Methods
Digitizing Stylus
Custom-fabrication using FeatureCAM and CNC mill
Three IRED markers on either side
D position of the tip
Graphic description:
Slide 8
Methods
Scalpula Palpation
AA: Angulus Acromialis
TS: Trigonum Spinae
AI: Angulus Inferior
Graphic description:
Slide 9
Methods
Protocol
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)
LCS at the scapula, humerus and chest
Rotation matrices defined orientations relative to GCS
Graphic description:
Slide 11
Data Analysis
Scapula Orientation
Grap alt="graphic description follows"hic description:
Slide 12
Data Analysis
Humeral Orientation
ZXY Rotation Sequence:
First rotation (Hz): sagittal flexion/extension
Second rotation (Hx): abduction/adduction
Third rotation (Hy): internal/external rotation
Graphic description:
Slide 13
Data Analysis
Statistics
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
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
Graphic description:
Slide 16
Discussion
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
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
National Institutes of Health
(Project P01-HD33989)
Eastern Paralyzed Veterans of America
Veterans Affairs Pre-Doctoral Fellowship in Rehabilitation Science
Slide 19
Thank You
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
Graphic description:
The End
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Updated: February 26, 2002
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