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Scapula Orientation in a Virtual Wheelchair Push
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 1
Scapula Orientation in a Virtual Wheelchair Push
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/injury is a common and persistent problem among manual wheelchair users.
Physical demands and overuse of the arms
Shoulder position during propulsion may predispose to impingement
Movement descriptions are hampered by the complexity of the shoulder
Slide 3
Introduction
Shoulder Joint Complex
Graphic description:
Slide 4
Introduction
Research Objective
Inherent problems with measuring dynamic scapula movement in-vivo
- Record the relative position of the scapula in various stages of push cycle
- Calculate 3D orientation of the scapula relative to the torso
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
Method
Experimental Setup
Graphic description: photograph of
Slide 7
Methods
Digitizing Stylus
Custom-fabricated using FeatureCAM and a CNC mill
Three IRED markers on either side
3D position of the tip
Graphic description:
Slide 8
Methods
Scapula Palpation
AA: Angulus Acromialis
TS: Trigonum Spinae
AI: Angulus Inferior
Graphic description:
Slide 9
Methods
Protopcol
Six randomized hand positions:
-30°, -15°, 0°, +15°, +30°, +60°
Recorded chest markers in each position (10 seconds)
Left side analysis
Slide 10
Data Analysis
Local Coordinate Systems (LCS)
LCS at the scapula and chest
Rotation matrices defined orientations relative to GCS
Graphic description:
Slide 11
Data Analysis
Scapula Orientation
alpha = Protraction/Retraction
beta = Upward/Downward Rotation
Y = Forward/Rearward Tipping
Graphic description:
Slide 12
Results
Beginning of push:
- Maximally tipped forward (21.9° + 6.0)
- Minimally protracted (15.0° + 3.7)
- Slight upward rotation (1.5 ° + 4.7)
As the push progressed,
- Forward tip angle decreased
- Protraction angle increased
- Upward rotation angle increased
Slide 13
Discussion
Maximum relative changes in scapula orientations < 7 °
- Majority of scapula movement occurs at higher degrees of humeral abduction
- Large variance
Forward tip angles similar to Veeger et al., 1993 Larger up/down and protraction angles
- Four unimpaired males subjects
- Differences may be attributed to anthropometry and shoulder muscle imbalances
Slide 14
Discussion
Excessive internal rotation combined with scapular protraction are impingement positions
Scapula motion necessary input for musculoskeletal shoulder models
Future studies to investigate the relationship between scapular kinematics and shoulder impingement in wheelchair users is warranted
Slide 15
Acknowledgements
National Institutes of Health
(Project P01-HD33989)
Eastern Paralyzed Veterans of America
Veterans Affairs Pre-Doctoral Fellowship in Rehabilitation Science
Slide 16
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:
Return to Slide Series
Updated: February 28 2002
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